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Al Peckenpaugh
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OK, cant get one of my Mc91's tuned. Fussed with carb. After rev up idles way down almost stalls, then revs up to high idle. Acting like an air leak... Switched carbs because it's easy. No change. Pull engine, pressure check holds 18-20 lbs all day..... Check timing, dead on. Reinstall carb and header and put back on kart. Won't start!! Got spark, got compression, got fuel..... Scratching head.
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Tony Garbarino
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Al,
Put the tools down and go into the house and have a big glass of limoncello.
Tomorrow you will discover that you left the paper towel in the carb.
Sleep tight.
T
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Larry Brown
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Hi Al - May sound strange, but try changing the condenser. I chased a problem that I was sure was fuel related, but as a last resort I changed the condenser and the problems disappeared.
May not be the answer, but worth a try.
Larry Brown
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Tom Day
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I have witnessed what Larry is talking about.In my case it was the coil.
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Al Peckenpaugh
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I switched the engine with a fresh one off the shelf... I'll see how it works when we get to Avon later today. It's on my dual so if it doesn't work, I'll run something else. That dual whips my ass anyway....
I'll look into that other engine later. I'll post if I find anything conclusive.
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Larry Brown
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Hi Tom - Thanks for the comment, I know it sounds goofy, but there is a good reason behind it. Weak or erratic spark can do that. Mine did not show up until I had the engine warmed up and ran it for a while, ran fine up to that point. Made it even more challenging. Your coil was probably doing the same thing. As always, experience is a good teacher.
- Larry -
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Al Peckenpaugh
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It's not in the engine. I switched engines and it does the same thing. Fuel continues to flow through brass main tube after butterfly is closed and floods it out unless a little air is introduced. If idle is successful still dribbles too much from main. Turn needle in and it starves. I have to restudy the circuits in the HR carb again and try to figure out my problem.
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Richard Engel
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Al We had a least 5 Macs down I did not get mine going in sportsman Richie
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Doug Tenney
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Hi Al,I don't think adjusting your H and L needles will help. Sounds to me like the inlet needle is not sealing. There should be nothing coming out of the main discharge tube at idle. Check to see if the pressure holds as you sneak up on the pop-off point.
I know what you're thinking... too bad I can't fix my own carbs... and you'd be right.
Doug
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Al Peckenpaugh
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Hey Doug, Nope... new inlet seat and needle in carb, not leaking until pop off. Already checked.... Going with new soft plug on main nozzle. May have been leaky...
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aharp94
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good one
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Al Peckenpaugh
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Trading the two HR's for two HL's did the trick...
I don't know why those HR's acted like that. I have them working on other engines..... ???
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