900 Crank twisted?

[Repoman]

I blew a belt at the end of last year and have not ran my sled until this year since. When I bought the sled the engine would vibrate some while idling but it goes way when you add throutle. This year since the blown belt it seems the same and I put one a new belt followed the belt break-in process and it was fine. I crushed the left footwell when the belt blew last year and I bought a new one to replace it this week.

My question is, how can you tell if the crank is twisted and how bad does it need to be before you tear down the motor to get it trued and welded? My sled seems to run fine I do not have another 900 to compare the idling vibration to.

Can you do a crank index? should they be exactly opposite? I have indexed alot of jet skis before.

Thanks

 

[SNOADDICT]

900 vibration

I can't help you with the crank part but I do own a 900 and ride with a guy that has one as well and they all have a crazy vibration at idle, I've had mine from 300 miles and it hasn't changed I now have 2300 miles on it.

 

[JROD]

Cylinders should be 180 degrees apart. You can check it through the spark plug hole to check TDC versus BDC.

 

[arcticcatwill]

I blew a belt on my 800 (same bottom end), it didnt twist the crank but i did bend it. Just the pto side was bent .013'' out in the pto. The way I found out was when i cold seazed it after it was completely warm for over an hour, basicaly eventualy my crank seal went out cold air got in and a piston got a little to big. Anyways pulling it over slowly by hand listening to the cylinders, we saw the clutch wabble back and forth. Check for a little clutch wabble, you can even put a dial indicator on the crank pto itself too.
PS: mine was a $50 to fix the crank, Thank god for cranky joe.

 

[M7-Ballz 2 the Wall]

I blew a belt on my 800 (same bottom end), it didnt twist the crank but i did bend it. Just the pto side was bent .013'' out in the pto. The way I found out was when i cold seazed it after it was completely warm for over an hour, basicaly eventualy my crank seal went out cold air got in and a piston got a little to big. Anyways pulling it over slowly by hand listening to the cylinders, we saw the clutch wabble back and forth. Check for a little clutch wabble, you can even put a dial indicator on the crank pto itself too.
PS: mine was a $50 to fix the crank, Thank god for cranky joe.

If it is bad enough to hurt anything you will see the clutch wobble if you dont have a dial indicator just pull the plugs out and have someone pull the rope hard watch the clutch see if it moves try to put an extension between the cylinder and the clutch so there is a tighter gap to watch the wobble will be more noticeable that way. i highly doubt that you slipped it out of time by blowing a belt unless it got extremely over revved like 11/12 thousand

 

[ippielb]

Check your plugs regularly, that blown belt may have lost a crank seal, causing a lean out on one side.

 

[Repoman]

I know it did not over rev. I have recently put a new belt on and ran 80 miles, the belt looked fine (I stayed under 55 mph for the first 20 miles and then periodical hit 60 -70 after the 20 miles). The plugs are just slightly on the rich side (both are even). I checked my clutch alingment, they were off at the most .062" (1/16th) so I adjusted that by tightening my torque stop. My belt deflection is in the 1 3/8" to 1 1/2" with all shims in the secondary, I beleive I will need to remove either the .030 or the .060 shim yet. I will use a spacer to check for clutch wobble next.

 

[richardderkevorkian]

I know it did not over rev. I have recently put a new belt on and ran 80 miles, the belt looked fine (I stayed under 55 mph for the first 20 miles and then periodical hit 60 -70 after the 20 miles). The plugs are just slightly on the rich side (both are even). I checked my clutch alingment, they were off at the most .062" (1/16th) so I adjusted that by tightening my torque stop. My belt deflection is in the 1 3/8" to 1 1/2" with all shims in the secondary, I beleive I will need to remove either the .030 or the .060 shim yet. I will use a spacer to check for clutch wobble next.

That deflection isnt bad if you get it much tighter the sled will try to creep. I always leave My motor pushed forward about a sixteenth because it twists back under power so that way everything lines up under power.