670 doo stopped abruptly

[magnet]

Had good weekend this weekend till beachsleds machine tanked. ran good when we first unloaded off truck. about half hour into riding couldn't keep running and egt's wouldn't go over 750. dropped needles and it cleaned up a bit egt went back up to 850-900 still low but better. still couldn't keep running at idle though kept flooding itself. near end of day unit quit. finally got it going about 15 min later and 5 qauzillion pulls of the rope. started to go clutch had just locked up and moved about 5 ft egt's at abot 500 and sled quit and i went onto the hood nearly. tried to pull over no go. I can rock the engine back and forth about 1" to 2" but wont make full revolution. looked inside tops of pistons are washed clean zero carbon. any ideas would be great. tops of pistons are even still wet it looks like. 1 good thing is at least we have all summer to fix. It's a 98 670 twuin jaws pipes, k&n pods, and holtzman atac.

 

[Modman]

Had good weekend this weekend till beachsleds machine tanked. ran good when we first unloaded off truck. about half hour into riding couldn't keep running and egt's wouldn't go over 750. dropped needles and it cleaned up a bit egt went back up to 850-900 still low but better. still couldn't keep running at idle though kept flooding itself. near end of day unit quit. finally got it going about 15 min later and 5 qauzillion pulls of the rope. started to go clutch had just locked up and moved about 5 ft egt's at abot 500 and sled quit and i went onto the hood nearly. tried to pull over no go. I can rock the engine back and forth about 1" to 2" but wont make full revolution. looked inside tops of pistons are washed clean zero carbon. any ideas would be great. tops of pistons are even still wet it looks like. 1 good thing is at least we have all summer to fix. It's a 98 670 twuin jaws pipes, k&n pods, and holtzman atac.

If you can't make a revolution something inside is wrong. Maybe its full of gasoline if it was that rich but I kinda doubt it. Sounds more like internal damage. Either the starter ate itself, a piston is damaged and toast (piece of the ring stuck in the exhaust port?) or the crank is toast << this would be my guess. Possibly a rod bearing or a crank bearing went.

 

[H2SNOW]

sounds like you ate a main bearing ..probably

 

[magnet]

Well we got it apart this weekend. Peoblem found rotary/water pump shaft gear poooched. removed gear all turns well. Having a hard time trying to split the case though to clean up the shrapnell embedded on the crank gear. any ideas. Do yuo have to have the mag and clutch off to get it apart?

 

[Modman]

Well we got it apart this weekend. Peoblem found rotary/water pump shaft gear poooched. removed gear all turns well. Having a hard time trying to split the case though to clean up the shrapnell embedded on the crank gear. any ideas. Do yuo have to have the mag and clutch off to get it apart?

yes u need to take the mag off.

 

[magnet]

Thanks Modman. Upon further investigation we also found a cracked clutch on both sides outside had two cracks inside has 1. and secondary slides around like a limp noodle on the jackshaft. Not bad for a sled that was meticulusly maintained by a Martins mech. makes me like that place even more now. Just sucks that this was my buddys first sled experiance.( I know it's spelt wrong). But he is all good with it and can not wait till next season come on snow.

 

[magnet]

So here we are same sled still. trying to take off the mag but i need longer allen keys i got that part figured out now. But we figured we might as well take off the head and inspect cylinders while apart this is what i found. Pistons and cylinders look ok. however side that blew the hole in the pipe rave valve cleaned up really clean,probably from the overfueling, but the head has a lot of gouges in it.see pics. will this affect performance at all?

 

[pano-dude]

I would guess the head was like that from a previous problem.

no way something did that much damage to the head and not the cylinder or top of the piston

It'll run with the head that way.