No compression

[sonic883]

So I broke a piston ring awhile, so I ordered new ones. I put it all together and it ran well, after a few weeks, I got a high compression head and a new cylinder,I took the old cylinder off, and installed the new parts, and ever since then there’s barely any compression, I’ve tightened down the head bolts, and tightened the spark plug,( properly). Just no compression
I am almost certain it’s an air leak. I currently have the base gasket off. It’s a 2 stroke 80cc (66cc)

Pls help

 

[Greg58]

Those are for looks not function, regular 8mm nuts will give more accurate torque.

 

[sonic883]

Are you using the acorn nuts that were on the stock cylinder head? On your new cylinder head?

Yes, I haven’t thought of changing the nuts out.

 

[sonic883]

Damn are you across the ocean & had to have it imported? Them heads in the U.S are $48-$50 dollars.

I’m from Australia, always heard about the performance they present. The few rides I had it on I couldn’t tell if there was anymore torque than the stock head.

 

[DieselTech]

Cool someday I'm going to make it over there so I can run around in the outback! Yeah if your squish is not set to the proper gap you wont gain any performance from that cylinder head.

 

[DieselTech]

Lol when you get your bike running good, you gotta give your avatar a smiley face. If I had the funds I would fly over there & help you finish your bike.

 

[sonic883]

Cool someday I'm going to make it over there so I can run around in the outback! Yeah if your squish is not set to the proper gap you wont gain any performance from that cylinder head.

Cool, thanks for the helpful information.

 

[sonic883]

Cool, thanks for the helpful information.

That avatar I just randomly picked never really thought it displayed sadness, I almost always work through a problem, I just can’t give up I just solve problem by problem

 

[Chainlube]

You don't have to take the head off to check the squish band, you can just poke the solder through the sparkplug hole and up to cylinder wall, then roll the bike.

 

[Cisco]

squish gap, you want to measure that & .028"-.030" is ideal.

Thanks @DieselTech , I didn't know what squish meant. I'm thinking that squish can be adjusted by different thickness head gasket? Would changing base gasket thickness (to adjust squish) change port timing significantly?

@sonic883 , I had some trouble torqueing my CNC, high compression head. After each heat cycle, I had to re-torque the head in several, random patterned passes. I think the billet aluminum changes more from heat expansion than cast aluminum . It took several heat cycles and torque passes to finally get the head settled down.

 

[DieselTech]

That was the gaskets seating in, 1 or2 base gaskets wont affect port timing that much & yes they will affect your squish, I would try to stay to 1 base gasket, but 2 wont hurt you either. If you use more than 1 base gasket you usually will have to deck the cylinder to get your squish right. Yes you can adjust squish with your head gaskets is the best thing to do.