Stator replaced - Did not solve my problem

Mac

Mac

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Joined
May 2, 2003
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764
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New Jersey
Viper cant pull more than 8000 RPM. Seems to run OK at idle. Heat on all three pipes. After a test pass we then check with infrared temp tester. Two pipes show 600 degrees or so and the third shows 325 degrees. Im dropping the PTO cylinder and the plug is wet and not burning. The other look fine. I installed a new OEM stator. Also swapped a CDI from a friends Viper. I have tried a different coil. And swapped the spark plug cap resister. Cylinder Compression is 152. I'm running out of ideas to test. What am I missing?
 
Servo is working fine. I have the servo cover off. Yes it indexes. I even tried unplugging the servo and turning the barrel to open to see if it would get up on the pipe. Just runs on two cylinders. I just pulled the reeds everything looks great. Could I be drowning this cylinder with fuel somehow? I have the coil rack out. Pulled the small coil harness. I see nothing wrong.
 
Carbs? Needle and seat stuck open on PTO carb?
Might be a stretch, but somehow choke plunger open or damaged on just the one carb, feeding fuel?
What are compression numbers on all cylinders for comparison? I don't know your sled but 152 sounds a bit high compared to most gauges/Vipers, is this a 780?
Do you have a baseline compression test with the same tester, from when the sled was running good, to compare with the 152?
 
I didnt. Bob this is a Viper with a welded crank. Unless your thinking of something else.
 
Pull the pulsehose to the pump in case it suck's fuel backwards from pump.
Never herd of it on a viper but you'll never know..
 
yamalars said:
Pull the pulsehose to the pump in case it suck's fuel backwards from pump.
Never herd of it on a viper but you'll never know..
Click to expand...
Just checked, and the pulseline seems to be attached to the center cylinder..:o|
So obviously that's not your problem, sorry!
 
if that cylinder thats running real rich has 152lbs of compression, then it must be either in the carb rack for that cylinder or the cdi box,plug cap.

i would pull that reed cage out and use a mirror on a stick thru the hole and look at the piston skirts good.
 
Thanks everyone for the suggestions. This sled has 9400 miles. I knew the sled was running on two cylinders and jumped the gun in replacing the stator. I thought it was dropping spark at higher RPM after reading other posts of similar symptoms. I am now thinking the needle and seat are not closing properly and drowning the cylinder in fuel. The reeds are sealing perfect. I have never replaced the needle and seat. They look fine. Im gunna reajust the floa tand just reassemble for now.
Its snowing here today so i will be testing in the next day or so and let you guys know the result.
 
I have seen many viper cranks that are not welded and if they are only the rod pins are welded and they slip out of phase on the centers as they are not welded.
 
Also check the o-rings around the seats for the needle, these go bad often either by hardening or flatten/shrink and then don't seal properly even if the needle and inside of seat is fine.
 
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