BEC - Paper Gaskets / RTV Sealant
Guinness - 15/9/09 at 06:33 PM
Right, I've dismantled and split the cases on the old ZZR engine.
Found the source of the ends of the circlips as being in the gearbox. Stripped it apart, removed the bits of circlip left in there, fitted new ones
in their place, replaced the selector forks (looked a bit worn) and a couple of the gears (again the dogs looked a bit chipped). Then I re-assembled
the gearbox and have finally started the re-assembly of the engine.
I've joined the two halves of the engine using RTV sealant as recommended in the Haynes. And I've fitted a new paper clutch gasket to one
end of the engine.
But at the other end, I'm waiting on the ignitor rotor cover gasket and the final drive gasket. Then I'll need a sump gasket. These are
all on order at the local dealers, and will arrive some time tomorrow.
But, can I use the RTV sealant instead?
I have a spare paper gasket for the final drive, but it got soaked in oil during the dismantling. It's not ripped, just wet with oil.
How do paper gaskets work? Do they rely on soaking up some oil to expand anyway?
It would be nice to make a bit more progress tonight, as I really want to be back on the road this weekend.
Cheers
Mike
ReMan - 15/9/09 at 07:00 PM
I always grease mine makes them more likely to be reuseable.
I would'nt use RTV (Silicon) unless you can help it, too much risk of stray bits clogging the oilways. A very thin film of normal sealer if you
must
Guinness - 15/9/09 at 07:06 PM
OK, I'll hang fire until tomorrow then.
You grease the gaskets? Just a thin smear on both sides?
What sort of grease? Normal stuff I've got in the garage?
Cheers
Mike
Andy B - 15/9/09 at 07:09 PM
Reman is spot on with his advice re sealant. In the last year I have had at least 3 engines in that have suffered oil starvation as a result of
sealant clogging the pick ups.
However the trick with RTV is to use good quality sealant and when applying it drag it out until it is almost see through leaving just a thin film.
In general the problems are usually caused by an over application of really nasty quality sealant, a certain blue compound ending in ---mar springs to
mind.
As an alternative to yamahas and hondas hugely expensive sealant we use winzer wurth black RTV, one tube should las a lifetime and it is no where near
as expensive
regards
Andy
Guinness - 15/9/09 at 07:45 PM
I'm using Ducati's Three Bond. Hugely expensive grey stuff.
Hope I haven't overdone it.
Mike
gingerprince - 16/9/09 at 07:42 AM
quote:
Originally posted by Andy B
In general the problems are usually caused by an over application of really nasty quality sealant, a certain blue compound ending in ---mar springs to
mind.
Eep. That's the stuff I used to seal my crankcase back together! Though after I torqued it up I reached into the bits I could still see with a
clean wire coathanger and removed any bits of excess I could see so pretty confident there's nothing floating about. I was slightly disturbed
about how much excess there was of black sealant that had been done by presumably whoever had dismantled it previously though!
Coose - 16/9/09 at 07:42 AM
Paper gaskets should be oiled before fitting - it aids removal in the future and also the correct positioning of the gasket when torquing-up the
joint. Use the same type of oil that the gasket is trying to seal. 
Hylomar is actually really good if used properly - as Andy said, any sealant should be applied with the thinnest smear, with any excess removed if
possible before it goes-off. The problem is that people seem to think that the more you put on the better the seal. What actually happens is the more
you put on the shorter the life-span of you mains/big ends!
Three-bond is very good, though you may find it to be cheaper from Yamaha.
I wouldn't replace a gasket with any form of sealant unless desperate (i.e. in a paddock when it would mean not getting out in the next race),
mainly because the gasket could also be being used as a form of spacer (think base gaskets).