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1991 Polaris Trail Boss 4x4 250 Slow to start problem


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Hello everybody. I recently bought a '92 Polaris Trail Boss 4x4 250 for a project bike for my sons to ride. It's a 2 stroke air cooled motor, chain driven bike, and the previous owner had a shop bore over the motor .040 I was told. He also removed the front drive shafts, so it's basically a 2WD now. LOL. When I purchased it it was in pretty rough condition. Brakes didn't work, hard to start, rusty frame, chains were covered in muck, flat tires (wrong size too), torn seat, would grind when u put it in Drive, but when it did get it started it tore down the road like a bat out of Hell, so I knew I found a keeper. I have since fixed the brakes, replaced fuel lines, air/fuel/oil filters, tires, rebuilt the carb w/ a carb kit, replaced breather/vent/drain hoses on carb and reupholstered the seat, replaced the rear chain, and replaced spark plug and ignition coil. I use Bel Ray SL2 oil in her. I did not replace the battery. We ride this bike on trails and it runs pretty good now. Occasionally it will backfire (loud), but not every ride. Since the day I bought it it takes forever to start the engine. I mean like 30 seconds to a minute of trying to start her. I turn choke on, I flutter the throttle, and hold the START button. This is the only way she'll start. I hold the start button in for approx 10 seconds at a time, but I'm concerned I'm going to burn out my starter if this persists. Now after we ride the bike and she's warmed up she starts faster. Still not as fast of a start as my '98 Yamaha Big Bear 350 which immediately starts first try. It's stubborn on the FIRST start up. Now I live in Florida and it's always HOT when we ride, so even when the motor is cold it's enjoying 85-95 degree weather. Any thought or suggestions how to fix my quad's problem?


Sorry, I mistyped the Title of this Thread. Polaris is a 1992 NOT a 1991

PTB QC pic.jpg


Edited by MadMan
Type O in Thread Title
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:cute:LOL! Yeah that's true. She's old, but it actually runs good for it's age. It's just so slow to start at first compared to my '98 Yama Big Bear. That's thing starts like it's a brand new quad on first try. Makes me wish I bought a 2nd Big Bear for my kids. LOL.

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Age doesn't matter in my opinion, it's abuse, wear & tear. Quads if maintained can last a very long time. It runs good when warm, so it's probably jetted correctly..I think it's choke related.

Have you tried starting it with 1/2 choke? If you spray some starting fluid in on cold start, will it start up faster?

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I have experimented with Choke all the way out and partially out, but still a hard start. I haven’t sprayed Starter fluid in carb on a cold start yet. That’s a good idea. I did install a carb kit in her when I bought the bike and the carb was already really clean inside. This surprised me because the previous owner was missing the prefilters on the air box. He did have the MAIN air filter inside, but missing the 2 foam prefilters that go on the opening on the air box by the gas tank. I set the carb needle and airscrew so she idles good. Last time I rode the bike the starter sounded bad. Instead of normal sound, it made a whirl buzzing noise and didn’t turn motor over. Every other time I hit starter it did this. I think it may be due to replace it. Prior to this it always sounded normal and eventually would start motor and I’d be on my merry way. I’ve been price shopping a starter for the trail boss. Now the quad has some age on her, but we don’t abuse it. I have no idea if previous owners beat on it, but it was being stored under a tarp in the owner’s front yard, so she got rusty from FL humidity. The guy I bought her from was in process of restoring the bike and sold it because he needed cash. He admitted she was rusty when He bought it too. I have it running pretty good now, except this stubborn starting problem. This wkd I’ll shoot some starter fluid in carb before attempting to start quad and let u know what happens.

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  • 2 months later...

UPDATE; Well my starter died, so I installed a brand new one ($60) in the Polaris Trail Boss. To remove the starter it requires removing the CVT cover and pulleys (special puller tool $30) to access a few bolts on back of starter. I got the new one in place and re-installed the CVT. Quad is still hard to start with COLD motor, BUT I popped cover off airbox and sprayed starter fluid in it while starting engine and it immediately started running. After she warmed up I turned her off and tried starting her again. She starts immediately like she should. Thanx AjmBoy for the advice. BTW some how after removing the CVT and re-installing it while installing the starter my quad is now faster. It's faster off the line and I gained 10mpg on my top speed. Maybe my CVT was in dire need of lube or I don't know what, but some how this quad is quicker. When I bought it it's max speed was 35mph and now she goes 45mph. I was pondering buying a Clutch kit because I'm sure the CVT springs and internal parts are original. I'm thinking this would help performance on this 1992 atv.

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