Carb rebuild catastrophe!

[Mr.Vroom]

Hi everyone, I recently picked up a 1979 Gs550E, the previous owner told me that the carbs leaked after/ while running the bike and needed a rebuild. I was able to drive it the few miles to my house. When I got home, only carb one was leaking, I also noticed it blew white/blue smoke out of the pipe for cylinder one and two. The whole bike is mechanically stock. I took the carbs out, split the gang, soaked each carb body with out the jets and needles in undiluted purple power. Carb one had a broken needle tip that I removed by pushing it out with a home made right angle pick and a micro drill. ( I know that using a drill is frowned upon when using it to drill through the top of the carb, but I drilled out the bottom of the broken tip using different sized bits. I don't believe I damaged the metering hole but it is possible.) I then installed Key-Ster carb kits in all the carbs. I turned the air and fuel screws to 1 1/4 turns. I installed the gang two nights ago and started the bike. The pipe no longer smoked, there was a very slight hesitation at around 2-3 thousand RPM and a few small backfires, but nothing concerning. Then yesterday I took it for a short test ride, it ran FANTASTIC! But when I was cleaning the bike, carb 2 and 3 started burping up gas. They would leak a few ounces out the drain tubes, then stop, then leak some more. I thought this was a stuck float valve, I tapped the bowls with a screw driver, and that seemed to clear it up. Then today I was going to go out for a ride, but the bike was really boggy, it will no longer rev past 3500 and is leaking gas out of 2 and 3. Could it be that I installed the floats upside down? Why would the bike's performance change so rapidly? Thanks for your help guys! The photo attached is the tools I used to get the tip out. Thanks!​

 

[Suzukian]

Rebuild all the carbs, and adjust the valves. Put in new Spark Plugs as well. Make a level playing field. Make sure the wires are seated in the coils, and are well connected, without any corrosion, on the Spark Plugs. Also make sure you have set the floats to the proper level, and the needle valves are releasing gas the way they are supposed to. I doubt you could install the floats upside down, but shake them to make sure they aren't full of gas. )

 

[rphillips]

Like him, I wouldn't think the floats are upside down.... Just thinking out loud, Fuel leaking from overflow means too much fuel in those bowls. (1) Floats not adjusted right, (2) needle and seat not sealing properly (damaged or trash in them) (3) gasket or "O" ring on seat possibly leaking

 

[Brendan W]

What parts came with those kits?
Conventional wisdom here is that carb kits are perhaps not the best solution ( they suck)
Replacing the o-rings and seals is all that is needed in most cases.
Also, for some reason, the Universe has ordained that there will be grit in the fuel system just before and just after a rebuild.

 

[gustovh]

Check your fuel valve, it is not shutting off. Smell your oil for gas, I would change it.

V

 

[rphillips]

When do they leak? Is it they leak all the time running or not, or is it just for a while after quit riding and the eng. is turned off. If you come out in the morning and they are leaking, both the pet cock and a needle and seat got to be leaking.

 

[chris]

Hi, like the other guys are saying,make sure your petcock is 100%. It should only flow when the engine is running when it's in the on position. Long time ago I had a petcock fill my engine with gas. These days I use a manual petcock.

 

[Mr.Vroom]

Thanks for all the responses guys! To answer your questions, the Key-ster kits are Japanese made and come with everything but new floats and the short pilot jet I guess you could call it. I'm not sure how well the petcock is sealing, I was planning on rebuilding it, now I will for sure. The carbs would leak while running and a little bit after running, but they would stop eventually. I was wondering if that the carbs are being flooded and that's causing the poor performance? Thanks!

 

[Suzukian]

Better check your oil. If the carbs leak after you shut it off, there is a chance that you have gas in your crankcase. You can always put an in line On/Off valve, they are easy enough to get, and stop any fuel flow.

 

[rphillips]

If the leak quits after eng. is off a few min., the pet cock should be working properly. If it weren't sealing, it would still be leaking tomorrow morn. I sure wouldn't fool with it, at all, if it don't need it.

 

[Mr.Vroom]

I don't believe it is the petcock, I currently have the tank off the bike and its not leaking out the fuel path. It does need a new base gasket, but that shouldn't be related. I'm going to order seals for the petcock regardless. Tomorrow I will take the carbs back out, most likely a bit of crud is clogging the valve or the float height needs to be adjusted. I will check the oil too. I'll update as soon as I'm done!

 

[rphillips]

Replace the pet cock base gasket if needed, but if you do a little search about re-building pet cock in'erds, most don't have much luck doing it... If there is a pet cock problem replacing is the usual recommendation. Not say'in it never works, but there sure is a lot of folks that it didn't work for. I don't think anybody would recommend rebuilding one that is working properly... Just my opinion.

 

[Nessism]

Is the tank free from rust and debris? There could be crud entering your fresh carbs.

BTW, Keyster makes decent carb kits. They don't come with all the needed O-rings to rebuild a full set of carbs, but things like the jets and float valves, are good quality.

 

[Mr.Vroom]

Today I took the carbs apart. The float needle housing in carb two wasn't tight, so fuel was seeping past. The same thing with the main jets in carb 3 and four. I adjusted the float heights, they were all off a little, but carb 3 was the worst. I also held all the floats in water for a few minutes each to see if they would become saturated with water, they all were fine. I drained the oil and did have gas in it. I reinstalled the carbs and left the petcock in prime, I will see tomorrow if there was any leaking. My grandfather is right when he says "haste makes wastes"

 

[Rich82GS750TZ]

Why would you leave the petcock on prime and walk away? Asking for trouble and another opportunity to change your oil IMHO. The float needles are there to stop the flow when the float get to the right point, yes. But I think most agree those float needles weren’t up to the task when new.

 

[rphillips]

Get a manual and read and understand how the pet cock works . It should never be left on PRI. Many more things you can and need to learn from that manual, as time goes

 

[Mr.Vroom]

So the carbs are no longer leaking, that's great. But now the bike no longer runs right. The pipes for cylinder 1 and 4 are colder than 2 and 3. This makes me think that cylinder 1 and 4 are not firing. But they have spark and the spark plus look wet like they are getting fuel. Is this a tuning issue? Everything is set to factory spec. Would getting the carbs synced clear it up? I don't really know how that all affects the bike. It feels low on power when driving, but when sitting still it revs freely.

 

[rphillips]

I'll got to give up... It ran fantastic, but carbs 2 and 3 were leaking when you finished the ride,.. You fixed the leaks on 2 and 3, but now 1 and 4 aren't running properly.... I have no clue.

 

[Mr.Vroom]

There must've been crud in the main jets on 1 and 4. When I set the float on 2 and 3 I also set the height on 1 and 4, dirt must've got in the main jets. A hefty dose of seafoam has it clearing up. I think its good. Thanks guys!

 

[rphillips]

Still not a clue, but hoping everything is good to go and keeps on being good to go. you don't need any more trouble for a while