Kohler Magnum 18 lack of power

[smoreau 658]

Last spring I put a 520 together with a Kohler Magnum 18 in it and it runs great! starts fine and does all that I thought it should do tell tonight. I had my tall chute blower on it and going through the 6-8" drifts of snow and the engine really bogs down and acts like its starving for fuel under heavy loads. I have never put this tractor under any heavy loads sense I put it together. Well to day I put it to the test, and it did not perform like I expected it to. My two 417A's will walk all over the power that this magnum puts out. I am thinking of trying a KT17 carb on this to see if it makes a difference. Just wanted to get some other opinions before I make the switch. I have 8 hours of run time on this tractor sense I put it together and it has not used any oil, looks clean, and runs very nice except under heaver loads. Here is a pic of the tractor.

[Kelly 1,029]

I'm sure you put new fuel lines and a filter on right? how about the screen on the shut off valve in the tank, is it plugged? weak fuel pump? could be the carb, it sat for a while before you put it to use, try a few things, but the carbs are pretty easy to change on these.

[wallfish 17,083]

Maybe it's running on just one cylinder?

[smoreau 658]

All that stuff is new when it was installed. The fuel pump was pulled apart and checked for operation of the valves, new shutoff valve and grommet, and all new lines and filter. It is running 90 octane gas with no alcohol in it with stable. It is running on both cylinders, and compression was great on both cylinders when the engine was installed. I am a auto mechanic as my line of work, and know if it was running on one cylinder. Both plugs are new also. I am thinking that I might have a parochially plunged port in the carb. Its the newer style that is not adjustable except for the idle mixture.

Edited December 28, 2012 by smoreau

[Kelly 1,029]

I drove the tractor this summer it was very smooth, unless something happened in between then and now I would have to agree with Scott fuel issues, and not running on one cyl. but you never know, are both exh. pipes hot??

Vacuum leak at the intake to block?? I had a Onan lose power and had a blown intake gasket.

Edited December 28, 2012 by Kelly

[smoreau 658]

didn't check if one pipe was hotter then the other. It is a 417 muffler. Its not a split intake manifold like the onen. It could have sucked up a piece of rubber into the fuel pump and not pumping enough fuel. it did crank a little longer then normal for not being run in a month. But I just figured it was cold and not run in month. Its cold outside and I am in for the night, so maybe this weekend I will go farther on it. just wondering if they made a adjustable carb for the KT series engines that would work on this.

[Kelly 1,029]

I was thinking the intake to block gasket, not the upper and lower half like a Onan.

[smoreau 658]

Possible that could be it. I never removed it when I got it from you. The carb was removed and cleaned, and got a new gasket. I tried to do every thing I could so I didn't have to take it apart again.

[Kelly 1,029]

That is a sweet running engine, I'm sure it is a simple thing, just finding it.

[smoreau 658]

It acts like I need to make a adjustment to the main needle, but it doesn't have that adjustment. I think I am going to try swapping a carb off my 417 and see how it runs. If it works then I will do some work to the original carb. if not. then I will look else ware.

[Kelly 1,029]

I have some carbs here off twins, but not sure if they are the adjustable ones or not, if you figure it out and need one I can look before you stop by.

[smoreau 658]

I got one extra carb, but it has a electric choke on it for a generator. I haven't taken it off the engine yet. It was a running engine from a totaled live news truck. Has the tapered crank. planning to use it for parts for a future engine build. I will let you know if I need one when I get that far.

[JackC 617]

Is the governor opening the throttle properly when under load?

I assume you have the service manual. http://www.kohlerengines.com/onlinecatalog/pdf/tp_2289_a.pdf