old polaris tech or anyone that can help.. hope this message finds you, i signed up to the forum just for your expertise. I have a 89 trail boss 250 ive been working on, rebuilt carburetor, new fuel filter, will now start and idle and ride for about a mile and then keeps bogging down and dieng, i have to dissconnect fuel line and manually put a little gas in it with a small funnel and it will start again and do the same thing all over, runs way better now scence carb rebuild but it was doing this same thing before where it runs for a mile or 2 and dies. When i have gas line dissconnected and pour gas in with funnel it will be running and then bog down and die the more gas i pour in, ive mest with float tab and tryed every different bend up or down it doesnt seem to effect this at all. Ive read alot of your post and tryed every thing just about. I would appreciate your input. Thanks!

 

First thing I'd do is a good compression check.Sounds like as it warms up the rings may be loosing seal against the cylinder walls and and dies.If this is the case they'll usually crank back up when cooled down a little and run again until they get warm again and will die again.

 

Thanks for the reply! Yea i knew i shoulda done a compression test first but scence it idled and ran i put it off, im on my way to a friend's to borrow a compression checker, from what i read it should be 100 to 115? And one person told me 90.

 

100psi minimum on compression,but even at that when the engine warms up compression can drop further causing the dying problem when the rings loose their seal against the cylinder walls.

 

Looks like compression is 95 or 98 or so, tryed 3 times 4 pulls each.

 

Think you found your problem. Time for at least a new bore and over size piston.Make sure the rod doesn't have any up and down play. If it does,the bottom end will need to be split and a new rod kit,crank bearings and crank seals installed.

 

Dang, when i bought this a few weeks ago the old guy said low hours and only took to hunting camp a few times. He seemed honest but who knows if he even knew the condition of engine. Other wise it looks in good shape, I payed 250$ and got the 20$ carb kit, i might do a top rebuild on it but i dont want to invest the 150$ for kit and whatever boring the cylinder would cost. Ill probaly just sell it as a project for somone else to get my money back. Thanks for the replys old polaris tech and it was awsome to talk to a guy whos forum advice id been reading for a few weeks, sum dated back about 10 years ago

 

Same thing if you bought a 28 year old truck or car. The deeper you get into one the more stuff you find that needs to be repaired. Many can be money pits. I'm sure you can part it out as many people are looking for these old engine parts,body,electrical,gear case and other mechanical parts.

 

Welcome to the forums.

 

Welcome.