SN 771 hits low RPM Rev Limiter

[Kingler0642069]

Hi, everyone. im fairly new to the forum so forgive me if i am posting in the wrong section or anything.

i just purchased a 94 SN superjet with a 760 with a bad crank. i purchased a ported 771 (bored 760) and installed the new motor using the old pipe and carbs (riva red pipe and dual 38s). i used the stator out of the old motor and i am wondering if the stator could be my problem.

the motor starts right up and idles great. (had it at the river last night) it hits hard right off of the bat, but then hits a low RPM rev limiter and will not rev past this rpm. it makes the ding, ding, ding noise just like it is hitting the rev limiter. i am guessing it is around 3000 RPM. the temp sensor is not connected to the head and i just disconnected from the ebox and still no change.

could it be the stator or could i have other issues as well?

Thank you for any help!!

 

[Quinc]

Possibly stator or CDI.

 

[Kingler0642069]

ok. the old motor got sunk. i used the stator off of the old motor (it looked ok). could the old stator be junk after getting sunk? i used the flywheel off of the new motor. could there be a problem if the flywheel and stator dont match? (both off of 760s).

 

[SimonSimon]

Could be a few things. Are you sure you disconnected the right wires?

1. Make sure the timing mark on stator is lined up perfectly with notch on the case
2. Check pulser coil readings are in spec
3. The temp sensor lead on your CDI could be grounded
4. Make sure you have right flywheel/stator combo. No mix/match

 

[Kingler0642069]

i didnt line up the stator and case perfectly... i will bet that is my problem!!! i will dig into it tonight and see! i cant wait to get this going because it RIPS up to the point where it cuts out.

Thank you guys for the help!!

 

[Kingler0642069]

thanks for the help so far guys. i looked into the stator and i was lined up almost perfectly ( i moved it so the marks are lined up perfectly now). i am still having the same problem. it is cutting out in the mid RPM range. i took the carbs off last night (dual 38s) and they are NASTY!!! they are all rusty and gunky inside. i will get a couple of rebuild kits and hopefully that is my issue.

 

[SimonSimon]

Carbs won't be your issue if it's bouncing off the rev limiter rather than bogging when you give it throttle. Regardless I would definitely rebuild the carbs but first cross out the other 3 points I listed before rebuilding. Maybe post a video to help us determine what's going on. Are you 100% sure you have the right flywheel/stator combo?


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[Kingler0642069]

both the stator and flywheel are out of 62T cases. i could throw the old flywheel in that was with the stator i have in there now.
temp sensor should be good, i unhooked the pink wire in my ebox last night. i might put my carbs off of my 06 on there and see if that works...
i will post a video next time it is back together and running.

Thanks,

 

[SimonSimon]

both the stator and flywheel are out of 62T cases. i could throw the old flywheel in that was with the stator i have in there now.
temp sensor should be good, i unhooked the pink wire in my ebox last night. i might put my carbs off of my 06 on there and see if that works...
i will post a video next time it is back together and running.

Thanks,

How do the plugs look? Doubt you're running on one cylinder since you said it rips hard on the bottom but try throwing on a fresh set, worth a shot. Don't waste your time swapping out carbs yet. Just spray some premix down the carb throat with throttle open and see if RPM spikes. Also check your coils.


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[Kingler0642069]

ok thanks for the info! last night i took the carbs off and started cleaning them. i will put them back on and try the premix down the carb trick! i will get to reading tonight on how to check the coils! Thanks!!

 

[Joel Cleveland]

Check your heat sensor and wiring. Sounds like your hitting the overheat rev limit

 

[Kingler0642069]

that is what i initially thought but the sensor is not hooked up to the head and i disconnected the pink wire in the e box. Thank you.