BritBike Forum logo
BritBike SponsorBritBike SponsorBritBike SponsorBritBike SponsorBritBike SponsorBritBike SponsorBritBike SponsorBritBike SponsorThe Bonneville ShopBritBike Sponsor SteadfastCyclesBritBike SponsorBritBike Sponsor
Upgrade to: Gold Membership | Premium Membership | Vendor Membership | Site Sponsor Membership
Electric Starter Roller
CLICK HERE to see VIDEO
How the Electric Roller Starter works.


ORDER on eBay. CLICK HERE!

Buy your Electric Roller Starter here
ShoutChat Box
Comment Guidelines: Do post respectful and insightful comments.
Buy BritBike staff a coffee
Buy BritBike's staff a coffeeStill here since 1996 serving BritBike enthusiasts..
Search eBay for motorcycle parts in following countries
Australia, Canada, France, Holland, Italy, United Kingdom, USA
Random Gallery photo
Member Spotlight
awesomebsa
awesomebsa
vancouver, b.c.
Posts: 65
Joined: October 2006
Show All Member Profiles 
Newest Members
Borderlord, BMac, clive1, Dan87GT, B. Nicholson
10942 Registered Users
Top Posters(30 Days)
kommando 102
franko 90
DavidP 64
NickL 57
koan58 53
Popular Topics(Views)
1,068,400 mail-order LSR
a word from..
Forum Statistics
Forums35
Topics68,293
Posts685,239
Members10,942
Most Online14,755
May 5th, 2019
Who's Online Now
41 registered members (Allan Gill), 855 guests, and 868 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
Page 1 of 7 1 2 3 4 5 6 7
650 to 750 swap #788685 10/31/19 7:21 am
Joined: Oct 2019
Posts: 68
S
splash Offline OP
BritBike Forum member
OP Offline
BritBike Forum member
S
Joined: Oct 2019
Posts: 68
So 650.... piston skirt was cracked in half, pin still in connecting rod came back up and cracked the barrel on the left side. I been having issues with the left side and it came down to this. There are pieces of the piston skirt down in the crank case still. In order to put a 750 in what do I have or should change below the jug or barrels? I imagine having to turn the crank if i was going back to the 650 but is the 750 crank case different? Who has went from the 650 to the 750 and how far down did you have to change?

Last edited by splash; 10/31/19 7:22 am.

1970 Triumph tiger owner
Support Your #1 BritBike Forum!

Check out British motorcycles for sale:
British Motorcycles on e-Bay UK
British motorcycles on e-Bay North America
CLICK HERE to see VIDEO
How the Electric Roller Starter works.


ORDER on eBay. CLICK HERE!

Buy your Electric Roller Starter here
Re: 650 to 750 swap [Re: splash] #788687 10/31/19 8:51 am
Joined: Sep 2008
Posts: 1,220
S
Stein Roger Online Content
BritBike Forum member
Online Content
BritBike Forum member
S
Joined: Sep 2008
Posts: 1,220
All you need is a 750 kit which includes pistons, rings and a new head gasket. With the trauma your engine have seen, it'll need an overhaul of course.
There are alloy kits and cast iron kits, I'd go for the latter, on a street bike at least. No need to change anything below the cylinder barrels. In fact, the 650 cams are IMHO far better than the 750 cams, and can be considered an upgrade. With a Tiger head, the 750 will become a torque monster, and stronger than a Bonnie up to 5000 rpm or more.
The T140/TR7 top end will fit, but requires machining the crankcase mouth, and you need to use the shorter T140/TR7 rods, and the cylinder head

Last edited by Stein Roger; 10/31/19 8:52 am.
Re: 650 to 750 swap [Re: Stein Roger] #788702 10/31/19 5:22 pm
Joined: Oct 2019
Posts: 68
S
splash Offline OP
BritBike Forum member
OP Offline
BritBike Forum member
S
Joined: Oct 2019
Posts: 68
Originally Posted by Stein Roger
All you need is a 750 kit which includes pistons, rings and a new head gasket. With the trauma your engine have seen, it'll need an overhaul of course.
There are alloy kits and cast iron kits, I'd go for the latter, on a street bike at least. No need to change anything below the cylinder barrels. In fact, the 650 cams are IMHO far better than the 750 cams, and can be considered an upgrade. With a Tiger head, the 750 will become a torque monster, and stronger than a Bonnie up to 5000 rpm or more.
The T140/TR7 top end will fit, but requires machining the crankcase mouth, and you need to use the shorter T140/TR7 rods, and the cylinder head



Are the barrels sleeves which are pressed into the jug/fins and included in the kit? Overhaul as in opening up the crank case and cleaning out the pieces of old piston? What do you mean by Tiger head, should I get the 650 head machined, overhauled, and put on the 750 barrels? So if I keep the 650 head (top end) it will fit without machining the crankcase mouth?


1970 Triumph tiger owner
Re: 650 to 750 swap [Re: splash] #788705 10/31/19 5:45 pm
Joined: Dec 2013
Posts: 4,837
kevin roberts Offline
DOPE
Offline
DOPE
Joined: Dec 2013
Posts: 4,837
the easiest and cheapezt way is to just buy a big bore kit, like the morgo. it will come with cylinders, pistons, rings, and a head gasket.

you re-use everything else, and its a bolt -on that requirez no machining. ive been running one for 30 years and it still has 150/155 compression.

https://www.morgo.co.uk/product-category/morgo-750cc-big-bore-kit/

aerco makez one as well.

comprezsion ratios differ between kitz



every day you do not take a chance is a day of your life that you will never get back.
Re: 650 to 750 swap [Re: splash] #788706 10/31/19 5:48 pm
Joined: Jan 2017
Posts: 881
T
TR7RVMan Offline
BritBike Forum member
Offline
BritBike Forum member
T
Joined: Jan 2017
Posts: 881
Hi Splash, I have '73 Tiger 750 as Stein said a different motor, only a few parts interchange. I have personal experience with '70 TR6R with Morgo 750 kit. It is a most outstanding kit. No mods needed. Stock cams , carb, exhaust. Boyer ignition. As Stein said it has outstanding good power. Has proven very durable & reliable.

My good riding friend has had bike several years & put many thousands of miles on it with 750 kit. I have ridden this bike. I feel it will out pull my '73 Tiger in every condition. We've ridden hundreds of miles together. While 650 is a good bike in it's own right, the Morgo kit may be considered an upgrade. Has had no head gasket problems either.

Triumph made a special 750 twin T120RT for AMA racing. Was a USA made Routt cyl that replicated a stock 650 cyl visually. The Morgo cyl is different shape than original 650. The fins are longer & shaped to match the cly head fins. Morgo has 7 fins. Maybe the fins are a little thicker? Makes the motor look a little larger, but you really don't notice it at first glance. In my mind the longer fins are a good idea & can only help cooling. Some times fewer thick fins can cool better than 1 more thinner fin?? That's another subject.

The TR7RV & T140V 750 cyl is 1/2" shorter & only has 7 fins. The bottom short fin is missing & the upper fins are shaped a little differently giving cyl a fat squatty look compared to 650, to my eyes. The fins are slightly longer. one of the iconic visual aspects of the 650 is the tiny waist at bottom of cly. I miss that on my Tiger 750.

There is also an Aerco 750 kit, 8 fins, but similar shaped as TR7RV/T140. Visually it's chubby like my TR7RV with longer low fins. I have no experience with Aerco. The only ones I've seen locally are Morgo.

Which is best quality? Morgo or Aerco I don't know. I'd get the one you like the looks of best. Or stay with 650 original if you like looks of that better. 650 Tiger is great running bike with good power so just depends on what you want. There is no wrong choice.

In any case, I feel very important to use dedicated break in oil. I don't know how shipping is to Kona for oils though.

I don't know about others, but Boyer ignition has a very desirable advance curve. Basically liner to full advance at 3500rpm. Substantially reduces tendency to ping at take off & lower RPM especially in hot weather like what you have.
Don


1973 Tiger 750
Re: 650 to 750 swap [Re: splash] #788707 10/31/19 5:55 pm
Joined: Jan 2017
Posts: 881
T
TR7RVMan Offline
BritBike Forum member
Offline
BritBike Forum member
T
Joined: Jan 2017
Posts: 881
Hi Splash, On a side note, what caused piston to fracture? Detonation can do that... Not saying it did. Just keep that in mind to make sure mixture is not even a trace lean & timing is good. I like to run 36b instead off 38 even with Boyer. Again highest octane fuel with ethanol is better than lower octane without. The above mentioned TR6R with Morgo 750 kit is running California 91 octane E10. The best we have. Still have to keep it spinning. No lugging. Was good over the passes at 107-110f & we ran about 62-65 down the highways at this heat 200 miles. The other miles were cooler.

Don


1973 Tiger 750
Re: 650 to 750 swap [Re: splash] #788711 10/31/19 6:41 pm
Joined: Jun 2007
Posts: 6,606
HawaiianTiger Offline
BritBike Forum member
Offline
BritBike Forum member
Joined: Jun 2007
Posts: 6,606
Definitely need to find out the cause of the failure before repairing your bike or it will just happen again.
Sounds to me like you already have clues at the scene of the crime. Seems like I remember you fussing with the timing cover and never strobe timing it afterward.
On a 70 TR6, this is very easy to do. Get yourself a timing light. I have an antique Sears and it works just fine.

I highly recommend the 750 kit as it makes for a much more fun ride. Also, with you living on the Big Island, having more power is very helpful. You can gear your bike up a little and have a nice highway cruise all the way to Hilo.

Cheers,
Bill


Bikes
1974 Commando
1985 Honda Nighthawk 650
1957 Thunderbird/T110 "Black Tiger"
Antique Fans: Loads of Emersons (Two six wingers) plus gyros and orbiters.
Re: 650 to 750 swap [Re: splash] #788731 10/31/19 10:11 pm
Joined: Oct 2019
Posts: 68
S
splash Offline OP
BritBike Forum member
OP Offline
BritBike Forum member
S
Joined: Oct 2019
Posts: 68
Why it happened?

hmmmm, In August of this year I rode from El Palso, Texas to San Diego, Cali. I crossed the Az desert and climbed over the mountain ridge just after I entered Cali. Note, I changed the oil seal behind the points about 3-4 weeks prior to the trip without timing light and only pictures during reassembly of points. I had no problems until at the top of the mountain ridge. I was behind an eighteen wheeler going slow, I was just enjoying the views. I he got slower I continued to downshift. The RPMs were low and I was in 2nd gear going up with a valley here and there. Majority of the time I was at a low RPM and 2nd gear. I had just made it to the top of the mountain and the valves started pinging for the first time. I could feel on my leg she was hotter than usual then she just stopped running and I pulled over. I sat on the side of the road telling myself she just overheated and everything will be OK after she cools off. I sat and enjoyed the view. A half hour later I kicked her a few times back to life. This was the beginning of sometimes more than 2 kicks to start and sometimes only 1-2 kicks to start. My first thought was the needle in carb needed to be changed cause I was above 3 thousand in altitude over the ridge but why bother as I was on my way down. She ran fine in San Diego. I shipped her to Hawaii. I get her here and she still sometimes have to kick more than twice. I think some trash may be caught in the float needle as before and causing to leak as before or clogging the primer button. I carry on until the white smoke from the left exhaust is noticed. This is where I really began getting concerned. The symptoms added on (sluggish, lack of horsepower, rich fuel mixture on plugs until I mixed with aviation grade 100 low lead fuel (no more smoke from exhaust), hotter than normal on my calf when going up hill and pinging, pinging 75% of the time now without going uphill. Every mechanic I talked to about putting a timing light on it couldn't get to it until 3 weeks later. One told me it was/is the place I was getting fuel from.

I still don't know. My father bought this bike brand new in 1970 and maybe put 8,000 miles on it until he gave her to me. I put about 1500 on her since the begining of this summer. He rode her off and on over the years. No major overhaul or crazy mods done.


1970 Triumph tiger owner
Re: 650 to 750 swap [Re: HawaiianTiger] #788732 10/31/19 10:26 pm
Joined: Oct 2019
Posts: 68
S
splash Offline OP
BritBike Forum member
OP Offline
BritBike Forum member
S
Joined: Oct 2019
Posts: 68
Originally Posted by HawaiianTiger
You can gear your bike up a little and have a nice highway cruise all the way to Hilo.

Cheers,
Bill


Thanks Bill, Does adding a 5th gear come with adding a new gearbox or adding parts along with a new gear? For now I got enough on my plate unless I'm more than half way there to do the 5th gear add on.

What's the easy way to the crank shaft? through the primary case, eh?

Last edited by splash; 10/31/19 10:51 pm.

1970 Triumph tiger owner
Re: 650 to 750 swap [Re: splash] #788746 11/01/19 12:52 am
Joined: Sep 2013
Posts: 2,206
Q
quinten Offline
BritBike Forum member
Offline
BritBike Forum member
Q
Joined: Sep 2013
Posts: 2,206

this is my interpretation of your story .

the bike overheated going up that mountain pass
and the pistons expanded and seized onto the cylinder walls ... a four corner seizure .
the noise you heard was not the valves , they are noisy enough ... but the sound was detonation
..probably leading to the egde of , or into the even greater evil ... pre- ignition .

When the engine cooled down , the Piston shrank enough to run again .
Sometimes this can happen with little damage ... .
But it's more likely that it started a chain of events
made a little worse each time the bike was again run .

Overheating pistons , unable to shed enough Heat to the cylinders
Smear aluminum on to the cylinder walls and into the ring grooves ... and the rings stick .

Re: 650 to 750 swap [Re: splash] #788749 11/01/19 1:57 am
Joined: Jun 2007
Posts: 6,606
HawaiianTiger Offline
BritBike Forum member
Offline
BritBike Forum member
Joined: Jun 2007
Posts: 6,606
It's a pretty typical story of how a Triumph basically self destructs. I'll get some flack about that....
But, for people who are not that involved with these bikes, the amount of maintenance needed seems ludicrous, to them.
Having said that, the bike you have needs the least amount of attention than do most other years and models of Triumph.
Still, the basics need to be done. Keeping the timing correct, the valves adjusted and the carb working correctly is necessary in order to prevent the kind of failure you have experienced.
As far as gearing up, when you have the motor apart, it will be easier to change out the gearbox sprocket. Have a look at how many teeth it has. The TR6's often had 18 tooth sprockets so a bump up to 19 is a no brainer, as far as I'm concerned.
A five speed nets you nothing at all, except very slick shifting.
Cheers,
Bill


Bikes
1974 Commando
1985 Honda Nighthawk 650
1957 Thunderbird/T110 "Black Tiger"
Antique Fans: Loads of Emersons (Two six wingers) plus gyros and orbiters.
Re: 650 to 750 swap [Re: splash] #788757 11/01/19 7:58 am
Joined: Aug 2001
Posts: 8,008
triton thrasher Online Content
BritBike Forum member
Online Content
BritBike Forum member
Joined: Aug 2001
Posts: 8,008
Pulling up a hill at too low rpm.

Maybe weak mixture and neglected points and timing.

If it pings again, shut the throttle immediately.

If it seizes again, inspect the pistons.


Amateur Loctite enthusiast.
Re: 650 to 750 swap [Re: splash] #788765 11/01/19 12:57 pm
Joined: Oct 2006
Posts: 3,285
I
Irish Swede Offline
BritBike Forum member
Offline
BritBike Forum member
I
Joined: Oct 2006
Posts: 3,285
As you gain altitude, the air gets thinner and the carburetor setting gets leaner. The engine begins to overheat.
"Lugging" the engine at low speeds doesn't help, either.

Also, next time you get stuck behind a slow truck, just pull off he road and wait 'till he's gone.

Re: 650 to 750 swap [Re: splash] #788772 11/01/19 2:17 pm
Joined: Nov 2012
Posts: 1,186
K
koan58 Offline
BritBike Forum member
Offline
BritBike Forum member
K
Joined: Nov 2012
Posts: 1,186
An engine correctly jetted at low altitude will run progressively richer as altitude increases.

Re: 650 to 750 swap [Re: splash] #788814 11/01/19 6:44 pm
Joined: Jun 2007
Posts: 6,606
HawaiianTiger Offline
BritBike Forum member
Offline
BritBike Forum member
Joined: Jun 2007
Posts: 6,606
Reminds of a guy here who killed his bike with kindness. He came up the deceptive Haleakala grade in top gear a 50mph. He burned up his motor. That grade has taken out dozens of bikes over the years. Spin that puppy at a high rpm up grades. Downshift if necessary.
Nature of these old beasts. They are not commonly tuned for low end torque. They can be....see Thunderbird specs.....but the sport bikes are terribly inefficient at lower rpms.
Having said that, you can usually tell if the motor is having a hard time of it. Pinging is the first clue. But if you're facing a head wind, or have open pipes, or a bit deaf, you can't hear it.
Cheers,
Bill


Bikes
1974 Commando
1985 Honda Nighthawk 650
1957 Thunderbird/T110 "Black Tiger"
Antique Fans: Loads of Emersons (Two six wingers) plus gyros and orbiters.
Re: 650 to 750 swap [Re: splash] #788855 11/02/19 1:40 am
Joined: Oct 2019
Posts: 68
S
splash Offline OP
BritBike Forum member
OP Offline
BritBike Forum member
S
Joined: Oct 2019
Posts: 68
I just ordered 750 bore kit. No more low RPM cruising. Now to get into the crank case to pick out the piston skirt and to get the crank shaft turned.

Add +1 on the sprocket teeth just because I'm in there, eh? More torque I assume, right Bill?

LOL I'm gonna have to go back to my special tools thread and order tools to get through the primary case.

Bill, I'm going to the private airport by Lahaina on Maui next Thursday two times for tours there. Is there anything you can do with a 650 jug with cracked left barrel? I don't believe I'll need it anymore and have no clue what to do with it besides use it for a paper weight on my desk.


1970 Triumph tiger owner
Re: 650 to 750 swap [Re: splash] #788873 11/02/19 5:47 am
Joined: Jun 2007
Posts: 6,606
HawaiianTiger Offline
BritBike Forum member
Offline
BritBike Forum member
Joined: Jun 2007
Posts: 6,606
Yeah, that's a paperweight you have. Good for you going 750. you won't be sorry. If you asked Mr. Healy, the moderator, he would say that a 70 TR6 with a 750 kit would be one of his favorite bikes.
Keep at it and don't be shy about asking questions around here. Lots of folks with good expertise ready to lend a hand.
Cheers,
Bill


Bikes
1974 Commando
1985 Honda Nighthawk 650
1957 Thunderbird/T110 "Black Tiger"
Antique Fans: Loads of Emersons (Two six wingers) plus gyros and orbiters.
Re: 650 to 750 swap [Re: splash] #788884 11/02/19 10:27 am
Joined: Sep 2008
Posts: 1,220
S
Stein Roger Online Content
BritBike Forum member
Online Content
BritBike Forum member
S
Joined: Sep 2008
Posts: 1,220
A couple of the things a 750 kitted 650 has going for it are a better combustion chamber shape with less piston dome for the same compression ratio. Especially on a T120, the port size is better suited, and cylinder filling is improved at any speed. The smaller TR6 ports gives an almost too fierce throttle response and takes some getting used to, but I like it. A bigger carb will soften it a little.
The pistons are usually almost the same weight as the 650 and won't upset balance much.
Compared to a T140, with its bigger wrist pins and heavier pistons on shorter rods, this means less severe vibrations.
Tom Gunn, if I understood him correctly, says the rod to stroke ratio in the 650 keeps the internal stresses in the safe zone, but only just. The T140/TR7 comes very close to, or even over this threshold.
On the other hand, the bigger twins got stronger cases, very beefy rods, and a de-tune...
(Btw Don, the rods are 1/2" shorter, but the barrels are only 3/8" shorter)

Myself, I've come to like the long rod engines better and they seem to hold up well with a 750 kit. They're usually a little sweeter vibration-wise, or maybe I should say less harsh.
I've owned and worked more on T140/TR7s though, and once you learn to re-torque them correctly, and use them sensibly, they're pretty solid.

No old Triumph will last for extended mileages though. The valves and guides wear fast, even the best you can find will be toast after maybe 20.000 miles,and the piston rings won't last much longer. The primary transmission will be suspect then as well, the chain will need replacing and the shock absorber in the clutch center may have had it. Funny thing though, the Triumph clutch may work pretty well even when worn out.
With less than 10.000 miles on it, Id be surprised if your engine is worn very much, but sitting still isn't good either, bearings and cylinders can corrode, and the outer gearbox bits very likely rusted a lot.
My point is that you take this as an opportunity to give the engine a full overhaul.

SR

Last edited by Stein Roger; 11/02/19 10:30 am.
Re: 650 to 750 swap [Re: splash] #788932 11/02/19 6:56 pm
Joined: Jun 2007
Posts: 6,606
HawaiianTiger Offline
BritBike Forum member
Offline
BritBike Forum member
Joined: Jun 2007
Posts: 6,606
Triumph is an odd mix of unreliable vs built like a tank. For example, the gear box is pretty robust and only the early five speed boxes had weakness. They seem to run forever and just start whining a bit when they get high mileages(my bike)
You won't find a worn out engine sprocket.
Cam bushings almost never need replacing.
The lower end is usually pretty solid, but an experience like you've had will likely spell the end for your main bearings.
Maybe big ends, too.
On the other hand, the design is antiquated with very wide valve angles that are rough on guides and make a Hemi Head necessary. (high domed pistons, inefficient combustion chamber). This is the main reason good fuel is necessary and very long ignition advance compared to anything modern.
Triumph could have fixed these things very early on, but didn't. It's a source of great frustration for me.

Cheers,
Bill

Last edited by HawaiianTiger; 11/02/19 6:57 pm.

Bikes
1974 Commando
1985 Honda Nighthawk 650
1957 Thunderbird/T110 "Black Tiger"
Antique Fans: Loads of Emersons (Two six wingers) plus gyros and orbiters.
Re: 650 to 750 swap [Re: HawaiianTiger] #788951 11/02/19 8:55 pm
Joined: Sep 2013
Posts: 2,206
Q
quinten Offline
BritBike Forum member
Offline
BritBike Forum member
Q
Joined: Sep 2013
Posts: 2,206
Quote
Is there anything you can do with a 650 jug with cracked left barrel? I don't believe I'll need it anymore and have no clue what to do with it besides use it for a paper weight on my desk.

before you bin the cylinder
pull the tappet blocks out
... i doubt you're a new cylinder kit ... will come with any

Re: 650 to 750 swap [Re: splash] #788995 11/03/19 8:10 am
Joined: Oct 2019
Posts: 68
S
splash Offline OP
BritBike Forum member
OP Offline
BritBike Forum member
S
Joined: Oct 2019
Posts: 68
Thanks everyone,

oh yeah, the tappets and blocks are out.

I hear there is a 20 tooth sprocket.

So, I'm in the middle of learning of what needs to be replaced and what can stay. A large piece of the left piston skirt I believe is jamming the crank shaft against the case as I gently and slowly push down on the right hand piston which is still attached to the connecting rod. There are small pieces of the skirt on the center of the crank where the timing mark is. I only assume the crank needs to be turned, main bearings replaced, and new connecting rods or should I keep these from the 650? One pushrod was bent really bad on the left side so I figure just replace all four of them. New bore kit is on it's way and I plan on new valves and valve guides for the top end as well as resurfacing it. As far as machine shop is concerned I figure head resurfaced and crank shaft turned, eh?

IDK, it's my first time rebuilding a motorcycle. My rebuild experience comes from rebuilding a 78 Triumph Spitfire which I'm thinking about selling from New Orleans.

Last edited by splash; 11/03/19 8:15 am.

1970 Triumph tiger owner
Re: 650 to 750 swap [Re: splash] #789014 11/03/19 11:37 am
Joined: Sep 2008
Posts: 1,220
S
Stein Roger Online Content
BritBike Forum member
Online Content
BritBike Forum member
S
Joined: Sep 2008
Posts: 1,220
Splash, I think you're on the track. I doubt the crank will need grinding (which is the proper term). I would check if the rods are straight, if they are, re-use them. Some will have it that alloy rods are made of sugar, they aren't. I ran a tuned Morgo 750 T120 like an idiot (frequently up to 8000 rpm) for nearly 100.000 miles until the crank broke. The rods were still straight and round and were retained when I rebuilt it.
I'd change them today though, with that kind of use...
One of the beauties of a 750 with a TR6 head is that it won't make much power past 6500 rpm, and it's rpm that kills rods and cranks. Keep a Triumph twin under 7000 and it won't ever break.

Bill just about sums it up, solid bottom end and gearbox, less solid in other places. This is due to it being designed as a 500 and the basic dimensions were never changed. This means a cramped head for a 650/750 as the ports and valves grew in size while the guides grew shorter, along with high lift cams. Your bike may not need any head work, if the mileage is so low, but then it may all the same. On these bikes the valve gear have short rocker arms and the adjuster describes a short radius arc which push the top of the valve away the first half of the lift, and pulls it back the other way the second half. This rocking motion combined with far too short valve guides gives the valves and guides a hard time. There are better quality bits out there which may prolong service life, maybe double it, but not much more. Using "Elephant Foot" adjusters should help quite a bit, I use them on my Trident, but it's too soon to tell yet.
Around here we often use the K-Line system to repair worn guides, which means you don't need to disturb the guide to head fit. That's a good thing. I favor cutting an angle on the inlet guide top instead of using a seal, as the seals require a shorter guide, which is not what you want.
The real answer is to use the longest guides you can and low lift cams, but nobody seems interested in that.

Anyway, the best of luck to you, I'm sure you'll end up with a strong and reliable bike. There will be tons of info at your disposal on this forum, some of the best of it from Hawaii as you have noticed.

SR

Last edited by Stein Roger; 11/03/19 5:37 pm. Reason: "Morgo 750". "a short radius arc". "while the guides grew shorter".
Re: 650 to 750 swap [Re: splash] #789049 11/03/19 6:41 pm
Joined: Jun 2007
Posts: 6,606
HawaiianTiger Offline
BritBike Forum member
Offline
BritBike Forum member
Joined: Jun 2007
Posts: 6,606
The only thing I would add this this advice is to not re-surface the head. They can tolerate about 5 thou of bow in them without problems. Surfacing them causes a lot of problems.
If too bowed, they can be straightened quite easily if your wife doesn't mind you cooking the head in her oven.
I wonder how the push rod got bent........?

Cheers,
Bill


Bikes
1974 Commando
1985 Honda Nighthawk 650
1957 Thunderbird/T110 "Black Tiger"
Antique Fans: Loads of Emersons (Two six wingers) plus gyros and orbiters.
Re: 650 to 750 swap [Re: splash] #789151 11/04/19 5:03 pm
Joined: Oct 2019
Posts: 68
S
splash Offline OP
BritBike Forum member
OP Offline
BritBike Forum member
S
Joined: Oct 2019
Posts: 68
I imagine the pushrod bent when the pin broke out of the piston skirt pushing the piston past TDC which caused the valve to smash into the top of the piston bending pushrod???

I won't get the head shaved, thanks for the advice. I'm not sure about the connecting rods. Both slide about a 16th of an inch along the crank shaft. Is this normal with motorcycles or specifically Triumph cranks/connecting rod? My experience tells me to grind the crank and refit new bearings at the least. However, my experience was wrong about resurfacing the head.


1970 Triumph tiger owner
Re: 650 to 750 swap [Re: splash] #789152 11/04/19 5:48 pm
Joined: Aug 2001
Posts: 8,008
triton thrasher Online Content
BritBike Forum member
Online Content
BritBike Forum member
Joined: Aug 2001
Posts: 8,008
Measure and inspect the crankshaft big end journals, or just yank on the rods, up and down. Don’t regrind it unless it needs it.

The rods sliding along the crankshaft sounds normal.


Amateur Loctite enthusiast.
Page 1 of 7 1 2 3 4 5 6 7

Moderated by  John Healy 

Home | Sponsors | Newsletter | Regalia | Calendar | Bike Project | BritBike Museum | Spiders Cartoons | DVD- Manuals & Parts books
Upgrade to: Gold Membership | Premium Membership | Vendor Membership | Site Sponsor Membership
CLICK HERE to see VIDEO
How the Electric Roller Starter works.


ORDER on eBay. CLICK HERE!

Buy your Electric Roller Starter here
Powered by UBB.threads™ PHP Forum Software 7.7.3