Why is my snowmobile going backwards? - Snowmobile Forum: Your #1 Snowmobile Forum

REVO of Rustler · 05-22-2009, 07:35 PM

So I'm really new to the whole world of Snowmobiles, but I've been dirtbiking for about a year and a half.

So anyways, my neighbor had a 1985 Yamaha SS440 in the bed of his truck for a while with the engine out and a few other parts taken off. I was talking to him and he asked me if I wanted it. So I took and got everything back together and I got the engine running pretty good. Today I was working on the clutch just getting it working good. I was standing on the floorboards and whenever I would rev it up a little it would move about an inch backwards and then just roll forwards again. I got the back up on a car jack so that the track was all the way off the ground and I found out the track is spinning backwards. Do any of you guys know what would cause this? I didn't rebuild any of the drivetrain or anything. This just seems like a very weird problem...

ridgerunner · 05-22-2009, 08:34 PM

kinda a stupid question, but does the sled have reverse? when the engine is running, clutch should be spinning counter-clockwise when you are looking at it...

REVO of Rustler · 05-22-2009, 10:05 PM

It doesn't have reverse on it. I have no idea why it does this. It's almost like the engine is running backwards...

**BC_Dan** · 05-22-2009, 10:59 PM

If the timing or the ECU was messed up, it could be running backwards. That is exactly how PERC in the newer Polaris sleds work (along with ski-doo and the new arctic cats).

a 2-stroke doesn't care what direction it's running when it's running, but timing is everything... I would start there.

REVO of Rustler · 05-23-2009, 12:41 AM

Quote:

Originally Posted by BC_Dan

If the timing or the ECU was messed up, it could be running backwards. That is exactly how PERC in the newer Polaris sleds work (along with ski-doo and the new arctic cats).

a 2-stroke doesn't care what direction it's running when it's running, but timing is everything... I would start there.

It is the timing. It's firing before it gets to top dead center, so it just pushes it back down. Do you know of any ways to fix the timing? I'm new to most of this, so it might take me a little while to catch on. Thanks!

**smallengineguy** · 05-23-2009, 07:21 AM

You need to twist the stator plate (behind the flywheel) so the timing is more retarded.

REVO of Rustler · 05-23-2009, 10:30 PM

I was looking at the stator and the motor block and I saw two notches on the block and one on the stator. Is the notch on the stator supposed to line up in between the notches on the block? The notch on the stator is about a centimeter off from the two notches on the block.

REVO of Rustler · 05-24-2009, 12:04 AM

I just went out and took some pictures of the notches for clarification.

Do these notches need to be lined up?

**smallengineguy** · 05-24-2009, 06:38 PM

They can be moved, but not necessarily lined up. You can use a screwdriver between the notches to adjust the timing.

YamahaSS440 · 05-24-2009, 11:26 PM

Im not trying to steal ur post but can u post a pic of the whole sled? i have the same one and dont see many around. thanks

REVO of Rustler · 05-25-2009, 01:10 AM

Quote:

Originally Posted by YamahaSS440

Im not trying to steal ur post but can u post a pic of the whole sled? i have the same one and dont see many around. thanks

I'll try and get one tomorrow.

YamahaSS440 · 05-25-2009, 10:42 PM

Hey thanks!

REVO of Rustler · 05-26-2009, 12:16 AM

Here are some pictures.

The seat cover was a little torn up, so I had to do a custom repair job...

It still needs a windshield, but I'm gonna try and make one out of plexiglass.

**smallengineguy** · 05-26-2009, 07:17 AM

Looks to be in good shape! You could probably find a good used windshield on eBay.

YamahaSS440 · 05-26-2009, 06:51 PM

Yea pretty good shape, i bought mine for 100 dollars, and it needs nothing, the only thing wrong with it is the windshield is cracked. Mine has 4067 miles. ha i love the look of the ss and i dont see too many of them arond anymore. thanks for posting pics!

REVO of Rustler · 05-26-2009, 07:18 PM

No Problem!

REVO of Rustler · 06-01-2009, 11:52 PM

I bought a manual for this, and I got the timing as close as I could get it, and it's still going backwards! I am completely stumped as to what the problem could be. Is there something that I might be missing here?

JheLrey · 06-02-2009, 11:34 PM

Which way are you sitting on it? ;-) No clue... cannot help you but had to make the comment. I am a troll... just ask RJ

**RJ Gleason** · 06-03-2009, 08:52 AM

Quote:

Originally Posted by JheLrey

Which way are you sitting on it? ;-) No clue... cannot help you but had to make the comment. I am a troll... just ask RJ

Yes, you are the official forum "troll"!!!

The stator plate may still be too far advanced. I believe that it should be not more than 20 degrees BTDC when it fires.
Have you tried to crank it in the other direction?

sovatj · 07-08-2009, 12:47 PM

i have an 83 yamaha excel III 340 and the seat was torn up worse then yours seams to have been and i took it to a upholstery shop a week ago and they are doing the entire thing (fixing the foam and putting on brand new vinal) for only 85 bucks and this place is really good. just incase you wanted to fix it, its pretty cheap