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The gears are induction hardened, once the dogs have rounded off you have gone through that so need to get it done again.
You'll be lucky if they stay the same size and don't need re-finishing.

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Originally Posted by NickL
The gears are induction hardened, once the dogs have rounded off you have gone through that so need to get it done again.
You'll be lucky if they stay the same size and don't need re-finishing.

By switching the gears back to their proper places I'm using the sharp edges that haven't been worn. So hopefully 'Good Enough" for Barber. After Barber I have somebody who can back cut the dogs and heat treat again. He answered the call...

Last edited by Semper Gumby; 09/09/21 11:07 pm.
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What was causing the binding though? And the non selection?


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Putting a rake on the male dogs is easy enough, the females are a bit of a pain
to say the least. Don't go bananas with the angle, may be worth asking John Hill what he used.

Give the bloke who's doing the job the 2 shafts so he can make sure the gears still
slide nicely after heat treatment. (i bet they don't!) He'll probably end up using a
stone to finish the buggers on the splines.

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Nickl - 10 degrees

Mark - I think its the angle on the sliding gear dogs LS 2nd gear forcing the LS 3rd gear into the top gear. The first to second gear would overshoot and start to pull out. The the angle on the dogs would take over. Wear on the bent shift forks probably didn't help either.

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Hi

I think you want to give "Barber" a miss and sort your engine out, your scatter gun approach to your issues is pretty hard to follow. There have been plenty helpful suggestion to your possible problem and methods of assemble.
I'd suggest you fix your crank float before to start with before you junk the motor. Fix the crank float them move on the the G/B. If the gearbox is dragging to the extent you say, then there will be signs inside showing heat and wear to give you and indication where to look first.
If you have a junk timing side casing, cut the crank area off and section the gearbox area, this will allow you to assemble the G/B and see what's going on in there, you'll learn a lot (yes I know all G/B layshaft shimming is different with each casing).
If your 4th L/S gear is being pushed off the shaft, then the shaft is worn.
One or two degrees is all you'll need to back cut the gears.
As Nick said it takes time and patience to get these boxes working good.

My tuppence worth

John

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10 degs? hmm i tried 8 and that was too much really. The gears didn't last long but then
i didn't have them re-hardened. Gearchanges were noticeably heavier and slower but my box was
turning about 20% faster than standard.
I would have thought 5 may be more like it.

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To be on the same page:

[Linked Image from i.postimg.cc]

The drive is through the main shaft, and for 123 it drives the lay shaft that drives the main 4th gear attached to the sprocket, the sliding gear on the lay shaft engages 1st N or 2nd, Ist through the 1st gears with the sliding gear locking it to spin the shaft. 2nd locks the 2nd spinning gear to drive from the main shaft sliding gear on its spline, selecting 3rd slides the gear into 3rd driving through the lay shaft sliding. Top just locks the main shaft to the output gear and sprocket.

With the lay shaft pushed into the carrier you should be able to check all the engagements except top and it should be in the correct spot when you put the cluster in anyway.


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JER.Hill - The crank is fixed on the timing side with the roller bearing conversion so it "floats" on the primary side. The belt drive pulley is up against the splines and not shims against the primary side roller bearing.. I would think a primary chain in this set up would be prone to high wear while a belt would simply move back and forth across the clutch basket as it self centers on the front pulley. Hence my desire to have Dave M's KTM clutch with its Cush drive. I see only benefits to having a Cush drive in the system. But maybe I'm wrong about this... The end of this may be I go back to the timing side bush, lock the crank to the primary side as originally designed and re-install the stock chain and clutch and its Cush drive.

Race bike requires a track to sort but you are correct. There is a track north of Atlanta I can check into before Barber.

Nick - Noted thank you.

Mark - it's a really simple box. I can now hold the thing in my hand, move the selector plate and watch the shift forks push each gear into place. Somehow strangely reassuring. The funny thing is the cost cutting of BSA making the 2nd and 3rd gears the same size in the STD box and thus reversible (for when the dogs get rounded on one side) creating the large jump between 2nd and 3rd which in the mountains is so useless. It forced other compromises on the engine that made it to be merely ordinary - all in the name of cost savings.

Last edited by Semper Gumby; 09/10/21 2:58 pm.
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Are you using a roller for the timing side/ or is it a combi roller and ball ?, if the latter, then end float is sorted, if the former you may like to consider an additional ball bearing mounted to an outrigger plate outboard of the stator, see mark parkers motor, this will capture the crank , stiffen the drive train and nix any endfloat issues, allowing use of chain or belt.

here are the tooth counts i used in 2002 for close first and second, std 3rd and top

mainshaft 4 - 23, 3 - 26, 2 - 22, 1 - 16

layshaft, 4 - 17, 3 - 22, 2 - 25, 1- 24

This give the following ratios,
1st 2.029
2nd 1.471
3rd 1.145
4th 1

With stock CR options this is the best compromise i can come up with for a four speed, on 21 /47 gearing, clutch slip is needed to around 15 mph
once underway there are no big gaps.

std 1st with close ratio 2nd will get you off the line OK, but you will fall into a hole on the change to 2nd.

Close 1st and 2nd will give a little delay off the line but far more thrust once underway.

Also many have found that the CR 1,2 stock 3 , 4 , seems to give a sweeter change

Last edited by gavin eisler; 09/10/21 4:35 pm.

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Gavin - It's a Combi Roller and Ball. I would like it to be roller only...

Thanks for the ratio numbers.

Last edited by Semper Gumby; 09/10/21 4:50 pm.
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if its a combi ball roller, you should not have end float problems on the primary side, the crank is located at the timing side, apart from a little thermal expansion the primary drive sprocket is fixed axially. Devimead pioneered use of the combi bearing , my self and others have used it with no problems for decades, it does need careful setting up, but once done its pretty much fit and forget. I had to replace my TS combi not beacause of wear, if it wasnt for a small spot of condensation damage I would still be using the original Devi bearing fitted in the early 70s. i only changed it out because the motor was apart and I noticed one rust dot the size of a full stop.


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The stock gears have no rake/angle on the dogs, the twisting motion of the
shafts is what pushes them out of selection The shafts bow with the transmitted torque.
You are relying on the dog engagement and the camplate/selector forks to hold the gears
together. That's why shimming and getting full location is so important with these boxes.
A slight rake on the dogs will make the change slower but if you can live with that it will
improve matters. Too much cut angle will prevent high speed gear change and will knock
the dogs out more quickly. Getting the hardening right will not be easy, you could have
a stock gear tested first and try it at that.
The simple solution for your endfloat problem is to just use a ball race on the drive side.
That's all i have in the 750 race outfit i prepare at the moment, it won't live as long as a
roller but unless you plan to do the TT every month it'll be fine for a couple of years.

The engine is far from ordinary, it won more sidecar races in Europe and the UK than any
other back then, just put together well. Chris Vincent, Peter Brown etc never even used
an end feed setup, nearly all the troubles were with gearboxes not being able to handle
the power they were getting from the a65 engine. I used to push and beat 1200cc Honda
4's with my old crate, you wouldn't have got a triumph twin to come anywhere near. we tested
a 650 at a meeting a few weeks ago up against an 840 triumph and a 920 norton, both had
5 speeds and both ran on methanol, Won 3 races out of 6. Not bad for a 650 eh?

Last edited by NickL; 09/11/21 4:48 am.
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This is with Gavin's close 1 and 2 with a std box, this has the slick ball ended plunger and you can tell riding it. It swaps gears very sweetly and the whole thing is quite smooth. If you go in 47seconds he takes off slow from a roll because drag starts are pretty hard on stuff. I don't know if he uses the clutch, it's not really necessary. But into that 2nd gear and it pulls, it's maybe hard to appreciate the drive in that gear and speed it's picking up. It's running 20-38t but on a 17" wheel similar to 20-40 on an 18. I've used 8500 on one in second but this sounds like he's shifting earlier maybe.

If 2nd doesn't haul someone back I'd be surprised. And we can always do a better head. Which we are going to try because 34mm ports and carbs are flowing about the same as the 38mm version like this has, and more port speed is more hp right through it seems. That changes what you need for gears which are really to keep it in power, changes just take time.

A stock 650 even with a blistering start would be overhauled by the change out of 1st. They are hardly comparable. The tall gears gives the motor something to push against. I think some drag racers do not use first because of that, they probably use wheel spin though.



A main bearing NKIS30 This is from China std clearance $13au each but he had to buy five. Mowers and stuff I work on from the US have Chinese bearings so I expect it's good.

[Linked Image from i.postimg.cc]

Last edited by Mark Parker; 09/11/21 4:43 am.

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There's some stuff i will buy from china and some i won't, bearings are on the the list of won't.
The japs had to buy the companies to find out how to make the steel etc. Maybe in 10 years.......
Same with chains and a few other things.

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Hi Semper

Right. I understand now what you are referring to as "float", you are referring to work expansion. The timing side combo Brg is fine, you do not have to do anything to the crankshaft, so you can cut this from the conversation.
Now what you are identifying to us, is that your drive pulley is locking out on the crank spline and not against the inner race of the roller Brg as it should be.
Changing from the combi Brg back to bush is a none starter and just giving your self way more work.

What you need to do is determine your issues and concentrate on correcting them.
1) Inspect your pulley, spacers and identify all components are correct and shim to correct.
2) Pull the G/B, find and address the issues found, reassemble correctly.
3) Assemble the clutch and check/correct alignment as necessary.
Focus on what your issues are and correct, not jump around all over the place.

my tuppence worth

John

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Originally Posted by gavin eisler
Are you using a roller for the timing side/ or is it a combi roller and ball ?, if the latter, then end float is sorted, if the former you may like to consider an additional ball bearing mounted to an outrigger plate outboard of the stator, see mark parkers motor, this will capture the crank , stiffen the drive train and nix any endfloat issues, allowing use of chain or belt.

here are the tooth counts i used in 2002 for close first and second, std 3rd and top

mainshaft 4 - 23, 3 - 26, 2 - 22, 1 - 16

layshaft, 4 - 17, 3 - 22, 2 - 25, 1- 24

This give the following ratios,
1st 2.029
2nd 1.471
3rd 1.145
4th 1

With stock CR options this is the best compromise i can come up with for a four speed, on 21 /47 gearing, clutch slip is needed to around 15 mph
once underway there are no big gaps.

std 1st with close ratio 2nd will get you off the line OK, but you will fall into a hole on the change to 2nd.

Close 1st and 2nd will give a little delay off the line but far more thrust once underway.

Also many have found that the CR 1,2 stock 3 , 4 , seems to give a sweeter change


Mainshaft 2nd should be 23t.

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Ah, you are correct Nick , well spotted, my notes were wrong. I will edit the original post.


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There is no edit option? Oh well.


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Stock ratios with 21-47 sprockets. Which is way low for a hot 650 an a track with a decent straight. Changing at 8000.

[Linked Image from i.postimg.cc]

C/ratio 1st and 2nd.

[Linked Image from i.postimg.cc]

With std 1st and C/r 2nd 8000 turns into 4,495rpm and depending what was done to the engine might be dropping it in a giant hole.

Changing at less than 8,000 would be worse. And it would need balancing for high rpm. You could obviously use 9,000 if it made power to there, but you need drive by 4500 or less, and that high rpm shouldn't be necessary with better final drive ratio. And C/r 1st and 2nd, the engine needs gearing topush against.


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close Layshaft 2nd is 25t

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So complicated. There are three types of people in the world, those good at maths and those that aren't.

I'll try again: This has the John Hill PES 5speed as well.

[Linked Image from i.postimg.cc]

This is if you geared up to 20-42t. You can see how good 3rd to 4th is. It shouldn't die at that change.

[Linked Image from i.postimg.cc]

Last edited by Mark Parker; 09/21/21 6:53 am.

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Cool Mark. Great info - Can you show that last pic with all the numbers on the right in view?

Also can you post a pic with 22-26 in second and 25-23 in third as that what was in the box when I first removed it on my own. The person doing the install obviously thought the gears went 1-2-3-4 from right to left along the shafts rather than 1-3-2-4 like they should be. He had the CR 2nd turned around in the third position. I would like to see the numbers on that install/set up. So what I pulled out was STD 1st STD 2nd ??? 3rd and STD 4th!!!! Took me two hours to figure out what had been done. My eyeballs literally looked like my avatar. <<<<<<<<

OK Dumb questions:
1) Mark in the last pic - All the changes are from 8000 rpm?
2) So with a 8000 change the rpm drops to 5797 from first to second?
3) What sized wheels will result in these speeds?

Because I run 18" rims with 110/80-18 Avon (for the moment). I need to see I'm comparing Apples with Apples and not ...

My shift point has been 7700 rpms.

The NOVA website list percent drop between gears also which is nice. Mark anyway you could add another column?

Thank you guys - this is really useful info.

Also FWIW - i discovered an error in the 1971 A65 parts book on page 21. The mainshaft second gear STD part number 68-3120 is listed incorrectly as having 23 teeth. It should be 22 teeth as it is listed below for part number 31 68-3120. That helped add to my confusion about all of this....

Last edited by Semper Gumby; 09/21/21 1:39 pm.
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This is with 18" wheel. On the road my Brother's 750 uses 20-40t with an 18" Ben's 750 with 17" wheel uses 20-38t mine uses 21-36t.

Yep 8000 in C/r 1st puts you in C/r second at 5797, again from 8000 this time in at 6228 for 3rd and 6988 when you go for top. The available hp to accelerate the thing gets less and less at speed so it keeps rpm in a closer more powerful zone. You may only have a few hp left to accelerate you in 4th and if that goes in at 6000 it may not even make it there. Or it may have very few hp available and C/r would have it driving harder on the change. In have no idea what Quaif were thinking with the Triumph 5 speed and the one they made for the A65. John's box shows he understands ratios, it works helping the engine even changing at low rpm.

I think std gears would be better than just a C/r 2nd and a std 3rd always better except maybe a peaky 500.


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Originally Posted by Mark Parker
<snip>
I think std gears would be better than just a C/r 2nd and a std 3rd always better except maybe a peaky 500.

I met a guy at Topeka who swore he raced a STD gearbox and did really well.

Any chance you could send me a copy of that Excel file. I'd love to play around with it.

And I forgot to answer your question from earlier: we are limited to 32mm carbs in this class.

Last edited by Semper Gumby; 09/22/21 1:39 am.
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