QuestionQUESTION: My bike has only 9,000 miles,and this year it started leaking gas from the carbs. It starts ok with full choke and after a few minutes it will idle ok. Gas leak slows a little after idling but after the warm up and i give it gas it goes dead. Please let me know of the probable causes before i start taking apart things i shouldn't. Thank You.
ANSWER: Don,
your carbs shouldn't leak at all.
It sounds like the carb float needle/valves
are either worn or have gas varnish or whatever
making them stick. You may want to check
that gas is flowing freely from the gas tap,
if it has a vacuum line just apply vacuum
to it to open the valve, (suck on the vacuum hose)
The carb gaskets may have dried up as well,
check those if you take the carbs apart.
I think maybe a good carb clean may solve the
problem. Check the main jets and others with
a piece of guitar string to make sure they are
clear.
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QUESTION: Wayne, thanks for the advice, i've taken the carbs off twice now, cleaned everything i could see, nothing seemed to be stopped up, checked float valves and all needle valves i could find. I have a CLYMER instruction book for this bike. Not much help in the way of carbs breakdown. I got on the internet and found a parts list and drawings of the carbs. this helped. I had two bowl gaskets that i used on the number one and number two carbs ( number one being left side of cycle ). This seemed to be where the gas was leaking from , I first thought the gas was coming from the nipple between carbs one and two. After i took the carbs off for the second time, i could tell the gas was not coming from the nipple, it's really hard to tell where the gas is coming from because it drips from many places. After i put the new gaskets on, it seems to be leaking even more. The bike Idles great now and i can give it some gas and it runs better, but cannot open up all the way it will stop. I'm at my whits end, i wish i knew more about carbs but i don't. Any further advice will help. I also sent an email to a parts company and asked if they had a carb rebuild kit for this bike and what all it contained. I couldn't find a rebuild kit,,,just individual parts.Thanks so much for your time at trying to help me. It's really great to have somelike you that i can turn to for my problems. Don
ANSWER: Don,
can you tell if the gas is coming from the carbs
for sure? You don't have a leaky gas tap or
hairline tank leak?
The only other thing is leaking float needle/valves or
pressure building in your gas tank
due to a plugged tank vent that is pushing fuel
out of the carbs.
Check the tank for pressure buildup.
Check out this pdf for carb rebuilding:
http://www.thegsresources.com/gs_carbrebuild.htm
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QUESTION: Hello Wayne,,,I'm back again. Thanks for sending me the pictures of the total breakdown of the carbs. Wish i had them the first time i took them apart, they have been very helpful, but i still have the gas leak problem. The gas seems to be coming from number two carb. somewhere around the bowl gasket. I put another new gasket on , but no difference. It's just hard to tell because there is so much of it and it drips from many places when it starts flowing. The only time it leaks is when the motor is running, just as soon as i stop the motor the leak stops. If the number two float valve is leaking and the bowl is overflowing, where would the gas come out of the bowl? I rechecked the needle float valve and it looks fine. I haven't found any gummy stuff in any of the carbs, they all look like new inside. Nothing is stopped up. One thing i did notice this last time i took them apart is that the o-ring for the needle valve on number two carb is not very tight. I pulled the needle valve body out and it came out very easy and drops back in very easy. I took number four carb apart and the needle valve body o-ring was tighter and when you place it back in you have to push it in. On number two it will drop in easy. Could the leak be coming from around the o-ring? I've been thinking about switching the valve from number 2 carb to number 4 carb. Put them back together and see if number four carb starts leaking and number two stops. What do you think of this Idea? I know i need to order some parts but i would like to know if a normal rebuild kit will contain the parts i need. I'm still not sure weather the leak is coming from the gas nipple thats between number one and two carb. There is a local cycle shop on Vancouver Island but i don't go to that island often, I guess i need to call them and see if they have an assortment of o-rings. Again I would like to thank you for all your help and it's been a pleasure having you to help me. Thanks Wayne,,,,Don Hall
ANSWER: Don,
could very likely be the o-rings as well.
Check here for help on that:
http://www.cycleorings.com/
If nothing works, I suspect you
may have a warped carb body,
hope not though. O-rings
do get worn and can leak alot.
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QUESTION: Hello Wayne, It's me Don Again. I received the o-ring kit, such a great buy for so many rings. ( Thank you for telling me about them.) I finally found the gas leak, it was the tube between number one and number two carbs. The new o-rings did the job, I've also replaced all the other o-rings , cleaned everything,checked everything i know to check. The bike starts easy, with just a little choke and then i can release the choke and it idles great, smooth as silk, I can give it a little gas, runs good, a little more gas and it still runs good, then just a little more and it flutters to a stop. If I throttle it back down to an idle before it flutters off, It will continue running on idle. I've tried to rev it up by turning the throttle high and low,,quickly,, but this does not help. I've got new plugs and there is plenty of gas flowing from the tank. I haven't put the air filter back on the bike yet, Just figured i would get it running better before installing. Would having the air filter off make a difference in how the bike runs? If there is anymore you could tell me to check for,or if you have anymore ideas it would be appreciated. Thank You, Don
AnswerDon,
have you checked the carb slides to make sure they
slide freely and if diaphragms are rubber check
for cracks.
The air filter may help a little, but not alot.
Here is a big list of things to consider:
Idle speed setting.
Replace the spark plugs with some (my preference) NGK brand plugs? Heat range ok?
Read the spark plug color, black=rich, white=lean, light-brown=ok.
Air filter
Fuel filter or supply limited.
Stale gas or water in the gas.
Could be plugged carb jets, they are small and need thorough cleaning.
Gas tank vents in cap or tank.
Make sure it is running on all cylinders, when first started
before it gets too hot, see if all the pipes get warm.
May need the carbs syncronized so they all pull evenly.
Check air cut-off valves on some models. (bad idle or backfire)
Check compression, should be even, around 150psi or higher.
Intake air leaks.
Carb overflow misrouted.
Carb vacuum diaphragm.
Vacuum hose leaks.
Tight valve clearance
Leaking intake or exhaust valves.
No exhaust backpressure. = lean fuel/backfire
Failing ECU or spark control unit.
Failing pulser or trigger coil.
Failing ignition coil.
