no fuel to cylinder -too many cooks

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calliope

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I'm a new-born mechanic :pistols:Had 4 different 'mechanics' work on my 600 carburetor. All said it was fine. But no gas getting getting to cylinder - impossible to flood after 10 min. cranking - full choke, full throttle. Good vacuum at cylinder head. Lotsa gas in carb. Boot seals all tight. Think they may have screwed up the vent/vapour/vacuum lines but can't find clear photo of setup. Help?
 
If the 600 has the same fuel valve as the 900 I would ask if you tried setting it to the prime position because that will bypass the vacuum activated part.
 
I did check that with the hose disconnected from carb. Gas flows easily. Also checked gas in carb by unscrewing stopcock on bottom of each carb - lotsa gas. But it doesn't get from carb to cylinders.
 
Sounds like you need some good mechanics. If there is fuel in the bowls then something is plugged up in the carbs. there's a choke circuit, pilot circuit and main
 
You may be right but no one here except fly-by-nighters will work on a bike that old. I removed the air boot off one carb. Put my hand over the port on carb. Lots of suction and gas all over the place so guess gas is getting through carb circuits. Does the air side need to have some restriction to encourage through-suction?
 
Pull the plugs out and let the motor dry out. These bikes dont have a choke. Tgey use a starting enrichener. If you open the throttle while trying to start then you are working against the enrichener.

Make sure there are no vacuum leaks. Make sure the bowl vents arent blocked. The bowl vents are the t tubes between the 1-2 and 3-4 carbs and tge vacumm ports are tge ones sticking straight up by the carb holders (intake side)
 
calliope said:
You may be right but no one here except fly-by-nighters will work on a bike that old. I removed the air boot off one carb. Put my hand over the port on carb. Lots of suction and gas all over the place so guess gas is getting through carb circuits. Does the air side need to have some restriction to encourage through-suction?
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You can always take the rack of carbs off, flip them over and clean them...No need to seperate them unless you want to paint and stuff while they are out (So you won't break the synchronization).

You shouldn't really need a restriction to cause the suction...You should be able to start it with the boots off but it would run lean.

Do you smell a strong gas odor from the exhaust pipes after cranking? If yes than your exhaust valves are too tight and you are loosing the fuel. Just a thought.

Do the spark plugs get wet at all? If NO, you have no fuel delivery.

If you crank it with a squirt of either / starting fluid does it fire and try to start? If yes than your carbs are plugged and need thorough cleaning.
 
K. Now I'm worried. One guy who worked on it removed a t-tubing (I still have it - looks the material and diameter as the vacuum return to the gas tank). There is one one tube that goes from the left-most nipple (engine-side) to the gas tank. the other three have little rubber caps on them. Plugs are dry. I tried turning it over with one boot off to check suction - spewed gas all over the crankcase. I've had the carbs out four times - all cleaned and check for gunk.
 
calliope said:
K. Now I'm worried. One guy who worked on it removed a t-tubing (I still have it - looks the material and diameter as the vacuum return to the gas tank). There is one one tube that goes from the left-most nipple (engine-side) to the gas tank. the other three have little rubber caps on them. Plugs are dry. I tried turning it over with one boot off to check suction - spewed gas all over the crankcase. I've had the carbs out four times - all cleaned and check for gunk.
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If the plugs are dry but you are definately getting fuel in the carb throat than something is wrong. Did it run before and this suddenly happened? Or did you purchase this used and came upon this problem?

If the later, I would suggest checking the valve clearance and the cam timing.

Did you check for odor of raw gas in the exhaust yet?
 
It ran before. This happened after a mechanic overhauled the carbs because he claimed there was lacquer gumming things up. We were having problems with sudden acceleration at mid-speeds. I tried it tonight with no throttle, choke on full and it started but began to race up over 8000 rpm. First time anything has happened in two months of work. Turned off and adjusted the idle screw slightly. Would not restart but is kicking. Battery dead now - seems to drain the battery really fast (3-4 min of cranking) with ignition on. I've charged the battery 3 times today. Battery is brand new. Noticed a slight little pop sound near back of bike when I turned the key to ignition position. odd...?
 
You know I had similar problem , I changed pluse to 7 ngk to 8ngk had better lucj cause it fired right up . Toook a good look at old plugs they had gotten so soaked that there was nadda happening . But.........I also turned motor ove to release all excess vapors wneh pluds were out. Worked for me ,good luck .
 
Thanks guys for all the advice. Keeps me from hooking myself up to the battery charger. I put new plugs in. Will pull them all today and air it out. Who's and where is Rick?
 
Good news. After running the battery down twice it started and ran steadily. Little rough at first -lotsa smoke. Gradually set the idle down. Took it out for a run after about half an hour idling. Still runs a bit uneven below 3500 rpm. Stalled at stoplights a few times but always restarted. Thanks guys so much for the help.
 
I'm thinking "mudrunner" might be onto something.

If there's gas in the bowls and plugs are dry (all four!?), then it's unlikely that all four carbs screwed up at once to the extent that they deliver NO fuel. Not even one of them!??

But, if your timing is somehow totally jacked, then there won't be vacuum to suck the fuel into the combustion chambers.

I'd do a quick compression check...

Could be as simple as pulling a plug and seeing if it builds compression with your thumb.
 
Actually, I turned her over with the carbs removed and stuck my hand over the ports - good suction on all. I think Billy was on to something with the comment about the plugs. tested the spark on all of them. All sparked steadily but not particularly strong. I'm now wondering if the uneven running is electrical.
 
calliope said:
Actually, I turned her over with the carbs removed and stuck my hand over the ports - good suction on all. I think Billy was on to something with the comment about the plugs. tested the spark on all of them. All sparked steadily but not particularly strong. I'm now wondering if the uneven running is electrical.
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With an old bike, it could be anything and often is a combination of things. When I first got my bike it would go for about 20 miles great and then stop like it was out of gas.
 
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