engine running problems

[nick6]

To start it, i have to hold the flap closed and give it gas. then when i let go of the flap and the gas, it will run for like ten seconds and then start to sputter out. If i am quick enough and hold the flap shut, it will come back to life.....until i release it 10 seconds later. What is causing this? Second question.... What does the bypass screw bypass....what is it used for. what setting should i have it at when try to adjust it. also....when adjusting the fast idle screw....should i adjust it when the stairthingy is pointing up or out? thanks for any input.

[emersonbiggins]

Do you have a 34pict 3 carb that you are trying to adjust? Look on the side of the carb for the numbers. There is not enough room to explain it all in this post section but if do have that type carb, type "adjusting 34PICT-3" in google and it will bring up plenty of reading.

[jacklegged thing]

hey nick

sounds like you are having some choke problems! did you adjust the bypass screw or the volume control screw at all? generally these are factory set and dont need adjustment. the " fast idle screw" you referred to is for your throttle positioner. what that does is opens the throttle slightly when rear wheels drive the engine, say like when you are coming down a hill or decelerating. if adjusted properly it ensures an adequate air/fuel mixture and minimizes unburned fuel in the exhaust. To adjust you should have a tachometer. To start , loosen the set screw on the end of the throttle positioner and turn the adjusting screw clockwise until the stop washer on the pull rod contacts the throttle positioner housing. Idle should be about 1700-1800 rpm. (this is for a one peice unit). if you have a two pc. unit it will be connected to a lever. pull it back until it touches the "bottom stair" on the throttle positioner. if idle is not 1700-1800 adjust the screw accordingly. Then push down on the gas pedal until rpm is 3000, then let off quickly. engine speed should drop from 3000 to 1000 in 3-4 seconds. if not adjust screw counter clockwise until shorter time is met.

[Buckly]

I just bought a new 34pict-3 bocart or something. I put it on and the idle was way to high. everything else was right, timing dwell that stuff. so I adjusted the large idle screw. It starts and Idles fine, but I think its running to rich. Inside the exhust pipe is really black and sooty. I've read somewhere thats a sign of to much gas. How do I adjust that. Another quick question, My engine is suppose to be timed at 5 atdc. Is the notch on the pull suppose to be lined up with the case seem(where I've been running) or slightly to the drivers side of slightly to the passanger side? Thanks Bucky

[chinarider]

I would encourage anyone with an aftermarket stock-type carb (like Bocar, and anything else manufactured in either Brazil or Mexico) to consider replacing it with a German-made Pierburg (Kafer) 34 Pict 3. Aircooled.net recently began carrying them, and the difference in quality (and reliability) is remarkable. Their price ($190) is a bit high, IMHO, but after going through no less than 4 crappy Bocar carbs (each with main idle jet problems), it was worth it to finally rid myself of those idle/performance problems. The Pierburg jets are also bigger than the Bocar versions (more like OEM, that is), so there's no need to bore them out, or swap in larger jets. Also, the carb is an exact stock replacement, so there's no need to do any cutting/grinding to allow the throttle linkage to fit where it's supposed to.