Hey folks, to let you know how I made out, my first weekend as a DIY, ATV mechanic
$$ 1986 Polaris trail boss 250 cc, $350.00, parts to date; $40 manual; Time in; Priceless
* Was able to get all my plastic off including racks, (that was the easy part)
* Air box off
* Carb off, took it off as a kit including choke, throttle cable and lever. All in tact in a bag. I will devote a time to clean, lubricate and put it back in. I left all cables hooked up to the carb because I thought it would make it easier to remember where all went, when the time came.
* Took muffler off
* Took the motor and gear case off the frame: what a bit%$, One of the motor mounts I had to cut off. Looks like the motor is supposed to be held to the frame with three mounts, my bike only had two. The motor must have been bouncing around like crazy. In either case I'll have to find two mounts prior to putting this thing back together.
* Once I had the motor on the bench, I saw that they had welded a bolt to the muffler adapter. Looks like the adaptor was broken and instead of getting another the welded the bolt. I was able to get them off again another bit%$, Looks like the threads are ok on in the cylinder. When I looked up what parts are supposed to be there I saw that there should be studs and nuts as opposed to bolts, not sure the reason or what the difference would be.
* Also while motor was off I noticed that they had taken the starter off, I have bits and pieces, what concerns me is now that the starter is off the flywheel is exposed to dirt, mud water, etc. Not sure if I have the money for a starter right now, so should I consider making a cover for where the starter would normally go.
Next steps
o Next steps, dismantle top end down to the gear case and see what is happening in there????
o Stores order at this point
* 2 engine mounts, top and front
* Bolts or studs for the muffler adaptor.

 

I would fab a starter block-off plate for sure. That was a good idea keeping everything attached to the carb so you don't forget.

 

Check out www.dbelectrical.com for a starter.Way cheaper than oem and even have a grease zerk.

 

It sounds like you are making very good progress.

The '86 Trailboss that I had also had motor mount issues. When I got it, the motor would vibrate like crazy, enough that the drive pully wore through the back of the belt cover. I found the top motor mount was broken. Welded it (a few times), and that would work for a while but it would eventually break again. Finally, found a used on at a local Polaris dealer who had bins of old parts in their shop.

Here are some of the other problem areas that I found on mine.

1 Rear swing arm bushings were shot. I replaced these.
2 Gearbox cover was cracked where those cups are pressed in (and the swing arm bolts push into to). Had this welded.
3 Chain and sprockets were very bad. I never replaced but just kept well adjusted.
4 Drive clutch would lock in the "fast" position if driven full speed. This wasn't dangerous since it would still slow back down as usual, you just couldn't start going again until you popped the clutch loose with a screwdriver.
5 Frame was rusted out on the belly (I think water would get trapped in side the tubes). I just kept an eye on it and flushed it out really well to keep dirt out.
6 Rear disk brake did not work at all. I never bothered with this.
7 Front brakes were very "grabby" but I adjusted them enough to feel fairly safe. I remember that they pulled to one side.
8 The front shocks had no dampening left at all. It was just extremely bouncy springs.
9 The belt had been chewed up by a mouse and was half gone in one spot. It still worked fine.
It sounds like a real mess, which it was but the engine ran great and started every time very nicely. I never did anything to it except change the spark plug. It sounded like a diesel since everything was so loose.
I put chains on the back tires and it took me through some pretty tough terrain. It just couldn't do deep water since the belt cover was so holey.

Good luck on your project and keep us posted.

 

I don't know about that one, Thor. #9 made me laugh so bad I had to stop reading twice.

Frank

 

I have to say; I have been on several forums for different reasons i.e hunting, fishing . I have never been on a forum that was as enjoyable and helpful as this one.
Again thanks for you help and comments. I will keep you posted as I move along, as like this thread I will start the topic as "Rebuilding my 1986 250 Polaris trail boss"

Just as a little update, I have taken the top end apart down to the crank case, all looks pretty good, very little scoring on cylinder of piston.I think I am going to go with new rings a gaskets at this point and go from there.