Honda engine trying to rev to the moon. (long post)

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  #1  
Old 06-18-05, 01:20 AM
Jonney_Boy
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Honda engine trying to rev to the moon. (long post)

I recently Purchased a honda F501 tiller used. The tiller looks to be in good, original condition. It does not seem to have had anybody work on it previously (no marks on the bolts, etc). The tiller has a GX140 engine on it (earlier model, the new ones comes with a GX160 engine).

Unfortunally, the tiller has sat for a good 1.5 - 2 years and the carb was clogged. The tiller would only run when we poured fuel directly into the carb... so.. I took the carb appart and cleaned it out (best I could, first time working on a carb).

I pulled the bowl off, took out the main jet, and cleaned any other passages I could find with some carb cleaner..... all is good.. the engine fired up on first pull ..

now comes the prob...... the engine wants to rev... I mean it really wants to rev. With the throttle set to min the engine still wants to rev so fast i'm affraid it will blow itself up. I can hold the govenor linkage with my hand and the engine will sound right, but as soon as I "let go" the engine will basically go WOT and rev like nuts.

Now I also have another machine at home with a GX160 engine on it. The linkages on this engine looks to be identical to the GX140 i'm working on so i'm "faily sure" the linkages are connected properly.

From what I can see the carb has 2 moving plates in it.... one is the choke plate and on the other side is the throttle plate which is connected to the govenor linkage on the machine..... here's what I have observed...

On the working GX160 the throttle plate will sit in the 3/4 throttle position when the machine is off..... on the GX140 the throttle plate will sit in the 80% open position when the machine if off.....

When you start the working GX160, the throttle position imediately goes to the 10-20% open position (ie.. it goes almost to the idle set screw).... on the non working GX140 the throttle plate will go to the 80-90% open position..... I can close the throttle plate with my hand but I can feel the govenor linkage tugging on the throttle plate trying to open it.


so... my question is.... what did I do wrong and is there a way to tune the the engine properly.... was it some screw I set wrong when I put the carb back together (max rpm screw?)
 
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  #2  
Old 06-19-05, 12:21 AM
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Sounds like there may be too much tension on the governor spring. Maybe it's hooked up to the wrong spot making it too tight? Could the governor linkage be connected to the wrong hole in the carb throttle plate? Or maybe the governor linkage got bent a little?
 
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Old 06-19-05, 01:18 AM
Jonney_Boy
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I'm fairly sure the linkages are connected properly as there is only one hole for everything to fit in..... ie.. there are not a series of holes in which you can put the spring.

as for the govenor linkage.... it looks to be straight but I did give it a slight tug when I was taking the carb off by accident.. (the carb was stuck on the engine... when the gasket finally "let go".. the carb popped out and pulled the govenor linkage taught.........

"looks" to be no dammage to the linkage but I guess I should go and have a good second look.


Other things i've tried today....took the carb appart again today to check the float... looks good...
pin on the float... looks good also.
changed out the "main jet" in the center of the carb (since I did scratch the brass slightly but not enough to dammage the jet)..... no difference.
 
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Old 06-21-05, 12:50 AM
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You may have to adjust the governor, or worse, you could have internal governor problems. Check everything external first.
 
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Old 06-21-05, 02:54 PM
Jonney_Boy
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would you happen know where I can locate the instructions for govenor adjustment on a honda engine? I'm working on a GX140 horizontal shaft engine, but I would assume that it should be very similar for the more commong GX160 engines.

I have seen it being refered to a few times on the site but nobody (to my knowledge) has posted the procedure.

Today I pulled the carb out again and ran through it one more time... didn't notice anything "wrong"...... I then pulled the carb off my old honda lawnmower HR214) and tried to swap it with the tiller. unfortunally the nipple where the fuel line connects to is bent facing another direction and there is not enough clearance for me to fully sit the carb because of it....... some time tomorrow I'm going to pull the carb out again and see if I can swap it the other way around (put the tiller's carb on the lawnmower... not sure why I didn't think of this earlier.. lol)
 
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Old 06-22-05, 01:00 AM
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To adjust the governor, loosen the governor arm at the governor shaft that comes out of the engine. Move the governor arm away from the carb as far as it goes, and turn the governor shaft counter-clockwise as far as it will go. While holding these in that position, tighten the governor arm to the shaft again.
 
  #7  
Old 06-23-05, 10:55 AM
Azis
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http://www.honda-engines.com/Engines...s/31ZG9642.pdf page 2 check throttle connections, if this looks similar to yours.

Also..http://www.honda-engines.com/Engines...s/31ZE0601.pdf to set your carb.
If the pilot screw has no effect I would assume a fuel restriction causing a lean condition which can result in runaway rpm more so on Honda and Kawasaki engines.
 
  #8  
Old 06-27-05, 12:17 AM
Jonney_Boy
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I think Azis got the problem.

I tried swapping the carb onto and old honda lawnmower I have (also GX140 engine.. but vertical shaft). As soon as I fired up the lawnmower, it too also tried to rev like nuts .... hence... problem is in the carb.

Unfortunally, I don't have time to look at this carb anymore as i'm heading out for vacation in a few days and will need to use the tiller soon afterwards. We dropped the tiller off at a local honda repair shop and hopefully it will come back purring again .....

As for what is really wrong with the carb... I really wish I had the time to find out as I am truly curious what I "frogot to clean".

ps. adjusting the piolet screw (the black plastic screw) has no effect
 
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