I traded cheaply for a DR high weed mower that has not run in 10-15 years. I fix a lot of mowers of all sorts but this one has me stumped.
Had to put a carb on it to start with because somebody tried to "fix" the one that was on it and ruined the jet. And the needle valve and seat were eaten up by old gas and just funky. I went through this one pretty well and did what usually needs to be done. New plug, fuel lines, inline filter, fuel pump overhaul kit, belts, grease, battery, fuel cap etc. Pumps gas like mad.
Now the trouble began. It starts fine but as soon as the throttle (hand throttle) is advanced close to full it slows and the governor jerks it wide open and it dies. You can catch it and nurse it to run close to full throttle but as soon as it lugs it dies. Once again you can catch it and manually retard the throttle and it will run. I added a spring pressures to the governor thinking that might have something to do with it-no change. I opened it up just knowing something was screwy inside it but the following are all OK - valve clearance perfect, valves and valve seats don't really even need to be lapped, cam shaft/lifters are in time and fine, governor complete/not stuck/adjusted by the book, head gasket looks good. I have not tested compression but the cylinder walls are not scarred up and it doesn't smoke.
One thing I did notice, and I may be imagining it it that it seems to spit a little gas out of the carb intake when running and it seems to have very little throttle range on the low end. Starts about mid throttle, speed changes from mid to high throttle, until it dies. The hand throttle comes off the grounding pin about there and that's the bottom end I guess. The governor arm also moves back and forth just as you would expect at the lower running speeds.
I also opened up the carb (even though it's new) and it looks fine, open and clear. And I checked it twice.
I will admit, I don't know what the throttle linkage is supposed to look like but best I can tell by the book it looks good and all seems to be hooked up as it should as far as springs/linkage. There is no telling what has been done to the linkage in this things life but I don't have another one to compare it to either.
I'm stumped. Could it be the wrong jet? I compared the one that was in the old carb using letter drills and they at at least very close to the same if not identical.
The only thing I have not really pursued deeply is spark. I did put and inline spark tester on it and when it slows and dies I could not see a difference but I guess it could be. The coil ohms out fine at 2.66 ohms all around. I have never had a coil fire at low speed and miss at high. They are usually just dead or alive in my experience. What about the armature? I don't know what that could have to do with it but I'm running out of options.
Any ideas??
Thanks,
Bugman70
Had to put a carb on it to start with because somebody tried to "fix" the one that was on it and ruined the jet. And the needle valve and seat were eaten up by old gas and just funky. I went through this one pretty well and did what usually needs to be done. New plug, fuel lines, inline filter, fuel pump overhaul kit, belts, grease, battery, fuel cap etc. Pumps gas like mad.
Now the trouble began. It starts fine but as soon as the throttle (hand throttle) is advanced close to full it slows and the governor jerks it wide open and it dies. You can catch it and nurse it to run close to full throttle but as soon as it lugs it dies. Once again you can catch it and manually retard the throttle and it will run. I added a spring pressures to the governor thinking that might have something to do with it-no change. I opened it up just knowing something was screwy inside it but the following are all OK - valve clearance perfect, valves and valve seats don't really even need to be lapped, cam shaft/lifters are in time and fine, governor complete/not stuck/adjusted by the book, head gasket looks good. I have not tested compression but the cylinder walls are not scarred up and it doesn't smoke.
One thing I did notice, and I may be imagining it it that it seems to spit a little gas out of the carb intake when running and it seems to have very little throttle range on the low end. Starts about mid throttle, speed changes from mid to high throttle, until it dies. The hand throttle comes off the grounding pin about there and that's the bottom end I guess. The governor arm also moves back and forth just as you would expect at the lower running speeds.
I also opened up the carb (even though it's new) and it looks fine, open and clear. And I checked it twice.
I will admit, I don't know what the throttle linkage is supposed to look like but best I can tell by the book it looks good and all seems to be hooked up as it should as far as springs/linkage. There is no telling what has been done to the linkage in this things life but I don't have another one to compare it to either.
I'm stumped. Could it be the wrong jet? I compared the one that was in the old carb using letter drills and they at at least very close to the same if not identical.
The only thing I have not really pursued deeply is spark. I did put and inline spark tester on it and when it slows and dies I could not see a difference but I guess it could be. The coil ohms out fine at 2.66 ohms all around. I have never had a coil fire at low speed and miss at high. They are usually just dead or alive in my experience. What about the armature? I don't know what that could have to do with it but I'm running out of options.
Any ideas??
Thanks,
Bugman70