Sure hope someone can help...I'm not the best mechanic in the world or even in my rural community..lol but I enjoy tinkering with things..I'm restoring a 1988 Polaris Trail Boss 250..A Mikuni 36mm roundslide, which I took apart an cleaned..I did get it started but it ran wide open..Trying to idle it down did not good..If the throttle cable is the problem how do I correctly adjust that?..After starting it again, with the same high idle, I tried to turn it off,turning off the starter switch and the start button on the handle bar and it wouldn't turn off..What in the world did I do!!!...Pete

 

Hi Petelg18.
Well it could be so many things. I have rebuilt a 1987 polaris trail boss 4x4 (virtually the same as the '88) and ran into similar problems.

Let's start with the simplest things first. Is the big throttle spring installed properly in the carb?
If yes, is the spring wore out? I've had to replace this spring because the side of the spring was actually worn flat and it lost its "springiness/"

Without the engine running can you feel the throttle cable pull and release?
If not, then you need to loosen the cable. You can adjust the throttle cable both at the handle bar at the throttle body and at the carb at the cap to give it more slack.

If the throttle cable is not always stuck and is just getting stuck wide open occasionally then the cable might be bent, pinched, or just plain bad and needs to be replaced. Which leads to the next questions.

Are you using the oil injection?
If no, you need to know that the throttle cable is designed to adjust the carb and the oil pump simultaneously. If you removed the oil injection pump you will need a new single throttle cable. Check out Aaenperformance.com. You need cable ACA20021 if the oil injection pump has been removed. FYI, I have no affiliation in any way with this company. Just heard good things about them from Old Polaris Tech (OPT).

If you are using oil injection then something is wrong with the cable as stated above. If you need to replace please note the following. I purchased a cheap throttle cable and it would get the stuck wide open issue on occasion. I eventually disassembled the cable and shaved down the aluminum insert where it goes from one cable to two cables until it would move freely in the barrel. Then lubed it up with graphite, NOT oil.. Works like a charm now.

Give those things a try first and let us know how it works out.

I've attached some annotated pics. Hope they help.

You can do this! Good luck!

 

Hey my friend..Thank you so much for the valuable info you sent..I haven't been to the shop as yet to continue working on it..I have a 94 year old father that I'M sole caregiver for since my mom passed away..But I will definitely let you know my progress ( even if it's a slow one)..But thank you again for helping me..I MAY have other questions for you..lol..Pete

 

Obviously your father is your top priority, these old 4 wheelers will wait for us!

I have done a ton of work on my 1987 trail boss, so please reach out if you have questions. I am no mechanic but have learned a lot from others (especially OPT) on this site and would like to help out others if I can.

Keep us posted.

 

Hey Steve,you there?..Haven't had time to piddle with the 1988 Polaris 250.Been really busy.I did walk out to the shop,with my coffee, and was looking at it..I really think the high idle problem is with the incorrect linkage adjustment (which confusses me)..when I took the carb out I also removed the the "throttle..oil injection" cable..I screwed it in an out so much, I have no idea what the factory settings on it looks like..I know I"m "lame"..lol..I'll try to add a few pics I took and maybe you can tell what I'm talking about..If I'm not smart enough to attach them here I think I can send them to an email..My email is rebel18@rocketmail.com

This is on the handle bar

Also the handle bar.

 

Steve?..Pete here..Do you have an email address so that I can send a couple of pics and asks a few questions?..I still can't navigate this site..My e-mail is rebel18@rocketmail.com..Sorry for all the aggravation ....Pete

 

My 87 throttle cable for a 250 2×4 needs to be replaced but I can't find it and an 89 one didn't work any ideas