07 JCL 250A Carb Problem By tapntx (Read 7,478 times)

[tapntx]

I am normally pretty good at Carb issues. I have rebuilt many inline 4 carbs lately. And this Scooter carb has me confused.

I bought this scooter used, and the Air box was missing and a uni filter was in its place. I see some vacuum hoses that are plugged. but over all it seems to run ok. I have tried spraying carb cleaner around everything to see if it changes the rpm and nothing. I even slipped an old sock over the UNI filter to see if I could restrict the air flow a little to get more fuel in the Mid- to WOT to get a little color in that plug to no avail. I did remove the carb, and thoroughly cleaned it like I do all of my inline 4 carbs. Removing all of the jets, slide, Needle, needle jet, and run Carb cleaner through it all.

Here is my problem, the bike runs ok for what it is. But when it is idling and I am letting it down from my lift, just the slight shaking causes the motor to die. I can just jar the bike and it dies. It is definitely a fuel related issue. It is like it takes a big gulp of fuel and dies. The other issue is I cannot get the plug not to be glowing white. I went up on the main jet up to 145 and it is still perfect white. When I am riding it the only time it will die if I am stopping quickly and hard on the brakes. Otherwise it seems to run ok.

Any ideas would be greatly appreciated.

BTW this is the Linhai 257cc engine, not sure of the Carb model, but I am assuming standard for the year model and engine.

Settings are Pilot jet 38, Main jet 130 (was 115) Plug NGK DPR8EA-9 2.5 turns on the Air/Fuel screw UNI Long Air Filter Float Height 19mm Electric Fuel pump.

Thanks,
Todd

[Alleyoop]

I was going to say your fuel bowl is not filling up, and need to adjust your Float to allow more fuel in the bowl. But you already have checked the float. So now it may be electrical and something is moving and making it cut out. So check the two wires going to your COIL from your CDI. they may be loose and or may be touching each other when moved.
Alleyoop

[tapntx]

All good on the coil wires I checked those just to be sure earlier. It does not seem to be electrical, it is like it just starts to hesitate. Also when trying to adjust the Fuel air screw I rotated the carb to get to it from the right of the bike, and it died. I turned it back to the Left and it was fine. If the Carb is Level or tilted to the Left it will run fine, if it leans to the right or is shaken the least little bit it will die but only while idling. When I am riding it, it never misses a beat other than trying to die when stopping.

Thanks for the help!!!

Todd

[Alleyoop]

Tapntx,
You know what I think the problem is, it is that your Bowl Is Not Filling up to the level it should be. Take the Bowl Off and bend the little tab out toward you a little bit(YELLOW ARROW). I think it is shutting the fuel off to soon. And now that you mentioned that you turned the carb and it died that means that the fuel was not covering the Pilot Jet which is lower than the Main Jet.
here is a picture of the bottom of the carb and notice where the Pilot jet is it is off center of the carb(GREEN ARROW). So when you turned it part way sideways the fuel could not be sucked up by the pilot jet.
Alleyoop

[tapntx]

Mar 1, 2011 23:46:59 GMT -6 Alleyoop said:

Tapntx,
You know what I think the problem is, it is that your Bowl Is Not Filling up to the level it should be. Take the Bowl Off and bend the little tab out toward you a little bit(YELLOW ARROW). I think it is shutting the fuel off to soon. And now that you mentioned that you turned the carb and it died that means that the fuel was not covering the Pilot Jet which is lower than the Main Jet.
here is a picture of the bottom of the carb and notice where the Pilot jet is it is off center of the carb(GREEN ARROW). So when you turned it part way sideways the fuel could not be sucked up by the pilot jet.
Alleyoop

I will check this again, but I even re-set the float height to about 15 mm thinking the same thing with actually worse results. So it is back to the 19.

jrryan,

I will check them today, I was not able to yesterday because of running the bike. The scooter has about 4200 miles on it.

BTW here is a pic of the Plug with a 145 Main jet in it. The bike seems to run better after warming up, but I still feel like there is room for improvement.


Thanks,
Todd

[tapntx]

UPDATE,

I checked the valves and as I suspected all were in spec, .004 on the Intake and .006 on the Exhaust. I reset the Float level to 17 mm and still does the same thing. Just the slightest jar causes it to die. It just starts to sputter then dies. If I rotate the Carb (top to the Right) it will run, If I rotate the other way it dies.

Any other ideas, I still have not addressed the WHITE plug issue yet

Thanks for all the ideas.

Todd

[Alleyoop]

Tapntx,
Take a picture of the top of the carb if you can, Can it be that the wires from the ENRICHER are being pinched and shorting it out or something when you turn it that way.
Alleyoop

[jhbietz]

You may want to consider soaking the carb for 24 hours in carb cleaner. You can get it at most auto parts stores. Comes in a paint can with a basket to put the parts in. I think the last one I bought was around 15 bucks. That was the only thing that got the carbs on my CBR to finally work. Be sure to remove all the rubber parts before you soak it.

[tapntx]

Mar 2, 2011 13:49:14 GMT -6 Alleyoop said:

Tapntx,
Take a picture of the top of the carb if you can, Can it be that the wires from the ENRICHER are being pinched and shorting it out or something when you turn it that way.
Alleyoop

no pinched wires, Also the enricher does not seem to make a difference either way, since it is about 70 degrees here in Dallas, TX.

I did however get the shake and stop to quit. I closed the Fuel air screw to about 1/2 turn and lowered the needle to the top clip position. As I figured it was getting too much fuel on the low side, but is still too lean on the top end.

Todd

[tapntx]

Mar 2, 2011 14:31:57 GMT -6 jhbietz said:

You may want to consider soaking the carb for 24 hours in carb cleaner. You can get it at most auto parts stores. Comes in a paint can with a basket to put the parts in. I think the last one I bought was around 15 bucks. That was the only thing that got the carbs on my CBR to finally work. Be sure to remove all the rubber parts before you soak it.

I have cleaned a lot of carbs in my days the last one a 1983 CB650 set of 4, and that bike runs perfectly. I know to remove all jets and I spray cleaner through every orifice as well as Visual inspection. The carb was not dirty at all, and I cannot see any trash in the bowl. I am not sure but I think it is a different issue. I even put a Latex glove covering 75% of the Long Uni filter and still white as a sheet. The funny thing is you would think it would miss or bog down, no noticeable change and throttle response. It does not seem to be getting hot either.

Thanks for the info I will check the carb again I have had it apart at least 10 times I swear the inline 4 bikes are way easier to work on....lol

[jhbietz]

Like you I have cleaned many carbs over the years. I hate to admit it but I did have one on a 50cc that I could never get to work. I went through that stupid thing a dozen times to no avail. Finally out of desperation I bought a new one. Put it on, adjusted the mixture, set the idle and its run perfectly ever since.

[tapntx]

Ok, I thought I had solved my problem of it dying while just bumping it. It seems like it only happens when it is cooled off for a few minutes. I was playing around with it earlier riding it around the block several times, and stopped for a bit. Went to fire it up and same ol thing.

If the bike gets warm enough for the fan to come on, it will run perfect. Cant make it die shaking it. But if it cools down no matter what I do it will die when it is leaned over on the side stand or just a very tiny jar.

This is really strange!!!

Todd

[tapntx]

Yes, just as in the Diagram. I have adjusted many in my 50 years on this earth....... ;D

I spend a lot of time in AR street riding as well as Dirt. I love AR wish I could convince the SO to move there.

I actually bought 2 DPR7EA-9 this past weekend, and tried one, but thought the bike may be running too hot with them. But I am not getting better results with the DPR8EA-9 I just cant seem to get any color on the plug at all. I am running a #130 Main with a #38 Pilot jet. Needle in the Richest position with the Air/Fuel open to 1/2 to 2 1/2 does not seem to matter much. I wish I had the stock air box I could put it all back to normal and see if it would work right. I did try putting a Latex glove over 75% of the Long Uni Filter and it did not make any difference.

I may try that DPR7EA again for kicks. The strange thing is you would think as lean as it is running It would begin to miss back fire or just run crappy, but I do no notice anything of the sort. In fact the hotter it gets the better it seems to run. Seems to run the best after the fan has come on at least once.


Thanks for the great tips!!!

Todd

[tapntx]

Ok, just tried the DPR7EA-9 and the same thing, the bike has cooled for a few minutes and it is hard to start, and the slightest movement will make it die. Once it warms up, it will start easily and you cant make it die by shaking it.

Todd

[zugzug]

Sounds like the fuel pump to me.