650G - Burning through plugs!

[BrianB938]

I am kinda new to this Satoh thing and have really confused myself...HELP!!!

I have had the carb rebuilt (professionally), replaced the fuel pump and done a complete tune up. The tractor performs fine, but after about an hour or so of use, the tractor starts to bog down and I have found that I am fouling plugs left and right. It think it is running very rich (based on the smell). I am in Wyoming at about 5500 ft in elevation. The carb was rebuilt in Virginia so I am guessing that it was tuned at a much lower altitude. How can I lean this thing out and keep from burning through spark plugs?

 

[mit]

there should be adjustments on the carb to adjust the air/fuel ratio.however dont jump the gun.is there a choke on the carb? check that if it is opening.check air filter for clog.before making adjustments

 

[BrianB938]

I have replaced the air filter and there is a choke, but it is functioning properly. It is a Nikki carb. How do I make the air/fuel adjustments to lean it out?

 

[Outlander]

Is the float level correct? Too much fuel in the bowl will cause mixture problems.

 

[SATOHBULL]

Does it smoke when running, esp under load? If so is the smoke blue or black? If it is black, it is rich. Usually a float level problem, or dirt under the needle. If it's blue you are burning oil and fouling the plugs. Normally oil fouling will look oily on the plugs while rich fouling with be fluffy black deposits.

If it isn't smoking and the fuel system seems to be the problem check again for something fouling the float, maybe rubbing on the bowl, or sticking somehow.

Also, check the plug heat range, if it runs ok, doesn't smoke etc, the plugs could be too cold.

 

[BrianB938]

It does not really smoke at all. The plugs are fouling flat black, not oily. How do I adjust the float level? I am using champion N4C plugs. I thought I might step up to a hotter plug. Any suggestions there?

 

[mit]

tough problem.to adjust the float you have to drop the bowl.dont think it is a gas problem though.check compression.see if it is within specs.oil may be seeping in from somewhere and fouling the plugs.is there a timing advancer on the tractor?maybe the hose is collapsing on vacuum.

 

[Eagleview]

The mixture screw is the one with a coil spring around it protruding from the venturi(not the throttle stop screw) . With the engine stopped screw this in until it's seated . Turn it back out one and a half turns , start the engine and leave at idle and slowly turn it in or out until the engine sounds sweet . You probably only need to go a quarter turn each way before finding this spot . You should use a vacuum gauge to find this sweet spot but you probably do'nt have one . There are other things that have been stated but this answers you question about how to lean out the mixture . It sounds strange that it does it after an hour , i wonder if it's boiling the fuel in the carby and forcing it into the engine . Does it have a bakerlite spacer between the carby and manifold ?

 

[BrianB938]

I don't know if it has a spacer. I have now adjusted the mixture screw and changed the plugs again. I could not tell any difference when I adjusted the mixture screw. I did step up to a slightly hotter plug. The tractor starts up and runs fine, but when at throttle, and not necessarily under load, the tractor loses power, the governor engages, it almost dies, and if I clutch it (so it is no longer under load) it will fire back up. What is going on here?

 

[mit]

sounds like you are having some kind of ignition problem.check the wiring against the schematic.if u have points and they are arcking escessively the wiring could be wrong.