I need help with my 1985 trail boss 250.

[95hondaxr250]

Hi, I'm new to this forum but i have a feeling i'll be on it a lot now. So I just bought a 1985 polaris trail boss 250 2 wheel drive. I got it for $150 from my friends father and i was very happy about getting such a good deal. When i got it the gas was so old and it hadn't been used in a very long time but it ran, idled, and started with ease. so i got it home and rode it and realized the gas should probably be drained because it ran alittle shity after awhile. so i made a new 32:1 mix(the oil injector leaks up a storm so i don't use that)and when out for some mudding in the back and after that it ran like crap. so i knew it probably needed rings so i popped off the head and realized there was some play in the rings as i suspected. so i got a new piston and rings. i was just going to get rings but the piston was messed up. after honing the cylinder and putting it back together the bike started right up and ran better but not as it should. it doesn't idle(it stopped idling right after putting new gas in and going for a ride), bogs a lot, stalls and runs like crap after it is run for awhile, and pings and sometimes backfires. it pings when you give it more than a quarter throtle which it didn't do the day i got it and it didn't bamck fire when i first got it either. the rebuild has fixed 90% of the backfiring. I really think there is something up with the ignition and or the carb. i have cleaned it out and adjusted it so it idles but when in gear it bogs and dies. I know i have wrote a lot but hopefully someone will read it and give me some pointers.

also i am not new and engine work and adjusting carbs. i've had and still have many other bikes. i'm new to quads as far as owning one and also new to polaris. I just don't want you guys reading this and thinking this idiot doesn't even know how to set the idle and adjust the fuel air mix. i've turned both carb settings all the way in and out and it never changed anything which is mind boggling because i know the air and idle screw should change everything. if i touched the settings on my rm 125 it would run a lot different.

I almost forgot. I did change the spark plug. i'm going to try another plug but i don't think it will make a difference. i tried two different heat ranges and different gaps too but with no success.

So someone please help me.

Thanks,
Chris

[tecateboy]

well if its pinging you might have some detionaion problems, first try running a higher octane gas, and also, it wont idle, well either your too rich or too lean, cant really tell by it just not idleing, but try going up or down a size on your pilot jet. and your deal with the oil injecter, did you get a blockoff kit or something? cuz if that thing is still pumping oil it would make it not idle cuz its then getting way too much oil in it. or if you removed the oil injecter and didnt plug the hole into the carb boot your running too lean and it wont idle till you plug that hole, and if the hole isnt plugged that could be why you went through the one top end like nothing.

[95hondaxr250]

yea well i already tried 93 octane. i figured the mixture is off the when i play with the carb it seems to do nothing. it is so anoying. the oil has all leaked out so i think my oit mix is ok but i will check that. i'm going to try fixing the leak. it seems to be the injector itself. thanks

[tecateboy]

yea if you didnt plug your injecter off it still may be pumping oil if theres some in that tank. or if theres none in there it could be pumping air giving you a lean mix.

[MX86]

wouldn't be a bad idea to clean the bowl and float's in your carb.. especially if gas has been sitting inside it...

[95hondaxr250]

Yea. I just did that and it was very dirty but it still didn't fix it. thanks

[95hondaxr250]

Yesterday i was looking at the head gasket and the cylinder gasket for leaks. Every time I spray anything arount the head the idle goes up a bit. So today I took off the gas tank and tightened the bolts more. After putting it back together I could feel the difference in compression right away. plus when you rev it up it actually revs all of the way up. so i rode it around and after really getting on t he gas it still does that pinging but now it makes it up to half throtle where as before it would do that after a quarter throtle. so i had bought gasket material and sealer in case i had to do this.

This afternoon i took it apart again. cleaned the gasket surfaces, applies the compound and made the new gasket. now everything is back together and i'm letting it sit over night so it all dries nicely. i'm hoping that when i fire it up tomorrow it runs good. i was affraid that the bottom cylinder gasket was bad but it doesn't seem to be leaking.

Also when looking everything over i realized that the front engine mount is broken and there is an air vent for the clutch under the exhaust pipe. the rubber boot on that is falling apart. i'll probably weld the engine mount and put some tape on the rubber boot tomorrow. then i'll cross my fingers.

[95hondaxr250]

Hi. ok i've got the head gasket done with no leaks that i can find. so it runs better but not like it should. so not it's still doing the pinging. it has to be the timing. i really wish i had the manual for it but i don't. i'm reading in my book for my other bike and it says that the timing should never be adjusted and that if the timing is off than that means one of the ignition components such as the ICM or pulse generator are broken. does anybody know if this is the same for polaris? does anyone know how to set the timing on my trail boss. it's running too hot and breaks pings under load so what does that mean? please give me something. i'd really like to go ridding this weekend.

[tecateboy]

if im correct it would be that your detonating, when you took your head off to replace your head gasket what did the top of the piston look like?

[95hondaxr250]

hey i replaced the piston and rings but i had to take it apart again to reseal the head gasket. when i did that there was a lot of carbon build up but other wise idk.