2008 summit xp 800 running on one cylinder

[pincampbell]

sled has even compression both sides at 115,getting spark on both sides, have checked reeds,main jets are good, have tried two different computers, disconnected all wiring to handlebars with no difference, pick up coil looks fine, sled will start but back fires when fired up. any suggestions would be much appreciated

 

[cdnemsguy]

Tough one. Can you tell which side? What does the plug look like on that side? Float too low or fuel restriction on that side?

 

[pincampbell]

issue on pto side, has new plugs, just purchased

 

[cdnemsguy]

I dunno. I am still suspect that you are leaning out therefore the backfire. Have you checked the float height and needle/seat on the pto side so that your getting the fuel? Leads from the coil if broke will also fire a plug until there is compression(resistance) on the plug then the lead will intermittently fail. I am just throwing out some guesses here with the info I have.

 

[pincampbell]

thx,I will take a look tomorrow

 

[sscamaro_skwark]

If spark is good as you say you may want to try to spray some fuel into the cylinder that is not firing, engnes need air, fuel & spark (back to basics)
Also a good spark is less likely under compression if you tested it out of the cylinder & excess fuel to an extent is easier to ignite
just a thought

 

[pfi572]

Did anything happen with motor up till this started happening? Over rev ,blown belt? The reason i ask as crank could be out of faze. Pistons and timing out from top dead center.

 

[wrheaume]

Did anything happen with motor up till this started happening? Over rev ,blown belt? The reason i ask as crank could be out of faze. Pistons and timing out from top dead center.

Ever figure out what the problem was with this sled? I have a 2010 that's doing the same thing. Compression, reeds, carb boots are all good, pilot & main jets both cleaned. Without the choke on the PTO plug comes out dry and carboned up like its not getting fuel. I've had inake and exhaust sides both opened up, piston & skirts look perfect. Carb boal is full of fuel. It's got me baffled. SOMEONE HELP!!

 

[CANADIAN_BRAAAPER]

Just get a syringe full off gas, remove the boot on your carb coming from the air box, open butterfly (full throttle) squirt gas into carb, then attempt starting, if it fires on both cylinders you have a carb problem, remove the carb do a thorough cleaning, and re try. Worked well for me.

 

[wrheaume]

Thanks for the reply, I've done all of that, still not working so last night I pulled the head off the motor and found the crank is twisted out of phase. At one point in the rotation of the crank, both pistions are moving in the same direction. Anyway the whole motor is coming out this weekend.... The worst part is that I rebuilt the whole engine last spring after the season was over and now this happens with just over 100 miles on it. And of coarse there is only a six month warranty on the crank. Screwed over again!

 

[DRD]

Who's crank?


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[MGD]

Had the same thing happen to me, this is what i found when I split the cases.

 

[wrheaume]

Ouch, that could be bad. Mine could still be salvaged. Took it to Precise Engines in S-toon. They are really good. New PTO stub, couple new bearings, back in phase and GTG. One thing I did Lear from them is they NEVER put an 800r crank back together without Loctite on all the joints. Prevents future problems.... Once I get it back in we'll be testing it out in the mountains....