Strange. Don't know why it is happening.

Ok. I bought a bike that hasn't ran in years. pulled the carbs apart and cleaned them ( 3 times ). Tryed starting the bike with and with out choke. No go. Don't get a thing with no choke. With choke I get an small offer after winding it over 3 times. then nothing. Then wind it over 3 more times and get a backfire.

Pulled the carbs apart again but this time I put a main jet in one of the pilot jet spots by mistake. Put the carbs back on and the the bike started with the choke on. Turn the choke of bike stalls.

Pulled the carbs apart agiain and noticed the jet mishap. corected it and then the bike was behaving as before ( read above )

Pulled the carbs apart angain and switched all the main and pilot jets. Bikes starts and idels perfect. Runs perfect until half throtle and then dies. back off the throttle and fine again.

I am at a loss. Are my pilot jets too small. Do I need to set the pilot screw.

Help!!!!

 

NExt move would be to pull the tops of the carbs and see what condition the diapghram and needles are in. The slides should raise and fall without delay. Rickomatic has a great writeup on this. It could be a case of severe sync problems. One other thing, a too large plug gap or a fouled set of plugs can cause this too. Try a new set of plugs, gapped at .028". My Seca was really hesitant to start after winter spent under a cover, i just had to ride it out till it fired on all 4 cylinders, then it was fine. Lastly, check the condition of your air filter, if it is suspect, toss it and get a new one, unless it is a K&N or UNI, then clean it and reoil it. cruzerjd

 

Hi Triump,

Have you or anyone else from what you can tell played with the pilot screw? If not, I wouldn't play with that just yet. If you or anyone else has, reset the pilot screw to a default position. (I'm not sure what it is for your bike. Perhaps someone will chime in. Mine's 2 1/2 to 3 turns out from bottom.)

When you get the bike started and running, is the choke still on? Do you still need the choke to get the bike running? Does it still stall even when it's warmed up?

You might want to check your float levels (search forums for info). Make sure you don't have a crimp in you fuel line, and so on.

I have a feeling, though, the problem is not a lack of fuel, if it'll idle just fine.

So it sounds like you're getting too much fuel when you increase the throttle. Try pulling the air filter and see if that makes any difference.

I'm sure there'll be more advice, from both myself and others. But before I speculate any further, it would be nice to know the answers to the above questions.

 

I have not played with the pilot screw. I don't think ne1 else has either. If I put the main jets in where the pilot jets go then the bike will start and idel with out the choke. So I don't need the choke to keep the bike running. I am not sure about the stalling when warmed up. I will try that when I get off work and post with the results.

Thanks

 

Which bike are you working on?

If it's one of the 650s your pilot jets should be 40 and your idle jets 110.

If you didn't pull the idle mixture screws you didn't completely clean the carburetors. I suspect the top of your idle circuit is gunked up. By putting in way too big a jet you're getting enough fuel to idle.

Of course it won't rev with too small jets in place of the mains.

 

If you only pulled the bottom of the carb you didn't pull the emulsion tube, which is probably clogged. You need to pull the tops, spring, diaphram/main needle and then remove the bottom, main jet and push the emulsion tube out the top and clean it and the hole it came out of.

 

I did pull out the diaphram, slide and needle but did not take out the idle mixture screws. I will pull the carbs off again when I get home and pull out the emulsion tube and the pilot screws and give them a good cleaning.

I will post the results.

thanks

 

You need to pull the whole top side off.
Take out the Diaphragm Piston.
Pull the Fuel Bowl off.
Take-out the Main Jet
Take-out the Pilot Jet.
Remove the Main Jet Washer.
Drive-out the Brass tube above the Main Jet Washer. (Emulsion Tube)

Pull the Pilot Mixture Screws.

Clean the Emulsion Tube and All 16 to 24 Air Metering Ports.
Clean the center passage with pipe cleaners.

With the Emulsion Tube OUT.
Flush (Back Flush) the Main AIR Passage.
Shoot Carb Cleaner in the Main Air Jet Hole and watch it come out from the drilled Port where the Emulsion Tube fits.

With the Pilot Jet OUT.
Flush and back flush the Pilot Jet Passage.
(Ear Syringe)
Flush the Passage from the Pilot AIR JET ... out through ... the Pilot Fuel Jet.
Flush the Pilot FUEL Passage from mthe Jet hole out through the Pilot Mixture Screw hole with the PMS Out.

Fuel Bowl Metering Ports for Starter Jets
Brass Siphon Tube
Flush and inspect.

Open the Enrichment Valves and flush the Brass tube out the top.

That's going to help a lot!

 

I have done everything you listed except:

Bowl Metering Ports for Starter Jets
Brass Siphon Tube
Open the Enrichment Valves and flush the Brass tube out the top.

Don't know where these are

The bike will start and run with the choke on. It wouldn't do that before. As soon as I shut of the choke it stalls. The bike has aftermarket mufflers on it. Is it possible I need bigger pilot jets. I was thinking on drilling out the ones that are there. The smallest drill I have is a .73 mm. When I pule the main in the pilot spot the bike ran great up to half throttle ( I put the pilots in the main ). Someone told me the the pilots only help restrict the gas flow under decell because decell causes a huge vacuum which overcomes the restriction caused by the pilot screw. They told me that the pilot screw is what restricts the gas flow under normal conditions. They also said that larger pilot jets will cause bacfire under decell.

So with that said, do you think I should drill out the pilots to .73 mm or should I look elsewhere for the problem.

Also, what is a good way to check for intake boots leaks.

Thanks

 

Nobody drills jets. . . . nobody. Even if it worked, it would be putting a patch on a problem, then months from now, when that hunk of crud dissolves, that carb is out of whack! And all 4 carbs are plugged up differently.

I use a single wire from a wire brush and carefully poke it thru:

The brass tube sticking out of the bottom of the carb--the wire goes in a long way before hitting bottom. 1 of mine had crud there. This tube has a tiny side hole also.

The hole in the bowl that the brass tube sticks into has a tiny brass jet near the bottom. Compare the 4. Carefully run the wire thru. Spray carb cleaner thru this passage, and the spray pattern coming out should look the same.

Good luck- - - it's slow, picky work.

 

Using an unlit propane torch, run the nozzle around the boots while the bike is running. You'll hear an increase in engine Rpms if you have a leak as the gas from the torch moves around the boots.

 

Ok. thanks guys. I will give it a try. See if I can get this figured out. Maybe I should pull the carbs off my other bike. I know they are good and put them on this bike to see if that would fix the problem then I will know for sure that the carb is the prob.

Thanks
Again.

 

Ok. I have cleaned everything. The bike starts ok. Idels without choke. Will rev ok when alittle warm. won't rev when cold or after compltely warmed. Also, when I try to ride the bike, as soon as I start to let out the clutch and the bike comes under load it stalls.

Help!!!

 

Now ... you have to pull the Pilot Jets AND the Pilot Mixture Screws.
Flush-out the Pilot Jet Passage from Fuel Bowl end up through the Pilot AIR Jet Passage and out the Pilot Mixture Screw Hole.

Then, using a Rubber Ear Syringe filled with Spray Carb Cleaner ...
Flush-out the Pilot AIR Passage by inserting the tip of the Carb Cleaner filled Syringe into the Pilot AIR Jet and let the Flushing-out go BOTH ways in the Passage.

Some Cleaner will flush-out the Pilot Jet FUEL Passage and some will flush-out the Pilot AIR Passage exiting from the Pilot Mixture Screw Hole.

Once you have the "T" Passage (intersection where the two Passages meet) cleaned-out ... you will be able to have the Carbs draw upon the Pilot FUEL Jet Supply when adjusting the Pilot Mixture Screws.

If there is any crud in those small passages ... the Fuel from the Pilot Jet cannot ascend to the Pilot Mixture Screw for adjustment.

When you are done flushing-out the passages ... Probe the Metering Hole in the Pilot Fuel Jet to make sure that it is open and passing Fuel up into the Passages.

Since you wrote that the Bike ran with a Main Jet in the Piolt Jet spot ... I strongly suspect that the Pilot Fuel Jet is clogged and no Fuel is entering the passages making the Enrichment Circuit (choke) and the Main Fuel Jet Supply the only open passages.

You won't get the bike to idle right or take-off from a light without cleaned-out Pilot AIR and Fuel Passages supplying Pilot Fuel to the topside of the carb ... unless the parts and passages ate cleaned out.

 

Thank you very much. I will do that today. Will post me results.

 

Think I finally got it. 3 of the 4 main air jets were plug. I clean them before but because I have taken the carbs of so many times and re cleaned other parts I think some dirt must have been blown back through the main air jets plugging them. The bike starts nice and idles nice. I Moved the bike back and forth about 5 feet. Everything seemed ok. I was not even able to start the bike of before. I will be able to check it better when it warms up a little but I think it will be ok.

Thanks for all you help.

 

If the Main AIR Jets were Plugged you might want to recheck the Emulsion Tubes again. Those tiny holes surrounding the Emulsion Tubes don't take much to foul them.

Whatever might have entered the Main AIR Jets surely would have worked its way down the air passage and plugged up a hole on the Emulsion Tube, I suspect. Wouldn't hurt to make sure they are all still free and clear.