I need an OEM 951 DI balance shaft assembly. HELP!

[AZ Sea Doo XP]

Best price so far is $491 including shipping 420837446. HELP!

 

[Coastiejoe]

I just put your part number in eBay and came up with several, $99 to $150

 

[AZ Sea Doo XP]

they are for the carb engine, not the DI. big difference. thanks for looking

 

[hotrodssnova]

That's the number you gave us. Seen a few also.

 

[Coastiejoe]

Then I assume ther DI engine has a different number, yes?

 

[AZ Sea Doo XP]

all of the ones I looked at said they were for a DI but were for the carb engine. 3 of the 4 I found fit a DI. THANKS!

 

[AZ Sea Doo XP]

the old DI number is 420837445. the new DI # is 420837446. the carb part number is 420837387. so, yes. thanks!

 

[68ragtop]

Is the gear chewed up? The bearings & seals can be replaced if the rest of the shaft is ok.

 

[SabrToothSqrl]

I used to have one, but think I tossed it.

 

[AZ Sea Doo XP]

I took the one in the engine to a machine shop to replace the gear, bearings and seals. they didnt mark the placement of the gear before they removed it and it is off. I talked to several other people, they said the shaft is now a paper weight. I just bent over and bought a new one. thanks for the input!

 

[68ragtop]

Those weights and gears could've been reindexed. They have to be really close but it's not Percision The weights go 90° from each other straight up-and-down at the same time that the crankshaft is in the same position. I'd have to look in the service manual but I believe the air compressor side is at top dead center when the mag piston is.

It's not junk, very correctable.

 

[AZ Sea Doo XP]

the people I spoke to are machinists with a lot of experience. they both said it would be hit and miss. they said they could get it close, but close is not good enough. even if it is off a little, I can expect vibration. I cant risk it. Want to buy it!!! lol

 

[68ragtop]

Really not true. In fact I have bought several BRP rebuilt DI crankshafts & the CB gear on the crank has varied 1-2 degree's right from BRP. It's not quite as precision as you might think. I'm not saying its ok to be off, just saying they can be aligned without much trouble. In fact I had one that was off enough where I removed both weights to to re-align them. When the Mag piston is at TDC, the air pump should also be at TDC. when you drop the crank into the top half of the case, its easy to measure to see if the weights are in the right place. Here's a picture of one I did with the Mag side at TDC. you can see the weight on the pump is at TDC.
I rotated the weights 1+ degree's in the direction of the arrow to get it back to the correct location. you can see it in the marks as well if you zoom in.

I understand your concern on the vibration risks. I used to feel the same exact way. All of the ones I have done have run smooth as could be

Again, not trying to saying its ok to be off, just saying I have received them with the gear off a smidge, so BRP must think its ok to be a bit off. They are not hard to get them correct to match the crank, but you need to have the top of the case & the crankshaft to do it.

 

[AZ Sea Doo XP]

I understand what you are saying and appreciate your input. that being said, you are the lone wolf in the conclusion. Five people looked at it in person. not one was willing to move weights around with the hope that when it is installed it will not vibrate. the only way I would do it is if the shop doing the work guarantees it. By guarantees I mean if it doesnt work they pay to fix it and give me a loaner during the process! obviously. no one will do that. since I am the one that loses financially (again) if it doesnt work, I have no other choice but to go with new. Thanks again for your input!

 

[68ragtop]

If all of the machinists just had the shaft & its parts, I guess I can't blame them. I wouldn't & couldn't do that either. It would be a crap shoot with nothing to measure from.

But, with the crank & half of the case you can measure from the parting lines of the case & get them exactly where they need to be. The weights need to go 180 degrees to the piston stroke, it's not that much of a science & easy to figure out with the right tools. If you take a look at the weights you will see that they are just cast, its not balanced as an assembly.

Seeing your being thorough, drop your crank into the case. Make sure the bearings are fully seated & index the crank to bring the rod pins perfectly centered on the parting line. Then with a straight edge, check where that edge meets the gear.

Does it land on the tip of the tooth, in the root, or somewhere in-between?

 

[AZ Sea Doo XP]

they had the engine too. as I said and they said, close doesnt work. thanks for your input!