Trying to fix a carb overflowing problem (coming out of airbox) Already replaced all o-rings, and checked the float seat and needles, problem persists and it's actually worse than before. Is there a way to check if the needles and o rings are shutting off things correctly before putting back on to the bike? Also, could a too high float level cause the same overflow problem? thanks
edit: just now, while I was taking the carb off (the bike was idelling w/ chock, then notice the fuel leak from the airbox), I notice nothing was draining from the flow bows when I opened both carb drain screws. Both screws where completely removed are completely dry. Is the fuel bypassing the whole flow assemble somehow? does this indicate a leak else where?
are you certain you removed the drain screws and not the mixture screws ? (sorry, had to ask)
have you set your float height ?
Float or needle sticking or set too high, OR, worn needle and/or seat. Check the rubber tip on each needle. If it has a "dent" in it, replace them. :thumb:
When you reassemble them this time around, gently shake them. If the floats rattle, good deal. It is possible to jam them up if they aren't set perfectly.
Works on airplane stuff. :laugh:
Edit: Have you taken the bowls off yet? If the drain screws on the underside of the bowls are all the way out with no fuel flow, you have bowls full of crap. Some of that crap is probably under your needles, preventing them from seating.
Completely disassemble and clean the carbs. The crap is probably rust from the tank, so shine a flashlight in there and look for rusty water. If you find rust or rusty water, time to coat the tank.
the carburetor was from a fresh rebuild. I replaced most of the orings (previous needle seat in left carb had an worn/cut oring causing flooding) The mixture screws were set at 3 turns out (stock intake/exhaust) bows looked clean. If the needles were jammed close could fuel still get to the engine and allow the engine to idle and overflow. I'm still learning how a carb works, so sorry for the elementary questions. thanks guys!
If your floats are dry, fuel is not even going in there ...
Cool.
Buddha.
Quote from: flyingmachine on November 09, 2008, 01:16:10 AM
the carburetor was from a fresh rebuild. I replaced most of the orings (previous needle seat in left carb had an worn/cut oring causing flooding) The mixture screws were set at 3 turns out (stock intake/exhaust) bows looked clean. If the needles were jammed close could fuel still get to the engine and allow the engine to idle and overflow. I'm still learning how a carb works, so sorry for the elementary questions. thanks guys!
If the needles are jammed, fuel may not flow. Or, it may flow continuously. Depends on where the needles are jammed.
However... After reinstalling your carbs, did you place the fuel valve in the "Prime" position? If you placed it in the "ON" position, you're not going to get any fuel. The fuel valve only provides fuel in the "ON" position when the engine is running. "Prime" defeats the vacuum interlock feature so you can fill the carbs. :thumb:
I set the petcock position to prime. The engine was getting fuel, too much of it. Is there a way for the fuel to get to the engine without going through the floats? Looking into this site: http://www.650motorcycles.com/XScarbs.html . Could this cause the problem I'm having?
"Sometimes what appears as a flooding problem is actualy caused by vacuum fuel petcock diaphrams that are mounted on the tank itself, or mounted on the cycle frame. They get old and brittle and get a hole in the thin rubber vacuum diaghram. Intake manifold vacuum will then draw fuel directly into the intake ports and flood the motor, and possibly cause hydraulic lock, (non compressible fluid above the piston that stops the motor solidly from turning over). "
Is there a way to check the rubber vaccum diaghram for leaks?
Thanks,
Can I just remove the vac line from the petcock and plug both ends to verify the possible petcock issue? checked the bowls, they were bone dry, but gas was flying out of the airbox overflow hole.
Quote from: flyingmachine on November 10, 2008, 01:25:35 PM
Can I just remove the vac line from the petcock and plug both ends to verify the possible petcock issue? checked the bowls, they were bone dry, but gas was flying out of the airbox overflow hole.
Absolutely, and that's where I would start too.
Make sure your carb breather isn't blocked
thank, looks to be cleared. I can blow air into it, no signs of blockage