What do I have here

[pittss1c]

I bought a blaster off a tard. The owner previous to him did a lot to the quad, but the guy I bought it from knows next to nothing, but claimed it was a 240 and needed race gas.
I have it running pretty well now after fixing the exhaust and jetting it down considerably, but I am concerned because the compression is not all that high. (120-125). If this was a high compression engine, then it isn't quite right. (the need to drop the jet sizes may be an indicator as well)

If I need to re-ring it or something, is there an easy way to find out what 240 conversion this is?
Which brand/model of piston it is... so I can get the correct rings.

It pulls pretty darn hard so maybe I shouldn't worry about it yet.

 

[ron89]

thats about normal compression .. umm if the cylinderis black its most likely a stock head just bored 50over .. just post up some pics ..

 

[cirame1]

i believe thats good compression. i wouldnt worry about it at all. wat size jetting are u running anyway. and wat do u have for an exhaust and carb?

 

[blasterboy91]

if its not broke dont fix it

 

[pittss1c]

Not black

I need to take some pics.. maybe tomorrow.
The cylinder is not black, it is unpainted.
It has a Keihin pwk 28mm and an LRD exhaust.
When I got it, it had 168 mains and 52 pilots.
It didn't run very well. I welded the pipe to seal it back up, I dropped the main down to 158 for now, and dropped down the needle one notch. It pulls pretty well now, but can be rough in the first 1/4 throttle. (keeps 4 stroking) once it clears... it's wheelie time.
To get the bottom a little better, I backed out the air screw enough that I lost it while riding.... damn! I am going to try a 48 pilot next week.

The only concern I have is that It was jetted much larger and was supposed to be a high compression. (I was thinking maybe it was a worn out high compression setup)

 

[tjscott]

well you most certainly do not need to run race gas in any blaster that isnt a drag quad or if you live in an extremely hot environment.
people do not get that octane is only a preventative of knocking.
too little, the bike will knock.
too much, the fuel becomes too hard to burn and you lose power. for God sakes its a 2 stroke, its going to need some serious work for race gas, you will be fine with 89 octane even.
btw 120 psi is where i put in a new top end. I recommend buying a wiseco piston and ring, wiseco pistons are forged so you never have to worry about them shattering in your engine and totaling it instantly

 

[pittss1c]

Does wiseco make pistons regardless of the 240 kit? (vitos or other)

 

[Mrbrocco]

yea wiseco makes all sized pistons

 

[mr_3_0_5]

sounds ike you guys know ur sheeet.. anyway im in the same boat i just got this bike three days ago and was told it had a ct racing kit and to run race gas my probem is. at high rpm in 5th or 6th gear it sounds like a midget with a hammer is beating on head or piston or somewhere in there. is this detonation? am i running to low of an octane?? im running sonoco 100 right now.. any help woud be great. also motor has 170 compression