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Basically, I'm hoping for an informed discussion of questions like these with people who do more than bolt parts together, which would mean people who at least own a lathe and mill. However, as I said at the start, it doesn't seem very many people on Britbike fall into that category so this could be a very short thread.

I own a small RANDA lathe and pillar drill and various other tools so I hope that gives me enough qualification to try and answer question. I don't use these tools for precision mechanical work as they aren't up to the job, they are however OK for making spacers, drilling out holes etc.

In order to answer the questions I've broken them down individually as shown below:-

Quote
Beyond the pleasure that doing such precision mechanical work might bring, in monetary terms are you (me) wasting your (our) time?

Given the cost of farming out work to various machine shops, I would say you are not wasting your time and money especially when you consider that the work will have been done exactly to your own spec.

Quote
Are people who buy restored old British motorcycles today unlikely to put enough miles on them to reveal shortcomings in the mechanical work?

I think that would depend on how the bike is ridden and subsequently serviced. I imagine that most riders will ride less than 1000 miles annually and for most of the time the bike will be sitting in a warm garage and get an annual service. On the other hand, some riders will thrash their bikes relentlessly, pull wheelies and rev the bike past the red line and try cruising on the highway at 90mph. I guess that the former type of rider will not experience any mechanical failure for at least 15 years whilst the latter will probably blow the engine in a year or so.

The issue here is not so much the quality of the restoration but the fact that British bikes are fragile and don't respond well to mistreatment.

Quote
Would someone pay any sort of premium at all to buy a bike with documentation showing details of the mechanical work, or is chrome and powder paint all that really matters?

Yes I would pay a bit more if for example the bike has recently had new valve seats & guides inserted, aligned, diamond honed etc. by a renowned company such as the Cylinder Head Shop, and there is documentation to support this.

Quote
Does the average buyer of an old British motorcycle (as opposed to the average Youtube video maker) know enough, or care enough, about the mechanical aspects to even judge the quality of, say, someone else's work to install new guides and seats?

Some will and some won't but overall I think most will be happy enough just seeing an engine running with no apparent faults.

I have to say MM, you postings about the Ariel and other restorations have been extremely interesting and informative. I think you have raised peoples engineering knowledge and awareness considerably over the last few years, and who knows this may have helped to raise standards going forward. As Trevor said, I don't know how you find the time to do your machining, photograph each step and then post an almost daily update, I'm sure all the effort is appreciated by forum members.

I was hoping to read more about the Black Shadow restoration, but as you know, the VOC forum seems to be in turmoil as they try to migrate to another platform. Other than using this forum, I don't know if there is an interim alternative, but it seems like the restoration is stalled whilst you await clarity with the VOC.

Last edited by gunner; 10/23/21 10:32 am.

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Quote
Basically, I'm hoping for an informed discussion of questions like these with people who do more than bolt parts together, which would mean people who at least own a lathe and mill. However, as I said at the start, it doesn't seem very many people on Britbike fall into that category so this could be a very short thread.
I own a 70 year old lathe but no milling machine....In the last 7 years or so I have built from the ground up aTriumph race bike, a double engine Triumph race bike, a 70 Triumph and 79 Triumph modified street bikes and a BSA A10. All these bikes were built in the American hot rod tradition,stripped of frills with increased engine performance and built from whatever parts suit the situation...You can see much of the work done right here on Brit Bike.Other than actual engine machine work, I did it much of it with hand held tools and blacksmith techniques...But I have cut piston valve clearance notches , honed cylinders and refaced tappets by hand..
So...What do you want to discuss? grin. Seriously, I have learned something from just about everyone who posts here...Even my wife had some good ideas...


79 T140D, 89 Honda 650NT ,61 A10 .On a bike you can out run the demons
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Originally Posted by Magnetoman
Maybe it's not even reasonable to discuss the following on Britbike (or anywhere else, for that matter), since the posts of relatively few people here deal with issues beyond swapping broken items with replacement ones, or sending components to specialists to repair for them. As an indication, out of the ~60k threads, only a dozen (~0.2%) that weren't started by me mention the word 'Sunnen'.
My (now retired) Machinist had some very nice Sunnen equipment and other very nice machines in his shop. Dude knew his stuff, learned it from his dad who learned it from his granddad.

I'll wager you couldn't get through my book without just throwing it away. Definitely and literally "shade tree" stuff, but it's been fun for me, and at least I have warranted my work and only needed to pay up on a half-handful of occasions. (and nothing that was destructive to the mechanicals apart from one pair of rod journal shells, that in over 130 major client builds)


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Car was "restored" by a shop which supposedly specialized in that type of work. The amount quoted reflected only body work, no rebuild of motor or trans. The car was on offer for $45K.


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Originally Posted by gunner
As Trevor said, I don't know how you find the time to do your machining, photograph each step and then post an almost daily update,
Actually, the photography is the least of it. Even when my hands are greasy most of the photographs only take an extra 30 sec. or so each to take with my iPhone, and I've been using PhotoShop for over 20 years so most of them then take less than a minute to crop (composites and ones with added arrows and such take longer, but not a lot longer). Without exaggeration, waiting for the photos to upload to Britbike over my slow internet connection is a significant fraction of the total time needed for the photographs.

Writing does take time, but I have an advantage in that I've been doing technical writing for a half-century (note to BSA_WM20: I learned how to use trig tables in high school, but as a Freshman in college we had the just-introduced Wang calculators and a time-shared computer that used terminals based on IBM Selectric typewriters). However, the time I spend writing about my rebuilds isn't all "wasted" in that I use it to document for myself what I had done, plus organize my thoughts to (try to) make sure I hadn't overlooked something.

Taking BSA_WM20's estimate of AU$50k (≈US$39k) at face value, that certainly would be a lot to spend having someone rebuild a bike if you were only going to ride it 1000 miles/year. However, viewed in the context of a bike for competing in the Cannonball (gasoline plus wear and tear on truck and trailer, two weeks of motels and food for rider and support crew, shipping bike to and from the event, flying to and from the event, etc.), it's perhaps not outrageously out of line for a bike that likely would be able to cover the distance with only minimal daily maintenance. Put another way, if you were rich and wanted to compete in the Cannonball, how much of a premium would you pay for a bike that was likely to carry you the distance when the documented DNF rate is 33%?

Again, though, I'm not paid for my motorcycle work so I have the luxury of spending as much time as I want to do the work as well as document it. I would have to charge a lot if I were doing it this way as a business, and I'm pretty sure that few people would be interested in paying the price.

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Originally Posted by Magnetoman
Would someone pay any sort of premium at all to buy a bike with documentation showing details of the mechanical work.
Originally Posted by Magnetoman
Put another way, if you were rich and wanted to compete in the Cannonball, how much of a premium would you pay.

The diamond is emerging from the stone.


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Originally Posted by Hugh Jörgen
The diamond is emerging from the stone.
If you're implying I'm trying to drum up a sale for my Ariel, you're wrong. I love that bike and have no intention of selling it. My wife was a bit annoyed at the cost when I bought it so I assured her at the time that I would sell it as soon as the Cannonball was over. I've since fallen on my sword and explained it's here for keeps.

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...like I mentioned in the "magnaflux" thread; I let a crankshaft to do the test in a supposed specialized and good shop here but seeing the crank I doubt that actually they did the work so trust in papers but you did not saw or known (as others mentioned) the type of work that they did it is a bit difficult for me right now

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Originally Posted by Magnetoman
... I've since fallen on my sword and explained it's here for keeps.
[Linked Image]


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Magnetoman,

First post ever here,

I finally felt compelled to respond to your thread, having read and enjoyed your articles as an unregistered reader over the last decade or so, and which in my mind are the highlight of these pages.

As a toolmaker, enthusiast, and professional engine builder, your articles are an absolute delight to read and an education for anyone who wants to do a job right. Your magneto article for example is an essential read for anyone who has any interest or need for a mag which is going to make sparks every time and for a long time.

Frustratingly, I find it very difficult to sub contract any personal or professional work out, as it seems on a high proportion of occasions the result is less than satisfactory and does not meet the standard agreed and discussed with the provider, and this extends beyond engineering and motor vehicle parts..

The ultimate fact is an engineering product or service you provide and especially one for remuneration carries your name, and in my mind not only has it to do the job as intended and agreed with the buyer, but also has to be able to stand the scrutiny of others, who may for whatever reason may find the time or reason to unpick your work, and subject it to the scrutiny and tests to see if meets an acceptable engineering standard.

Clearly the use of precision tools and equipment is the only true and sure way to achieve the acceptable standard each and every time, and the work of the production Engineer depends on this approach. However there can be no doubt too that there are also many examples of outstanding work which has been produced with only the most basic tools and circumstances and is a complete credit to the skill of the Artisan.

It’s very hard to see any reasoned argument against your approach to your projects, and I appreciate your devotion to document and record it for others to enjoy. How anyone attends to the maintenance and repairs of their own machinery is their business of course, but really there is no need to knock your approach, even if theirs is different..

Roland

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Originally Posted by RolandM
there is no need to knock your approach, even if theirs is different.
First, thank you very much for your kind words. However, for anyone who hasn't noticed, this certainly isn't the first of my threads that Rohan has trolled.

Offline someone wrote yesterday to say my posts have shamed him into doing a far more thorough job on his rebuilds than he used to. Hey, anytime I can bamboozle someone into squandering more of their time and money than they otherwise would have I count it as a success.

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Ha ha.

Firstly, I'll confess to whenever I see anyone posting complete bollocks, or shades thereof, I'm bound to add to it !!!
And you can interpret that as you will.
If you can't tell the difference between being 'trolled' and corrected, then you still have stuff to learn.
(And how right I was, you guys can't even spell Lemon P160).

And I'll speak to your earlier line with some of my own experiences.
"Does the average buyer of an old British motorcycle (as opposed to the average Youtube video maker) know enough, or care enough, about the mechanical aspects to even judge the quality of, say, someone else's work to install new guides and seats? '

Now I have a late 1920s Raleigh engine (project, as always) and on cleaning up the head, noted that someone had installed new bronze valve guides. Now bronze guides in a vintage iron head - with no lube system - is in itself not generally a good idea, bronze does like being lubed, or it needs big clearances not to seize.. But these ones had been fitted with apparently too much of an interference fit - and the iron surrounding the guide had cracked, visibly and quite deeply. I'd say this had rendered the head scrap, as I doubt this can be reliably repaired. Fortunately, I chanced upon a replacement head, still with its iron guides intact. So I say that whomever fitted those new bronze guides shoulda stayed at home that day !!

Todays project involved getting a prewar's brakes up to scratch. Now someone in the past has fitted new brake linings to these shoes. But the copper rivets come up flush with the brake lining materials' surface. How useless !!
If used like that, this would render the drums scrap in short order ?.

Lotta DIY stuff I see ain't up to snuff .... ? Which is why buyers like to see receipts from reputable professional tradies ???
How you judge them may be another matter entirely, but recommendations go a long way.
If folks have got a 'home' workshop that they can do EVERYTHING themselves, then good luck to them.
And the knowledge to do it.
Figuring that a home chroming outfit would need at least $30,000 of chromic acid alone killed that idea for me ...

Flush rivets - now why on earth would someone do that ?
A chance for the rivet counters to get counting ?
[Linked Image from i.postimg.cc]

These rivets appear to have some depth to them, it may be possible to countersink drill them to get some clearance.

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The T140D I am selling had the valve work done on a $325,000 Newan head reconditioning machine.The cylinders bored with a torque plate on Sunnen's best ..The crank was machined on a equally expensive Swiss made crank grinder....The shop has an excellent reputation for building race engines. I assembled the engine...The engine is tuned well ....Is this engine better than one built by a guy using less precise equipment? Since I am just a hobbyist does this make the engine less than perfect?
Are the few here Magnetoman claims have the tools, including himself, capable of building a better engine? This is all that really matters, yes?


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Quote
I don't think everyone understands that it can be horribly expensive just to return many things to as-original specification. Also, people who buy into the urban myth about the Bronze Age quality of the original machining don't realize how much improvement to lifetime and functionality can be made by simply blueprinting the the engine and gearbox, i.e. making sure they have the specifications the designers gave them. I suspect Alp Sungurtekin didn't go 175.6 mph on a pre-unit Triumph without having done more than just bolt the engine together.

But surely the point is than very few want or need to go 175.6 mph on old British iron.
One of he reasons why old British Iron is so heavy is it was grossly over engineered in the first place.
The fact that so many are still rolling around 50 to 100 years after they were made is testiment to that fact.
Have a chat to any racer about just how much can be shaved off most of them with a reasonable certency that the bike will finish a race.
And as to bronze age quality , I have just gone back through Vanhouse which was just as well because my recollections were wrong.
The tollerances on parts, at least up until 1952 when BSA won a Maudes trophy were so wide that it was still considered a feat to be able to assemble a bike from spares bought over the counter and have it actually run and that speaks plenty about the general precision of availible parts when there bikes were new.
Back when I was a school & working part time in factories there was a trades qualification called the "fitter-Turner" and the "fitter -machinists"
The turner / machinist refers to the fact that parts were not expected to fit without modifications.
Indeed the pulleys we bought for our Victa powered mini bikes came with nothing more than small pilot hole for the shaft and a raised boss for the grub screws.
The customer was expected to drill the hole to suit the shaft of what ever the pulley was going onto.
Fifteen years latter on when I entered the workforce full time this trade had vanished as parts were now very much plug & play.
The old mechanical workshops would have a lathe against a wall some where that was never used unless a part was NLA.
As for measuring tools, I learned to use & read micrometers & verniers in high school but never saw one on a shop floor anywhere apart from the clutch & brake workshop who use verniers to measure the diameter of brake drums & micrometers to measure clutch plates .

Perhaps top end tuners churning out land speed record attempt motorcycles would use precision measuring for valve guide clearences but for most workshops , no rock is more than good enough.
I can remember spending a few too many afternoons in Doc Kellys Speed shop who specialty was making very fast Triumphs , all done by feel.
The only measuring tool remember seeing was what looked like a modified depth gauge that he used to measure bores with , a circumference band which he used to measure rings with and loose feeler strips
Places that had things like micrometers would keep them in locked cabinets only to be signed out by the supervisor or foreman.

As for things like valve guides the only "test" I can remember seeing been done was the thumb test where the valve would be oiled and dropped into the guide then raised up a second time and dropped in while the mechanic had his thumb blocking off the rocker end.
If the valve remained suspended by the air pocket but dropped strait down when the thumb was removed then the valve guide was clearance was fit for purpose.
Those who have to see numbers might be horrified by this type of approach but those who do the job day in & day out have the experience to know by look & feel , much like the calibrated thumb in the plug hole compression test.
Some where there would be a Vickers number ( Brinell would be better ) for dead soft copper so one would know if the head gasket was fully annealed or not, or you could roll your thumb over it and see if you thumbnail can leave a full crescent indentation .
While there is nothing wrong with fine precision, it costs time & money some have both in spades while others have neither.

Back to the question of pretty vs mechanically perfect, again just going on my recollections of what I see on these pages
I remember a lot of people requesting help to find the best spray painter or where they can get perfect plating .
Add to that endless posts about the merits of dipping vs spraying vs powder coating

Not quite as many looking for the best machinist so the obsessision would appear to be well & truely baised towards the pretty
People post pictures of their bikes & carry on about who painted them where the mufflers came from etc etc , rarely a world about internals

Last edited by BSA_WM20; 10/24/21 12:30 pm.

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For the record, Alp's Triumph engine has aftermarket cases, barrels and all internal parts except for an original Triumph crankshaft and head casting...He estimates as much as 150 HP....
My build threads are all about engine internals and mechanical stuff because I don't care about paint or chrome or manufacturer correct parts... There are a few others here doing the same who lack tools to machine cylinders , valves and crankshafts...

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I deleted my other posts because I felt they weren't worthy.......but I've read every reply.....even the ones that have absolutely nothing to do with MM's original question. frown

There's some very interesting reading on this thread and I thank the posters for it.

Here's what I keep coming back to. MM knows (I hope) I'm a fan of his work.......started way back on Brit-Iron-L and the Guggenheim (sp?)

The problem I see with having detailed descriptions of work completed is........if the buyer isn't qualified (like me) how do they KNOW if what they're reading or viewing is the correct way it should be done? No disrespect intended but how do I know MM is doing it right? Do I hire someone else to interpret the information or do I just blindly take the info as 100% correct?

I work for Eddie Vannoy ( https://www.mecum.com/auctions/vannoy-2020/ ) and his brother Mark........some of you might have heard of him and know he sold off a large portion of his collection recently ($15 million +-) Eddie paid $24,000 one time for a Matchless........just because he wanted it. Eddie never rides motorcycles....I'm pretty sure he never heard that Matchless run before he purchased it. (at auction). He has a couple of full time mechanics that work on his stuff.......machine shop stuff is farmed out. I had a chance to ask him last week about MMs question. His answer was........for him, it would just be paper and he doesn't put a value to it. Race or famous owner history is something he values.......but if he wants, he has his mechanics take something apart and put it back together.....that's their job. He's more into the "pretty" because his stuff doesn't get ridden.......or at least the motorcycles don't and most of the 4 wheeled collection.

Gordon

PS.... BSA _WM20 wrote, " I can remember spending a few too many afternoons in Doc Kellys Speed shop who specialty was making very fast Triumphs , all done by feel." Brings to mind watching The Worlds Fastest Indian. Burt sitting in a interview with a rod (?) in his hand and he keeps running his fingers around it.......my bet is those were his main instruments.

Last edited by Gordon Gray; 10/24/21 3:51 pm.

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Originally Posted by Hillbilly bike
valve work done on a $325,000 Newan ... Is this engine better than one built by a guy using less precise equipment
I'd say, maybe. Certainly, less precise equipment would do no better, but once you bump up against fundamental limitations, doing "better" doesn't buy you any further improvement. However, a relatively-less-skilled worker using that $325k machine can have a head installed and ready to accurately machine for a new guide or seat in a few minutes, whereas it would take a lot longer for a more skilled machinist to accomplish the same job on a mill.

Although a mill is capable of achieving tolerances beyond which there would be no further advantage, it only can do so with more expensive labor and slower throughput. A commercial engine rebuilding shop using a mill can't compete with one using a purpose-build $325k head rebuilding machine. But, even though the precision could be the same, the lesson for the person looking for a shop to do work is it would be a lot easier for a skilled machinist using a mill to screw up than it would be for a less-skilled operator of the purpose-built machine.

Originally Posted by BSA_WM20
Doc Kellys Speed shop who specialty was making very fast Triumphs , all done by feel.
The skills of such people are mythical, but count me as very skeptical of the reality. As written before, internal combustion engines are quite tolerant of wear and abuse. By the time you get some of your mower engines to repair, which were running until the owner decided they couldn't delay work any longer, you must wonder how they still could have been functioning in their decrepit condition.

Even for fast street use, a few thou. additional clearance on the valves won't affect the performance all that much, it just will require new guides that much sooner. A too-wide margin on the seat won't degrade performance too much. Too much clearance for the piston only will cause it to rattle a bit more. Certainly, countless motorcycle engines are put together by feel alone and run "just fine." However, put together more precisely they would run better and for longer.

Originally Posted by Gordon Gray
...if the buyer isn't qualified (like me) how do they KNOW if what they're reading or viewing is the correct way it should be done? No disrespect intended but how do I know MM is doing it right?
Many things in life are like this. When we can't judge something for ourselves, we rely on the advice of experts. I'm not qualified to judge the scientific data to know if Covid vaccines are safe and effective, but I know I can rely on the judgements of panels of experts at the FDA and CDC to make that determination, which is why I've had two doses plus a booster. Thanks to the principle of six degrees of separation, you may not be able to judge something you're reading, but you almost certainly have a friend who can.

In the case of my own work, you have the circumstantial evidence that after having rebuilt it down to the last nut and bolt, it made it across the country with one "trivial" breakdown due to an admitted screw-up on my part of not Loctiting the points screw, and two others due to design flaws of the drive system and valve train. Plus, everything I did in the rebuild and re-rebuild is documented in excruciating detail in over 700 pages on a thread with over 1.2M views that outside experts, self-appointed experts, and total wankers can scrutinize and comment on. But, I make no warranties, expressed or implied...

Originally Posted by Gordon Gray
I'm pretty sure he never heard that Matchless run before he purchased it. (at auction). ... for him, it would just be paper and he doesn't put a value to it. Race or famous owner history is something he values.......
Fair enough. For someone who never starts his machines, there would be no point in spending money for anything but the externals. Whether or not a bike that Mike Hailwood rode at the IoM even had a piston, let alone its clearance, would be irrelevant.

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Originally Posted by Magnetoman
Originally Posted by Hillbilly bike
valve work done on a $325,000 Newan ... Is this engine better than one built by a guy using less precise equipment
I'd say, maybe. Certainly, less precise equipment would do no better, but once you bump up against fundamental limitations, doing "better" doesn't buy you any further improvement. However, a relatively-less-skilled worker using that $325k machine can have a head installed and ready to accurately machine for a new guide or seat in a few minutes, whereas it would take a lot longer for a more skilled machinist to accomplish the same job on a mill.

Although a mill is capable of achieving tolerances beyond which there would be no further advantage, it only can do so with more expensive labor and slower throughput. A commercial engine rebuilding shop using a mill can't compete with one using a purpose-build $325k head rebuilding machine. But, even though the precision could be the same, the lesson for the person looking for a shop to do work is it would be a lot easier for a skilled machinist using a mill to screw up than it would be for a less-skilled operator of the purpose-built machine.
One advantage is the Newan can greatly reduce valve seat runout that most machinists in a shop cannot do...So the guide clearances on my Triumphs and A10 are .0008 on intakes and .0012 on the exhausts. This reduces oil consumption and improves cylinder sealing...doing this with traditional valve tools will risk a stuck valve or even break off the valve head from stem flex from seat -valve being non Concentric....Single axis valve machines can be knocked off tolerance by a hard spot on the seat insert. This may be not noticed by a less skilled worker...


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Originally Posted by Hillbilly bike
One advantage is the Newan can greatly reduce valve seat runout that most machinists in a shop cannot do...So the guide clearances on my Triumphs and A10 are .008 on intakes and .0012 on the exhausts. ... Single axis valve machines can be knocked off tolerance by a hard spot on the seat insert. This may be not noticed by a less skilled worker...
(You missed a zero on the intake -- I'm sure you meant 0.0008").The Newen and a ball head cutter in a mill both rely on a pilot to keep the cutter Concentric with the guide. However, a big advantage of a Newen machine for valve seats in a production environment is separate profiled carbide cutters aren't needed for each engine since it has a single-point cutter and uses CNC to create any desired seat profile. If a Toyota head is done after a Ford head, instead of the downtime needed to change cutters (and the cost of maintaining a large inventory of cutter shapes), all the operator needs to do is pull up a different profile from the machine's memory. As for the "hard spot," that strikes me as a marketing, rather than a real, advantage given the quality of seats from major manufacturers.

Interestingly, old school runout gauges used 0.001" indicators, which was fine for old school recommended runouts of no more than 0.0015"/inch (i.e. 0.0026" for a 1¾" valve). Because I can do a lot better than that with the tooling on my mill I found a gauge that is missing its indicator in order to modify it with a 0.0001" indicator. You are only able to work to better than 0.001" if you have instruments that measure to better than 0.001". Such a "precision" runout gauge is available from Goodson for a mere $615. Again, though, it takes me a lot longer to accurately cut a seat than it does someone with a machine like a Newen.

Addendum: I wonder what guide clearance and seat runout someone would get if they took their Triumph head to a "typical" machine shop to have the work done. Hillbilly bike cites real performance advantages to having the job done to modern standards, but are most shops using those standards, or older ones?

Last edited by Magnetoman; 10/24/21 7:08 pm. Reason: Addendum:
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Thanks, I fixed the zero....The auto shop I used for years thought .0015 and .0025 was the limit with their equipment based on experience with Brit bikes. I have seen valves seize at these clearances if the run out is sloppy..
What clearances do you use on the old Ariel with exposed valve springs..


79 T140D, 89 Honda 650NT ,61 A10 .On a bike you can out run the demons
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I'm not trying to be argumentative......I'm on your side.......but you asked.

"In the case of my own work, you have the circumstantial evidence that after having rebuilt it down to the last nut and bolt, it made it across the country with one "trivial" breakdown due to an admitted screw-up on my part of not Loctiting the points screw, and two others due to design flaws of the drive system and valve train."

I'm sorry doc but all that really proves to me is........the work was good enough.

What about a potential buyer that has never heard of BritBike.com or Dr Falco?

Gordon

Last edited by Gordon Gray; 10/24/21 7:27 pm.

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Originally Posted by Hillbilly bike
What clearances do you use on the old Ariel with exposed valve springs..
My list of specifications says 0.002" for the inlet and 0.0025" for the exhaust. Although I subsequently improved my tooling significantly with a ball head cutter, with my Neway cutters I achieved a seat runout of just over 0.001".

Originally Posted by Gordon Gray
I'm sorry doc but all that really proves to me is........the work was good enough.
Unfortunately, the breakdowns show me that my work was only almost good enough.

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Originally Posted by BSA_WM20
Perhaps top end tuners churning out land speed record attempt motorcycles would use precision measuring for valve guide clearences but for most workshops , no rock is more than good enough.
I can remember spending a few too many afternoons in Doc Kellys Speed shop who specialty was making very fast Triumphs , all done by feel.
The only measuring tool remember seeing was what looked like a modified depth gauge that he used to measure bores with , a circumference band which he used to measure rings with and loose feeler strips
Places that had things like micrometers would keep them in locked cabinets only to be signed out by the supervisor or foreman.
I spent a few too many afternoons at Doc's workshop as well, and felt it the next morning. It was all very exciting to somebody in his early 20s, but in hindsight Doc was a butcher. It's easy enough to make something go fast (for a while) with clearances on the loose side, and they obviously wore out quicker because they were thrashed, not because they were already halfway to their wear limits when assembled.
It's certainly possible to get within the fairly broad tolerances of the period by feel. In fact, the BSA Service Sheets used to be worded that way. If I have a choice, I like to have the numbers in front of me, though.

There's a continuum from "but it runs", through "mechanics" like Doc and Barry who largely worked by feel and the factories which at least had go-no go gages to precision engineering such as that done by RPM or Magnetoman.
When it's all said and done, "acceptable" is going to be quite sensitive to the intended use and individual sensibilities. Design limitations come into play as well. Having a pre-1930 motorcycle cover 3,000+ miles in 2 weeks is an achievement, just as it was when they were new. Doing the same with a late 1930s machine is much less challenging, and one would be rather disappointed not to do that with a 1950s machine, even a "grey porridge" commuter.
Having the occasional 100 mile weekend ride is different, and riding a 10 mile return trip to work every day is different again.

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Originally Posted by Magnetoman
Originally Posted by Gordon Gray
I'm sorry doc but all that really proves to me is........the work was good enough.
Unfortunately, the breakdowns show me that my work was only almost good enough.

All I can add is......personally I would pay a premium for ANY bike you worked on. You wouldn't have to show me any proof of methods.....period.

In our small circle.......you'd fit in that "famous owner" category.

Gordon Gray in NC, USA


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Originally Posted by Magnetoman
Originally Posted by Hillbilly bike
One advantage is the Newan can greatly reduce valve seat runout that most machinists in a shop cannot do...So the guide clearances on my Triumphs and A10 are .008 on intakes and .0012 on the exhausts. ... Single axis valve machines can be knocked off tolerance by a hard spot on the seat insert. This may be not noticed by a less skilled worker...
(You missed a zero on the intake -- I'm sure you meant 0.0008").The Newen and a ball head cutter in a mill both rely on a pilot to keep the cutter Concentric with the guide. However, a big advantage of a Newen machine for valve seats in a production environment is separate profiled carbide cutters aren't needed for each engine since it has a single-point cutter and uses CNC to create any desired seat profile. If a Toyota head is done after a Ford head, instead of the downtime needed to change cutters (and the cost of maintaining a large inventory of cutter shapes), all the operator needs to do is pull up a different profile from the machine's memory. As for the "hard spot," that strikes me as a marketing, rather than a real, advantage given the quality of seats from major manufacturers.

Interestingly, old school runout gauges used 0.001" indicators, which was fine for old school recommended runouts of no more than 0.0015"/inch (i.e. 0.0026" for a 1¾" valve). Because I can do a lot better than that with the tooling on my mill I found a gauge that is missing its indicator in order to modify it with a 0.0001" indicator. You are only able to work to better than 0.001" if you have instruments that measure to better than 0.001". Such a "precision" runout gauge is available from Goodson for a mere $615. Again, though, it takes me a lot longer to accurately cut a seat than it does someone with a machine like a Newen.

Addendum: I wonder what guide clearance and seat runout someone would get if they took their Triumph head to a "typical" machine shop to have the work done. Hillbilly bike cites real performance advantages to having the job done to modern standards, but are most shops using those standards, or older ones?

And the problem with this is the same one I have with the mythically perfect "machined from solid billet " CAD parts, is what ends up happening is the shop owner puts a $ 10/hr dullard on the end of the machine to recover the costs as quickly as possible because the machine can not make a mistake, till it does, but the operator who does not know any better keeps on feeding new parts into the machine & pressing the buttons turning good parts into scrap, some thing I have seen countless times in industry.
Or he puts a $ 50 /hr technican on the end so prices himself right out of the market because the number of customers who are willing to pay the same for a valve guide machining as a replacement heat ( remember we are talking about old British motorcycles not F1 race engines ) would be pretty close to zero.
And that is assuming that some one has programmed in the specifications for a 1943WM20, a 1973 B50MX or even a 1928 Ariel all of which would be very doubtful .

And of course we are now going in the endless circle.
Precision costs money and the cost rises exponentionaly with every order of magnitude
So then the costs have to be weighed against the benefit in one of those things accountants & political lobbyist love, a cost benefit analysis .
Do I want a bike that will go just fast enough to outrun the local police & occasionally win a drag against my circle of peers ?
Am I happy for it to self destruct just so long as I can be the fastest on the night ?
OR do I want it to run for long distances with a mean time between failures that could only be dreamed of when the motorcycle was new
Or do I want to ride a "Budget Brit" for the minimum outlay & maximum fun ?
Will the fine precision last long periods of storage or will cams. cam followers. bearing races & rolling members end up either corroding or Brinneling due to not being used , or valves sticking due to corrosion from lack of lubrication cause by lack of use, let alone things like stiction caused by oxide growth over time , and of course wear from actual use itself negate the fine precision used in the remanufacture ?
Right down to the question is turning an old production bike into something that would have cost 5 years wages back in the year it was made so would have never actually been made, is being true to the ideal of riding a historic vehicle or are you really just making a hot rod without the extensive body work changes.

All very personel questions that will have a different answer from each & every one of us so none will ever be universally applicable.

Then when talking about precision in the orders of 0.0001" or the implied +/-0.00005 just how accurate will that actually be be when the simple act of touching the part or even measuring the part can cause enough temperature change to affect the reading so of course those reading will need temperature compensation and at that level of precision the difference in the thermal properties of the actual different grades of steel come into play let alone the temperature of the workshop & the presence or absence of any breeze that may be in there and the temperature of said same breeze and of course the temperature rise caused by the maching process itself regardless of what type of cooling is used .

Does a valve seat that is 0.010 wider than it should be really affect the performance of the engine ?
Well to all effects & purposes the answer is no. There is probably a point where there will be insifficient clamping force to prevent leakage but at what seat area ?
In theory it will transfer more heat & cause the valve to run colder than it should and reduce the sealing pressure so make it more prone to leaking ,,, in theory
The burning question is does it make any difference in practice in the actual engine, so a 13:1 dope burner running at 10,000rpm probably but a 7:1 street bike, not likely and a 6:1 SV no way ?
A valve guide true to 0.00001" is fine, but the valve does not heat uniformly nor does it expand uniformly and of course we can all appreciate that the stem itself will become conical from the effect of thermal expansion so the cold assembly precision can quickly vanish at operating temperatures

Last edited by BSA_WM20; 10/25/21 1:39 am.

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