86 250r dies after running 2-3 minutes!!! HELP!

[Taiser]

Posted this in another forum but this one has more traffic and hopefully more ideas! :(

Here's my original post and the follow up from the other forum...

Post #1

OK. Finally got my rebuild of an 86 250r going. All the parts are from e-bay...I mean every nut, bolt, plastic and part was bought there because these machines are IMPOSSIBLE to find up here. The engine is new (less than 10 hours), carb is BRAND NEW and so is the intake boot. Had a few problems at first (resolved) now a new one has cropped up...

The carb is a BRAND NEW 39mm Keihin striker carb. The bike fired up on the first few kicks and I was able to ride it for about 10-15 minutes with no problems. The idle finally works good (1400 rpm) but I have to screw in the idle screw almost all the way in for it to run smooth but I'm assuming all I need is a bigger jet, which I will look into later on. I'm at 800 feet ASL so I'd assume the stock jet would have been fine. She's also a bit harder to start than I like...takes 6-7 kicks, jet problem again (too small) I'm guessing?

Any hoo the last few times I've started it up to adust the idle it runs fine for about 3-4 minutes then just DIES like it's out of gas. Hitting the throttle does nothing just before it dies but when I first start it and hit the gas it reves fine. It's like somebody turned off the fuel and once the gas in the carb is gone it just quits!!! Remember the carb is BRAND NEW. I checked the spark after it dies and it's fires fine.

Trying to start it after it dies is useless but wait an hour and it's ok. Fuel is new too. I'm figuring this has to be fuel related but why would it run ok the first day I got it going (except for the idle)? I'm going to pop the fuel line off and check the fuel flow later today but it does the same thing if it's on main or reserve. Anything in the carb that might cause this? Thinking a stuck float needle but again IT'S BRAND #$%^&* NEW!!!! I really don't want to tear a new carb apart unless I have to!!

Any comments or ideas on what else might have been missed?



Thanks guys.


#2

OK I'm ready to SNAP!!!!

Came home from work and took another boo at it...again if fired up then just stopped running after about 3 minutes...while it's running everything is fine, throttle response etc all fine. I checked the gas cap and vent tube...no problem, checked the fuel flow on both main and reserve that's fine, checked all the vent lines to the carb (2 of them, one on each side) and air goes through no problem. Can't check the overflow because it's on the muffler side, but when I calm down a bit, I will, but again THIS IS A NEW CARB!!! WTF??? The whole reason I got a new carb was to avoid these #$%^&* problems! I KNOW it's running out of gas just by the sound of it when it dies. I'm thinking of popping off the carb and checking to see if the overflow works then even opening it up, but there should be no reason... especially when it ran fine when I first put it on!!!

Any ideas??? Getting desperate and pissed here!!!

[factoryX]

I had the same problem, ran fine but as soon as got warmed up it died, it was the spark plug for me, try buying a new spark plug brushing it does not always work.

You may have just burnt the plug thats all...

[factoryX]

also it was fine on idle but if I gave it gas it did the same thing.

[Taiser]

Plug is new, spark is good and strong :( It's not getting time to warm up, 2-3 minutes and dies, that's from a cold start :cry:

[factoryX]

what color is it?... running an airfilter? try running it with out? could be just to much air getting in there. idk at this point.

[factoryX]

http://3wheelerworldforums.com/showthread.php?t=13242&highlight=250r+fuel+problem This as close as I could find....

[smvorndran]

Sometimes the exciter/pickup coil on the stator plate will go bad. It's essentially a crank position sensor that tells it when to fire. They sometimes crack, and will only work while they're cool. You may still have spark, but it may give an incorrect reading, and it could be firing out of time. Just a thought. I had a Hodaka dirt bike that did that.

smvorndran

[Erics350x]

Pull the fuel line and let the gas run in a can for a few seconds to see if the petcock or tank cap is clogged. If not pull the carb and check out the float and needle.

[Macs]

Have you tried flipping on the choke when it tries to die? It sounds like your float level might be too low or a problem with the needle valve. Right when it dies open up the float overflow and see what you get out of it. If everything is right there then i would look for a clog downstream. If you find nothing there then it will be on to plan B.


New parts can still have problems. Especially a carb that might have been sitting on a shelf for the last 20 years.

[Taiser]

Electronincs are new, stator is original but the motor has less than 10 hours on it, never been opened. I just ordered a complete new harness (wires, coils, rectifier etc) just in case though.

Already pulled the fuel llines and checked the flow to the carb, all was fine. Air filter is new and clean (why would it run fine for a few minutes then die due to the air filter???), choke does nothing when I pull it. I'm 99.9% sure the float bowl is running dry, but why did it work fine at first? I'm gonna pull the carb tonight and take a peak inside because that's gotta be it. I may try leaving the carb all attached and just poping it off the intake and hopefully the overflow has a screw, I'll check and see if the gas starts gurgling. Maybe a piece of crud got in there, but I don't see how, I took out the petcock when I got the tank and cleaned everything...this is just weird. I'll let you guys know, and maybe post pictures. Anybody got the specs on a Kiehin 39mm striker carb? :D

[Macs]

That is what i am betting. Maybe a piece of shipping material got caught up in it.

[johnny's X]

I had the same problem with my X. I tried everything. After alot of frustrating hours I looked at the fuel line and it was a bit to long and it was holding in a pocket of air. The air was holding back the fuel from entering the carb. I cut the hose shorter and the problem was solved. Try it out and see if it works

[Blown 331]

I had the same problem with my X. I tried everything. After alot of frustrating hours I looked at the fuel line and it was a bit to long and it was holding in a pocket of air. The air was holding back the fuel from entering the carb. I cut the hose shorter and the problem was solved. Try it out and see if it works

Damn, I never thought of that, I think I might have that problem on my first ATC70.

[Taiser]

Damn, I never thought of that, I think I might have that problem on my first ATC70.

Thought of that already, the original line went down a bit in front of the carb (kinda like a smooth drain trap), nothing excessive cut it shorter anyways, now it's straight to the carb...no joy! :(

Gotta be the carb bowl running dry!!!! I remember my old honda 200 would go quite a ways with the gas cap vent turned off, and I remember it would go a bit as well with the petcock left accidently off, any idea how long a 250r will run with just the fuel in the carb bowl?? It's dying on me in about 2-3 minutes just idling with a few revs added in...sound about right? When it dies it's not a clean kill like turning off the ignition, it sounds just like it runs out of gas!!! #$%^&* :mad:

[DeePa]

you fuel bowl isnt filling back up. it sits for a while, fills up, runs, dies, and then takes a while to fill back up.

pull the carb apart, try a different carb, all that jazz

if fuel does in fact run out nice from the petcock, it has to be your float needle

[Mosh]

I could be way off base here,But Doesnt a 250r Rev to the moon as they run out of gas?

If yours is just idleling and just stops,I would think maybe electrical.

Most 250R's I have seen the idle goes up to around 4000 Rpm,then die out as they starve for fuel.

[Taiser]

My first 2 banger trike so I don't know. I never ran out of fuel when I had my YZ because I'm anal about that so I don't know. Thought about the electrical and got a whole new wiring set up coming just in case. But again it ran fine at first then this just started after I played with the needle settings, which really has nothing to do with the idle. I just video'd what's going on, will put it on you tube and add a link later, you guys can hear what's going on.

[Taiser]

Well it didn't even make it to a few minutes this time...maybe 30 seconds. I didn't have a chance to check the carb out yet. Here's a youtube video of what it's doing.

http://www.youtube.com/watch?v=Z-fs7L1w1QI

[ChrisD]

hmmmm

Let's be systematic. Do you have a timing light and a battery nearby?

I saw that you turned off the choke. Why don't you try to see how long it will run with the choke on. Maybe we can determine if the fuel issue is really the problem. I would try to keep the bike running by moderating the choke on and off. It sounds like your bike is REALLY loaded up too.

At the same time, I would hook a timing light to the plug wire and have someone hold the trigger (or tape it) You would like to see that the light keep flashing without interruption. It really does not sound like an ignition problem though.

I see you are running your airbox lid. After I put a 39 PWK on my 85R, everytime I put the airbox lid on, the bike ran like crap. Try taking off the lid and see how it runs. THere is a possibility that it is restricting the air flow, flooding out the motor and fouling the plug.

Try that and post again.

[Andrew_250R]

I am having similar issues with mine. Mine just won't idle. Yours looks like it is loading up pretty bad. Have you pulled the plug after it died. Is it wet? Do you have air/fuel mixture screw adjusted? I ran mine out of gas once and it just started to rev like nuts. I didn't think it was running out of gas because it reved so high. But once I turned it to reserve it started to run fine again.

[ChrisD]

Andrew...do you run a stock carb or aftermarket? My 86R would not idle until I changed the pilot jet.

I do love the Keihin carbs, but to get them working fully you have to work with the pilot jet, the taper and width of the needle, the clip position and the main jet.

[DeePa]

i would pull the 17mm plug on the bottom of the carb, let the fuel drain out, then turn the petcock on and see if fuel flows out fine.

IF it does, it sounds to me like youre actually lean. The bike doesnt return to idle fast at all...maybe its because of your idle screw being adjusted to the highest setting.

What are you running for jets?

Can you get a picture of the plug right after it dies?

Mike

[DeePa]

And when 2 strokes run out of gas, they have to be hot to rev to the moon...also called dieseling i think...the heat of the plug acts as spark even though the ignition switch is off...really scary when it happens...

If the motor is dead cold, its not going to diesel and rev to the moon

[Andrew_250R]

Andrew...do you run a stock carb or aftermarket? My 86R would not idle until I changed the pilot jet.

I do love the Keihin carbs, but to get them working fully you have to work with the pilot jet, the taper and width of the needle, the clip position and the main jet.

Here is a link to my thread

http://www.3wheelerworldforums.com/showthread.php?p=649600&posted=1#post649600

[Yamatrike400]

And when 2 strokes run out of gas, they have to be hot to rev to the moon...also called dieseling i think...the heat of the plug acts as spark even though the ignition switch is off...really scary when it happens...

If the motor is dead cold, its not going to diesel and rev to the moon

Yeah it is scary, i was going WOT down a road and i let off the throttle but it kept going at full throttle, i hit the kill and it was still dieseling..it did eventually stall though from braking.

[Taiser]

"I saw that you turned off the choke. Why don't you try to see how long it will run with the choke on. Maybe we can determine if the fuel issue is really the problem. I would try to keep the bike running by moderating the choke on and off. It sounds like your bike is REALLY loaded up too."

Yeah I have played with the choke before on other tries it does the same thing, still dies! :(

Don't have a timing light, but like I said when I first put it together it ran fine for a few runs, at least 15 minutes each, except it would have trouble idling? 99% sure it's not the timing but I have a whole new wiring harness and electronics coming, coil, rectifier, cdi etc just in case and will trow those on if I can't solve this by playing with the fuel.

Air mixture is set at two turns out, but I have played with it from 1/2 turn to 3 turns out. Where it's set at now sounds the healthiest. I will try taking the airbox lid off and see what happens but if it's that simple I'll shoot myself. Maybe it is fllooding???

Needle is set right now at one stop above middle so it's running rich, that's probably why it's loading up when revved. It did not do that on the middle setting before, but I'm experimenting, I'll be putting it back to standard.

Yeah I was guessing that it was not revving because the engine does not get hot enough to diesel it.

Fuel mix was at half a tank 20:1 but I topped it off now with 32:1

Running jet that came with carb suppose to be good for my altitude. I will try taking the plug out the bottom of the carb and see what's up. If fuel is jaming up I'll take the carb apart, I'll post a pic of the plug tomorrow after running it again. I will probably order a larger jet because I have to have the idle screw all the way in just to idle :(

I'm going on fly-in fishing trip on Saturday, coming back on Friday :D so I may not be able to get everything done but I'll check what I can tomorrow after work and post back up! I'll post pics of the fish I catch next week too! :w00t:

Really appreciate the help guys!:beer

[WaimakRydah]

is your fuel tank getting air into it. My 200s used to die after afew minutes then i found out that the air vent switch on the tank lid was switched off. I think 250Rs dont have the switch and are vented via tube.

[threewheelin-feelin]

have you tryed pouring some gas directly in the cylinder after it dies to see if it fires up then? if it does then my guess is float, needle and seat issues causeing it to run dry

[factoryX]

when you give it gas it bogs alittle.... sounds like a fuel or air problem.

[roger86200x]

Pour gas mixture in the carb's air inlet when its about to die and seee if it runs...

get a spray bottle and spray it in..... thats easiest


Change the plug too.... even if its new it could have a problem..... is it a resistor type plug? (Does it have an R in the plug number (ngk does if resistor anyways))

The resistor in the plug could be bad ... it heats up after sparking a few times and could be cutting off or limiting spark... I know you said you think its fuel but if you try what I said above and it doesnt run than Id try a new plug.

The BEST thing to try is putting the gas in the carb like I said and it should run forever like that as long as you keep spraying it in....

Roger

[Dammit!]

Real hard to tell from the video but, is your spark plug cap on all the way? It doesn't look like it. Did you take the little round cap off the new plug when you put it in because if that's a stock R plug cap, it's not designed to use that piece that comes on the plug itself. It goes right onto the screw portion underneath.

[Tri-Z Pilot]

dieseling is when the combustion chamber is hot enough to sustain continual combustion even though the ignition system is off. this often happens when the motor overheats from a lean condition. dieseling can also occur from incorrect ignition timing, but when that is the case after the igntion circuit is cut (or in this case lead to ground) the motor just barely keeps itself running before it die, while the overheated type usually has a high eratic rpm range.
when motors rev high when they are running out of fuel its because they are starting to run lean due to the decreased fuel amount.
if i were you i would buy a new plug i have bought new ones that were junk,and after it dies feed some fuel or ether down the spark plug hole then try and start. if it fires, voila! fuel problem. if not, most likely electrical.
well hope that helps

[Texas 200x]

Make sure your not kinking the fuel line in anyway when its hooked up. Try running it till it dies and shut off the petcock when it dies. Then you can open your fuel drain on the bottom of the carb and see how much fuel is in the bowl. It seems like the fuel is getting restricted. Take the gas cap off and run it you know it is venting plenty then.

[Twilight]

Real hard to tell from the video but, is your spark plug cap on all the way? It doesn't look like it. Did you take the little round cap off the new plug when you put it in because if that's a stock R plug cap, it's not designed to use that piece that comes on the plug itself. It goes right onto the screw portion underneath.

I have done this and had the same problem, it would rev right off the plug!

[Taiser]

SOLVED

Thanks for all the advice guys BUT you are not going to believe this...

After busting my brains on this thing and being gone fishing for a week I came back and took another look at it. I took the jet plug off the bottom and fuel flowed fine. Spark is ok blah blah blah. Had to be something so I started taking the thing apart again and there she was....

the cable tube that goes into the carb was not sitting inside the carb cap. It had somehow got caught on the edge lip area of the carb cap! I'd assume it would just rev like mad like that but it was obviously the problem. :crazy:

Don't know what was going on but once it got inserted the tube in she fired up and went right into an idle just fine. Saddest reason I've ever seen for problems! She runs fine as long as I need BUT now have another problem...hopefully simpler to fix...

After running and then turned off, she's hard, if not impossible to start back up. Anybody know why that would be? I'm thinking a weak spark, even if it seems ok. I do have an entire electrical system still coming and will be replacing it, but why would it be fine until shut off? Ideas.

[Mosh]

My friends R was hard to start,like that after it was shut off.

He pulled the stator cover and found the flywheel rusty and pick-up rusty.
He cleaned them off with steel wool,and adjusted the gap at the pick-up to .017" and has been fine ever since.

[Taiser]

Hmmm since my motor has been sitting for 20 years that may be worth looking into...thanks! :D