FS651V No High RPM

[Auto Doc's]

Hello Hayward51,

3600 RPM has been the industry "safe" standard for many years, anything much beyond that is asking for trouble. Yes, it can be done but why take the risk.

I managed to blow up a few "racing mowers" in my youth, several were rather explosive with internal parts finding their way out of the engine.

 

[txmowman]

I will check the valves and spray the exhaust today.

Don’t waste your time. If the engine otherwise runs smoothly, valve lash will not increase rpm.

 

[Hayward51]

Don’t waste your time. If the engine otherwise runs smoothly, valve lash will not increase rpm.

I've got it up to 3550 (no load) by my tach. I'm still puzzled why I'm limited RPMs after new rings installed. Valves were lapped and set during reassemble.

 

[txmowman]

A weak governor spring, damaged linkage or control panel, something in the wrong location. If it’s none of that, live with 3550. Governed engine don’t maintain a consistent rpm anyway, 50 rpm isn’t even noticeable.

 

[MParr]

A little FYI. Clean and mark the throttle cable on both sides of the hold down clamp before loosening the cable clamp. When everything is hooked back up, you will only have minor adjustments to do.

 

[Auto Doc's]

I've got it up to 3550 (no load) by my tach. I'm still puzzled why I'm limited RPMs after new rings installed. Valves were lapped and set during reassemble.

Hello Hayward51,

If this engine were on a generator, the exact high idle setting would be critical to maintain the needed 3600 RPM to and keep the generator steady at 60Hz output.

On a rider the difference of 50 RPM is not an issue.

Also consider that the engine is still breaking in new rings, so there will be a minor wear in period before the parts get into harmony with each other.

 

[RevB]

I tried the governor adjustment by the book. I'm evidently doing something wrong. I have the same problem. I hold the gov. arm and throttle lever on carb while tightening and throttle is wide open. When I start the engine and go to WOT, the gov. is pulling back from being full throttle. I still get 3450 RPM. There's no other holes to move spring nor a tab that I see to bend (except throttle stop). Could it be that I still have the gov. spring attached while adjusting

 

[txmowman]

Yes, the governor spring can stay installed while adjusting. The governor isn't pulling back; it is pushing out. It is the governor spring that is pulling back against the centrifugal force of the governor. If the spring is too strong, this will reduce the RPMs. If the engine is steady at 3450, then I don't question that you have adjusted it correctly. Either the spring has been changed with the incorrect one, or you're just going to accept 3450 as your max RPM. Again, other than blade tip speed, the HP loss would be minimal, if any.