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Four Cylinder Question

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zanichbug

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Mar 7, 2024
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Location
York, Maine
I have a 1982 Suzuki GS650G and just rebuilt the carbs. The petcock says RES. FUEL. PRI.
Does one know if there's a certain amount of time to prime the bowls?
That is, can they overfill and flood things?
I tried a few minute's worth but the bike wouldn't catch.

IMG_0908.jpg
 
I have had mine flood if left on PRI overnight on my Suzuki, and I've left the manual petcock on the Scrambler on "ON" over an entire weekend without it flooding. It's all about how good the float needle and seat are.
 
Thanks, guys!! Got that issue sorted out, it seems. But when the bike turns over, it kicks immediately into full throttle with extreme revs. So I kill the engine before something bad happens. The throttle control on the untouched right grip does not feel stuck; with engine off, it behaves normally. Any ideas? Thanks..
 
Have you checked the throttle system on the carbs? Sounds like it may be stuck open down there and the cable isn't doing anything about it.
 
Cable binding? I pulled the bars back on my DR, and in doing so, pulled the throttle cable. Did OP mess with the handlebars any?
 
I immediately back off the enrichment lever to about half as soon as it fires. On mine I have my thumb on it (left side bar) at the same time my fingers hold in the clutch lever. Yours may be down near the steering stem though. Yours looks to be on the left bar as well, you hold it to the left when cranking and use your thumb to move it halfway to the right as soon as it starts. You might have missed hooking it up on the carb end. Easy to check with the bike off manipulate the lever with your thumb and watch the carbs to see if it actuating the slide on the carb end.
I assume you threaded the idle speed screw in the same as before you took the carbs apart. Maybe back it off 2 turns until you have this sorted.
 
Wrong pilot jet size, pilot screw too far out, or if they are 3-circuit carbs with an enrichment jet like the later Suzukis, then you can mix up and put the enrichment jet where the pilot jet goes. Or maybe you just have the idle bypass/ throttle stop screw set to too open. In fact, if the carbs are set up correctly and in proper condition, you should be able to back the "idle speed" screw all the way out and it should start and idle.

The fact that you recently rebuilt the carbs means there's plenty of stuff to check, which could have been set wrong when putting it back together, or even could have been intentionally set wrong to make it just run with the carbs in their prior unrebuilt state. IDK how the 4cyl idle speed linkage goes, but I'd start there.
 
William Wolfen said:
Have you checked the throttle system on the carbs? Sounds like it may be stuck open down there and the cable isn't doing anything about it.
Click to expand...
Do you mean that knurled knob under the 4-pack of carbs? Mine is all the way backed off, meaning it's loose. The throttle grip on the right retracts the cable normally, and retracts normally as well.
 
grumpy48 said:
Cable binding? I pulled the bars back on my DR, and in doing so, pulled the throttle cable. Did OP mess with the handlebars any?
Click to expand...
Not that I know of. I never moved the bars, and the cable responds correctly to the throttle handle on the right grip.
 
mr72 said:
Wrong pilot jet size, pilot screw too far out, or if they are 3-circuit carbs with an enrichment jet like the later Suzukis, then you can mix up and put the enrichment jet where the pilot jet goes. Or maybe you just have the idle bypass/ throttle stop screw set to too open. In fact, if the carbs are set up correctly and in proper condition, you should be able to back the "idle speed" screw all the way out and it should start and idle.

The fact that you recently rebuilt the carbs means there's plenty of stuff to check, which could have been set wrong when putting it back together, or even could have been intentionally set wrong to make it just run with the carbs in their prior unrebuilt state. IDK how the 4cyl idle speed linkage goes, but I'd start there.
Click to expand...
As I asked below, is the idle-bypass throttle stop screw the knobby knob on the stem below the carb bank? Thanks...
 
zanichbug said:
Do you mean that knurled knob under the 4-pack of carbs? Mine is all the way backed off, meaning it's loose. The throttle grip on the right retracts the cable normally, and retracts normally as well.
Click to expand...
No. I mean like the bit the throttle cables pull on. I've mostly worked on single carbs, so I'm not the best and helping figure out the specifics of a 4 carb stack.
 
When I crank the throttle, the cable actuates the center pull, and all for carbs respond. Maybe I will disconnect that or let off at the throttle adjuster at the handle grip and see what happens... I assume that the bike would then simply not start.
 
The bike should start with the throttles closed. There's an air bypass in the carb inlet to allow metered air for idling with the butterfly closed.

If it doesn't start with the throttles closed, then you should look at the pilot circuit, ensure the pilot jet is the correct size and not clogged, the float level is correct, etc.
 
AndyA said:
Those look like CV carbs. Make sure the slides aren't stuck in the up position.
Click to expand...
The slides slid pretty well by hand upon rebuild, the diaphragms then closed them upon releasing them. Question: If the float bowls get overfilled, what happens when you start the bike? I do not understand the vacuum process. When I start it, she races instantly. Choke cable moves all four carbs well. Throttle seems the same. I am going to drain the float bowls and start over with PRI...
 
If the float level is too high, it can cause it to race. Note, that's among the things I suggested you check, in post #15, but that's something to check once you've determined that it won't start with the throttles closed. One step at a time.
 
William Wolfen said:
That means it's a vacuum operated petcock. Reserve and fuel(on) require manifold vacuum to flow. Prime bypasses that and just let's the fuel flow. Flow into the bowls is still controlled by the float and needle in the carb.
Click to expand...
Another few questions. Carb bank is off the bike. There are air "T" fittings between #1 and #2, and also between #3 and #4. They didn't have tubing on them going anywhere? Are they just venting out of the carbs? Fuel came out of them when I turned the bank over.... I was pretty careful rebuilding the carbs this past spring.
 
zanichbug said:
Another few questions. Carb bank is off the bike. There are air "T" fittings between #1 and #2, and also between #3 and #4. They didn't have tubing on them going anywhere? Are they just venting out of the carbs? Fuel came out of them when I turned the bank over.... I was pretty careful rebuilding the carbs this past spring.
Click to expand...

Probably vent lines for the float bowls.
 
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