How to seal the crankcase cover...

[Bo]

Hi,
I have some trouble sealing the left crankase cover... Some of the screws won't tighten anything, they just keep turning. The former owner tried gasket+sealant, and it was leaking. My Yamaha dealer told me that the gasket alone should be enough, but it's not (leaking quite heavily, far worse than what I use to have). I bought some Yamabond, and tried to close it with that alone, it's curing, so I don't know yet if it works. However, I'd like to know if anyone had some experience putting anything in the hole where the screws are, in order them to tighten the whole thing...
Sorry keeping asking what are without any doubt dumb questions, but I don't have much mechanical experience.
Thanks
Bo

[Lucky]

If the bolts just turn, then they probably are stripped.  there is a way to fix them and it's not that hard to do.

check first with one of the longest bolts to be sure.  the bolts are different lengths and need to be kept in their proper positions. I usually draw the outline of the gaskett on some cardboard and put the bolts in it to keep their position while i'm cleaning the old gaskett off the cases.  one or 2 of the bolts have copper washers (I believe where the dowles are) for sealing, & they must be reused.

Go to a well stocked auto suppy store with one of the bolts and ask for a Helicoil kit with extra inserts for all the bolts you need to secure (that the holes are stripped)

the master kit will have a tool for cutting new threads into the case holes, & a tool for inserting the coils.  work slowly & be sure they go in straight.  you will be cutting new, oversize threads in the case, so turn in the tool 1/4 turn at a time, clockwise & counterclockwise, going a little deeper each time, then follow the directions on the package for inserting the new threads.  be sure to blow out all the metal chips out of the hole before screwing in the inserts (do a google search for "Helicoil" to get an idea of what they look like)  it's pretty easy to do.

when you put the new gaskett on (and do use a new gaskett) clean the old case surfaces well and yamabond the new gaskett to the engine, & not the cover or you it will get pushed out of place as the cover goes past the flywheel, resulting in a leak. yamabond the case surface too, as well as the grommets where the wires go thru, but don't fill the space between the grommets.
--Lucky

[Rick G]

My bike could not live with out my heli coil kit , it seams the the bottom screws on the stator cover and the bottom screw on the oil filter and favorites to strip. I havent seen the self drilling kits in a while  , like Kucky describes. The package will tell you what size pilot drill you will need.  To start the job  you need to measure the depth of the hole with a piece of wire , then put a piece of masking tape  around the drill bit  at that distance, so that you will not drill too deeply, then do as Lucky instructed. I believe its very importandt to pull the stator wires , gently back and forth , to get the Yamaha bond inside the bore in the grommet , but as lucky sayes don't put any in between the grommets.

[Glyn Pickering]

Just a question on the yamabond. Is it really that much better than the sealer you can buy from most automotive shops? My yamaha dealer is a fair way away, did honda make a similar sealer does anyone know?

Cheers

Glyn

[Lucky]

I started using Yamabond because I was told right off these cases were just a pain to seal, and i've never had the yamabond leak, other than my messing up the gasket. (putting it on the engine & not the cover is importaint)

now my dirty little secret:  My dealer doesn't sell Yamabond #4, they sell Hondabond #4...same thing. :)
--Lucky

[QBS]

As stated above, the is attached with several different length screws.  Be sure that the proper length screw is going into the proper hole before concluding that the hole is stripped out.  To test: take your longest screw and attempt to screw it into each hole.  If it bottoms in each hole and then refuses to screw in further, then that hole is not stripped out.  Be gentle with this test.  After bottoming, Do Not force the screw to turn further or you will find what yoou are looking for.  Namely, a stripped hole.

Sorry, I can't tell you how to determine which screw goes into which hole.  Cheers.

[Lucky]

Without having a case in front of me, i'd say the easiest way to tell which bolt goes where, (and Bo never said they were out of order, although that may be the reason he thinks their stripped) would be to insert the bolts into the case, off the engine. I believe they should all stick out roughly the same amount out the other side.  

Helicoils actually bypass this problem, as the new threads are on the outside end of the hole anyway...

--Lucky