Rebuilding my first 787, looking for some advice.

[69DartGT]

Hello, I am going to rebuild the 787 in the 96 XP I am restoring. I am going to get all the parts I can from OSD. But where is
the best place to source or have rebuilt a the crank and counter balance? Thanks Scott.

 

[mikidymac]

Competitive crankshafts is probably the best there is but pricy.
A member here was doing the balancers but I don't remember who.

 

[69DartGT]

Thanks for the info.

 

[shamrock246]

They did mine, awesome to deal with.

 

[69DartGT]

Can I ask what it cost you?

 

[shamrock246]

I think it was around $600 ish in late 2021.

 

[cloudmaster_321]

Northern Crankshafts may do the Seadoo cranks, you'd have to call them. They have done others for me when i've rebuilt snowmobile engines.

 

[69DartGT]

Thanks for info, I am going to have my crank and CB done by Andrew at AP custom and Precision LLC. He is the
guy that does all of Nick Jarmans work.

 

[burtshaver2021]

Thanks for info, I am going to have my crank and CB done by Andrew at AP custom and Precision LLC. He is the
guy that does all of Nick Jarmans work.

Hoping your going to document the rebuild here?

 

[69DartGT]

Hoping your going to document the rebuild here?

I sure am.

 

[azsxr]

Don’t forget the oil in the balance shaft
and the arrows on the piston go towards the exhaust witch is the same side as the intake lol

 

[69DartGT]

Well, I started opening up this 787 that was in a parts 96 XP that I got to rebuild for the 96 XP I am restoring that had a SBT motor in it.
The SBT motor was not even able to be used as a core! I was told this 787 had a top end kit put on it over 10 years ago, but never ran after that.
I found out why, they put the pistons in backwards and the PTO piston clipped the top ring on the exhaust port. You can tell it only fired briefly. The only damage I can see is a few tiny dents on top of the piston and head from the piece of ring that broke off. The cylinder walls look great with nice cross hatching. Now the other surprise was, they put Wiseco 778M08296 82.96 mm bore pistons in it.

So I am going to take the cylinders and pistons to the guy that does my machining and have him look at them to see if I can just do a honing and ring job on them. I also want him to check if they were chamfered correctly. If his says they won't work, I guess I will have to find different cylinders bore and put WSM pistons in like I had planned to do with this one. I never thought that It would be bored over to the limit since it wasn't a SBT motor. I also broke a head bolt off in the process, I have a love HATE relationship with these old seadoos.

 

[burtshaver2021]

Forged pistons, slightly larger piston to cylinder wall clearance needed than the standard cast pistons they come with. If it hasn’t ran much since the rebuild, cylinder walls are good, cross hatching is good, would you not feel comfortable just replacing the rings, heck, even the wrist pin and caged needle bearings are probably still good. Unfortunately I think your stuck with a forged piston with this bore.

 

[69DartGT]

View attachment 67908
Forged pistons, slightly larger piston to cylinder wall clearance needed than the standard cast pistons they come with. If it hasn’t ran much since the rebuild, cylinder walls are good, cross hatching is good, would you not feel comfortable just replacing the rings, heck, even the wrist pin and caged needle bearings are probably still good. Unfortunately I think your stuck with a forged piston with this bore.

I have read up on these pistons, if they work I would be fine with them. I know you have to warm them up good before you get into it. Which is what we do with all of our toys anyway. My grandpa taught me that a long time ago.