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Re: H carb
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Posted by RK Smith on March 30, 1999 at 17:30:44:
In Reply to: H carb posted by Gene on March 30, 1999 at 03:02:22:
Gene, please pardon me if I say that is the most incredible piece of news I could possibly hear about an H carb - since - the only way for gasoline to get to either the main jet or the idle jet is through the "seat" under the main jet adjusting screw "needle". This is because both are feed from a shaft that the main jet is centered in and the idle jet shaft fills from the bottom of that shaft. So, if you say nothing you do with "that screw" affects the engine, then your main jet needle is "not seating at all." If it did, it would stop the engine with gas starvation. There is some bad gunk in the bowl shaft that feeds to the main jet needle and the gunk is letting enough gas through the "seat" to allow the engine to run, and the gas flow is just by chance about right. Now, unless the governor throttle is set completely closed, then adjusting the idle mixture needle will not have much affect on the engine, just to lean or enrich the mixture. Long and short of story is your carb is filthy, needs complete rebuild, after complete clean out. If you won't do that, at least take it apart and remove the main jet needle, nut, packing nut (this is leathery-like packing under the nut which is made of graphite),and the main jet. Then run a tiny drill down the hole from the main jet needle position through the seat (the seat is a brass or bronze insert between the main jet needle and the main jet shaft. Clean that out as best you can, make sure no junk is in the seat or the shaft. Put it all back together - you can wrap "string type" graphite packing from a hardware store around the needle after the needle is put partially through the nut. Don't move the needle all the way to the fully seat position in the nut, because when you tighten the nut on the packing, you will damage the seat or the needle or both. If you do all that, you should get control from the main jet needle. Now for the idle needle, it won't have much affect unless the throttle is shut down almost completely, so that the only gas is coming from the idle jet, which has a small venturi on the side of the carb throat just under the throttle baffle. If the engine is warm and the throttle closed down, then the main jet doesn't feed gas to the engine, only the idle jet, and you will see a change when you adjust it at low idle. Adjust your throttle control screw (the one with the head pointing out at you)so that at low idle, it is almost shut, about 1 1/2 turns off seat position. Then at about 450 to 500 rpm, changes in the idle adjust needle will cause the engine to rough or smooth out. Good luck. The kits just cost about $25, and you probably ought to rebuild the whole thing.
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