I am in the process of putting my motor back together after my piston skirt blew apart. I pulled motor, split case, replaced seals, bearings looked and felt excellent.
My question is, there is a collar on the crank shaft that fits into a seal. I put it into the case seal, but it was a very tight fit. I thought something was wrong. Should it actually go into the mag housing seal or was I correct. I removed it for now. I had to tap it, to get it into the case seal, it would spin with crank. Also, it didn't seem to want to go in as far as I thought it should.










Without seal




Installed in mag housing




As for the rebuilt, I bought this machine knowing nothing about it. Replaced all fluids, cleaned it up, drove it down the alley and the motor seized. Once I pulled it apart, I realized that the oil pump was completely rusted, didn't move with the throttle cable. So ultimately, I believe the pump failed causing the motor to blow. The counter balance shaft was in bad shape due to the fact the water pump housing bearing was in pieces. I had a machine shop sleeve the shaft witch turned out real nice, I hope it holds. Got all my new parts and started to reinstall last night, but ran into this issue. I might ad, I am in no way claiming to be a mechanic, this is my first tear down. I hope I don't annoy everyone, cuz I am sure I will encounter a few more questions.




Thanks in advance for any help you guys provide
mark

 

You have two collars,one inner,one outer. Item #11. Dirt Cheap Yamaha, Polaris, Suzuki & Kawasaki OEM Parts & Accessories – Cycle Parts Warehouse Common problem on the 400 oil pumps. You can block off the injector at the intake manifold and premix or go back with a new oil pump.

 

I do see that now, so I just tap that colar into the seal that is in the crank case. I didn't buy a new one, so they must just fit that tight sliding over the crank shaft. I recieved my block off kit already, not going to risk that happening again. The o-ring is just rubber, correct.

 

Easier if you just lube the collars and work them in to the seals. O-ring for the oil pump body,correct. Depends on how the block off plate is designed. Plus it should have a new bolt to block of the injector bolt on the intake manifold.

 

Part #10 shows o-ring, I don't remember taking one off

 

Also, the collar was very tight going over the threads, that's why I was nervous

 

On the o-rings(#10) the inner one keeps oil/gas from seeping in to the counter balancer area,the other one is supposed to keep the counter balancer oil from seeping into the crank case area or pooling up,so the idea is.. My two cents, it'd be hard for that much oil either way to get past the collars and seals to begin with. O-rings are just a safety or stop gap idea that someone came up with. I'm sure over the years I've left one out at one time or another..

 

One more thing, when installing the seals, do you push them all the way in to the bearing, or just flush with the case. I pushed them all the way in, now the crank seems a little stiffer to turn over. I'm wondering if thats why the collar looked to be not going in all the way. I haven't tried the tapping on either end yet.

 

Once you get everything assembled and tighten the slotted nut,the collars will usually flush up with the bearings. If a crank shaft becomes very hard to turn afterwards,a good whack on the crank shaft end will usually loosen/align bearings,etc up and the crank will turn easier.Just the nature of the beast on the 400s.

 

Hope this doesn't duplicate, I don't see my post.
Does the starter get its ground from the motor? Looks like I only hoop up the positive cable, correct??