ok to start, im completely lost on this one. I completely cleaned teh carbs, and i mean completely! before cleaning it only ran on the rt cylinder, after cleaning it ran beautifuly on both, and all of a sudden it only runs on the left....... If i plug the air jet on the carb mouth with my finger, it will start firing, but not right. I have pulled teh carbs and checked to make sure i put everything back together right, it is, re set the needles to 3 1\4 out, same thing after reinstall. If any body has any idea where i should start on this one, let me know. Im about to give up and list it and go for another, it seems like the left cylinder has not even half the power of the rt, and am really getting to the point of giving up, im not about to spend 400 on a set of carbs to see if it is or isnt the problem.
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lost on tuning
- Thread starter brilamb2
- Start date
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- carburetors chopper
What you say says that it's almost certainly a float or float needle related problem, I think. If you can, drain the fuel from the bowl of the bad side, and then let it fill up again. It may unhang the needle. You could also have a bad brass float in which case you'll want to replace the float. You don't say what year or carbs.
Well it is an 81 with the bs 34 carbs, and,thw float needles move free. Also thw drain screws are froze in the bowls. I'm stuck with this and need some advice. When I pull the carbs the float needles work smooth when I blow through thw line, and I forgot to mention the idle rises when I plug the air port.
The '81 carb would have pretty much indestructible plastic floats. The fact that all was good, then it changed indicates something changed and it can only be a float valve situation or the rubber diaphragm. The needles can move freely but still hang for some reason now and then. Were the seats real easy to get out? That could mean a bad seat o-ring.
THe o-ring around the needle seat when you pull it out. Originals are usually loose by now and can let gas through like a bad needle and seat. The fact that you can affect the bad side somehow by covering the air jet makes me think it's not electrical. But I assume you've checked for spark on that side. Check the float level on both carbs. 22mm to the most distant round part of the float, if the gasket isn't attached. 21mm if you have to measure from the gasket. If you bought new carbs, you'd have to be doing this with them or more. If you hold the throttle open does the bad side clear up some? Is there loud popping in the bad side exhaust?
Great spark on both sides, just not getting enough fuel to keep running. Gonna pull the carbs off again and blast air through them again. Gotta be something plugging the primary is the only logical idea. If anybody has any other ideas I'm open to them.
littlebill31
Smells of Raw Fuel
That o-ring around the float needle valve can cause a lot of problems. I've had the valve fall out before 'cuz the o-ring was so far gone. And crud gets caught up in the screen as well. The o-ring and washer in the mix screw will also cause a bad idle. Since it clears up when you give it throttle then see what position the throttle is in when it starts to clear. Idle to 1/4 is the pilot circuit. The pilot circuit and/or floats is most likely the cause. I always ask, but are the plugs over the pilot jets? Also make sure the ports in the intake throat are clear. They are extremely small. They are the 3 holes above the butterfly.
littlebill31
Smells of Raw Fuel
Most likely is the floats.
Blocking the pilot air jet fattens the mixture; engine vacuum starts to draw raw fuel. When blocking the jet manually results in better running, it's an indicator of a lean condition, possibly caused by blockage in the pilot circuit; carbs often need two or three repeated cleanings before all the scale and crud are out. Do another cleaning: strip the carbs, blow out passages with solvent and compressed air, inspect float, float level, float valve screen and O-ring, and check function on the bench; do what you need to do to get those bowl valves operating. If you don't have inline fuel filters, install them. Refer to www.amckayltd.com/carbguide.pdf .
The carb guide grizz referenced, or here's where we break the floats down on the bs34.
http://www.xs650.com/forum/showthread.php?t=6344
KentMoney
XS650 Addict
fuck brilamb2, I sent him a TCI module and pick up and he never payed me via PayPal as stated. BEWARE
