1981 GS750L - Carb Help

[Guest]

Okay gentlemen - I need your wisdom please. Here is what I have done to the bike. I have managed to turn a running bike into a 450lb garage space eater.

I have pulled the carbs off and completely followed the details provided here on this wonderful website. I am very detailed and double check everything twice to make sure its perfect. I dipped the each carb per the instructions, checked each item to make sure it is clear. Replaced all the o-rings with the wonderful set from Cycleorings.com(i forget his name; but great service and super fast shipping with great instructions and advice).

Here is my problem. The bike starts right up without choke and idles around 2-2500. If i pull the choke it dies immediately. The throttle is very responsive (like it should be I believe). Once it warms up it settles around 1200-1500 then magically dies. I can keep it running with throttling it up. I did this thinking I had the idle set too low or something -- took it for a ride and almost crashed. About 2-3 miles up the road it dumped fuel all over the rear tire and I almost ate it. I pushed it back home and cannot find where the fuel is coming from -- looks like the "vent hoses" per the instructions. Fuel was everywhere and it never leaks before.

The bike had some spray foam configuration for the old air box, leaking petcock valve and ran really good. I just could not stand the smell of gas in my garage and the spray foam looked like garbage. I would love to get this thing back to riding condition - Please help

[Larry D]

Carb cleaning and o-ring replacement is good. What else have you done ? It's sounds to me like you need a new petcock and an overhaul of your air intake system, it needs to be airtight.

[almarconi]

Before installing your carbs you need to bench sync them. If one of the butterflies is opening more than the other you will have issues. Your choke linkage may also need adjusting. Did you measure the float height when you
installed the floats? If carbs are overflowing either floats are set wrong or needle valves are bad. The air box boots need to make a tight seal on both the intake and exhaust side of the box. Once you get everything mounted, you need to set your mixture screws at idle and finally do a vacuum sync.

[markusarealuis]

Responses

Thank you guys for some of the responses. I should've been more clear.

New petcock installed
New intake boots installed
New airbox installed
Bench synced
Oiled throttle/choke cables
Changed oil/filter
New spark plugs
New gas line and vacuum hoses
Check for intake/exhaust boots leaks -- seem to be very good seal

Probably forgetting something....

[koolaid_kid]

If it dumped fuel I would suspect either incorrect float level or a dirty needle and seat.
When I rebuild carbs, I always set them in a container, in correct orientation to the ground, and connect a fuel source to them. If they start leaking in less than 30 minutes, I pull the offending carb bowl off, remove the float, and clean the needle and seat with carb cleaner.
I repeat until they do not leak, then install them on the bike.

[Crankthat]

If it dumped fuel I would suspect either incorrect float level or a dirty needle and seat.
When I rebuild carbs, I always set them in a container, in correct orientation to the ground, and connect a fuel source to them. If they start leaking in less than 30 minutes, I pull the offending carb bowl off, remove the float, and clean the needle and seat with carb cleaner.
I repeat until they do not leak, then install them on the bike.

Have had the same issue as you.
Left in prime and took for a ride with fuel mixed with oil.
The fuel getting past the float needle filled my crankcase to push a mixture of fuel and oil out my airbox and from there on back tire.
Would follow koolaid_kid advice and double check your float level.
You should check your petcock position also and if it is not in prime determine if it is letting fuel through in on position while the bike is not running.
Would imagine your oil is full of gas too, if so your site glass below oil fill up cap will show more oil then it should, and your oil will smell very strong of gas.
You will have to address that also.
I flushed mine by changing oil only, putting a few miles on bike then changing oil and filter.
I have read on here that most people have just changed the oil and filter and rode it like that without any problems, but the choice id yours.

[eil]

If it dumped fuel I would suspect either incorrect float level or a dirty needle and seat.

From the description, this is what I suspect as well. Could also be a stuck float (or two).