1994 225 tlrs 2 stroke stutter!!!!!

[SCasares]

The motor runs great idles great and always fires right up. BUT has a terrible stutter some times it mostly happens at half to full throttle.
Ive replaced all the fuel lines and pumps so I don't believe its a fuel starvation issue. im thinking its electrical? maybe a relay? or bad ground somewhere? would a bad thermos switch cause it to stutter like that? I don't have any alarms going off though.

Any information/advice will be greatly appreciated thanks!

[TownsendsFJR1300]

Sounds like dirty carbs. I don't see an accelerator pump on the parts diagram.

Start by draining and catching what comes out of the carb float bowls, looking for any crap...

I'd do a complete tear down making sure ALL jets are removed and verify their clear.
Doesn't take much to clog them.

https://www.boats.net/catalog/yamaha...lrs/carburetor

[walleye1]

Them carbs need to be flow tested after cleaning them in an ultrasonic cleaner.

[SCasares]

Thanks for the advice y'all, I was able to do some trouble shooting today and figured out it is the Thermo sensor P/N 6R5-85790-00-00 I can't seem to find it anywhere it seems to be discontinued. Any advice on where to find it will be greatly appreciated thanks again!

[panasonic]

Thanks for the advice y'all, I was able to do some trouble shooting today and figured out it is the Thermo sensor P/N 6R5-85790-00-00 I can't seem to find it anywhere it seems to be discontinued. Any advice on where to find it will be greatly appreciated thanks again!

Would you mind sharing what exactly you found and how you found it?

I am guessing that the faulty thermo sensor was intermittently telling the CDI of an over temp and the engine was going in and out of RPM reduction mode. Is that your thoughts?

[SCasares]

Correct, it would jump in and out of limp mode. I just started chasing wires and cleaning contacts until I came across that sensor that looked questionable. Went out and ran it with the cowl off and wiggled it while it was in gear and sure enough it started the awful stuttering.

[99yam40]

since you cannot find a replacement I would pull the sensor and test it to make sure that it is bad.
could be the motor is getting hot in that spot where the sensor is located due to plugged cooling passage or the wiring is the problem.

if that sensor is saying overheat , it should be setting alarms also

[BQUICK]

I've got similar with 1989 200 but just one hard jolt almost like hitting something. Then it runs fine for an hour or so and might do it again. Not thinking fuel due to sudden nature of it.....