heiden big bore cylinder o-rings not allowing jug to seat fully

[Jaymichael]

Hey guys, so ran into a problem tonight installing my new big bore cylinder into my engine. Previous to installing the pistons I dry fit my heiden tuning big bore cylinders onto my bottom end to confirm it fit nice and flat with no binding anywhere, all was good. Installed the base gasket, the large cylinder o-rings, rings and pistons. As I lowered the jug down onto the engine bottom end I found that the jugs stopped with about a couple mm of spacing before they fully seated. I double and triple checked nothing was binding or caught. I played around with it, tapped with a rubber mallet trying to get it to fully seat to no avail. I even put the head and upper cover on with some washers and gently tightened the 4 inner nuts to see if I could suck it down flat, it didn't. Pulled everything apart for inspection. I found no signs of contact or binding. I can only suspect that whats happening is that the large o-rings that go around the base of the cylinders are taking up the space, I noticed on the heiden jug there is no relieve for those o-rings as there is on the factory cylinder assembly. Seeing as how there was no instructions that came with the big bore kit and nothing at Mikes on his website I cant determine if maybe I'm not supposed to install those o-rings? Or do I need to just fully torque the engine down to take up that space? If those o-rings are left in they would essentially have to be squished right flat before any pressure would be placed on the base gasket, which doesn't make any sense to me.

Can any one who has installed one of these big bore kits chime in? O-rings in or out?
Ive attached 2 pictures showing the relief for the o-rings on the stock jug and the lack of a relief on the big bore kit to clarify what Im talking about

Many thanks

 

[angus67]

No relief=no orings

 

[Jaymichael]

I did come across another thread about this, seems it had something to do with the crank spreading, I have confirmed this is not the case in this instance

 

[Jaymichael]

That has to be the case I'm figuring, its just strange as I had come across a few peoples descriptions of installing this kit and them mentioning that they had installed the o-rings, perhaps the big bore kit has been updated to no longer having the o-ring reliefs?

 

[TwoManyXS1Bs]

Here ya go:

http://www.xs650.com/forum/showthread.php?t=40397

 

[650Skull]

I bought 3 kits when Mikes first had them for sale and they didn't have the recess for the o rings then

 

[zzblazezz]

My big fin kit did not require the o-rings.

 

[Jaymichael]

Thanks for the reply everyone, that clarifies it for me!