Superjet revs but won't accelerate.

[smoofers]

Your midshaft bearing is most likely worn out and needs to be replaced. The engine side coupler threads on to the crankshaft and I promise you it isn't moving from its original position. The midshaft is press fit into the midshaft bearing and the bearing ID or midshaft OD might be worn enough to not allow the shaft to stay in place. The other thing to check would be your motor mounts... You usually shouldn't see your midshaft/coupler get pushed back that far unless you are majorly flopping the ski enough to let the motor move that much in its mounts.

 

[Bayerj]

Looks like your pic with the clamps on, you are stretching the rubber ring with all the holes in it. Clearly not moving the shaft in the bearings, which is what you have to do. I bet when the clamps came off, everything went back to the way it sat in the previous picture. Do it right. Take the midshaft out and put it in a press and get it back to spec

 

[mbrick]

Agreed, looks like you are temporarily stretching the rubber "bushing" in the midshaft housing. As soon as the coupling rotates a bit it is able to pull back apart to it's natural position.

I think your next step is to pull the engine, and then midshaft so you can measure the midshaft against the service manual spec. Either it slipped, or the bearing is shot.

As one option you can get a new midshaft assembly from JetManiac here on the forums (link) and drop it in.

You're close to getting it solved, nice work so far!

 

[ejn1214]

Which bolt/s do I loosen on the motor mount, to slide motor(engine) forward, in order to remove midshaft & midshaft bearing?

Bolt A OR Bolts B1 and B2?

 

[Baja 252]

Bolts marked "A". Be aware, between the bedplate (engine) and the mounts (that will stay bolted to the hull) are shims of different thicknesses. There could be different ones for each mount, so don't mix them up. When you go back together (after the mid shaft is repaired) put the same shims back in the same location and check the alignment to see if further shimming is necessary.

 

[mbrick]

Just A, and the B1/B2 + bracket will remain in the hull. After you remove the 4x A bolts, the large bedplate can slide around on top of the brackets.

As Baja mentioned, keep an eye out for shims and washers, don't mix up the shims.