Need help with mid to high range misfire!

[McQuade]

Hi all, I have an 85 200m I purchased with a donor bike. The donar ran great but no brakes or plastic. The other bike would start but not run past idle, and was leaking oil so I replaced the engine, coil, battery and carb from the running doner bike. I'm STILL having the same issue. Starts first pull with no choke idles perfect. Touch the gas slow and it will begin to climb rpm then about mid range it sputters and zero power. Won't move the bike. Hit it fast and it stalls. I've cleaned the carb to immaculate shape, new fuel and lines. Plugs good. The only thing that I didn't swap from the other frame was the little black box that has a connector with five or six wires. Could this be it? It has a different harness is why I havnt as the donor was an 84 and the plugs are different. Any help?

[cap]

That black box is the CDI.
Did you replace the whole carb or did you leave the slide attached the throttle cable and screw it onto the new carb? That slide is where the needle valve sits in the bottom and it may be too lean. Move the clip down on the end of the needle to raise it up a notch.

[McQuade]

I tried both cables/slides. The CDI box is literally the only thing I've not swapped.

[cap]

Possible, might be able to swap plugs so as to use the doner bike cdi

[McQuade]

That was my last resort, only because I wasn't sure if splicing would alter resistance through the wires. I will try that. I guess I was only curious if a CDI could cause this. I'm a cert. diesel tech, not familiar with capacitor discharge systems. My camaro has one but it's integrated, and never had to replace it. Thanks CAP. I appreciate it.

[McQuade]

Okay so I replaced the cdi. No difference. I put it in gear and it won't move nothing. It isn't running well but it revs high enough it should at least catch a little... I'm at a complete loss on this one. Any help would be appreciated

[atc007]

If you are absolutely sure your carb IS spotless . It will be spark. Ohm out your stator . There are manuals on here and the internet, free. You can pop the recoil and flywheel off and clean the stator,flywheel for piece of mind. Also your advancer under the CDI cover ob your cam is likely rusty/dirty/possibly broken springs/not advancing. This should have her purring. Complete flush and service, Adjust your valves and timing chain ,and she'll be like new.

[cap]

You said it ran good on the donor bike? Do you have good fuel flow from the tank? Tank cap vent open?
It sure sound like the main jet is plugged up, you should be able to blow or spray through both jets from one end to the other and the small ports around the end should be clear.

[atc007]

Good eye cap. I agree. Man,, I have found myself simply skipping through posts lately and only picking up half of what is there. Not cool! But if it was the tank,it should run like a champ for a minute,then starve.

[McQuade]

Tank flow is great. I've cleaned the jets four times today. Still nothing. Idles perfect. Mid to high is "bubbly" and inconsistent. But you can rev it up to half and it will run great, it points to the needle valve, but I'm seeing nothing wrong. It ran on the other frame perfectly that same day

[McQuade]

Would a bad ground do this?

[cap]

Bad ground will cause a weak spark, wire brush the coil mounts to clean it up.
More things to check,
airflow- pull the air cleaner and run it up, bees nest in the air tube maybe.
Is the thumb on/off switch jiggling around.
Spark advance springs under the CDI cap.

[McQuade]

Checked, and cleaned. No difference. I can see the springs move out and they are free moving. It runs with the choke fully on. Not well, but it does quieter.. Hmm

[DohcBikes]

Valve adjustment, check it cold at tdcc.

Now that I see you changed the whole engine, i'm leaning away from this suggestion, still worth a look.

So many times i wish i could teleport. If I were standing there i could fix it LOL...

[danbur55]

Bad ground will cause a weak spark, wire brush the coil mounts to clean it up.
More things to check,
airflow- pull the air cleaner and run it up, bees nest in the air tube maybe.
Is the thumb on/off switch jiggling around.
Spark advance springs under the CDI cap.

Lift the airbox lid had same thing on 82 200e was dirt dauber nest at top of backbone