Honda CB72 Racer

[s3nss]

Hello guys ,

last year my father bought a honda CB72E racer with some special parts ; tomaselli clip ons - four leading front brake - akront rims - high compression pistons - close ratio gearbox etc etc . this week it was alive for the first time , was not running so well but after modifying the jets it serious kicked some ass :)
Did a couple of test runs , and discovered a leak at the outgoing gearbox shaft , where the front gearwheel is fitted,i think its the seal inside the bronze bush !! Not shure ,, but ok now my question ; does anyone have a drawing how its all fitted ? i cant see it from the outside . So if anyone can help us , in advance thank you !
attached a picture from the gearbox shaft and the machine complete ...
excuse me for my drossy english but normally i write/speak dutch !!

[rrekr]

Hello and welcome s3nss,
That is a fabulous motorcycle. This is not a standard CB72/77 arrangement as far as I know.
The stock setup is a lip type oil seal outside the bronze pushrod bushing. Could that be an "O"ring
showing inside the bushing? When you said close ratio, is this the 5 speed gearbox setup? Hopefully somebody familiar with this setup will chime in. By the way, you're English is fine.
Randy

[s3nss]

Hello and welcome s3nss,
That is a fabulous motorcycle. This is not a standard CB72/77 arrangement as far as I know.
The stock setup is a lip type oil seal outside the bronze pushrod bushing. Could that be an "O"ring
showing inside the bushing? When you said close ratio, is this the 5 speed gearbox setup? Hopefully somebody familiar with this setup will chime in. By the way, you're English is fine.
Randy

thanks rrekr !

I'm shure its an oil seal inside that bronze bush and not an O-ring , but the question is how do i replace it ? Is it possible through the clutch side ? Is it possible to remove the bronze bush on any manner ?
The close ratio gearbox is an 4 speed setup with a very long first gear .. If you want , i upload a movie for you !

John

[rrekr]

John,
The bushing in the stock maindrive gear is quite thin and to my knowledge was never sold as a service replacement part. If these were simply installed out of sequence, (hard to imagine), there is a chance you could go in from the clutch side on the mainshaft. The hole through the stock mainshaft will start as 13mmØ and then neck down to 12mmØ. You could possibly use a rod less than 12mm to knock out the seal and bearing. I would reinstall in the factory order to insure lube to the bushing. Be particularly carefull when you reinstall that very thin bushing, the factory original had a heavy press. As far as the movie, YES! Also,if you EVER take the engine apart, I would love to see some pictures.
Thanks,Randy
PS When I said thin, I was referring to thickness.

[s3nss]

John,
The bushing in the stock maindrive gear is quite thin and to my knowledge was never sold as a service replacement part. If these were simply installed out of sequence, (hard to imagine), there is a chance you could go in from the clutch side on the mainshaft. The hole through the stock mainshaft will start as 13mmØ and then neck down to 12mmØ. You could possibly use a rod less than 12mm to knock out the seal and bearing. I would reinstall in the factory order to insure lube to the bushing. Be particularly carefull when you reinstall that very thin bushing, the factory original had a heavy press. As far as the movie, YES! Also,if you EVER take the engine apart, I would love to see some pictures.
Thanks,Randy
PS When I said thin, I was referring to thickness.

Thank you very much Randy ! This will help , i hope ;-)
If i ever take the engine apart i will take picture's . recommended i think , to put it all together !
Can i buy the seal at a bearingshop or something like that ? Or anything like that ? Or do i need to order the seal at honda ?ebay?

regards john

[s3nss]

http://nl.youtube.com/watch?v=-hXfBoverz0

sorry for the bad video quality but the sound is amazing :-)
it's the intention to race with it next year in the 250cc group

here a movie from the honda cb550 ( mike hailwood replica) he race's with
not for winning , only for fun!

http://nl.youtube.com/watch?v=nm503vsuOAI

[LOUD MOUSE]

I agree with Randy that this seams to be reversed as for parts installation. As for me I'd get a tool with a hook and using the hole I'd pull the metal part out. I suspect you will find a seal behind it. Don't get to worried about damaging the metal part as when you reinstall it (followed by the seal) all it does is place a depth limit for the seal. HONDA part number for the seal is 91205-259-000 and if ya can't locate one I have them here in TEXAS. Come to think of it ya may want to look at the clutch end of this shaft and check for an "O" ring inside the shaft where the Clutch Lifter Joint/Piece installs. HONDA part number 91305-259-000. ...........lm

John,
The bushing in the stock maindrive gear is quite thin and to my knowledge was never sold as a service replacement part. If these were simply installed out of sequence, (hard to imagine), there is a chance you could go in from the clutch side on the mainshaft. The hole through the stock mainshaft will start as 13mmØ and then neck down to 12mmØ. You could possibly use a rod less than 12mm to knock out the seal and bearing. I would reinstall in the factory order to insure lube to the bushing. Be particularly carefull when you reinstall that very thin bushing, the factory original had a heavy press. As far as the movie, YES! Also,if you EVER take the engine apart, I would love to see some pictures.
Thanks,Randy
PS When I said thin, I was referring to thickness.