Kohler 36hp - running strange

[Shootertexas]

I recently acquired a Garage Queen Craftsman 54" cut lawn mower with a Kohler 36 hp motor. I really haven't had the time to really get into why it runs like it does. I though I would come on here and see if anyone had any similar experiencs and migh be able to guide me where to start.

I have taken the plugs out and re-gapped them, checked the air filter and checked the fuel flow.

It starts just fine with just a bit of choke and seem to be idling fine, no smoke (white or black) or the smell of un-burnt fuel.

Here's the strange part.... When running at full power (i haven't run it enough to actually tell if that's the only time it does it) it runs ok or so it seems but every so often the engine will gain power (not any higher RPM) and quietened down a bit for a few seconds before returning back to its original sound.. It's very hard to accurately describe.

Coil packs? Carburation? Valve Lash? Anyone else had a similar experience? TIA

 

[Auto Doc's]

The engine identification information off the label is needed for accurate information.

Does the engine lose power when this occurs?

Is this water cooled, and you are just hearing the cooling fan cycle on?

 

[Tiger Small Engine]

I recently acquired a Garage Queen Craftsman 54" cut lawn mower with a Kohler 36 hp motor. I really haven't had the time to really get into why it runs like it does. I though I would come on here and see if anyone had any similar experiencs and migh be able to guide me where to start.

I have taken the plugs out and re-gapped them, checked the air filter and checked the fuel flow.

It starts just fine with just a bit of choke and seem to be idling fine, no smoke (white or black) or the smell of un-burnt fuel.

Here's the strange part.... When running at full power (i haven't run it enough to actually tell if that's the only time it does it) it runs ok or so it seems but every so often the engine will gain power (not any higher RPM) and quietened down a bit for a few seconds before returning back to its original sound.. It's very hard to accurately describe.

Coil packs? Carburation? Valve Lash? Anyone else had a similar experience? TIA

I doubt it is 36 horsepower, maybe 26 horsepower. Sounds like it is hunting and surging. Typically a dirty carburetor, and an all too common problem.