Tuned head swap

Today I found out that my 2 cyl has horrible compression. It should have 170 +-15 psi but it has 140 and i can touch it even after a long ride. the rest are only around 150. my bike doesnt run too bad considering and I was thinking about doing a valve adjustment and making sure all the valves were in good shape soon.

My question is since I have another head can I just adjust the valves on that one and swap it to the one on my bike? I figured this would save some time waiting for parts and the new head gasket might help a little with the low psi if it is indeed ring issues and not a stuck or bent valve.

140 shouldn't cause cold exhaust. Sounds like you're having other issues. Doubt the head gasket will help - I would adjust the valves and check you spark/ignition if that doesn't help.

Try retorquing your head.

140 pounds is not "horrible" compression. I have engines run really well with compression as low as 80 pounds. You have another issue other than compression here.

munkybrain2010 wrote: My question is since I have another head can I just adjust the valves on that one and swap it to the one on my bike? I figured this would save some time waiting for parts and the new head gasket might help a little with the low psi if it is indeed ring issues and not a stuck or bent valve.

Simple answer. YES.

zed1015 wrote:

munkybrain2010 wrote: My question is since I have another head can I just adjust the valves on that one and swap it to the one on my bike? I figured this would save some time waiting for parts and the new head gasket might help a little with the low psi if it is indeed ring issues and not a stuck or bent valve.

Simple answer. YES.

He's right, I was just trying to point out that swapping the head won't necessarily resolve the issue. I hope you didn't take that wrong. The FSM I have says 90psi is when you might start having combustion issues related to compression.

zed1015 wrote:

munkybrain2010 wrote: My question is since I have another head can I just adjust the valves on that one and swap it to the one on my bike? I figured this would save some time waiting for parts and the new head gasket might help a little with the low psi if it is indeed ring issues and not a stuck or bent valve.

Simple answer. YES.

Yes?? Please explain how replacing the head and the head gasket will help with a ring issue? I don't see the connection. :dry: Ed

Well! Am i the only one who fully reads posts before replying ?

I said YES to his SPECIFIC question regarding preparing his spare head to swop.

It will save time waiting for parts as he was going to do the valves anyhow.

I never said anything about rings.

The text regarding rings and gasket was a STATEMENT he made NOT A QUESTION.

zed1015 wrote: "Well! Am i the only one who fully reads posts before replying ?"


Simple answer. YES. :laugh:

Right on thank you! What would the cold exhaust be related to?

i assumed it was my compression because the cold pipe is the cylinder with low compression. I mentioned the head gasket because mine doesnt seem to be spewing any air or oil but there is a ring of oil around the mating surface, is this normal? Will a retorquing help?


It actually doesnt run bad at all and idles pretty nicely.

I also just replaced the coils with brand new emgo 4ohm's.



Ive pretty much resigned myself to just letting the engine blow up since I have experienced every problem with this bike and I was pretty fed up. I may just take off the valve cover and check it out before i do that though since I can tool around on my Seca.

Thanks every one sorry for throwing like 10 questions into one post but Im so close to having a smooth running bike... you know the feeling

My first guess with 140psi would be too rich or no spark.

A pipe cool enough to touch after a ride is a sure sign that that cylinder is not firing at all. To make a bang, all you need is fuel, air, compression and spark. Since compression is present, one of the others is missing.

Re-torquing the head may stop the oil leak. It's certainly worth a try.