My buddy just bought a brand new Kohler 27hp longtail and the throttle opens up when not in the water but as soon as you go to take off in the water he gets to about 1/2 throttle and the motor starts to shake really bad and dogs down. not sure if a plug is fouling they look good when we pulled them or maybe the govenor isnt opening. I haven drove it this is just him telling me what he sees. Thanks

Has he checked to see if it is running on both cylinders?

Is it that the throttle is not opening or he is just not getting full power? my guess is the later. The throttle itself will not react differently whether on the trailer or in the water.

Sounds like when he puts it under a load it is not getting full power...

I would ck to make sure both cylinders are running and then start running down other things.. Good Air Filter? Some fuel delivery problem-line is pinched, leaking air, something like that...... Ck the compression on both cylinders.

I am assuming it is immediate when he gets in the water-not after he runs a while-that would lead you down a different path....

How old is motor?

Post up some more info, and I am sure someone on here can point you in the right direction...

Its right when he goes to take off the motor just acts like its not getting to full power. The motor is brand new 2010 just had it in the water for the firs time yesterday. I will give him a call and try to get more info, like I said i havent been their to run it either. He said he was going to go get new plugs and run it I will post up what he finds out after that. THnaks again

If it is brand new and never even run before, I would go straight to the dealer and let them figure it out if he can... wouldn't even fool with it. It is under warranty and they will be better equipped to chase down the problem.

Is that possible?

I just talked to him he said thats where he is headed. He said he isnt waisting his time and money to fis a new motor. I will post up what they find out with it. I told him try plugs he said he was going to run it down to the dealer quik and see if they can figure out whats wrong

My motor did that last year. It would idle in the water all day and when I gave it gas, it spit, sputtered and shut off. I took it to a small engine shop and they said it was a clogged jet in the carb.

I put money on a fuel line air leak!