1992 Yamaha 175 2K rpm + rough running

[ybmug2]

It will get to 2k rpms and shake like crazy and seems like it is running on 3 cylinders. Has anybody had this problem and how did you fix it. I looks like the spark cuts out a 2k rpm when I put the timing light on it on one side of the motor. The injection has been disabled an the float has been secured in the up position. I have read some posts which describe a safe mode. I think this is what is happening. What other things can I check? Thanks, Steve

[Craig]

Sounds like u are running on 3 cylinders. Have u checked compression?

[ybmug2]

Thanks for the reply. The compression is good. It seems to be electrical. Another reply I got suggested that the motor was going into Safe Mode which seems to cut out some cylinders. Thanks Again

[jb123]

analog or digital gauges?
does your buzzer work ??

[ybmug2]

I have digital gauges. The tach works, but the speedometer stopped working since I got it back from the shop that messed up the engine to begin with. (Long sad story) Anyway, I heard the buzzer last season. Any help is appreciated.

Thanks
Steve

[jb123]

OK so no GAUGE warnings ???
esure your gauges work right,with key ON, pull motor oil sensor, turn it upside down to simulate low oil, you should have warning on gauge AND buzzer.
secondly pull thermosensor wires, think its a pink and black at the top of one of your heads, touch them to make sure gauge flashes AND buzzer goes off.
sounds like your buzzer doesnt work if youre not hearing it now, and it SHOULD !!
then you need to run it and find out if it is an oil warning or overheat issue. if you pull apart the pink and black wires and it STOPS buzzer it is your thermosensor going off.

[ybmug2]

Thanks for the help. I cannot seem to find the temp sensors. I see the holes they go in on the heads, but I think the shop may have kept them. Can you tell me what they plug into. Is it a harness or the CDI itself? I don't see any loose wires.

Steve