Well, I finally decided to change gears a little bit and pick up a two stroke that needs drivetrain work instead of engine wotk. Got a hold of a nice 2003 trailblazer 400 that runs great, is nice and straight with no busted plastic and has brand new itp tires. The kid I bought it from said he bought it from a friend that took it part to fix and he never hot it back together. The kid said it drove fine after he got it back together but it needed a secondary clutch so he got a used one and put it on but after that, it would not go into high and would just grind. It goes into reverse just fine and you can drive it in reverse all you want with out it making a noise. Shifts into neutral fine but when you push the shifter forward, it clicks like it's going into gear but just grinds like it's not all the way engaged. I unhooked the shift linkage and put it into high manually with a pliers but it clicks into high but still grinds and the machine won't move. I can snap it back into reverse and it's fine. What am I looking at here if I want to fix this? Is it the silent chain or something more serious? I checked the fluid and even though it's a tad dirty, it is not milky, thick or full of metal.

Sure would like to get this one back on its feet again. I sold my little 2002 Trailblazer 250 to my daughter and this one would make a nice bigger twin to it if I decide to keep it.

Thanks,
Mike

 

Sounds like the slider gear(6) dogs or the drive gear(4) dogs are worn. Could even be a simple as a snap ring(2) jumped the slot on the shaft. If this happens the two gears wont engage properly. I've had that happen before and you might get lucky as to parts that need to be replaced.Reverse is usually never a problem because it's used less often and it gear to gear engagement rather than chain driven like the forward gear is.Either way sounds like it's tear down time and always replace the silent chain and seals also.

 

Thanks OPT,

Does the rear suspension need to be removed to remove the gearcase?

Thanks,
Mike

 

Nope it can stay. Just have to remove the funky brackets,clutches and clutch backing plate. Can't remember if I pulled this one out the left side or through the top of the frame. Either way getting one out is the hard part. Once you've done one it's not that bad. On this one also you have the gear case support bolt with the drain plug. Have to loosen the lock nut,turn the bolt back in far enough to remove the drain plug. Don't forget to install it back on the gear case BEFORE you reinstall it. Then after the gear case is mounted,turn the bolt out until it touches the frame. Turn 1/8 turn more to snug it and then tighten the lock nut against the drain plug.

 

Thanks OPT,

would the snap ring, #2, get popped out of the groove if someone tried forcing the secondary clutch off? The only reason I asked is they just replaced the secondary a few days ago before I bought it and they were riding the machine before that. The kid said the grinding issues started after he installed the new secondary. I know they usually just pop off but if it didn't I could see someone getting strong armed with it trying to get it off.

Thanks,
Mike

 

Shouldn't have affected it by working on the secondary clutch,but anythings possible. Main reason I think that I found a couple where the circlips had jumped and were distorted was from people that got po'd and tried slamming them into gear. You really won't know until you break it down. Look at the shift fork and gears closely for wear. Silent chain could even be the cause if it's stretched and loose jumping the two gears. The chain was the number one thing to replace in most of them anyway.

 

Thanks OPT,

After I get it torn down and fix the problem, what do I use to seal up the two case halves? Can I use three bond? I assume I can use Amsoil chain case lube in it in place of the polaris AGL. Unfortunately the Amsoil stuff is pretty popular here.

Thanks,
Mike

 

ThreeBond is what I always used on engines and gear cases.It's similar to the old Yamabond and other semi hardening sealers. ThreeBond 1104 was the best but it was replaced by 1194. Found out after years of smearing it around with my fingers that the old good stuff had a little lead in it.. Amsoil,Agl,either one is fine.

 

Thanks OPT,

I got the gearcase apart today. The 19 tooth gear, #4 had it's 3 ear broke off. Everything else is fine as far as wear, even the #6 slider. The chain is tight too but I am ordering one along with seals. When I replace the gear, do I replace the engagement dog as well, even though there is no visible wear or damage? How do I change out the 19 tooth gear. Can I pull the bearing and reuse it?

Thanks,
Mike

 

Very lucky if that's all the damage there is. Yes you can reuse the bearing.Use a gear puller or you can even place the bearing on top jaws of a vice and have someone hold the shaft assy while you tap the center of the shaft to free the bearing. Then remove the circlip(best to replace these if in doubt) spacer and gear.Slide on new gear,washer and clrclip then the bearing. Examine the slider gear dogs carefully. If not rounded and worn you can reuse it. Possible faulty heat treatment on the drive gear or a just a freak lug break.