Do a compression check. If that left cylinder is down at all, suspect that stator (they call it a rotor) may have gone. The magnets are held in with plastic and that starts breaking, releasing particals of magnet throughout. It’s right under cyl one. I’ll show pics later.
I found a guy at work who used to work on stuff like this, I'm gonna see if he'll give it a look. I don't have the tools and stuff to do that myself.....
I think its one on the left and one on the right. I gotta delve into it next week. I finally put the old Grabber into storage, so I now have room on my side of the garage to tinker with it.
I went back and fixed it for accuracy lol.
Scotty, I'm not sure if the sled motor is identical. If you spend any time searching R1 stator failure, you'll see a lot of people experienced this. The rotor is behind this cover on the left side.
Exactly! It was bad! Worst detonation I have seen! Piston wasn’t that bad, but it was a forged JE, only looked sandblasted, the pits are 1/8 of an inch deep in places! It going to need a new head!
According to people I've talked to, they aren't identical to the bike engine, but I'm not sure what differences they have. Gearbox being one major difference.....@Scotty Overkill
The stator is connected by screws to the cover and the rotor goes over top.
View attachment 152560
You can see pieces of magnet and the failed plastic shroud. On the inside of the rotor, they should all be evenly spaced, and attached by pressed metal material, but some brilliant Yamaha engineer thought plastic would suffice.
View attachment 152558 View attachment 152559
Not so much.
If your sled has this motor, you may want to replace that rotor with the updated part, which does not use plastic. Those shredded pieces of magnet will stick to... the crank, cams, oil pick up screen etc. Not the aluminium block. They clog one small passage and you're fooked.
New part:
Old part:
for a young dog
Just fixed a broken decomp thing on the end of the cam,,,
