LOW Compression on Rebuilt 61x problem.

[LIVE2RIDE Powersports]

I have a rebuilt 61x. No hours on it yet. Fires up good and runs strong. Only problem is i have a Westcoast head on it with 26cc domes and only has 165psi in both. I was expecting well over 200,

Whats up with it, if anything?

 

[Big Kahuna]

does that head require a head gasket? if not did you use one?? or the domes size is correct for 165 lbs.

 

[LIVE2RIDE Powersports]

does that head require a head gasket? if not did you use one?? or the domes size is correct for 165 lbs.

yes i believe it does require one. There are no o-rings for it. would it have o-rings if it doesn't need a head gasket? I used a new oem gasket on it.
Thanks

 

[Big Kahuna]

ok, could not remember about the westcoast heads. Sounds like your domes are correct for that compression. Did you use OEM Base gasket???? if you used an AM gasket that was thicker then that would drop compression. Is there any port work? Raised ports will lower compression as well.

 

[LIVE2RIDE Powersports]

ok, could not remember about the westcoast heads. Sounds like your domes are correct for that compression. Did you use OEM Base gasket???? if you used an AM gasket that was thicker then that would drop compression. Is there any port work? Raised ports will lower compression as well.

Ya my friend did some porting on them. He said its a basic (Stair stepper) port job. It is running a new WSM base gasket that came with the top end.

I was told by many on here that 26cc's would produce so high of compression it would be hard to turn my motor over. Then i talked to jetskihaven and he said that westcoast was bad about there heads for yami's produced less then stock. Which in this case is turning out to be true cuz my stock motor hit 165 in both as well.

I also had another set of domes that came in the head that were mint with no markings about size and they made 145. So i opened the new 26cc race domes and got 165. I don't mind running 165 but wanted around 190. Just don't want any issues with my motor right before summer.

Thanks

 

[x2skier]

Are you using a high quality gauge?

 

[orangefinger]

Oem head gasket 7-8cc + 26cc =33cc-35cc ....

If you use the westcoast head you with stock oem headgasket you will either need smaller domes , I think 25cc or have them remachined or a diff headgasket !!

I had several of these in the past

 

[Mark44]

Have you checked your squish?

Mark44

 

[Big Kahuna]

on the porting, did he raise the roof on the exhaust? if so, that will lower your compression

 

[LIVE2RIDE Powersports]

Are you using a high quality gauge?

Yes, its a very high quality gauge. I think snap on.

Have you checked your squish?

Mark44

No idea what that is.

on the porting, did he raise the roof on the exhaust? if so, that will lower your compression

Ya i think he raised them alittle. He said it wasn't a radical port job, but will be noticably more snappy.

 

[LIVE2RIDE Powersports]

Who can i send my 26cc domes to to get machined? All i want is 180-190psi. Or would a ADA head be better, i can get one of them from a friend.What head gasket should i buy?

 

[Shifty]

You can only take material off of your domes at this point; effectively lowering your compression even more. I would go ADA if you can swing it, its tried and true.

Porting can lower compression, I wen't from 185psi before porting to 160psi after porting.

 

[LIVE2RIDE Powersports]

You can only take material off of your domes at this point; effectively lowering your compression even more. I would go ADA if you can swing it, its tried and true.

Porting can lower compression, I wen't from 185psi before porting to 160psi after porting.

Ok, i can get a ada head for 50 bucks from a friend. I will try that. What gasket should i get, copper or just stock?

 

[Shifty]

I don't have an ADA myself, just RIVA. The ADA I am thinking of is the girdled type, They use O-rings to create the seal against your cylinder. If you can find it for $50 I wouldn't think twice about snagging it.

 

[LIVE2RIDE Powersports]

I don't have an ADA myself, just RIVA. The ADA I am thinking of is the girdled type, They use O-rings to create the seal against your cylinder. If you can find it for $50 I wouldn't think twice about snagging it.

Ok, will do. I will post back my results. Thanks