02 Mt Cat 800 surging 200 rpms

[dichdoc]

02 MT Cat 800 144 EFI, 2800 miles. Starts and idles great. When you get up to speed (around 5500 rpms) it will surge approximately 200 rpms. The surge gets more pronounced and rapid the faster you go. Once warmed up it seems to be worse and under a more severe load (going up a hill) it has difficulty and will barely make it up, feathering the throttle seems to get you up the hill. I have swapped out secondary clutch and coil from an 02 MC 600 with no change. I went through the primary clutch and no change. The fuel injectors seem to be working (at idle) I have run it with the APV servo wires disconnected with no change. I have run it with the Servo wires connected and the cable held wide open with no change. Compression was low but I'm thinking maybe stator. Can someone give me a tutorial with specs for testing the stator and would it be the same stator as a 600??? Travis

 

[Demon13]

Pull exhaust and have a look at your piston skirts.

 

[trailthumper]

Sounds like you need to clean your power valves, It will serge and bog when they are all gumed up and sticky

 

[trailthumper]

Sounds like you need to clean your power valves, It will serge and bog when they are all gumed up and sticky They could even be stuck open and they are easy to clean

 

[dichdoc]

power valves move freely and have been cleaned "recently".

 

[WATDAFOOK]

Pull your reeds and inspect them..Sounds like you have a air/fuel issue..

 

[dichdoc]

Pulled the reeds they look good. Spark plugs are cardboard colored if that matters. I'm really thinking stator does anyone have the test procedure????? TB

 

[dichdoc]

I swapped out the APV servo and it took off and ran great. I swapped the old one back in to confirm and it went right back to running poorly. I have ordered a new servo motor. Just didn't want this to be another dead end thread like I ran into many many times while researching this problem. TB

 

[Ancient Sledder]

Thanks for sharing the fix. I will have to remember that.

 

[OLIVE DRAB DEAN]

Check the ground strap from the engine to the bulk head. Down near the recoil to the front. Even if the connection is dirty it can give grief. I know, found out the hard way. Cleaned it up and sled runs good. Hope this helps.