Carburetor problems

Gordon Brennan · May 24, 2010, 03:40:50 PM

I wasn't going to post this because carb problems can be so wide ranged ...... but. Carburetor: Bing 24mm Type 53. Motor 1251/5A Iron Barrel. Bike Penton Mudlark. Bike is jetted for Trials and bike is used for Trials. All jets and needles are new and clean. The bike runs great and has been all spring.
Now .... I'm at a Trials yesterday and for safety sake I put a new plug in just before the event. Bike is running great for 2 loops. At the 3rd section of the 3rd loop, I notice my GAS cap is gone. I never fill the tank so it wasn't splashing around enough to notice. By the rules I can't ride backwards on the loop so I had to walk the bike back to try to find it. Someone remembered seeing something on the trail and that was it. I get the bike back to my truck, put more fuel in and try to start it. This is a one kick bike. Best starting bike I own. But nothing. Several kicks in, some friends resting between loops help me. By holding the throttle wide open I finally get it started, but have to hold it open to keep it running. Loaded up big time. Thinking I'm all set, I start on my 3rd loop, only to get 3 sections in and the bike dies. It will only run wide open and as soon as I let up it dies. The plug is soaking wet and black as night. What happened?
Sorry for the (novel) of a question but I wanted to get as much as I could think of out there.

Gordon Brennan · May 24, 2010, 03:57:46 PM

Hey Folks,
After you solve my carb issues, hop over to the New England Trials site http://www.newenglandtrials.org/ There's a picture of my bike on the home page! Read the caption. I thought some of you might enjoy it.

gooddirt · May 24, 2010, 04:10:07 PM

If the carb has a cable type choke (not on the slide) it maybe that the choke plug broke up. Its at the bottom of the chamber, need to fill in the small cup area. LG

Gordon Brennan · May 24, 2010, 04:14:00 PM

Forgot to mention that part. The choke is not being used and is sealed off. Even the air orfice going to the choke has been sealed.

Lew Mayer · May 24, 2010, 04:41:40 PM

Dirt in the float needle and flooding?

Lew Mayer

Rocket · May 24, 2010, 06:09:43 PM

Cool picture!!

joe novak · May 24, 2010, 07:23:39 PM

Hello, I would remove the spark plug, inspect it, and install the original plug which you replaced. It could be a (new) fouled spark plug. Check the ignition system for proper grounds and loose connections. After that, I would remove the carb and clean it internally, especially the small orifices like the air/idle passage. I also agree with Lew about the float needle not sealing well, perhaps due to dirt.

firstturn · May 24, 2010, 07:52:47 PM

Try what Lew said first.

Ron Carbaugh

Paul Danik · May 24, 2010, 08:49:39 PM

If you don't already have an in line fuel filter, now might be a good time to put one in.

It sure sounds like some dirt got into the tank when your cap was off and made it's way to the carb. You might want to also make sure your tank is clean, take it off and dump that gas and really rinse it out.

If gas is constantly flowing from the bottom of the carb that is a good indication that the float needle needs attention, but you might also have a clogged passage or jet, I have been in that situation a time or two myself

Dirt can lead to a wiskered plug so you might have some overlapping items to content with. Sorry if I repeated what some of the others have already mentioned.

Hope this helps,
Paul

Gordon Brennan · May 25, 2010, 06:41:27 AM

Paul, I think I'm leaning towards a piece of dirt on (in) the float needle. The top of the motor was pretty wet. I do have an inline filter but they're not fool-proof.
I have had the carburetor apart several times to adjust float and experiment with jetting, but Genuine nos didn't have the float needle and seat. I don't have the carburetor with me to look at. How does the float needle seat come out? Who might have the needle and seat?
Thanks folks.

Gordon Brennan · May 24, 2010, 03:57:46 PM