Hey all...I'm getting ready to have my sons Trailblazer 250 bored out by a local shop as the compression was down to about 82psi and would barely fire. I have only had a cylinder bored one other time to a motorcycle many years ago. Is there anything I should request to have them do or anything I should make sure that they do for a proper bore job? I'm not really looking to spend alot on trick machine work just the basics done properly.

 

First thing you need to do is get a new piston that is the next size up from stock. Then take it and the cylinder to the machine shop so they can get exact measurments and bore it out. Thats weird that an 02 needs rebuilt already. What kind of filter are you using? Sounds like alot of dirt is getting into the cylinder. The 250's should go years without a rebuild.

 

It just has a stock type air filter with the foam wrap. I'm not sure but it almost looks like it may have over heated at some time. The cylinder appears to be out of round like when I turn the piston 1/4 in the hole. Plus dark 'burn like' streeks up and down both the piston and cylinder wall consistant with each other. I bought this machine used so God only knows what kind of abuse it's had. I know the thing has been flipped by somebody. I just finished straigtening the steering shaft yesterday. Anyway I figured I would let the shop supply the piston. Not really sure if it's been bored before so I'm assuming they would measure it before getting a new one.

 

I would go with a Wiseco piston or something more durable than stock. Cost should be about the same for much better quality.

Steve Lubecki

 

My 02 250 recently siezed up as well. I just had the dealer fix it, I didn't want to deal with engine problems. It was less then 400 to get it back running.

 

Go with a wiseco piston.
Try and always run a good quality injection oil, and don't mix them.
I've had great luck with Polaris oils.
Keep your filters clean.
Good luck

 

Getting a cylinder bored this day and age is a crap shoot . Here is some advice for you if you are doing it locally :

Ask to see the equipment .

If you are at a really good shop that has what it takes to do the job right , they will be happy to show you there equipment , they know as well as I do that few shops really have what it takes . If they have it - the boss will love to show it off . ( I know I do :-) )

What is needed is a boring bar . Kwik-way , Rottler and Van Norman are 2 of the top of the line machines for the job . Listen for a brand name .

Also they will need a good set of rigid hones , most will have Sunnen or Ammco brand . These are not spring loaded POS hones - this is the good stuff .

Champhering ports is also part of the job . Most will use a small rotary file on a Foredom , CC specialty , or even a dremel will work .

Many shops will *send it out* ... Hard telling what kinda job you will get .

If you see a hohn hooked on a drill and are told that's how they do it you need to RUN !

Take a minute and check out the place before you let them bore your cylinder . Myself personally I LOVE poeple who want to see how it's done . If a shop has the tools to do it , ,they will be happy to give a 10 minute tour - it's good for business .

Rick