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rebible
07-26-2015, 07:48 PM
I have a quick question. I have a new (for me) Yamaha 90 2 stroke that I am setting up on a RIB. I finally have everything rigged and have now started messing around getting it running.

When running in a tank unloaded, it idles fine. But, when I up the rpm it starts kicking out at 2500. I read the troubleshooting guide from CDI and found that the problem goes away if I disconnect the over-rev wire in the powerpak. Also sometime it isn't there for awhile.

The only problems I have found so far were: bad float needle valves, carb syncing, clogged spitter, and loose spark plug wire connectors. I haven't timed it yet, as that requires a test wheel that I don't have. My test wheel plan is: I bought an OMC for a crossflow 150 off of craigslist that I will drill vent holes in to get the right rpm.

Questions.

Is there something wrong beyond the rev limiter cutting in too early that requires me to change the CDI? or can I run it without the over rev limiter?
I know on the OMC looper that the powerpaks can fail and melt your piston, is this the case here?

I would rather spend the money on some hydro-tec heads than a new CDI.

thanks
robert

Fast Fred
07-27-2015, 05:49 AM
i would test the box out, by the book. they usually just drop dead when faulty.

Revengable
07-29-2015, 10:08 PM
With trash bouncing around in the carbs check the emulsion tubes/Main jet area real close.