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Discussion Starter · #1 ·
I have a 1998 Suzuki quadrunner 500 that will run at idle for about a minute then sputters and shuts off when I put on the throttle it immediately bogs and sputters then shuts off
I've put a new carb in it and sparkplug has strong spark and good compression air filter is good so are the intake boots and fuel lines.
I'm decently new to this
anyone got any ideas
 

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(Edit).. Doh..

Does it start straight up again, or after a bit of cranking and perhaps a bit of throttle playing, or does it need a long rest before it will go again ?

If you start it and don't let it idle, but start riding it, will it behave till you idle next ?
 

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Some of the new carbies we can buy are not tuned correctly for or bike, climate, altittude fuel etc.. Does this new one run the same as the old carby ? Is the new carby, to cure a problem, or the cause of it ? Could be..
 

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Discussion Starter · #4 ·
(Edit).. Doh..

Does it start straight up again, or after a bit of cranking and perhaps a bit of throttle playing, or does it need a long rest before it will go again ?

If you start it and don't let it idle, but start riding it, will it behave till you idle next ?
the issue was happening before I replaced the carb because i went to clean the old one and the jets were all stripped out with no force on them it starts and will idle choke on without a problem the second the choke comes off it sputters and when you put some throttle on whether the choke is on or not it bogs down and sputters then shuts off
 

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Discussion Starter · #5 ·
the issue was happening before I replaced the carb because i went to clean the old one and the jets were all stripped out with no force on them it starts and will idle choke on without a problem the second the choke comes off it sputters and when you put some throttle on whether the choke is on or not it bogs down and sputters then shuts off
it starts right up without a problem as long as choke is on
 

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Well it sounds like the original problem was a fuel shortage problem. We should fix that, then worry about tuning the new carby.

There are filters on the fuel tap, inside the tank, and I suspect, the fuel tap will be an auto one that turns itself off when there is no vacuum being applied to it. If it's an auto tap, the center position is called prime and it stays flowing all the time in that position. First step is turn it to prime and pull the fuel hose off and make sure fuel flows out freely. If it doesn't, then either it's not an auto tap and we have it on closed, or the internal filters are blocked.

Then, if that's ok, there is a fuel pump we need to check. The fuel pump also operates off vacuum.
The way to test the fuel pump is, with the tap on prime, pull the fuel hose off the carby, and lay it on it's side into a bottle. Then find the vacuum hose that goes to the pump. On most models it's a fatter middle hose on the left side of the carby. The fuel hose is left rear. Trace both hoses though to be sure. The other hose on the left side supplies vacuum to the tap. So, with the fuel hose on it's side in a bottle, suck two or three times hard on the pump vacuum hose till there is a good strong vacuum built up, then relaese it suddenly. The fuel should come out of the fuel hose as a full diameter slug of petrol about ten or so mills long. If the fuel comes out full diameter then the pump works, but we need to test it is getting enough vacuum with the motor running. The pump needs a nice strongly fluctuating vacuum to work, so if the vacuum hose is old and soft, or been replaced with thin walled hose, the hose can partially collapse with the fluctuations causing not enough fluctuation at the pump. Check the vacuum hose is thick walled and sound.
To test it running, we leave the fuel hose in the bottle, on it's side(on it's side is important), but we reconnect the vacuum hose to the carby. Start the motor and with it idling the fuel should come pulsing out of the fuel hose, still pretty near full diameter but a shorter squirt. If that's ok the motor should run at idle. Hopefully by then you have found your problem.

There's one more test for the pump, which is to check the vacuum the bike produces is adequate when the motor is under load. To test that we do all the same test, prime, fuel hose in bottle, vacuum hose on, but we hop on the bike, put the brakes on , start it, put it into gear, and open the throttle till the motor starts laboring. It needs to be running well enough at idle, before you try this test. You need to have found the original problem before trying this. With a load on the motor the vacuum drops away, but if the motor is tuned, the valves adjusted, no air leaks anywhere loosing vacuum, there should still be enough vacuum to keep a near full diameter slightly pulsing flow of fuel out of the fuel hose laying on it's side. If you have the hose dangling down, the fuel dribbles out continuously and it's real hard to tell if it's a decent full diameter flow.

If you do those tests you will probably find your problem, but, if those first two tests show ok, but you still have your symptom, then the carby is suspect. Your problem won't be the thing we are doing the last test for.. Either way, you may have to fix the fuel supply problem, then tune the carby.

Hope all that's understandable and not to difficult. It's important to be methodical, and those are the easiest things to do.. easier than pulling the carby for nothing.. check the fuel is getting to the carby.. then we go from there.
If there are any questions fire away..
 

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Well thank you very much Sir. Most gracious of you.

You do pretty well yourself. I saw your carby cleanig post, and some others I believe. On some forums they have a page for stuff like that, and those notes on fuel supply probably would be good.. I seem to reprint them often.. haha.

Or is there is a page of them somewhere ? Anyone..
 
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