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#852428 06/25/21 11:33 pm
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Printed ports to try on the flow bench.
[Linked Image from live.staticflickr.com]
[Linked Image from live.staticflickr.com]
34mm Koso Oko, Ford Ranger valves

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Are you planning a new head casting Dave? What size are the valves? Do you have any flow numbers on them yet? They look really good.

The std casting isn't very tall, why oval seem to work well in them. Going wide being one of the big advantages the A65 has over Triumph and Norton heads, and the triples.

These flow around 160cfm through a 34mm pwk, some read 164 or so but could be the lack of accuracy of home made gear. I cannot get them much better than that. It's probably possible but changes are hardly worth the trouble because returns are small after a certain thing and can start going backwards.

[Linked Image from i.postimg.cc]

[Linked Image from i.postimg.cc]

That's with a 42mm MAP valve. Bigger valves will actually pull more air through, around 180cfm for a 44.5mm valve, but the port opens more and is a bit big for a std size engine, because the rpm would be extreme. Though I haven't tried one. Without the carb they are all about 10cfm more through a radiused entry. I could probably make a better flowing bell but it's a bit pointless.

We should have a big valve 34pwk combination on a 734 big bore pretty soon. The PWK are really nice because the throttle is pretty light. And they are physically small and don't particularly look out of place. Starting is usually one kick. I ordered jets from 145 to 180 or so to suit the Firebird. 150 seem about right but if it goes on the dyno I want some alternatives. Generally jets kits come up to 140 mains, which are small. Though a bigger displacement may be different.

From what I can read from the knowledgeable the std exhausts ports flow heaps. And high compression means the exhaust valve can be fairly small. Stock is 35.8mm and MAP has a 37mm oversize so I'm not going over that size in the future even with the biggest inlet.


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Eventually want to cast a new cylinder and head. This is an 80mm bore (XS750 pistons) which is why I need a new head (some say not just for the engine) and cylinder. The outer four studs will go down into the case.
I do not have flow numbers yet, I got the parts off the printer. I have drill the adapter for the cylinder to fit the A74 holes.
The valve are from a ford ranger with 7mm stems, do not remember the head sizes off hand.

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The 44.5mm Jaguar valves have a reduced stem near the head. They are nice nitrided valves but I haven't been able to get them lately. To get an idea of how much flow you need this calculator is pretty good.

http://www.wallaceracing.com/calcafhp.php

I just don't know which head would be better on a 750. The 42mm is faster in the port. It varies where ever you put the probe and it's hard or impossible to hold it in the centre down in the port a bit. Both are over 400fps a little in the port. And the big valve one must be faster in the carb because more air goes through.

But how it is in the real world I don't know. It's predicting high rpm but I think it would have good power on the lower end of the predicted range.

The 42mm valve one like the ones above is like a fluke of being especially effective, with decent flow and speed. It's boosts midrange and top end somehow.
On a 750 it predicts over 80hp and I know it will be strong from virtually idle. Even on a 650 it makes the gap between 2nd and 3rd not mean much.

A friend moved the 4 outer head studs out a bit for a bigger bore.


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Just rechecked, the exhaust valves are used in the 2000-2010 F150 16 valve 4.6L and 5.4L trucks and 4.6L cars '92-07.. I think they made a few of them. The intakes are the 3.0L V6 '99-'08.
Intake - 1.661", 42.19mm, exhaust - 1.421", 36.09mm.
Wallace calculator gives 6536 PRM.
What did your friend do about the bolt in the pushrod tunnel which is closer to the bore than the outer bolts?

DMadigan #852540 06/28/21 12:08 am
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I think the bores were extended out. He uses .5" of valve lift with offset roller rockers. On my 883 I need to use 9mm head studs because 8mm even at a depth of 35-40mm pull out. And the cylinder is heat treated to T6.

[Linked Image from i.postimg.cc]


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"8mm even at a depth of 35-40mm pull out" - which is why a new cylinder/head is needed with proper size head bolts.

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This happened as power levels went up. Being metric thread, drilling and tapping to 9mm is easy, if done by hand and feeling the centre of the hole. Liners instead of nicasil limit the centre bolt to 8mm so that's what Ben's 750 has. The difference between 8 and 9mm is significant 10mm is slightly bigger than std. The problem with std size bolt and studs is distortion in the bore. What through bolts would eliminate, but then they have to stay in the case.

The R/h case is a bit compromised with a breather hole which I welded shut on the latest R/h case on the 883, with a reinforcing bar. Drilling holes between the crank and cylinder I would avoid, other than an oil hole to the roller which isn't were they crack. A 744 would probably be fine. The 9mm studs distort the bore slightly but it doesn't smoke, they feel totally different when torqueing.

The 750 is the nicest smoothest engine. And easiest to build. It would be good to have CNC programs for making the drive side bearing plates. They keep the primary chain in line and control crank end float.

If we consider a Spitfire engine as a race engine with 10.5-1 comp the std 68 701 flows 109cfm so 56hp is predicted between 5,606 and 7,102.

So high comp with a 42mm valve head on a 744 should be 84hp to 87 or so and a 44.5mm valve version over 90hp. But rpm is predicted over 8,000 or over 9,000. It depends if they are calculating port flow or port flow with carb.



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Like the sound.
Instead of the outboard outrigger bearing you could use a modern generator and skim the stator support a little to put the outrigger bearing just outboard of the sprocket. This is a GSXR1000 rotor on the crank.
[Linked Image from live.staticflickr.com]
There is approximately 10mm of clearance between the back side of the rotor and the sprocket with the rotor sitting on the stator mounting surface. If the earlier narrow hub sprocket were used there would be another 7mm of clearance. You could fit a 6005 25 x 47 x 12mm bearing in there, possibly a 6205 25 x 52 x 15mm.
The rotor fits on a taper so the adapter would be the taper and inner bearing race surface.
The stator would mount to the primary cover. This is the wrong one (0.5mm too large in diameter) but gives you the idea.
[Linked Image from live.staticflickr.com]
Just about ready to test. I need to make collars to hold the valves in position.
[Linked Image from live.staticflickr.com]

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Off track a bit but the GSXR1000 stator/rotor with outrigger bearing will fit in the case.
[Linked Image from live.staticflickr.com]
The Lucas stator mount has to be recessed 0.41" for the 6005 outrigger bearing support which also holds the GSXR stator. The crank shims inside/outside the distance piece will set the exact position of the crank.
The lump on the left stator cross section is the wire harness. This would be rotated so it exits at the rear post and tied off.

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I just use a 16005 bearing in both places.

[Linked Image from i.postimg.cc]


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Originally Posted by Mark Parker
I just use a 16005 bearing in both places.

[Linked Image from i.postimg.cc]

Same on mine.


Now let’s all have a beer beerchug

68’ A65 Lightning “clubman”
71’ A65 823 Thunderbolt (undergoing restoration)
67’ D10 sportsman (undergoing restoration)
68’ D14 trials (undergoing transformation)

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What do you mean by "both places"? You have another16005 bearing somewhere?
Here is a modified drawing with a 16005 bearing outboard of the Lucas rotor.
[Linked Image from live.staticflickr.com]
6005 bearing inboard of the GSXR stator on the left and a 16005 bearing outboard of the Lucas rotor on the right.
Is that essentially what both of you have?

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Originally Posted by DMadigan
What do you mean by "both places"? You have another16005 bearing somewhere?
Here is a modified drawing with a 16005 bearing outboard of the Lucas rotor.
[Linked Image from live.staticflickr.com]
6005 bearing inboard of the GSXR stator on the left and a 16005 bearing outboard of the Lucas rotor on the right.
Is that essentially what both of you have?


Essentially I copied Mark, the design is slightly Different but it is as good as the same on paper.

Because my belt drive is wider than the standard setup I have my primary case spaced out. But with a better design it need not be.

I believe marks other 16005 is on the mainshaft outrigger.

Your setup looks very neat Dave and possible adds improved charging over a standard RM21? Does it require the crank case machining to house the GSXR setup?


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68’ A65 Lightning “clubman”
71’ A65 823 Thunderbolt (undergoing restoration)
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You could say a bit advanced charging. The GSXR1000 generator is rated at 400W at 5000 RPM by sources that I could find.
The white outline on the left is the 6005 bearing and GSXR stator mount. The stator face of the A65 case has to be lowered by 0.41". Obviously easier on the earlier models with the removable stator mount or the studs alone mount. Easy enough to reverse with a spacer.
Yes, one 16005 in the outrigger but where is the other one?

DMadigan #852695 06/29/21 10:19 pm
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Originally Posted by DMadigan
You could say a bit advanced charging. The GSXR1000 generator is rated at 400W at 5000 RPM by sources that I could find.
The white outline on the left is the 6005 bearing and GSXR stator mount. The stator face of the A65 case has to be lowered by 0.41". Obviously easier on the earlier models with the removable stator mount or the studs alone mount. Easy enough to reverse with a spacer.
Yes, one 16005 in the outrigger but where is the other one?


All interesting stuff. Mark has two outriggers. One on the crank and the other on the gearbox mainshaft. (Sorry it’s a short and sweet reply, bedtime here). Hth


Now let’s all have a beer beerchug

68’ A65 Lightning “clubman”
71’ A65 823 Thunderbolt (undergoing restoration)
67’ D10 sportsman (undergoing restoration)
68’ D14 trials (undergoing transformation)

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The head on Ben's bike above has 44.5mm inlets with 38mm TMs, looking at the flow figures on that big carb head the smaller 34mm port may not particularly flow less with that valve, but it will be higher in speed. Which should have it drive harder making more power across the range. It may or may not be better than the 42mm valve version. Which I think could have been the ultimate production head as the more efficient port easily fits into the std 68-701 casting with no break throughs. And a 744 version would have been a rocket. Easily done and super effective.

I've done 3 of these heads which all flow about the same. I should have valves for them all soon. The Thunderbolt head on the Firebird read 168 compared to 107 stock for each port. These Lightning ones read around 170-174 and 164-5 through the carb. A stock 68-701 109 and around 105 through the carb. The numbers are just numbers and show at least a substantial improvement.

I ordered some MAP rods for the Firebird and when I fit them I need to decide between a 90degree crank I have or the 360 re-balanced to 56% which BSA testers said was best. Both would be fun to experiment with, though I already know how smooth the 90 can be. I'm hoping the 360 would be as smooth at 4,000 then get smoother. And lumpiness below that isn't too bad, it doesn't need to run under 3,000 really though I often do as it's smooth and flexible but being dead smooth at 2,000 isn't as useful as higher up.

This is the head for Nick, part done, that's been winning so well for them on the 750. It has 42mm inlets and std exhausts. On it are different possible inlet valves though this early model head has small valve seats the 42 being the maximum. It takes luck to fit the 44.5 valve on std seats, but they must be the later heads that came with 40.5mm inlets.

[Linked Image from i.postimg.cc]


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Originally Posted by Mark Parker
Are you planning a new head casting Dave? What size are the valves? Do you have any flow numbers on them yet? They look really good.

The std casting isn't very tall, why oval seem to work well in them. Going wide being one of the big advantages the A65 has over Triumph and Norton heads, and the triples.

These flow around 160cfm through a 34mm pwk, some read 164 or so but could be the lack of accuracy of home made gear. I cannot get them much better than that. It's probably possible but changes are hardly worth the trouble because returns are small after a certain thing and can start going backwards.

[Linked Image from i.postimg.cc]

[Linked Image from i.postimg.cc]


That's with a 42mm MAP valve. Bigger valves will actually pull more air through, around 180cfm for a 44.5mm valve, but the port opens more and is a bit big for a std size engine, because the rpm would be extreme. Though I haven't tried one. Without the carb they are all about 10cfm more through a radiused entry. I could probably make a better flowing bell but it's a bit pointless.

We should have a big valve 34pwk combination on a 734 big bore pretty soon. The PWK are really nice because the throttle is pretty light. And they are physically small and don't particularly look out of place. Starting is usually one kick. I ordered jets from 145 to 180 or so to suit the Firebird. 150 seem about right but if it goes on the dyno I want some alternatives. Generally jets kits come up to 140 mains, which are small. Though a bigger displacement may be different.

From what I can read from the knowledgeable the std exhausts ports flow heaps. And high compression means the exhaust valve can be fairly small. Stock is 35.8mm and MAP has a 37mm oversize so I'm not going over that size in the future even with the biggest inlet.


Hi Mark, have you done any moulds of the stock ports (thunderbolt or Lightning heads)?


Now let’s all have a beer beerchug

68’ A65 Lightning “clubman”
71’ A65 823 Thunderbolt (undergoing restoration)
67’ D10 sportsman (undergoing restoration)
68’ D14 trials (undergoing transformation)

DMadigan #852764 06/30/21 11:57 pm
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The better '71 stock port.

[Linked Image from i.postimg.cc]

On the left in this one.

[Linked Image from i.postimg.cc]


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It looks as though most of the modification is to widen the port around the guide restriction, yes?
On a completely different note, after looking at the "SlickShift" post on the Triumph board, there likely is a way to add this to an A65. The shift shaft and clutch lifter are fairly close to each other. The main difficulty is the shift shaft mounts to the inner timing case and the lifter mounts to the outer timing cover.

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Yes Dave and lift the floor. But this is a '71 with the deeper and wider bowl.

I have a stock '71 head in like new condition but the front rocker middle mount has been broken off by the stud going too far down making it pretty unusable, but good to measure against the others for a calibration head, once I establish exactly what its got.

I took the inlet guides out of the stock 68-701 I have left and will port it to the 42mm valve size and 32mm round std carb mount. The one above is done to 30mm but there is no reason to have them so small. I can do it like this with it going oval inside the head. It was around 138cfm for just the port and 144.4 with a radiused entry. I can get it fairly decent at 32mm, possibly over 150 but the carb will restrict that, the better 34mm moves the carb back. So if you had a stock Spitfire it could look totally stock and kick butt all the same because it could be close.

I used to think it required a big carb to get decent flow but the 34 is so close to a 38mm without lifting the guide 4mm and having break throughs and patching. I was thinking a casting could be altered a bit, and it could, but probably not to make a 744 or smaller motor better. A very peaky high rpm 744 might make more hp right in the top end, but though you can get more cfm it's not that much more and it may not make more power even if you buzz it. Personally I would not make a head, even a 4valve, getting it smooth and reliable at high rpm for what the std casting can do I think would be better.

From the side.
[Linked Image from i.postimg.cc]

You can get it pretty good without raising the floor, but if you go wider still and a bit higher the floor can be filled which even if you don't get more flow at that stage the port's smaller and faster and can be better flowing in the end.

This is the bearing housing on the front, the rear one I just bolted a piece to with bearing captured and seal but it's a bit wide and wouldn't fit, I've narrowed it a couple of mm and should put it on the Firebird which needs one. But one piece are better. The hole in the front one is for timing, just put it on full advance and put a drill in the hole and mark it.

[Linked Image from i.postimg.cc]


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Quote: Personally I would not make a head,


I dont know Mark, I think if you were to redesign it enough so that you could use a flatter chamber (weslake style) I think it would be a good thing. You'd have a much better turn into the bowl for a start. you could then get away with flat top pistons also which should be a weight saving on the reciprocating mass, and I am sure a better combustion profile.

The first head I did anything to was a late OIF head, I did nothing more than widen the port around the sides of the guide, this had a good response and helped high RPM.

The best one I ever did was a small port head, keeping the 38mm inlet valves and just raised the floor only and 928 carbs, still with filters and standard exhaust. This pulled like a train and rev'ed really well. I came up with some fag paper maths at the time and wasn't looking for high revs, I was trying to target my max power for around 6000 revs, what I wanted was something very tractable with good pull, the SRM race cam I helped also with top end also and was a good combination and I got more than what I was looking for.

Aside of that the early small port heads are better than the later heads anyway, some have put 40mm valves in them (my currently used head has them) but I don't think its worth it, they respond better all round with the smaller valves on this head IMO.


I have David Vizzard book which I think I saw a screen shot from on another thread, its an interesting book but I still haven't a decent quiet place where I can really study the book properly enough to make the information stick. Its not light reading by any stretch if you intend to learn from it, although an interesting read regardless.
If you don't mind me asking Mark, are you adjusting the strength of the vac from your flow bench to replicate real life comparision to how much a piston can draw at a realistic rpm? Im not trying to call you out, I am curious if your able to measure comparable results at slower vacuum depression.

AIUI, the book displays 2 manometers, the U tube manometer which will be for the total vacuum, as taken before the vac system. The other being an incline manometer which which a more sensitive gauge and will display around 10x the scale of the U tube manometer. This will (I think) take its actual flow readings from the head.

I need to get my head around the "test piece" which it goes on to mention, AIUI this is used for calibration of your flow aparatus.

Either way your yielding great results from your bikes. I'm just a curious sod who enjoys learning.


Now let’s all have a beer beerchug

68’ A65 Lightning “clubman”
71’ A65 823 Thunderbolt (undergoing restoration)
67’ D10 sportsman (undergoing restoration)
68’ D14 trials (undergoing transformation)

DMadigan #852828 07/01/21 11:27 pm
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Allan there is a page that shows Harley heads in various stages and the hotter ones, or more advanced have the hemisphere closed with squish areas. That could be good. But I'm just thinking for practical application of what we have. I could not make a head and I've welded one up before to use flatter pistons and squish areas but without having the ports the best. Ones with better ports were better.

There is a danger with high dome high compression pistons that more compression can lose power because it blocks flow. 650cc engines probably more susceptible needing smaller chambers.

On my 883 the guide is lifted and I've done all sorts of things to make a 38mm port flow but it's probably more effort than it's worth because it wants to make power over 8,000 where it will never run. It's power is excellent in the midrange but that head on a 750 would probably have you waiting for power to come in
and using rpm where that was working best you probably would not do unless you were drag racing and a bit smaller with less flow may be better anyway.

A 750 that responds like the 34mm carbs on the 650 would be great. I didn't know that head would do that. It's no bottomless pit but it's very nice if you can hang onto the vibrating bars. It's probably capable of high rpm, but even if it was smooth you don't really want or need to use more than 7500 really. Nice to known it's there but not used much.

Last edited by Mark Parker; 07/02/21 2:42 am.

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Just arrived from MAP in the states. Delivered to the door Friday today after ordering last weekend. So apart from some other nice stuff a few valves.

These are the nitrided stainless swirl pattern inlets 42mm and std nitrided exhaust valves. Why they are good is because with a K-linered guide they can be fitted fairly tight reducing wear. And when they do eventually wear out they can be lined again without removing.

(pictured are actually the big exhaust valves. I have them in the Firebird but std exhaust valves in Matt's winning sidecar. So the only reason to require bigger exhausts is worn seats or using a blower, according to Vizard.)

[Linked Image from i.postimg.cc]

The beauty of this set up is it fits straight on a stock 650 bottom end. The calculator predicts over 70hp but that remains to be seen. Seems no problem with piston to valve clearance, just needs good springs set to the correct fitted length. Nice on a stock 650 and enough flow for possibly a predicted 82-87engine hp on a 750 race motor.

I may be able to fit the steel rods before I can get it on a dyno. And hopefully have it balanced smoother at higher rpm. But it's a bit hard to get motivated to pull something that runs nice apart.

This shows how the 34mm id tube is squashed and lined up, Then the tags just welded on. The oval is right out to the 1/4"UNC screws. I just fit helicoils in the holes.

[Linked Image from i.postimg.cc]

Last edited by Mark Parker; 07/02/21 7:41 am.

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A quick first measurement, at 0.40" lift, 10" H2O, 90F, 34mm Oko wide open no venturi, the flow through the as printed port is 82 CFM. The print surface is much rougher than a stock port so next is to smooth it off.
From the calculator, as a street engine it gives 65 HP, as a typical race engine it gives 71 HP.
Too bad they do not make clear print wire. That would be interesting to see. Maybe plugs could be printed and cast in clear resin.
[Linked Image from live.staticflickr.com]

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