SOHC.co.uk Forums > CB750

cam shaft oil starvation

<< < (3/4) > >>

K2-K6:
Welcome ChrisD and interesting addition to the experience.

It's something that can affect all of them on the site in that the cases of these are, if in good order, very easy to seal when rebuilding.

BUT, and it's a big one, they need a VEEEEERRRY small amount of sealant to do that really well and the risk (as many have found) is that too much causes much more of a problem than the risk of a small oil leak which is fixable with labour, unlike a trashed top-end.

Boringly!! I've always used Blue Hylomar for this without any problems, with the joint surfaces cleaned and dry (wiped with alcohol) you can put just a very thin smear on and let it dry before assembly. If you have to strip it in tghe future you find all but nothing squeezed out of the joint, so nothing gets to travel around the motor.

ChrisD:
Hi top end fixer and cheers for the welcome, yep did use blue holymer on the 88 rebuild and yep plastered it on, so goes to prove to much is not always the best?. Just in process now of getting carbs sorted and came across a few bits in the rebuild kits that are of no use to my beast, namely the air screws that have holes in them and the bike would not idle, so brought a ultrasonic cleaner and cleaned up all the carbs and refitted the old air screws and bingo more or less a perfect idle staright away. Just got to sync them up and hopefully smoothnerss will return (do get a slight pop from No2 pot but it seems to have always done that).

Cheers Chris.

K2-K6:
Yes thinking of the logic of it now the cases bolt up in an all-but metal to metal contact to maintain the tolerance of the main crank bearings, so if you succeeded in keeping much joint sealer in the gap the bearings would probably suffer.

I've taken apart stuff for other people in which the oil puck-up has been all but covered with bits of silicone and similar, guess that's another way of killing the oil supply to critical parts.

They really do survive on good oil distribution and will really go to quite high mileage if kept in good order.

Be interested to see some pics of your K0 when you've got through the refresh/build.

Bryanj:
All I can say is that back in the 70's when i worked for a small independant dealer(now a big Kawasaki dealer) we actually kept as spares on the shelf cam, cam towers and rockers due to the number of locals with 750's that pulled them for non existant gearbox trouble and buggered up the cam with gasket goo of a myriad of colours.

We even had a machinist who would spend the time to grind the cam bearings and bore out the towers then make split phosphour bronze bushes pegged in (as long as the lobes were OK). From memory charged about 70% of new parts cost

Seamus:
Using sealant on the pucks is not unusual. It is recommended by Hondaman in his book on 750's, but not too many other places. Also the recommended sealant is Hondabond or yamabond (also threebond)

Navigation

[0] Message Index

[#] Next page

[*] Previous page