Topic: Removing alternator for racing CB750

[ttr400]

I know it was discussed at some time but I can't seem to find it.

I would like to remove the charging system and starter gears etc and run a total loss system. My question is what is the best way to block of the oil holes on the crank? Or how do you guy's do it.
Not sure but I think it might have been Rob from voxonda.

Kevin

[voxonda]

Hey Kevin,

Some turn a alloy ring on the lathe and shrink in on the crank. What I have done is take the innerrace of a bearing and glued it on with Loctite, after more than a year no problems.

Cheers mate,

Rob

[lordmoonpie]

That's all I did - turned a little alloy top hat shape on the lathe and interference fitted it to the hole - same for the starter. You should see some pics of mine in the ultimate motor thread Kevin...I have the same setup on the CB45 racer and it's been leak free for 8 years of racing now.

[ttr400]

Thanks guys.

Do you think it would require a seal on that end of the crank?

Kevin

[voxonda]

Thanks guys.

Do you think it would require a seal on that end of the crank?

Kevin

Hi Kevin,

No, it does not. Do you use the oem cover, or make your own? I used the oem, but make it slimmer but cutting approx. 50 m/m.

No pic's yet?

Cheers, Rob

[754]

You dont need a seal.. the stock ring gear has a seal to  keep oil in the bronze budhing. The alloy spacer can be a slip fit, but no real clearance, with a press fit tho, it cant come off easy , if you forgot it, might lose pressure..
 my 836 is welded shut!

[ttr400]

Got it, I was worried of a pressure loss there. Shrink fit sleeve it's going to be.

I'm going to machine a cover to replicate the CR cover. maybe later I might have it cast in magnesium.

No pics yet rob, but it is coming along. mainly getting all the parts together etc. I'm busy with the frame and swingarm at the moment and all the new brackets to finish. Can only weld them on when the Tanks and bodywork get here.

Kevin

[lordmoonpie]

My cover is slimmer and replicates the CR cover in magnesium. About a year ago there were lots of them doing the rounds at the big classic shows but now, nothing :-(

I suppose the 750 needs a bit of oil pressure down there but my little 50cc minarelli racer years back had the kickstart hole plugged.....with a wine cork! 

[kos]

WE use silver solder to plug that starter gear hole, as that will not heat the end up enough to warp crank. Then use the OEM bolt, cut off flush and a slot milled into end of bolt to install or remove with flat bladed screw driver.

If you don't care if your friends laugh at you when and if they see the insides of your engine...I know someone who stuck a piece of solder in the hole and held it place  with a small hose clamp 'round the crank!

And no..it did not effect the crank balance one bit.


He won Daytona with it!

KOS

[lordmoonpie]

Superb story Mark - it just goes to show how some of these winning bikes have fixes on them that the restorer or show bike would just cry to have on them. One of the Ducati dealers here in the UK used to say that he built race bikes to look like a million dollars from 30 yards away....don't look any closer 

[voxonda]

Know what that dealer means, ever looked at a MVAgusta 350/500 up close?

[Sam Green Racing]

If you don't care if your friends laugh at you when and if they see the insides of your engine...I know someone who stuck a piece of solder in the hole and held it place  with a small hose clamp 'round the crank!

And no..it did not effect the crank balance one bit.


He won Daytona with it!

KOS

  The trick is, don't let them see inside your motor In a mad rush to get the bike out, the old motor literally had insulation tape wrapped around it. I meant to do somthing with it after the first outing but forgot, 4 years later

In respect of the pipe clip, what a simple way to ballance your crank.

Sam.