Pony carb still not 100% and fuel tank shutoff valve kit?

[quote="Neil"]I gave the pony another run on the test stand today with the Bar's Leaks in it and it mostly closed up. I'll give it a couple more runs to see if all of the weeps stop.
I've been having to run the pony with the choke partly on, indicating that I'm not getting enough fuel. I can get it to idle under 1000rpm (guesstimate about 750) but with 1/3 choke. I went through this carb a whiles back with a kit from BFIC; I removed all the plug passages and whatnot, including that little plug that you have to drive all the way through to remove. I suspect that might be my culprit because adjusting the idle screw has no impact. It's either not letting atmospheric pressure down past the idle screw, or somewhere along the way from the idle well there's a blockage. I have a spare carb from Jeff S. so I'll put a kit through that one and see if results are better (but I'd still like to get the original working properly).
It also struggles at high idle, so I checked fuel flow from the tank (ok) and float level (a little tricky but I raised it up pretty high - I'll try even higher to see if that helps - it's not yet running out of the bowl breather.
Any other tips welcomed!

Lastly, is there a kit for the Zenith fuel tank shutoff valve? I need a new bowl gasket and I'd like a new strainer element. I made up a bowl gasket out of regular gasket paper but it still seeps. If there's no kit, what type of gasket material would folks recommend?

Cheers,
Neil.[/quote]

Neil,
If you have a small diameter bowl as my 3j has, check with a local small engine repair shop. You may find what you need there. Or use an "O" ring for a gasket.
Ed

Thanks guys. A piece of information I neglected to mention is that I'm running it without the air cleaner. I'll fit that today to see if it changes anything, and I'll drop by the small engine place for a gasket. The good news is the freeze crack situation seems to have improved - I'll give it another run today to see if more of the sealer picks up.

Dan, on that carb, I'm either not getting enough atmosphere to "pump" the idle gas, or there's not enough gas flow through the orifice(s). I can see this is going to dog me now until I get it right ; ). I'll compare it to the other carb to see what it looks like. Oh well, it's good to have it on a test stand where I can tinker with it. However, that electric start I got off Jeff is starting to look good since I have tennis/golf elbow and have to pull the rope with my left hand.....

Cheers,
Neil.

Mine starts easily, even when hot. High speed is good but even mine doesn't idle real well.
Check for vacuum leaks, but I would definitely raise the fuel level a little more in the bowl.
As far as Air Cleaner, if its got oil in it, then I believe it will add some air restriction to the flow through the carb.

One thing I forgot to mention about the poor idle (needs choke) is that I've noticed a certain amount of "backwash" coming out of the inlet manifold. It's not chuffing or anything but there is a definite air movement in reverse. From my (cough) long and dignified experience in engines : ), I know that there is sometimes inlet valves open at the very beginning of the compression stroke and also overlap with the end of the exhaust stroke, but this is usually to take advantage of the inertia of air movement. Has anyone else noticed this phenomenon on their pony? I thought my valves were in pretty good shape although I didn't actually lap them.
I wonder if this is problematic?

Cheers,
Neil.

So I started thinking about my pony not running well without part-choke. At low idle (800rpm), if I have to have the choke closed, it means that the pony is relying on fuel pulled through the main circuit instead of via the idle circuit. In other words, the fuel supply via the idle circuit is insufficient to support good idling. There could be a couple of reasons for this:
- insufficient vacuum in general: I don't think it's this because otherwise even with choking it wouldn't run. That said, I've been running it without the air cleaner fitted. Perhaps it needs that extra restriction to set up the right vacuum conditions?
- insufficient vacuum at the idle port adjacent to the closed throttle: possible - the throttle shaft is a little loose but I wouldn't have thought loose enough to lower the vacuum at that point. The rate at which the pistons are pumping way way surpass the tiny gap around the throttle shaft. I could test for this by smearing some thick grease around the throttle shaft to "tighten" it up temporarily. I also think that the part-choke probably means that fuel is being drawn through the main circuit.
- fuel level not high enough for the idle circuit to properly prime. I have a new float in from BFIC but I have to say it doesn't seem to adjust much. I'm thinking of cutting some off the bottom so that it can float higher in the float chamber to give me more adjustability. I floated it in a cup of gas and it only takes a third of the float to make it "float" in gas.
- blockages: I've cleaned this carb scrupulously so I'm quite certain it's not blocked.
- gaps or leaks internally where there shouldn't be: I did wonder about some of the passages and whether some are open where they shouldn't be. Might have to conduct some research with a hose and some silicone to see if there's a problem.

I believe it also won't run at high idle (3000rpm) without choke either. That would lead me to suspect the float level.
Comments?
Cheers,
Neil.

So I started thinking about my pony not running well without part-choke. At low idle (800rpm), if I have to have the choke closed, it means that the pony is relying on fuel pulled through the main circuit instead of via the idle circuit. In other words, the fuel supply via the idle circuit is insufficient to support good idling. There could be a couple of reasons for this:
- insufficient vacuum in general: I don't think it's this because otherwise even with choking it wouldn't run. That said, I've been running it without the air cleaner fitted. Perhaps it needs that extra restriction to set up the right vacuum conditions?
- insufficient vacuum at the idle port adjacent to the closed throttle: possible - the throttle shaft is a little loose but I wouldn't have thought loose enough to lower the vacuum at that point. The rate at which the pistons are pumping way way surpass the tiny gap around the throttle shaft. I could test for this by smearing some thick grease around the throttle shaft to "tighten" it up temporarily. I also think that the part-choke probably means that fuel is being drawn through the main circuit.
- fuel level not high enough for the idle circuit to properly prime. I have a new float in from BFIC but I have to say it doesn't seem to adjust much. I'm thinking of cutting some off the bottom so that it can float higher in the float chamber to give me more adjustability. I floated it in a cup of gas and it only takes a third of the float to make it "float" in gas.
- blockages: I've cleaned this carb scrupulously so I'm quite certain it's not blocked.
- gaps or leaks internally where there shouldn't be: I did wonder about some of the passages and whether some are open where they shouldn't be. Might have to conduct some research with a hose and some silicone to see if there's a problem.

I believe it also won't run at high idle (3000rpm) without choke either. That would lead me to suspect the float level.
Comments?
Cheers,
Neil.

Neil,try checking your fuel lines from the fuel tank to the carb. I had a recent experience with my D4 in which it refused to run-not getting gas. The fuel lines were steel and the ethanol from this modern crap they call gas had attracted enough moisture to shut the line off. I purchased new fittings and some copper lines and soldered the fittings on. Problem solved! Hope this helps you out, Larry.

Thanks guys!
Toby - mine is a 3J and it doesn't have that breather there but it does have a similar one on the carb float bowl. I've cleaned that one scrupulously so I think I'm in good shape there. I've also cleaned out the main crankcase breather so I think that one's ok too.
Larry - yes, I installed all new piping and I've verified that the flow out of the end of the pipe (after it's flown through the tank and bowl assembly is sufficient - it'll drain the tank in about 5 minutes.

One thing I do need to test is to fit the pony air cleaner - I'm currently running the engine on a test stand and I don't have the air cleaner fitted, so I need to do that to eliminate that as a variable. After that, I'm going to "shave" the float because I don't think that my fuel level is high enough in the bowl. I have an aftermarket float and who knows if it has the exact same geometry as the original float. I might try plumbing a temporary sight gauge using that bottom plug up to the float breather hole so I can see exactly what level the fuel gets to with the pony not running and then with it running. I suspect it might be too low for the idle circuit to function correctly.

Cheers,
Neil.