I have a 2001 Polaris Trailblazer 250. I just got the thing running after putting a new piston and rings in it. it has about 105 compression. Now, when it is running, it just doesnt seem to have the zing a regular two stroke does. I have been out of this game for awhile, so maybe I am expecting to much!! lol But, can someone tell me how to adjust the carb on this thing? I see what looks like a mixture screw, as it has a spring on it, and then a smaller screw next to it. any help would be appreciated. thanks!!!

 

The screw with the spring on it should be the bigger of the two and phillips head, that is the idle screw. The mixture screw is a smaller screw with a flat tip head is the mixture screw. Turn your mixture screw in all of the way, but just to where it stops, don't tighten it. Now back it out 1 1/2 turns. Next tune your idle to where you like it.

 

105 on a new rebiuld sounds a little low to me , that might be somewhere to look if the carb adjustment wont do it
a 250 even stock should lift the front tires pretty easy
good luck

 

I was thinking the same thing. Should be up around 120 somewhere, shouldn't it?

 

sounds like they didint hone the cylinder out when put new rings in. i would say around 125 psi would be about the compression.

 

Thanks. I will check the carb today. and I will be really ticked if I have to end up putting another piston and ring set in it. It holds the compression, and does not leak down, so can I feel comfortable that there is not a leak elsewhere in the motor??

 

Did you ride this thing before you rebuilt it? Secondly, have ever ridden one of these before? It really is not a good wheelie machine. In fact in stock form even brand new, you have to really pull hard on the handlebars to even get the front wheels off the ground. These do not run like a 250R. These motors are not designed to run anything comparable to something like a 250R. Also the CVT clutches used in these Polaris's are nothing like a quad that has gears and a manual clutch.

Compression testers aren't always as accurate as you want to think. Use another tester just to see what it may say. 105lb of compression does seem slightly low but once the rings get broke in it will actually gain a little more compression.

You rarely have to adjust the carb settings unless someone has already got in there and mested up the factory settings. Unless you start adding performance stuff like a pipe or different air filter.

 

No, I didnt ride it before I acquired it. A friend owed me some money, and gave me the quad instead. The last two stroke I had was KX 250 years ago. so, I am a little rusty. I replaced the piston and rings. I did not have it bored, as the cylinder walls were fine, so I just put another stock piston and rings from Wiseco in it. Also, no Reed valve in this. wow, I thought just about all two strokes had these. LIve and learn I guess. Also, getting what appears to be a little knocking sound going on in the motor. maybe it is just two stoke noise. not sure. ??????

 

Well, not having it bored out for the next oversized piston could very well be why the compression is where it is. Did you measure the piston clearance with the new piston. If you did the clearance with a wiesco piston should have been about .003" - .005". Anything over this would cause the compression to be a little lower than it should. Secondly, this would also allow for enough clearance for the piston to slap around a little more than normal. These engines are some what known for this anyway. Also because of them being an air cooled motor all those cooling fins, tends to magnify that slapping sound.

This type of motor is called a piston port motor. Instead of a reeds stopping the air from flowing backwards, the piston actually acts as the set reeds. Another reason why they don't run like a 250R or KX250. This quad was not build to be a high performance quad. More of a fun trail quad. Their are performance parts you can buy and make them run ALOT better but, it will never run like the 250's you are used to.

 

if you put a new set of rings and piston in w/out honing the cyclinder the rings wont seat good hence you wont have top compression.