CV15S High RPM problem

[arch252]

I picked up a JD LX255 at a great price but the guy was shady about what was wrong with it. I had to replace the head gasket and do a complete breakdown on the carb. At some point someone has tinkered with the linkages and it appeared that the carb had caught fire because the choke plate cap was melted and I had to put on a new choke kit.

I got it started and running, but it runs at dangerously high RPM. I have to move the throttle lever to the low throttle position to run it at the normal operating RPM. Moving the throttle lever up increases the RPM's significantly. I've also noticed a significant loss of engine power when the PTO is engaged.

The carb itself (Walbro) has two adjustment screws, a low idle on the top and a fuel mixture screw on the bottom right (in the picture). There are two adjustments on the linkage, what appears to be a low and high throttle limit. I've made minor adjustments to all of those adjustment screws just to see if anything changes and it did not.

Any suggestions would be appreciated.

There are two pictures of the linkage, one with the throttle in the high position and one in the low position.

 

[RoperGuy]

Now when you say it revs dangerously high, it makes me think your governor is not set up properly, witch might also explain bogging after pto engagement.

 

[arch252]

Governor inside the case or the linkage on the outside. I'm really hoping you're not talking about the governor gear inside the case. Oh brother...

 

[arch252]

What about the governor gear connecting rod that goes though the crankcase and connects to the L shaped linkage on the outside. I had that L shaped bracket off, does the position of the connecting rod matter when I attach the L shaped bracket? Would that cause this problem?

 

[RoperGuy]

No just the outer linkage, I've had plenty of used/free machines where the previous owner had removed the carb and wouldn't run right after. I assume you know how to adjust the throttle cable and set air/fuel mixture.but I would suspect the unexpected when buying used. simple things like a return spring or linkage place meant can mean a lot. Is this an original carb for your make?

 

[arch252]

I have another LX255 in excellent condition so it gives me something to compare it to and the outer linkages appear to be set the same, I am wondering now about that governor gear connecting rod so I'll check with that tomorrow. The carb does appear to be the original OEM.

 

[primerbulb120]

What about the governor gear connecting rod that goes though the crankcase and connects to the L shaped linkage on the outside. I had that L shaped bracket off, does the position of the connecting rod matter when I attach the L shaped bracket? Would that cause this problem?

It would indeed cause your problem. If it is installed incorrectly, all kinds of issues can occur with the engine RPMs.

 

[arch252]

Very good to know, thanks guys! I'll get to it as soon as we get home and I'll let you know if that solves the problem. Makes sense with the PTO issue, if it's already at max RPM's and I have it throttles down then the governor can't compensate with more RPM's when the PTO is engaged.

I thought that connecting rod would naturally rest in the "correct" position since the governor gear inside would be 'folded up' when the engine is not running. Not sure which way to turn the connecting rod before I re-tighten down the L shaped bracket to it but I'll just tinker with it and see if it makes a change.

Thanks again!

 

[arch252]

I'm trying to attach photos. These are close ups of the connecting rod to the L bracket. The clean one is my mower, the dirty one is the one I'm working on. In mine the connecting rod is horizontal and the other is vertical. I'm feeling very good that's the problem. Can't wait to get home!

 

[arch252]