4 stroke riding mower surging

[PmDavis300]

i cant get it to stop, i cleaned the carburator 3 times now, put in a carb kit, adjusted the governor and replaced the anti surge spring. also, the gas is good and checked the breather and its clear. what could be causing this surging?

 

[raven7]

Re: 4 stroke riding mower surging

It sounds like it's running lean. Try to add a small amount of choke to richen it while it's surging to see if that helps?

 

[j_martin]

Re: 4 stroke riding mower surging

It sounds like it's running lean. Try to add a small amount of choke to richen it while it's surging to see if that helps?

If it does, raise the float a bit. If that doesn't do it, open up the main jet a bit. Check for the obvious, like a leaking gasket on a carb extender tube.

I worked on a car that had all kinds of die off's etc. Determined it was running lean and needed a carb kit. Owner said it just had one put in. I ordered the kit and he watched me like a hawk while I worked on it. When I went to pull the jets out he said that wasn't necessary, the last guy didn't do it. I said, well I have the gasket for it, so lets pull it out and look it over. Under that main jet was a curl of brass that had been there since factory, through several "overhauls" of the carb. It indeed was the trouble all along.

Moral of the story. Do it right, and leave no corner or orifice unexamined.

hope it helps
John

 

[DJ]

Re: 4 stroke riding mower surging

If it does, raise the float a bit. .


John

Agreed. Either lean or a vacuum/breather leak. Or, beather (crankcase) clogged.

 

[KRS]

Re: 4 stroke riding mower surging

If the engine has a cowl and a fan, then it's hard to test for a leak with a propane bottle, if not, then try that.

How else do you guys check for vac leaks?

KRS

 

[DJ]

Re: 4 stroke riding mower surging

Hard to test, just look at the system for any OBVIOUS issues.

You can clean the breather though.

 

[Howard Sterndrive]

Re: 4 stroke riding mower surging

I'd do a valve adjustment

 

[rbh]

Re: 4 stroke riding mower surging

If it does, raise the float a bit. If that doesn't do it, open up the main jet a bit. Check for the obvious, like a leaking gasket on a carb extender tube.

I worked on a car that had all kinds of die off's etc. Determined it was running lean and needed a carb kit. Owner said it just had one put in. I ordered the kit and he watched me like a hawk while I worked on it. When I went to pull the jets out he said that wasn't necessary, the last guy didn't do it. I said, well I have the gasket for it, so lets pull it out and look it over. Under that main jet was a curl of brass that had been there since factory, through several "overhauls" of the carb. It indeed was the trouble all along.

Moral of the story. Do it right, and leave no corner or orifice unexamined.

hope it helps
John

(I ment to Quote the OP. OOPS)
I would play around with the springs positioning first before anything, one hole out one way or the other will make that engine surge.
try a position were there is more tension from the spring, if it surges faster back it off 2 positions then 3 and so on.

 

[seaboo]

Re: 4 stroke riding mower surging

It sounds stupid, but have you changed the oil? If the float hung up and dumped gas into the crankcase (causing too much oil in it) it can cause surging. Do not assume that because the filter LOOKS clean and clear it may not be. If the mower was running rich (or blowing oil back into it--again normally from gas in the oil) the filter will look GREAT but the pores cloged. Change the filter, oil and plug (you won't have more than 15 bucks into doing that and you will have elimiated those as trouble items). My money is on the air filter being cloged (even though it looks clear).
It will suprise you how often this is the cause.