engine "missing" at 7000 rpm and up

0

02ViperMtn

Member
Joined
Jan 4, 2009
Messages
166
Age
48
Location
Kamloops, BC
Last ride my sled seems to miss under load when i try to get the rpm's up over 7000 rpm. Engine is either missing on a cylinder or cutting out entirely over 7000 rpm. I have'nt yet noticed any other electrical issues, and sled runs great otherwise. I have pulled the wiring harness which was well taped and wraped and confirmed not rub throughs under the engine. Plugs looked good but i never did run it wide open and hit the kill switch and check them then.

Any other ideas? Stator, coils?
 

i clean the carbs thouroughly every season, but only rode three times this season so it sat a lot. I have never looked at the reeds.

In terms of the carbs, i don't understand how it would be such an obvious power drop soon as the motor gets to around 7000 whether its wide open or lighter throttle. It really feels like a miss. I've got the barbs off and will check the reeds next time i get the chance.

I am thinking i need to put it back togethor and take it out and run it hard and hit the kill switch and see if i have a wet plug. I also think i should unplug the lights and see if that changes how it acts?
 
Check for water in the float bowls,under hard load the water droplets get sucked up to the main jet and plug them ,then when you let off they fall back down and it runs fine untill the next WO run and then it happens again,yamaha float bowls are shallow and the main jet sets very low in the bowl and the motor will not pull the droplets thru the main jet.
 
Check your reeds!! This similar issue happened to me on a Viper. Vipers are known for chipping the stock reeds. I had have a reed missing.
 
check for sooting in the plug boots caused by arcing inside the boot. They seem to be O.K. until high rpm/load then they will stutter like a rev limiter
 
i pulled the reeds today, 2 are chpped just slightly on the ends, very minimal, any idea if this could cause much problems?
 
The slight chipping is probably not causing your problem, if they aren't chipped very much I just keep running them.

Now this is noticeable at above 6000rpm. That's from experience.
 

Attachments

  • 1230081258.jpg
    1230081258.jpg
    44.6 KB · Views: 6
Last edited:
thanks sxlover, the chipping i am seeing is not passed the seal on the ends of the reeds! I have a stator on order. The poor running mau have been a blessing in deisguise. When o tore into things i found my oil pump cable bracket had snapped off. It was brohe and tack welded 2 years ago. It may have broken when i was tearing things apart or proir to. Everything appears ok from the outside. A new oil pump should arrive shortly too.
 
Good to hear you found the oil pump broke now, before you ended up with a melted motor. And the reeds should be fine then if they aren't passed the seal. Good luck, hope you can get it all figured out.

Another thing that a lot of people forget about trying is replacing the spark plug caps on the end of the wires. I haven't had one go bad on our 05s but I have replaced them on our 97s.
 
i've taken the recoil off of the flywheel and see that the mag rotor is very rusted on the three pickup surfaces. Can this be the source of the "missing" at 7000 RPM? Help!!
 
i'm still working on this issue again, if anyone has more insite it would be great, i have bought a stator and i am looking at putting that on now.
 
I had the new stator put in. That was the problem. It is an RM Stator and so far so good. The old one was the OE stator and had about 3000km before failure.
 
You must log in or register to reply here.


Back
Top