Name that miss! (250R) Part 2

[RUNMYTA]

I am about to lose my mind!! The problem: My 89 R has a highend miss that only happens at WOT at the top of each gear. I have replaced rad valve, intake boots, cleaned carb and checked the jetting.. So that should eliminate the fuel system.
Electrical: I have replaced coil, CDI, and stator. Plus I double checked the ground.
Symptoms: After warm up at WOT at the top of each gear bike pops and feels like it is firing every other rotation. Most of the time I can put in a new plug (B8ES) and it will run perfect for 5-10 minutes then starts again!!

Here is my mods: 1989 250R
Stock cylinder, resleeved 1st bore, no porting
ESR TR6 pipe and silencer
38mm PWK 160 main 50 pilot at 1500ft above sea level
Stock air box with lid and foam filter

I will send the person that solves this miss $25.00!!
PLEASE HELP!! MIKE

[Guy400]

Have you replaced the spark plug wire or at least Ohm'd it out to make sure the plug wire is good? I'm not sure what the resistance is supposed to be. Check macdizzy.com for the plug wire specs.

BTW, help here is free. No need to pay anyone:)

[4TraxRider]

It could be your rev limiter, but i doubt it. You could play with teh jetting a little to trya nd make it pull longer.

[powerslider]

What are you gapping the plug at? Try it at .018 , what does the plug look like after wot plug chops, you may be large on the main jet for your setup. The pipe you have is not a top end pipe, are you trying to over rev to much, short shift it and stay in the powerband. What is the compression, what fuel (octane) are you running????

[Fleshwound]

that sounds like your main jet...

[beerock]

check your ground..(I know you said you did this)

you may want to check the ohm's of the stator as well. it may be bad. I think its suppose to be .4 ohms.im nto sure on this.

were the wires to the cdi ever cut?

check the wires to see they are spliced well.

we replaced the stator on my friends bike and it turns out the stator we replaced it with was bad and the other was fine.(so it masked the problem)

what size jet are you running.

what does the plug look like?

[Ralph]

this is probably a dumb thing but make sure your ground is on bare metal on the frame or wherever it is. check the plug gaping, make sure there is no air leaks on the carb or boot or anything, check ur reeds,

[airheadedduner]

Check your spark plug wire too, make sure its not broken on the inside. I broke mine once and at high RPM it would miss. It got worse and worse till it wouldn't run at all.

[RUNMYTA]

Thanks for all the help guys.

It had to be one of these two things!!
I replaced the coil with a "supposedly" good used one. Well my riding buddy just bought a NEW coil and wire so I put it on my bike. While I had the R warming up idleing it suddenly reved to the moon like it was running out of fuel. So I killed it and pulled the fuel line loose from the petcock and no fuel was coming out (had half a tank of fuel)!!! So I cleaned the petcock and ran it and now it runs perfectly!

So either it was starving for fuel or I had a bad coil??

Thanks for the help!!!! MIKE

[phatswinn]

probably the coil or the fuel lines

glad ya found ur prollem