I just sent my 250R cyl out approx 2 weeks ago to have a new piston put in it, and the company called me back and said my cyl bore has a crack in it. approx near the intake port. They told me that my cyl was now junk. I was told I could resleeve it but I could run into problems with over heating. I just talked to some one else the other day, a local guy and he said I could resleeve my cyl but I would have to use a special sleeve that is approx. 3 times thicker than the stock sleeve. He also suggested that since I have to use the thicker sleeve that I could go for the 295 big bore kit since it use the same exact sleeve for just a few dollars more. I really liked the idea of the 295 kit, but I need to know HOW RELIABLE is this kit? I have heard some things about the 295 kit having head gasket problems. Is this a good kit and is a fast kit when done? I will mostly just drag the 4 trax and not trail ride that much. The 295 kit will cost me approx. 350 - 400 dollars. Let me here what you think.

 

The problem with the 295 kit is that uses a cylinder that was designed to run 250cc. Larger diameter sleeves lose reliability when then are bored thin, this causes the tendency to crack. If the cylinder is bored to accept a larger sleeve, then its cooling capacity will probably be diminushed.

I nearly turned my 250R into a 295, but I was told that I would encounter similar problems. Although I am not an expert, I would suggest looking into the either the Pro-X 310 jug, which can be reliably set-up to 330cc, or possibly the new PSI jug. I have not tried it but supposedly it can go well over the cc size of the Pro-X jug and it features an exhaust valve. Check it out, it certainly looks trick: www.psiperformance.com. Hope this helps.
-Mike

 

Go to www.macdizzy.com
Read some of the treads or E-mail him. He know a ton about 2 strokes!

 

They're tough to get to make serious power that they are capable of, the bore grows cubically while the port area grows slower. I haven't had any problems with overheating or a lack of reliability. If anyone were to have problems, I think I would have, with the mountains of compression that I have and massive port modifications(read less piston wear area). I run a O-ringed head and have never to date had problems with leaks. Would I have gone with a 330 or 350....yeah maybe simply because the port design and layout of the Pro-X cylinders are better, but we were looking for the challenge of how far a stock cylinder could be pushed...well...the steady diet of twin's proves we did something right....

 

i just purchased ct310 cly kit. i race harescrambles and use a paul turner type6 pipe, 38pj carb,12/39gearing, stock reed cage and pump gas w/bel-ray mc-1 mixed 50:1. i raced this combo sunday and was very happy with my combo it's very smooth from top to bottom with a slight mid range hit. after the race i drag raced a 330 i rode the 330 and the other guy rode my bike, 330 pulled a little harder on top but i think that was due to gearing. his bike has paul turner hand formed race pipe, 38pwk airstriker, stock reed cage,13/39 gearing and pump gas. he liked how smooth my bike was. i considered both a resleeve and the pro-cross 310 and choose the pro-cross w/removable combustion camber, because i could get it for $970.00 to my door in 2 weeks. including all gaskets, porting, and jetting. the resleeve jobs range from $500.00+gaskets and jets to $900.00 complete. so i figured why not get a whole new top end and still have a good 250 cly and head as a spare. by the way the guy with the 330 who rode my bike is the current points leader in the missouri state harescramble series, 2-stroke open-B.

 

Well, first of all, the CT310 cylinders are actually 295 cylinders because without machining the cases you can't get more than 303. The max a 310 cylinder can be bored to is 303. I wouldn't recommend the 295 sleeve because they have problems with overheating. The reason people have problems with the head gaskets is that they aren't using big bore gaskets. The PRO-X cylinders have better porting, better cooling and they come complete with everything you need to bolt it right in. You would be better off with the complete aftermarket cylinder kit.