My motor idles pretty decent, but it will not rev up. It back fires through the carb pretty bad and also the exhaust. I have checked my valves, and diodes and disconnected the rev limiter. I am running a 32hp pd with stage 1 heads and aftermarket carb. I am out of ideas please help.

Water in the fuel?

Had something similar happen to my buddies boat in teal season. Turned out to be water in the fuel

Easiest way to tell is to pour off some gas in a clear container and see if it stratifies (water comes to top)

Otherwise sounds like a timing issue

I checked the fuel, it appears to be water free. The only way timming can be off is if the key sheared under the flywheel? It also appears to be fine. I also appear to have a good spark and my compression checks at 150 psi on both cylinders.

Well I aint no mechanic

Give it some time I guarantee somebody will see this and be able to help you out

Doesn't sound like a PD problem, sounds like a modded motor problem. Your title is misleading!

You are correct it has nothing to do with PD, it is a Modded Briggs Issue.

it seriously sounds like a timing issue too me.

It does not take much movement of that flywheel for the timing to be off. DO you know if it has a offset key in it?

It has a stock key, that keeps jumping in my mind also I will double check it.

flux capacitor?

IS this in the water or out of the water? I had my main jet plug up, and it would rev fine with no load, but with a load nothing.

You were on the money, sheared key, back in business!!!!!!

Good deal.

glad you are back in business.

Well there you go ............ MMT Guru's ....... doin' tha deal !!!!!!

See River does give good advice and Sundance doesnt even listen to him.

How would one check for a sheared key? I'm having similar, not exact issues. I get the backfires both carb and exhaust but it will rev and will run normal once rpms are up. My issue is I need to set the idle to 1600+ rpm's so it doesn't cut out when I put it in gear. At roughly 17oorpm idle I get 1000 rpm in the water and in gear.

I have checked vacuum leaks, water in the fuel, played with carb adjustment and a number of other things. Weird thing is the other day, in the am (was about 20 degrees out) I would run hard and it would drop power...got down to idle and I could run it again and it would run minute or two and drop out again. On the ride home around lunch it ran fine all the way home.

rockhopper, It does not sound like a flywheel key to me. Thats more likely to be a coil wire short if it cuts out one minuite and works fine the next. If at idle and it cuts out at first throttle-up then you must adjust the carb to factory spects then go from there. I didnt catch if you were moded or not.

Are you always a smart A$$?

Rail, you are a big man behind a computer and I bet it ends there. As for as intelligence is concerned, you sell cranes, come on you kiss a little client A$$ and make a sale, not much challenge there. Cranes, vacuums its all the same. Some people actulally benefit from this site, If you want to bash go play on tranny.com