542B bobcat runs rough above half throttle

[jon2]

hello all, i could use some expertise with my 542B bobcat, it runs rough above half throttle. starts and idles good. it has solid state ignition the carb is clean, new plugs, new fuel filter the fuel pick up tube looks good

 

[Bswwood]

Air filter? Timing? IF it has a good tune up and service I would probably do a compression test on the cylinders, could have a valve not seating, rings, head gasket, or something. Harbor freight has an inexpensive cylinder compression tested and leak down tester, might be a good idea to check both ways. Rule those out and we can go from there.

 

[Bswwood]

Air filter? Timing? IF it has a good tune up and service I would probably do a compression test on the cylinders, could have a valve not seating, rings, head gasket, or something. Harbor freight has an inexpensive cylinder compression tested and leak down tester, might be a good idea to check both ways. Rule those out and we can go from there.

Also check valve clearance, intake is 0.009 and exhaust is 0.023. Is this an ongoing issue or did it just start out of no where?

 

[SkidRoe]

Just one other though might be the coil. Sometimes they will begin to break down, and will idle fine, but not like revs.
I would also have said the condenser, but if you have electronic ignition, you likely no longer have one.
Cheers - SR

 

[jon2]

The compression is over 100 but I don't recall. Air filter is clean. How can I check the module ?

 

[jon2]

The compression is over 100 but I don't recall. Air filter is clean. How can I check the module ?

its been doing it a few years but only for about 10 seconds when it was cold then it would clear up. now it never clears up. i will get a compression tester myself and check it again. thank you