7 replies to this topic

[ChrisB7]

I have recently replaced the crank seals and also the large O ring on the disk valve cover but engine oil still seems to be getting through into the cylinder. Bike smokes a fair bit as a result. Does anybody have any ideas of what else I can do to stop the engine oil getting through?

[pedronicman]

ChrisB7, on 25 July 2011 - 06:00 PM, said:

I have recently replaced the crank seals and also the large O ring on the disk valve cover but engine oil still seems to be getting through into the cylinder. Bike smokes a fair bit as a result. Does anybody have any ideas of what else I can do to stop the engine oil getting through?

I would be 100% sure that the gearbox oil is passing between the centre crankcases
as it is only sealed by sealant as thhese engines aren't fitted with a centre gasket.

If you split the engine to fix it make sure you use a good quality case sealant
like THREEBOND engine sealant.
Do not use silicone houshold sealnt.

Cheers

[ChrisB7]

pedronicman, on 25 July 2011 - 06:49 PM, said:

I would be 100% sure that the gearbox oil is passing between the centre crankcases
as it is only sealed by sealant as thhese engines aren't fitted with a centre gasket.

If you split the engine to fix it make sure you use a good quality case sealant
like THREEBOND engine sealant.
Do not use silicone houshold sealnt.

Cheers

[ChrisB7]

Thanks for the advice, that's a job to be done over the next few weeks!
Cheers Chris

[Reginald]

Hi, from this conversation it sounds like crankshaft seals can be replaced without splitting the cases?? And how necessary is to rep;lace the rotary valve o ring as I am currently ordering parts and haven't included that?
Any advice welcomed.

[ChrisB7]

Hi, Yes I replaced both seals without splitting the engine. One seal sits in the disk valve cover and the other sits in the magneto plate that sits behind the flywheel. (the flywheel cover bolts to this plate) I replaced the O Ring in the disk valve cover just as a precaution even though the original looked ok. Obviously, I have been unlucky in my attempt to minimise the work as I now have to split the engine to replace the sealant. I originally thought that there was a gasket between the two sides of the engine.

Cheers Chris

[Reginald]

Well with the help of Feetfun [thanks Dave] and some advice from Martin on locking the engine with a bolt thought the cases we replaced the clutch side oil seal - still leaking and burning oil - bugger - is it worth doing the rotary valve o ring? or could I be up for a spilt the cases job?

[Reginald]

Well she's been dismantled recently and the induction valve cover o ring looked stuffed ie flat it also appeared to sucking air thru cases. Splitting the cases was worth while as kickstarter engagement dogs were chipped. Piston still standard and didn't need re bore - so new rings only.
gearbox and big end was fine [those main bearings are huge].
Looking fwd to having her back together.