Broken tooth on the main crank shaft

[zmilos]

Hi guys I’m trying to rebuild the RXP 260 engine That has broken chain I noticed that the block needs to be split in two half’s to replace the chain is it possible to break the new chain open and guided in and join it up again like you doing car engines motorbike chain also I noticed a missing tooth on the main crankshaft gear Can you be replaced or do I need a whole new crankshaft any thoughts many thanks

 

[Chester]

That part is not available separately. I think I have a good crankshaft but the shipping might be a lot.

Chester

 

[zmilos]

Thanks mate I should be able to come up with a new crankshaft here I might have some old ones as well that have gears that are in good nick I’m just trying to find out is the crankshaft in two parts does this gear screw on the crankshaft or is the connection done by friction.
There is a crankshaft extension that screws on the end of the crankshaft where the driveshaft locks in ,and that can be removed
Thanks

 

[zmilos]

Also how dangerous would it be to put a new chain on the existing crankshaft with one missing tooth!!

 

[Rikky001]

Worst case the timing chain jumps of and bend some valves and wrecks your engine

 

[mikidymac]

You should never chance a bad sprocket. Only bad things will happen.

 

[ski-d00]

The gear is pressed on the crank, not screwed. You can press the gear off no problem. The problem is getting it back on in the correct orientation and the correct depth. I have heated the gear up and put them back on in the correct position and to the proper depth but it is a royal pain. Easier just to buy a good used crank.

 

[zmilos]

Thanks heaps for the info mate sounds like an impossible job with the crankshaft on the engine any thoughts on leaving the sprocket the way it is with one missing Tooth.Ski did 67 hours all up I’m trying to work out how this happened in the first place possible loose chain??
This JetSki was used for racing and looking at the parts they used to put it togetherIt it has a lot of Riva racing add-ons including the computer that has been mapped to 10,000 RPM 18 psi boost 80 psi fuel pressure big injectors looks like this engine was pushed to its absolute limit.

 

[ski-d00]

Chains break quite a bit and not just on the modded engines, see plenty on stock motors. BRP had a recall on chains around 2011 but I've seen pretty much all years break them but usually is on the 215 or 260.

I wouldn't use it with a broken tooth. It's not like it has 50 teeth in contact at all times. It has like 10 so it is a major increase in load on the remaining teeth.

 

[Rikky001]

Thanks heaps for the info mate sounds like an impossible job with the crankshaft on the engine any thoughts on leaving the sprocket the way it is with one missing Tooth.Ski did 67 hours all up I’m trying to work out how this happened in the first place possible loose chain??
This JetSki was used for racing and looking at the parts they used to put it togetherIt it has a lot of Riva racing add-ons including the computer that has been mapped to 10,000 RPM 18 psi boost 80 psi fuel pressure big injectors looks like this engine was pushed to its absolute limit.

Obviously, the gear on the crankshaft is the weakest link and race engines are modded for a reason, being powerful. Usually there is little focus on durability as the engine comes apart each race. It seems the engine reached its maximum capability.
Running the engine with a missing tooth on the crankshaft would be plain stupid as the design condition is all teeth to be intact. If the engine was run to the maximum I would strip the engine and see what "damage" has been done further down. Maybe you don't see obvious damage but once you start measuring bits and pieces you find things out of tolerance. It is just free advice but I don't suggest replacing a single gear wheel or the crankshaft without finding out the actual status of the engine. If you don't have the proper measuring tools you only guess and best case it will be an expensive guess with no warranty for success.

I have been there myself, the expensive things teach you good lessons... Good luck with whatever you decide,

 

[zmilos]

Just try using my 10 t press to pull gear off no luck even after heating it up next up I’ll try the freezer it and see if it works other than that I’m just doing some maths and working out what the load on the remaining teeth will be and maybe just try to use it again

 

[Rikky001]

Hahahaha I like your sense of humour, doing some math and maybe just trying to use it again - rather conflicting things as the math is pretty much exact.
The math is the easy part as you will see that with a tooth less your deflection goes up of the link, this in combination with the increased chain speed my friend will result in a quick game over. Most probably the chain will go first this time but your engine will be a total loss, trust me )

 

[ski-d00]

You will need a large press to remove the gear, around 35,000 lbs as I recall. It has a .004" interference fit which is a lot. Take it to your local machine shop and they will have it off in 5 minutes.