Base Gasket STILL $%#@%!#@% leaking.

+1 on having the dowels in, make sure the height is not a problem. Use a depth mic or the rod end of a set of calipers to find the depth of each bore for the dowels, add them together and then measure the length of the dowels, remembering that you will be taking the gasket into consideration, find out if they will not hold the cylinder block up. Being "new" this could be your problem.
Those dowels are there to make sure all of the top end engine parts are running true, piston to bore/ cam chain, etc.

My bike's been running fine for at least 10 years without the dowels.

the only 3bond in that area should be around the base of the 4 back studs if you replaced them....the base gasket should go on dry....something aint flat.....

Glass beads can get into every hole, it did mine. My guess is something is not flat. If using a feeler gauge, use one that's .001 and you'll have better luck. Ten years without dowels! Man thats funny. Always someone saying "can't be done", someones else is doing it. For ten years even! What do people actually learn as they go? I think all the time I got it all down and small animals, children will tell me stories then point and prove it. I give up. And shave that block by the way! Must be warped so bad it can be seen easily with an edge. Never been a fan of sealer that never gets hard. And sometimes no matter what kind of sealer, it will squish out every time when the bolts are tightened. And since it doesn't get hard how do u know its ready? DOWEL VS SEALER VS BLOCK:blink: And if I click on an emotican ( some kind of motorcycle ) one more time and it shows me the word instead of the pic I'm quitting this forum, thats just ridiculous. :woohoo:

The sealer doesn't get "hard" because it has silicon rubber in it. It does CURE and become fully rubberized overnight which means it will form a good flexible joint material.

Finally fixed and leak free.

The solution was a combination of things:

The cylinder studs were not sealed at the bottom (i.e not blind holes), but were open to the crankcase. This was causing crankcase pressure to push out sealant around the studs. Used ARP Thread Sealant.

The new dowel pins were actually a bit tall, combined with accumulated gunk in the dowel holes in the block, caused the block to not tighten down enough. Cleaned dowel holes, trimmed down dowels on a lathe.

Used a thick, soft aluminum shim with Yamabond 4 on both sides (recommended by Redline Cycles). This also solved my pinging problem when the bike gets hot.

Torque head to 31 lb-ft. This is the FSM torque. I had been using the APE recommendation of 36-42 lb-ft for their heavy duty studs, but I noticed that the gasket was being crushed flat in the areas around the studs and actually lifting up in the spaces between.

I have no idea which one of these changes made it not leak but I am a very happy camper.

-Dave

beefsquasher wrote:

...Used a thick, soft aluminum shim with Yamabond 4 on both sides (recommended by Redline Cycles). This also solved my pinging problem when the bike gets hot. ...

Interesting...where does the shim go?

Quote
Torque head to 31 lb-ft. This is the FSM torque. I had been using the APE recommendation of 36-42 lb-ft for their heavy duty studs, but I noticed that the gasket was being crushed flat in the areas around the studs and actually lifting up in the spaces between.

i find this strange .

if all of the surfaces are true u should not get this?? unless the cases and block bent as u torqued??.


Just a note for u if it fails again.
i had to have my case top milled. it was not flat from the factory.


i use ape studs too. i torqued mine to 40 then 42 after a heat cycle, then 42 again after another cycle. i'm sure the odds of stopping a leak by re-torquing tighter are not as great as starting tighter and preventing the leak in the first place.
does this motor have higher compression and larger pistons??
if so u should seriously look at more crank case venting. poor venting is known to cause leaks.

Good to hear you got that under control. Things like that can really wear on you

44 foot lbs and zero leaks for many miles.

You may want to check the height of your case studs as I had a problem with seepage in the center of my engine also. If you find that they vary in length you can try the APE head nuts as they are taller with more internal thread or add an extra washer under the stock nuts as a test. I also agree with checking the case end of the studs as some are exposed at the bottom into the case. Good luck!
David

Made it to 30 ft-lbs on the nuts. Then I was hovering just under the specified 22 for the head bolts when one of them popped. WTF.

Why did they taper it in just to taper it back out to the threads? What purpose does that serve other than weakening it? I'm planning to replace it with a 12mm with no taper and threads all the way down.