Seadoo 800 Counter-Balance Shaft

[Michael73]

G'day SBT

My counter balance weight spun on the shaft and vibrated the bearing on the shaft to death, seized the bearing and then proceded to rip thru the crankcase.

What would cause the weight to spin on the shaft?

My mate is an alloy welder and is gunna TIG it up for me.

Thanks for your help.

[Joe St. Louis]

What most likely happened is the bearing seized, which then caused the gear to spin. On the SD 800 countershaft, the front bearing is sealed and the rear bearing is open. the rear bearing could fail if the cap with the o-ring at the rear of the case is leaking. The front bearing could be damaged if the seals failed. Of course there are 101 other reasons the bearings could have failed, but I think those are the most likely. :D [img]/graemlins/winkanim.gif[/img]

[Bill O'Neal]

When reassembling a 782 motor, we put a bead of silicone around the case plug at the counterbalancer to preven water from entering the cases at that plug. When disassembling 782 cases, we often see signs of moisture and rust on the cb bearing. It is good insurance to seal that plug well. The oem oring is just not enough to keep the water out.

[Michael73]

Ok Thanks for that, I understand that the open bearing is lubricated from oil that you put in the crankcase fill plug, but the other bearing is just sealed forever, never to get lubricated, only what was put in there at assemebly.
Do you get many seized counter shaft bearings seized, or I am i just over reacting (even thou it does 6000+rpm for extended periods).

[Michael73]

Also the weights on the shaft, are they of equal rotating mass, even thou one looks smaller, but only one has the gear so with if you could imagine it without the gear would they be the same weight.

[Bill O'Neal]

Michael,
I have seen lots of damaged CB shaft bearings, but I will defer to SBT's Joe St. Louis about this question, as he sees hundreds of counterbalancers come through SBT.

I totally did not understand your last post. Is there a question in there somewhere?

[Michael73]

CB = Seadoo counter balance shaft.

What I meant was, even thou 1 bearing on the CB dosent get lubricated, is this any reason to think that the bearing would fail (ie: seize) quickly (ie: before the other one on the same shaft?). :D
And there are 2 weights on the CB shaft, would these weights have equal rotating mass?
Just out of curiosity (not that i will do it) what would happen if you didnt install the CB shaft, would the crank die quickly, or would it just vibrate a little more?
I'm still trying to read thru all your old posts.
This site is fantastic, we get good answers, even to the most stupid questions, and also the difficult ones, much better than that *Retarded* jetski news group....
I congratulate all concerned for and excellent internet site.. A credit to you all..

[Bryan Glynn]

You're welcome, and thank you! We are all trying! Tell your friends!

[Bill O'Neal]

I haven't noticed a problem with the two different bearings and the way they wear. When one fails, it is usually due to water being introduced to the bearing at one time or another.

The CB's on the shaft are of equal weight as far as I know. If you remove the shaft from the motor, it will shake badly and definately shorten the main bearing life. Leave it in there.

[hman]

I have a 96 xp and there is no fill plug for the counterbalance shaft,when I rebuilt the motor I was using a manual by Clymer and there was no mention of having to fill the the counterbalance shaft area with oil before assemblying the cases.Is there any way to get oil in now other than splitting the cases again,and what kind of life expectancy can I expect if I just run it without the oil in there?