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Posted (edited)

Ok, i have a 2002 shee with a compression or 120. i am at about 500 feet(texas). My mods are reed spacers, v force reeds, 34mm mikuni carbs, two k&n filters, toomey t5s, and what i believe is a mild port. I did not install these mods unfortunately so i am not sure about the port or the last rebuild. should i rebuild. The guy i bought it from said to run race gas but compression is only 120. So where do i start? I was thinking also about getting a shaved head or cool head to raise compression just below the point of needing race gas. Thanks guys! Parker

Edited by P-man
Posted

Hm, at the elevation around DFW I would think 120 could be possible, depending on the porting. After I had some porting done my compression was a bit lower then i thought it would be.

Posted
Hm, at the elevation around DFW I would think 120 could be possible, depending on the porting. After I had some porting done my compression was a bit lower then i thought it would be.

How do i know if it is the port or if the top is shot? I want to raise the compression any way either by rebuild or if that isn't the problem then by a shaved head or something. Doesn't that help with power?

Posted

You can pull the head and check the piston-wall clearance and your ring-end gap clearance. Try this, drop a few drops of 2stroke oil in the spark plug hole then kick it over to check compression and see if it goes up much from 120.

Posted
You can pull the head and check the piston-wall clearance and your ring-end gap clearance. Try this, drop a few drops of 2stroke oil in the spark plug hole then kick it over to check compression and see if it goes up much from 120.

ok ill try that, how do you check the "piston-wall clearance and the ring-end gap clearance"? caliper?

Posted
You do that with feeler guages. If you don't have one I would recommend a Clymer's manual. It explains how to do all this. You can get one from FAST.

 

 

I tried putting oil in the spark hole. i put a little in the left side and it went from 120 to at most 125, i put a little more oil in the right side and it went to 150, then to 145, and eventually to about130 or so. I might have put to much, idk? I put more than 2-3 drops. so what do i do?

Posted

Are both sides even? That is usually the main thing you want before doing a rebuild. If they're even they're usually ok, unless they are both way low. At 120 i would say you're ok. I see you're in teh DFW area, i live up in frisco. lmk if you need help w/ anything

Posted
Are both sides even? That is usually the main thing you want before doing a rebuild. If they're even they're usually ok, unless they are both way low. At 120 i would say you're ok. I see you're in teh DFW area, i live up in frisco. lmk if you need help w/ anything

well without the oil they both were right at 120, i put more in the right cylinder if that could have made a difference. sorry, but what is Imk?

Posted

let me know

 

the more oil could have caused it to seal off better. its an old trick i've heard of doing, but haven't heard if it works perfectly from application to application.

Posted
let me know

 

the more oil could have caused it to seal off better. its an old trick i've heard of doing, but haven't heard if it works perfectly from application to application.

 

so what would you say i need to do? why would one go up to 150 or so, could the oil just have increased the volume in the cylinder raising the compression?

Posted
so what would you say i need to do? why would one go up to 150 or so, could the oil just have increased the volume in the cylinder raising the compression?

 

I don't think it would that much. Personally i'd run it. if you want to raise the compressin some mill your stock head or get a coolhead (which i may have another one for sale soon).

 

If you got the $$$ and are worried about it do a rebuild.

Posted (edited)
I don't think it would that much. Personally i'd run it. if you want to raise the compressin some mill your stock head or get a coolhead (which i may have another one for sale soon).

 

If you got the $$$ and are worried about it do a rebuild.

 

about how much does a rebuild cost? also, where about in fort worth should i go to get a head milled? what machine shop should i trust

Edited by P-man

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