I bought this bike:

http://www.nsr250.net/forums/viewtopic.php?t=6812

When I went down to look the bike over the owner informed me the bike hadn't been started in 3 years. We got her running, but not very well. The bike would die with any throttle. We both figured this was due to bad gas and dead battery. I decided to go ahead with the purchase. First thing I did was order a new battery. So I got the battery in flushed the tank and pulled the carbs for a clean and put in new spark plugs.

I figured this would remedy the issue, however it did not.

When I get it up and running the front cylinder doesn't seem to be firing or at least the exhaust pipe from the front cylinder stays cool to the touch even after several minutes of running. The rear exhaust pipe does warm normally. It will only stay running on full choke. At one point I got it to take some revs, then the engined revved out of control and kept running even after turning off the kill switch and disengaging the key entirely. After a few seconds it slowed and died. It has done this twice now. I also notice it seems to run better when sitting on its kickstand and when I get the it upright or even lean the bike over to the non kickstand side it really spits and sputters and wants to die.

I know this is a broad question and could mean many different things, however I have never owned a 2 stroke and know little about them. Anyone ever have this happen to them? What was the solution? Ideas and thoughts welcomed.

Could be the float valve in the carb sticking? Did you check the float heights?
I'd have another go at the carbs if it's not been run for three years.
Looks very nice.
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it wouldn't be fun if it was easy!

Not an expert but most likely it need a carbs cleaning.

A bike running after shutting it down seems odd and not like a stuck float (although, I would check the floats no matter what, as well as pull all jets and clean them if you haven't).

For the front cylinder not running, check the spark plug, is it wet, dry, fouled, etc.. Is there even a spark?

if the spark plug looks like it did when you put the it in new and it's getting spark, then I would look at fuel, otherwise, check your electrical system.

I've cleaned all the jets and pulled the floats and cleaned the plungers as well. Both moved freely and everything seemed in proper operating condition, however my knowledge is limited.

I'll pull the front plug and check its condition and see if it is getting spark. I am comfortable with working out basic issues and am hopeful this is not a major one. There is a shop I have worked with before, so I am going to call them and find out about their knowledge of two strokes.

Thanks for the replies, it will be Tuesday before the shop opens so keep the thoughts going and I'll look into everything I can between now and then.

Open up the manual that came with the bike... Bunch of sections on trouble shooting carburetor/electrical issues.

Try fresh plugs (again). If the bike ran with stale fuel, you would have fuel fouled your plugs and that may be causing your issues.

So I tested the spark from the spark plug wires and got a strong blue spark. I pulled the front plug and noticed it was wet and smelled of gas. I cleaned and replaced it. When I started the bike again it was running on both cylinders, within 30 seconds the idle dropped and it sounded like it was back on running on one cylinder. I repeated this several times, cleaning the plug in between each try and finding fuel on the plug each time.

What does it mean when the plug has fuel on it?

It's not sparking or there is too much fuel. Check your float height, your jets are in properly and have correct jetting for your settings. Try swapping plugs or a new plug.

Give the float valve seats a clean with a Q-tip in a power drill and some brasso, does wonders!
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it wouldn't be fun if it was easy!

nxrsr20 wrote:It's not sparking or there is too much fuel. Check your float height, your jets are in properly and have correct jetting for your settings. Try swapping plugs or a new plug.

+1 Most probably the float height or seal, on the front cylinder carby. Need to watch this as it most probably means that you are leaking fuel into the front cylinders crank case. This can cause hydro locking if you leave the tap on for an extended period of time...

check the carb air solenoid valves and the carb breathers to make sure that there is not a blockage somewhere

Thanks everyone for the imput. I will be loading her up tomorrow and taking her to the shop. I will be handing of the manuel and showing him this thread so he can view all of your responses.

Thanks again averyone and I'll keep you guys updated as to what the problem is and will get some pictures of her up when she's all back together and running like a champ

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it wouldn't be fun if it was easy!