Slugish running after heating up

[rchleger]

2000 workhorse runs great when cold, after the engine gets wormed up it gets real slugish. The engine was just rebuilt last month (had the same problem before rebuilt), By accedent I found that if I leave the air breather open it runs a little better (?), just cleaned the carb. (stock) don't know what jet size it is or how to check, don't need a hot rod cart just want it to get me from camp to deer stand and back.
I know you guys can help, so lets here it.

Thanks.

 

[strokerace31558]

coil could be getting hot, u may wanna run a hotter burning plug,or voltage regulator pehaps .

 

[Nubs]

welcome

this is not very common but the mufflers have been known to plug with oil buildup. i have a dozen 4 cycle mufflers here and some weight 4lbs more than others. i would loosen it at the ex manifold and run it a little to see if it has more power, if so a new or good used one should fix it. to much back pressure will overheat the engine

 

[rchleger]

OK, I'll try new plugs, Need more info, on voltage regulator...
Tryed removing muffler, seamed to help a little but still got slugish after running for a while.
I also modified air intake ahead of filter this seamed to help a little but again not much.
Any other sugestions?

Mabee my expectation are to high for this engine, but after it gets hot I can't go up a 3 foot ditch in the yard without almost coming to a complete stop.

Thanks for the advise sofar

 

[Nubs]

are you running a drive new belt, if it climbs the hill cold? then its either over heating or the belt is bad is my guess

are you sure the valves are set right, should be on new rebuilt but its very common for them to loose power when they warm up if the valves are set to tight.

 

[rchleger]

Rebuilt engine myself, have checked valve lifters set at .05, the belt is not new I reused the existing belt (looks OK) that may be my problem. I'm also wondering about the clutch's, the one on the engine I feel pretty good about but the one on the transaxle I'm not sure.
Is there any way to check this clutch?

 

[divot61]

runs strong when its cold, sluggish when its hot, hmmm. recheck the valve lash and set them at .004 cold, and if you have compressed air blow off the air filter or replace it with a new one. for a quick check on restricted air just take the filter out and see how it acts for a min. did you lap the valves in yourself, or have a shop do it?

 

[rchleger]

Thanks for the input, I'll reset the valves at .004, the filter is new. when I pop open the air filter It does seam to run better. Yes I did lap the valves myself.

I m woundering if the transaxle might have some drag on it, Think Ill try hard inspection in this area, any sugestions from prior issues.

Again thanks for all the input, this is a great site for info. and helped me with not just this issue but many prior to this. You can't buy a book that will have this much knolwage so easy to access.