crankcase gasket.

[no sub for cubes]

hi guys

I have my motor in bits at the moment after suspect main seals leaking,before pulling it apart i had quite a bad oil leak from between the case halves,on now inspecting my cases although both halves look in good condition the one half looks alot newer than the other one.im guessing that the are not an oringinal pair from the factory
Im concerned about putting them back together after the rebuild and still having the same leak in the same place,so my question is if i made a gasket out of material less than one mm thick does anybody see a reason that this would cause a problem,alter tolerances or anything?
i just think maybe if i made a gasket instead of just using sealant it might be an advantage and seal the area better where the leak was.


                                  appreciate any input 

[kaw rider]

bolt the bare cases together and put some oil into the trans. see if you can find leak.

[no sub for cubes]

I  have already identified where it was leaking from,both case halves look ok,im just concerned because im sure their not a matching pair when i mate them together again im gonna have the same problem?i could just put it down to whoever built it last time never used a good sealant,but id be well annoyed if i put it all together and then had the same prob,just thought maybe it would be poss to make a gasket out of 1mm or smaller material and put that between the 2 halves,id feel more confident with that..or a guess if thats not possible i will have to buy a recommended sealant(any suggestions?) and chance it.

[cbxracer30]

I think maybe you should lap the cases in, I use piece of glass and large sheet of fine sandpaper or emorycloth. I adhere the sandpaper to the glass and wet it , then swirl the case around in a circular motion . You will be able to look at the case and see where it is polishing up and when it looks ploished all around the edge your done-don't over do it.After doing both cases you should be able to seal them with yamabond or motobond.

[no sub for cubes]

typical of me i have already started assembling the right hand case with the crank already in the new bearing,but that is a great option something id never thought of might be worth doing that. cheers cbxracer30 

[cbxracer30]

This has worked well with cases I've had welded due to rocks or rods tryin to get and or tryin to get out. hope everthing works out.

[Johnniespeed]

I would trust Yambond,Kawasakibond,Hondabond or 3Mbond to seal a leak better than any gasket could. That is because they are a nonhardening sealer and can expand and contract with each thermal cycle. I have heard that antique aircraft used silk thread on engine case halves. Old style gaskets just dont seem to last as long as the new sealers do. I think the lapping in of case halves would be a must, and the assembling of empty case halves to check for leaks is a brilliant idea. Just dont overtorque the case bolts, that will not fix your problem.
 John

[no sub for cubes]

thanks guys,you have convinced me to go with the yamahbond and lap my cases,id have to be stupid i guess not to do at this stage as ive got it apart 


                               

[hughes]

Sounds like you have a good plan in place. Yamabond is what I have been using with great results. Their is another that is perfect for sealing non gasket mating surfaces and is great for making up for imperfection in the surfaces. Gasket Maker by Loctite, it's a red gel type sealant that works great.

[flyin9]

i use loctite 518 Anaerobic sealer, it is all i have ever been advised to use by my instructors at school and used by them in their personal businesses also. i found a data sheet for it and its pretty neat      http://www.farnell.com/datasheets/40179.pdf

[no sub for cubes]

cheers guys,thats the beauty about being part of the sight always someone with an answer to give you from the benifit of their experience,ive got plenty of choice to go with for a gasket sealer,just waiting on a new gear drum,should be here before friday and i should have me bottom end back to together