GZ250 fuel issue

bplandis

2006 ST1300
Joined
May 6, 2018
Messages
58
Location
Nashua, NH
Picked up a -08 GZ250 for my wife to learn to ride. Has 3K miles on it and ran rough when I bought it. Obviously with the miles was not ridden much.

Had carb off an seems jets are all clear/clean upon visual inspection. When cold bike runs great. Fires right up, very little choke needed. Once it warms up idle slowly drops and it dies. Once it dies will not start. Almost like vapor lock we used to get on an old big block farm truck we had growing up.

I let is set and cool a bit, if you hold throttle wide open it and crank it a while will sputter 3 or 4 times and finally start. Like its flooded.

As it start to die like its running out of fuel, if you crank the idle screw up enough it will run but idle super high.

Have had carb off several times this week and no real improvement. Done tearing it apart. Idle/air mixture screw have had from 1.5 to 3 turns runs the same.

New carb is $400, and dont see any knock off options. Berrymans chem dip? Rebuild kit?

Thought I would try here prior to reaching out to a local shop. Thank you in advance for your help.

Brad
 
Several things it could be...
I am sitting in doctors office at the moment, but I will try and give some ideas.
Air leaks between carb and cylinder?
Clogged petcock or crap in tank.
Remove gas cap and see if you do have vapor lock?
I have found that while the jets may look clean and appear open, that when looked at with a jeweler's loop, there were pitted from the crap in our fuel...
 
If you have access to a can of Berrymans and have only cleaned the carb with aerosol cleaners up to now, I would strip the carb down again and give it a good dip in the Berrymans. You have to be a near expert on taking the carb apart by now. The reason I am saying this I had the same thing with my wife’s 250 Ninja carbs, cleaned them, well I thought I had with the aerosol, when I used the chemical dip what a difference.

Good luck,

Mike
 
Larry tried not to ring the courtesy phone. Stick will grab a can of berrymans dip and let jets soak overnight. What stumps me is runs great for several minutes when cold then just acts like it runs out of gas.

Larry will pull the tank again and pull the petcock apart. Air leak had not thought of..
 
Sorry for the abrupt post, my doctor came in and caught me answering your post :rofl1:
If you have any carb or choke cleaner (spray) or even WD40, start the bike and spray the rubber manifold boot and see how it responds.
If you have a cracked/loose/overtightened boot it will suck it in and you'll see smoke from the exhaust etc.
What I was saying before the doctor so rudely walked in, was I've found the main jets pitted bad enough to cause flow issues.
You may not be able to see it without magnification.
I swapped the jets out, and all was good again.
Hope its something simple for you.
 
You can't really tell if jets are clean by visual inspection. Clean them with jet cleaning tools or buy new ones.

Run a crap ton of techron through it.

I would rebuild the carb. A good one off eBay for a gz250 is like $50.
 
I use fine wire to clean all the fuel passages in the carb. I would also try running it with the fuel valve on prime. These will sometimes go bad on a gz. We have several of these bikes used for msf classes. They are a very reliable bike.
 
Brad,
Just one thing to check.......
If it is a manual old fashioned choke then make sure it is working in the correct direction, that is when it's on it's on and when it's off it's off and not viccy verca.
I had a buddy with a C15 that was struggling to sort it out and it had me stumped for a while before I noticed he was putting the choke lever in the wrong position for hot and cold running.
It sounds very familiar but probably isn't.
Upt'North.
 
Pulled it one last time today tore it down again and cleaned.

Pulled pet cock and seems to be good and clean and oring undamaged. Runs the same regardless of prime, reserve, on.

Improvement. Now runs fine as is when cold. After a few minutes wont idle. As long as you keep working the throttle it will stay running. Low speed/idle circuit issue?

Choke I believe is good as it idles correctly with it when cold. Clicks when it all the way open and locks in.

Ordered a rebuild kit with new jets, orings. Should be her Monday.

Larry will run down and hit it carb spray around the clamp and see if I am getting an air leak.

Appreciate the suggestions.... more than anything ready for the better half to quit jabbing me for buying her a bike that does not run right and swears she heard me say "wont take much for it to run right."
 
Carb spray no change and no smoke out the pipe.

Next stop All Balls rebuild kit Monday or Tuesday. Will report back once I go through it
 
Did you try removing the gas cap when it starts acting up, to see if anything changes?
Still wondering if you have a fuel vapor lock going on.
The TW200's had that issue, and it drove folks nuts trying to figure it out.
Check the pin hole vent in the cap.
 
Did you happen to add an external fuel filter? I've seen them vapor lock on motorcycles when added. Choke is with the lever towards you and off is forward.
 
Did you pull the pilot jet out and clean out the holes drilled 90 degrees to the tube? I'd also check the float height. Good chance somebody else had it apart before you bought it.
 
Yes sir ran it with the cap off and did the same. Did not dip jets, but have cleaned them a number of times. Typically dont like to throw parts at a problem, but will see if the kit solves anything.
 
Put a all balls rebuild kit in it today. Runs better. Starts without choke, idles smoother.

Same issue once warm just act like it runs out of gas and once you let it die will not restart. Left a message with a local tech to see if he can take a look at it.

Kit came with a jet that I did not use. One in carb that is the same does not have a hole in the top of it. May swap it tomorrow and see if that make a difference.
 
bplandis said:
Put a all balls rebuild kit in it today. Runs better. Starts without choke, idles smoother.

Same issue once warm just act like it runs out of gas and once you let it die will not restart. Left a message with a local tech to see if he can take a look at it.

Kit came with a jet that I did not use. One in carb that is the same does not have a hole in the top of it. May swap it tomorrow and see if that
Click to expand...
Did you ever get the problem solved? I just picked up a 2005 gz250 with 2700 miles. Its for my daughter to learn on.
I'm having the same exact issues as you.
I've tested with the gas cap loose with same results.
Pulled the carb and spray cleaned it using a thin wire in jets.
Fuel flows great through the petcock in the run position.
Im running some seafoam in new gas and the tank looks clean.
No fuel filter to check. I will add one soon.
No air leaks at the rubber boot.
Air filter looks good.
I'm picking up a new plug, and doing an oil change this weekend.
My neighbor thinks it might be an electrical component warming up and losing connection. But the bike starts right up in 3 to 5 minutes after dieing.
If it's vapor lock, how is that fixed? I'm at a loss here.
 
Sounds like it might be an issue if this has a vacuum operated petcock for the fuel or just a restricted petcock. Did you check to see if you have good fuel flow to the carbs? It may not be flowing enough to keep up with the engine. At first when you start the float bowl is full so it starts normally and after it runs a bit and the bowl fuel level drops it runs out of fuel. After sitting the fuel slowly refills the float bowl so it restarts.

I see you check the fuel flow as I re-read your post. Did you remove the float needle seat valve when you cleaned out the carb? Some of these needle seat valves have a tiny screen inside that can get gummed up from sitting and restrict fuel flow to the float bowl and cause the float bowl to run low on fuel after starting and running a bit. After it sits the fuel slowly fills the bowl and it will restart.
 
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bdalameda said:
Sounds like it might be an issue if this has a vacuum operated petcock for the fuel or just a restricted petcock. Did you check to see if you have good fuel flow to the carbs? It may not be flowing enough to keep up with the engine. At first when you start the float bowl is full so it starts normally and after it runs a bit and the bowl fuel level drops it runs out of fuel. After sitting the fuel slowly refills the float bowl so it restarts.

I see you check the fuel flow as I re-read your post. Did you remove the float needle seat valve when you cleaned out the carb? Some of these needle seat valves have a tiny screen inside that can get gummed up from sitting and restrict fuel flow to the float bowl and cause the float bowl to run low on fuel after starting and running a bit. After it sits the fuel slowly fills the bowl and it will restart.
Click to expand...
I did not remove that.
My next plan was to remove the tank and open up the peacock. But I will check that screen and seat valve. Thanks for the tip!
If those don't help, I will dismantle the carb and soke for a complete clean, then rebuild.
I see a lot of people are having this same issue with the GZ250s
 
The carbs in newer small bikes like this have very small jets and passages as newer bikes run very lean mixtures. Unfortunately this makes them prone to issues if left to sit for long periods of time. Always use a fuel stabilizer if the bike will be left to sit.
Some of the small bikes like this GZ250 Suzuki may actually be built in China under license from Suzuki, I know the Suzuki GW250 is and many Chinese built carbs have pressed in jets that cannot be removed to clean them, some do some don't. Some also have the idle air screws or idle mixture screws capped off so they can't be adjusted or removed for cleaning. In most cases these caps can be removed to access the mixture screws for adjustments or removal for cleaning the carb. If the screw has a metal cap over it, in the past I have carefully drilled a small hole in the cap then screwed a small sheet metal screw into the cap and used a pair of pliers to pull the cap out. The cap does not need to be replaced.

I found this video on rebuilding a Gz250 carb that shows you how to remove the needle seat and cap off the idle mixture screw.

 
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