Blade bog issues; Would a carb accelerator pump help/affect blade bog?

DrewRiley

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  • / Blade bog issues; Would a carb accelerator pump help/affect blade bog?
Long story shorter, I've had a number of issues with my riding mower recently (Kohler CH20s, Command 20). To list a few things, I've had to replace a broken rocker arm, some frayed wires, and a couple of ignition coils. While I was doing all of that, I cleaned and rebuilt my carburetor which kept bending the choke plate until it broke. (I made a new one to replace it.) The motor now starts fine, but when I engage the blades it seems to want to bog down, especially when I start cutting grass. The bearings in the deck aren't exactly new, but they do all turn freely, and the blades are freshly sharpened. I did put a tach on the motor, and at full throttle, no choke, I'm only getting about 3200 RPM. With the blades engages, I'm seeing about 3000 RPM.

I've tried adjusting the needle valve on the carb, but it doesn't seem to do anything, so I'm thinking I'm just gonna start with a new carburetor.

I see that I can get a carb with OR without an accelerator pump. I know that these are mainly to help reduce bog when accelerating (which I don't really have an issue with currently), but I'm curious if an accelerator pump would have any potential affect on reducing the bog I see when the blades are engaged? Currently, my carb does NOT have a pump.

FYI, I've also put a new air filter on, double checked that the governor rod is adjusted per the service manual, and double checked that both coils are firing (they are), and I went ahead and changed the fuel pump just to rule that out. If I manually push the governor when at full throttle, I can get the rpms up to about 3750, but if the blades are engaged, I can only get up to about 3200 pushing on the governor. I also notice that a get a bit more gas spraying into the carb when the blades engage.

Lastly, everything seemed to by cutting just fine before my rocker arm broke and I started having some carb troubles, so that's why I'm leaning towards the carb now.

Thanks for reading, I appreciate any insight.
 

Rivets

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  • / Blade bog issues; Would a carb accelerator pump help/affect blade bog?
I would start by rechecking the rock arm valve clearance on both sides. If they are in specs I would recheck the governed top speed 3744 in hole #2, with an orange spring (WOT is 3600 rpms) and 3120 in hole #1 with a clear spring (WOT is 3000 rpms). I doubt a carb with accelerator pump will help.
 

DrewRiley

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  • / Blade bog issues; Would a carb accelerator pump help/affect blade bog?
I would start by rechecking the rock arm valve clearance on both sides. If they are in specs I would recheck the governed top speed 3744 in hole #2, with an orange spring (WOT is 3600 rpms) and 3120 in hole #1 with a clear spring (WOT is 3000 rpms). I doubt a carb with accelerator pump will help.

This motor has hydraulic lifters, so there’s no clearance adjustment. I did bleed them before installing the replacement rocker arm.
 

ILENGINE

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  • / Blade bog issues; Would a carb accelerator pump help/affect blade bog?
The only time the accelerator pump will help is on the initial blade start due to the sudden load put on the engine.
 

DrewRiley

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  • / Blade bog issues; Would a carb accelerator pump help/affect blade bog?
The only time the accelerator pump will help is on the initial blade start due to the sudden load put on the engine.

Thanks. If I replace the carb I won’t worry about the pump then.
 
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