EagleJason
New member
My 01 SXR 700 (SX 700 F, machine says SXR on it but SX700F on title) died today. Not sure what happened. Last Sunday it was running fantastic, 100mph and still accelerating up hill (200 lb rider). By yesterday afternoon it was acting weird, it would still accelerate, just slowly, i still was hitting 80+ so all 3 cylinders were running but sled wouldn't rev over 6500. Temps were around 0F. Today at -22F i started the machine, allowed it to warm up and it didn't want to really pull again. It's done this before and after a few minutes, it'll usually warm up and run. Today i ran up to a friends and shut it down while he gassed up. I put new plugs in it since it was struggling (2 were black and wet). I restarted it, but it backfired so hard it blew the exhaust off (sounded like a gun shot). I put the exhaust back on and it would start but not run, then spluttered. I let it sit for 20 minutes and tried again, it just backfired a few times but never started... What's going on?
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What do the pistons look like? Thats the first place I would check. My guess is a ring went.
I have the same problem with my 600 SXR and I am guessing it is a CDI issue. put the sled in the garage and heat up each of the three CDI's and then try to fire it up. If it runs then it would indicate to me that there is an electrical issue with the CDI's when it is cold. I have looked my sled over from stem to stern and cant find anything wrong yet it will run after the sled has been sitting in the heated garage over night but doesn't have power and backfires when it has sat outside and gotten cold.
EagleJason
New member
thank you both. once it's a tad warmer, i'll work on it and check both of your ideas, however at -36 this morning and -25 right now i have no burning desire to touch any metal objects with bare fingers.
EagleJason
New member
finally had a mechanic at least look at the machine, it's been so cold (-47), he thinks it's the head gasket. due to the build up to it and the fact that it now turns over easier than before, that was his take. if it's warm enough tomorrow (unlikely, it's -30 and dropping now) i'll move it down to his shop for compression testing and final analysis.
EagleJason
New member
borrowed a compression tester, 120-122 each. called the 'local' yamaha dealer, apparently that's normal for a redhead. i guess that rules out headgasket, piston or ring.
the engine will fire but not stay running, the dealer said that means it is NOT the cdi, that would either be a yes or a no proposition.
the dealer's sr tech said it's most likely the TORS. they said unplug it, then plug each wire into themselves. i've found the tors on this machine, (still can't on the vmax) but haven't found the way to plug it in to itself.
i'll test that and then have a better idea of what's going on.
they said it could be belt dust in the carbs if the tors didn't resolve it.
the engine will fire but not stay running, the dealer said that means it is NOT the cdi, that would either be a yes or a no proposition.
the dealer's sr tech said it's most likely the TORS. they said unplug it, then plug each wire into themselves. i've found the tors on this machine, (still can't on the vmax) but haven't found the way to plug it in to itself.
i'll test that and then have a better idea of what's going on.
they said it could be belt dust in the carbs if the tors didn't resolve it.
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Did you check the reeds ?
or the crank has moved out of phase on the center pin.
you can do a hill billy check pretty easy: take out the spark plugs, take a long screwdriver and insert it into the head to touch top of piston. Then rotate the clutch by hand slowly bring each cylinder up to tdc,be sure its the highest point and take a sharpie marker and mark your primary clutch at a exact spot each time. do this for all 3 cylinders. your marks on the clutch sheave should all be exactly the same space apart, 120 degrees from each other.
you can do a hill billy check pretty easy: take out the spark plugs, take a long screwdriver and insert it into the head to touch top of piston. Then rotate the clutch by hand slowly bring each cylinder up to tdc,be sure its the highest point and take a sharpie marker and mark your primary clutch at a exact spot each time. do this for all 3 cylinders. your marks on the clutch sheave should all be exactly the same space apart, 120 degrees from each other.
EagleJason
New member
i have not checked the reeds yet. i will if the TORS fix doesn't work. I think it may be slightly off time, so i'll do that check as well when i have the chance.
thank you for your replies and assistance.
thank you for your replies and assistance.
EagleJason
New member
oddly, i put disconnected the TORS, it didn't work. i stood there looking at the machine, walked over to the laundromat, yes, i use a machine for hauling laundry too, and realized this all started when i changed plugs. i walked back over, put the old partly fouled plugs back in and it started on the 2nd pull. it would not rev over 3000 rpm, so i reversed what i'd done to the TORS and restarted it. it immediately would rev to redline. took it out and ran it a little, then went and bought new plugs for it. threw away the ones that had caused the misfires. i'll let you know how it runs on the new plugs.