Jet troubleshooting

[PoppaDre]

After two years of tinkering around and reading forms, I have finally come to the conclusion my main jets are too big. I got my bike two years ago, and got the carbs cleaned at my local Suzuki dealer ($300 later). On the ride home i noticed i could not get my bike past 1/4 throttle. Check the carb diaphragm and there are all intact and no holes. Tested ignition coils, and many other trouble shooting steps in the clymers guide. Pulling out my carbs they are black. So the only thing I can think of is that the jets are too big, and putting in too much fuel into the cylinders. If anyone can give me some advice on what jets to use, and if i need and washers or spacers. Can i just used pod filters to solve the problem or should i keep stock box (preferably not because getting the carbs out is so much work) and just buy new size of jets?

Thanks

 

[Big T]

What size mains jets are in the carbs?

Using pods is going backward

 

[Guest]

Check a few things first.
Voltage at the coils with the ignition on and headlight off. Compare to voltage at the battery.
Make sure the needle jets aren't bad.
Make sure the spacer is installed on the jet needle properly
Clean the carbs "for real"
Check the valve clearance
You say the carbs a black? Do you mean the spark plugs?

 

[pyro254750]

Not sure if the carbs are similar or not, but i had this same problem with my gs1100 when i first got it on the road. First the bike wouldnt run, turned out to be bad coils, once it DID run it would only run with choke on and i couldnt get it past 1/4 throttle. As it turns out, my jets were too small. Someone had installed a vance and hines 4-1 exhaust on the bike before i purchased it and not rejetted it, and between the plugs being fouled from running lean and the lack of fuel, it would do little more than idle without missing and dying. I did some research and found vance and hines jet recommendations for that exhaust, so i purchased those jets (pilot and main) as well as 2 sizes larger and smaller for tuning purposes. The bike ran tons better but still wasnt quite right. Raising the needles up with a couple nylon washers did the trick.

 

[KEITH KRAUSE]

After two years of tinkering around and reading forms, I have finally come to the conclusion my main jets are too big. I got my bike two years ago, and got the carbs cleaned at my local Suzuki dealer ($300 later). On the ride home i noticed i could not get my bike past 1/4 throttle.

Did you road test the bike before taking it to the dealer and it ran beyond 1/4 throttle? Sounds like you're saying the dealer carb cleaning caused the problem.

 

[KEITH KRAUSE]

What happens just beyond 1/4 throttle? Falls on it's face/bogs? Immediately back off to 1/4 and it clears up quickly?
Simple check first. Might sound crazy but it happened to a co-worker...
Took his bike in for some work. Came back and it wouldn't accelerate beyond 50. I lifted his seat and the mechanic had left a shop rag in his airbox and it was starving for air. Ran fine up to approx' 50 and then would just hit the wall.

 

[PoppaDre]

What size mains jets are in the carbs?

Using pods is going backward

97.5. They match up with the manual. I was hoping that would be the fix

 

[PoppaDre]

What happens just beyond 1/4 throttle? Falls on it's face/bogs? Immediately back off to 1/4 and it clears up quickly?
Simple check first. Might sound crazy but it happened to a co-worker...
Took his bike in for some work. Came back and it wouldn't accelerate beyond 50. I lifted his seat and the mechanic had left a shop rag in his airbox and it was starving for air. Ran fine up to approx' 50 and then would just hit the wall.

Haha. The bike ran but very bad before i took it in so i wasn't sure. I loaded it up in the back of the truck to take it in. I only really got it going after i got the carbs/bike back from dealer. If i hold it past 1/4 throttle it starts to bog down and when i let off the throttle it takes a little while to get it to run "properly" again.

 

[PoppaDre]

Check a few things first.
Voltage at the coils with the ignition on and headlight off. Compare to voltage at the battery.
Make sure the needle jets aren't bad.
Make sure the spacer is installed on the jet needle properly
Clean the carbs "for real"
Check the valve clearance
You say the carbs a black? Do you mean the spark plugs?

When i took the bike in they replaced one coil and said that the were both working good. Just took carbs apart and all the jets look good. I always drain gas for storage. I have yet to check the valve clearance since i don't have the tools for it yet. HOpefully next weekend i can get it done. And sorry yeah i mean to say plugs.

 

[PoppaDre]

Not sure if the carbs are similar or not, but i had this same problem with my gs1100 when i first got it on the road. First the bike wouldnt run, turned out to be bad coils, once it DID run it would only run with choke on and i couldnt get it past 1/4 throttle. As it turns out, my jets were too small. Someone had installed a vance and hines 4-1 exhaust on the bike before i purchased it and not rejetted it, and between the plugs being fouled from running lean and the lack of fuel, it would do little more than idle without missing and dying. I did some research and found vance and hines jet recommendations for that exhaust, so i purchased those jets (pilot and main) as well as 2 sizes larger and smaller for tuning purposes. The bike ran tons better but still wasnt quite right. Raising the needles up with a couple nylon washers did the trick.

My bike is kind of hard to start, and if i pull the choke out it has no hope in starting, so i am thinking it is running rich. or maybe not enough air? Is that where the valves come in?

 

[almarconi]

Your first mistake was taking it to the dealer to have them clean your carbs. Get yourself an o-ring kit and a can of carb dip. Take the carbs completely apart, soak them and reassemble them. Bench sync them. In the meantime, check/adjust your valves. Put carbs back on the bike, set your mixture screws using highest idle method or a color tune. Vaccuum sync your carbs. Make sure your battery is fully charged and you are getting at least 12 volts to the coils.

You can't make any assumptions at this point until your valves are adjusted and your carbs are clean. A bike that is hard to start more than likely has neglected valves. Your choke issues could be caused by dirty carbs. Plug chops are the way to tell if your jets are correct. Go at this in a systematic approach and you should be able to get the bike running well.

 

[BassCliff]

Hi,

I just wanted to remind you that in your "mega-welcome" are a couple of maintenance lists that are guaranteed to get your bike running like it should. If you can't find your "mega-welcome" then just go to my website (link below) and click on the READ ME page. There usually are no shortcuts to a good running classic bike. Do it all right the first time and your bike will love you for it. Keep us informed.


Thank you for your indulgence,

BassCliff

 

[KEITH KRAUSE]

If the problem starts at 1/4 throttle position then it shouldn't be the main jets. The main jets regulate fuel flow from 3/4 throttle to full open.
Like others have said, you probably need to completely clean the carbs and inspect all the o-rings and rubber parts like the diaphragms, check float levels, etc. Good info at this site will help you do a good job. Lots of help here if you get stuck on something.

 

[PoppaDre]

Today i want to try and tackle the valve clearance check. Unfortunately i do not have the shim tool and being a Sunday everything is closed. Is it possible to do it with out the shim tool? Also my weather stripping on my air intake box is all rotted away so i am going to pick that up at the local hardware store today. Also wondering if i should upgrade my filter to the K&N replacement filter SU-5500. Or is the stock filter okay. I got it replaced 2 years ago.