1980 john deere tuning

[RylFlsh85]

Just trying to see if anyone out there can tell me where i can get some good service info for my liquifire 440, it seems to idle fine, but i have a real sloppy throttle, i have cleaned the carb and tried to adjust it but it still doesn't take off.

Any info would be appreciated.

[Surface Tension]

Which carb do you have, I'm guessing you have a Mikuni but need to know for sure.

Explain sloppy throttle and take off.

Bogs when you give it gas? If its a Mikuni you'll have an external fuel pump, have you checked that out. Have you checked all the fuel lines and connections. The impulse line for the fuel pump can have an air leak and you won't know it. You could pull the gas line off the carb and pull the engine over and check to see that its pumping. You also have a drop tube inside that gas tank, if that rotted off or is leaking you'll be sucking air.

If that all checks out low compression or a bad seal will make it bog. While its idling spray starting fluid at the shaft on the clutch side of the engine. If the idle increases you have a bad seal.

[RylFlsh85]

Yeah it bogs down, but not all the time, it will take off every now and again but after your goin along it bogs out again, the pump is pumping fuel i have tried that, but ill have to give the starter fluid a try and see what happens.

The guy i got it from put new rings in it so the compression is really good that is why i was a little confused at first, i havent worked on too many sleds so your help is awsome, thanks.

[Surface Tension]

That sounds like you have a fouled plug or intermittent spark. Next time it does that pull the spark plugs and test each one for spark. Or just replace them.

[hanson]

Surface Tension definitely has you on the right track.

I hate to start thinking about the major repairs first but a bad crankshaft seal (like ST mentioned) is going to cause you a world of problems and frustration while trying to figure out what is wrong. These older sleds (all brands) are very susceptible to leaky crank seals.

You can clean, tune, and rebuild a carb until you are blue in the face and its not going to fix the problem. If you have good compression, good spark, a cleaned and properly adjusted carb, and fresh fuel and it still isn't running right, you probably have a crank seal problem.

Start with the easy things first- new plugs, check spark & timing, new gas, clean the carb, etc.

[RylFlsh85]

The plugs is the first thing that i checked, and the way things are looking it just might be a seal, i was just hoping that maybe the carb was out of wack but i had a guy take a look at it that knows a little more about that carb and he said it was set up right but he never mentioned anything about the crank seal so that might be the next thing to check when i get a chance.

Thanks for all the info!!