HELP- bogging engine

[Pwgsx]

ok, I have a kdx200 engine in a kx125 frame. It ran great untill the engine went out and I had it rebuilt. The shop did a great job and everything was fine until a few months ago. I would start it up with 3 kicks and run it for about 5 min. and then it would BOG DOWN. I replaced the plug and checked every little detail but it still is bogging down. I brought it to a repair guy and he tested it and said the stator was bad so we replaced it and it seemed to be fixed and ran fine. A few months later it is doing the same thing. Does anyone have any ideas of what it causing this???? It runs fine cold and about 5 min of riding it boggs down when you give it throttle.
Thanks

 

[m0rie]

Cdi?

 

[Pwgsx]

I was thining of that but didnt want to drop $200 if I wasnt sure.

 

[m0rie]

Try and pick one up off Y-A-B-E. They show up pretty often. I think there might even be a whole ignition system up right now.

-Maurice

 

[John Harris]

Borrow one from someone else who has the same model KDX and try it on your bike to be sure that is the problem before you jump into buying a replacement. Or maybe you would not mind having a spare anyway. Cheers John

 

[nickyd]

bad ground near stator? check your grounds.

 

[BJH]

I had the same gremlin. The CDI may be the most likely culprit but check your carb float level too.

 

[nickyd]

BJH - what did your bike do? Mine just won't come on the pipe and makes mythotically misses - almost like I was blipping the clutch - I checked KIPS/Jetting/Plug/CDI. Tonight I am pulling flywheel....I have a buddy's spare bike so I might be swapping out stators to see if that is the culprit....its really pissing me off

 

[cicone]

BJH - what did your bike do? Mine just won't come on the pipe and makes mythotically misses - almost like I was blipping the clutch - I checked KIPS/Jetting/Plug/CDI. Tonight I am pulling flywheel....I have a buddy's spare bike so I might be swapping out stators to see if that is the culprit....its really pissing me off

Bingo---That's exactly what mine did when the stator coil bit the dust. Bike runs, but breaks up at high rpm---just doesn't want to catch. Assuming that the jetting is good and it ran like a champ before, that would be my first guess. You can test resistance for the stator by removing the fuel tank and DISCONNECTING the two leads that go to the stator----white/red stripe and black. Often you will get a reading within spec because the device may only malfunction as it heats up. Could still be bad. As for the prior posts---ditto, check all connections and grounds. If that's not it---probably the CDI. Most have told me that the primary coil rarely goes bad. Good luck.

 

[nickyd]

Bingo---That's exactly what mine did when the stator coil bit the dust. Bike runs, but breaks up at high rpm---just doesn't want to catch. Assuming that the jetting is good and it ran like a champ before, that would be my first guess.

FINALLY!!! someone that brings something to the table other than "repack your silencer" or "your jetting is wrong"...or "KIPS".......thanks cicone, I'm pulling it today - now I just need to find a way out of work early so I can get to it....

 

[cicone]

If it is a bad stator---I recently got a replacement that tested infinity(no circuit)---and it was brand new, some thoughts. My last one only lasted 6 months. I'm no electronics wizard, so someone correct me if I'm wrong, but since I now have a bad CDI, I wonder if the improper voltage control there can mess up a stator coil?? Maybe?? Also, make sure your grounds are good. While you're in there, remove the stator plate and make sure the contact points to the crankcase are nice and clean. Be sure to tighten the screws holding the plate on firmly---I use an impact driver because it's easy to bugger up a phillips head by being too aggressive w/a screwdriver. Remember when testing the coil it must be removed from the circuit i.e. at the wire ends with them disconnected or your reading will be faulty. FWIW, when my cdi went the symptoms were very different. It ran great and then it was like someone hit the kill switch---not breaking up at high rpm, but flat out dying. Started a couple of times after that but only ran about 30 seconds. Now it won't start, period. Keep us posted.

 

[Pwgsx]

well for now we put in a stator from another bike and it is still boggy when it hits the mid to high rpms. I am trying to get a CDI box from somone so I can check that next. the carbs and everythign else seem to be ok.

 

[cicone]

hmmmmm???

 

[skipro3]

Hey PWGSX, is this all on the same batch of gas? I ask because I once got a bad batch and didn't realize the problem until I ran through it and bought more. If you have'nt tried it, then try a fresh gas / oil mix. A long shot but at least it's a cheap test. BTW, drain and refill the bowl first. Sometimes contaminates like to hang out in the bowl long after the gas has been changed.

 

[Pwgsx]

yea i completley drained the tank and cleaned the carb at the same time. i even tried different oil. by the way, what brand do you recomend and oil/gas ratio??

 

[cicone]

did you check the ground where the primary coil attaches to the frame? if your friend has the same bike, try his cdi---easy to do. ordering parts for my cdi rebuild---having issues w/the diodes though---5 of them, but 3 different looks---no luck getting Jag's input. curious, reeds in good shape?

 

[Pwgsx]

yepp

 

[nickyd]

mine is fixed now....believe it or not I replaced the silencer with the stock unit and she rips wheelies in 3rd gear now......thought for sure it was electrical but as it turns out it was not.....

 

[cicone]

That's why we always start with the simple stuff. I and many others have posted here about a loss of top end from clogged silencers---my mistake to assume that your troubleshooting had progressed to the point of electrical issues, as all else was eliminated already. Like you said to all those repack your silencer folks----repack your silencer!!!
Sorry for the misunderstanding and glad you figured it out!!. :yeehaw: Oh yeah----check your jetting!!! :laugh:

 

[KAY DEE EXER]

FINALLY!!! someone that brings something to the table other than "repack your silencer"

mine is fixed now....believe it or not I replaced the silencer with the stock unit and she rips wheelies in 3rd gear now......

:rotfl: LMAO... Glad to hear you fixed it... :cool:

 

[nickyd]

SONOFA!!! no one was supposed to notice that!!!!!!

 

[Pwgsx]

I wish that was the case considering I just got a new power core silencer but this was going on before I installed that. :bang: