Breaking up over idle

[kpnone]

I have an air cooled '08 DRX90. The engine is breaking up anywhere above idle. I checked everything I could think of including removing the cylinder, swapping CDI and coil, inspecting carburator, checked all wiring, cleaned stator and pickup. It seems, to me, to be an electrical problem since nothing else seems to be wrong. I don't have an electrical harness (no battery) and all connections are soldered. I attempted to check the output on my stator, but couldn't get a good reading. I was told that running without a battery could damage the stator. Is this true? Does anyone have any ideas or could you tell me how to check the stator output? Thanks for any help.

[riding4fun]

Did you try a new spark plug?

[mydirtkids]

I was under the assumption the stator is fine if you are not pulling a load (headlights etc). I have not had any problems running this way on our bikes since I removed the electrical. Coil go bad? Plug? Fuel filter and lines good?

So far your symptoms could be stator, these things do go bad. I just replaced one on our trail bike. Seems though starting also is pretty difficult when ours went bad (both times).

I have also had rollers (in the variator) flatten out after ONE practice causing bogging when trying to rev. This kinda sounds like it is cutting out when really it is not ignition related at all. It does not cost a nickle to check this if you have some tools.

Coil go bad? Plug? Fuel filter and lines good?

[fomospede]

i would definitley take the clutch apart and inspect it very well if it is engaging to early (soft or broken spring) it will sound as if
it has other issues!
We just went thru this and now know that these are finicky machines that can fly when well tuned;)
also you can download the service manual from drr.com its definetly not the best but it does help!

[stoneman]

my 2006 ac 90cc did samething.
It was a bad tether cord. Disconnect wires and runs fine now.

[jerkyboy]

Make sure you have a good ground, motor to frame. Some times when I change motors I forget to put the ground back on and soon as you hit the throtle it brakes up.

[kpnone]

Thanks for all the suggestions. We just got back from the track and we definately have a clutch problem now. Its not hard to start, so maybe not a stator?? I'll dig into the clutch and see what's going on. btw I just put a new belt and torque clutch on 2 days ago...

[kpnone]

OK. I took the clutch apart everything looked good. The weights looked kinda scuffed up (Dr Pulley sliders, not rollers). I replaced the Dr Pulley variator with my stock and 3.5g rollers, removed the pillow springs from the clutch and it's hitting pretty hard now. This would have probably saved us a DNF on the second moto today as it absolutely WOULD NOT get going out of the gate. It bogged badly on the first moto too, but after about 100 feet it finally hooked up and my son had to pass 5 other riders to win the moto.

Side note, I've been pretty happy with the Dr Pulley HIT clutch. It really does hit hard when the pillow spring are removed, but it seems to hang up (pads stay engaged) like this. I'd call it an acceptable trade off for the improved launch. The Dr Pulley variator on the other hand hasn't impressed me. Probably because I can't seem to get the tuning right on the sliders. Someone more experienced might not have these problems as this is our first year racing.

Finally, the engine is still breaking up. I did try another coil, I replace the plug before each race, my grounds are all clean and well connected. The engine is smoking as if rich (no the rings aren't bad) and the plug reads rich, but I'm running a 155 main right now vs the 158 that hasn't smoked all season. So, back to the drawing board any more suggestion are appreciated. Thank you.

[thequadfather+2]

remove the kill switch and see what happens. Your kill switch may be the culprit, probably one of the most common electrical problems.......

[Logan #34's Dad]

Originally posted by kpnone
OK. It bogged badly on the first moto too, but after about 100 feet it finally hooked up and my son had to pass 5 other riders to win the moto.

Side note, I've been pretty happy with the Dr Pulley HIT clutch. It really does hit hard when the pillow spring are removed, but it seems to hang up (pads stay engaged) like this. I'd call it an acceptable trade off for the improved launch. The Dr Pulley variator on the other hand hasn't impressed me. Probably because I can't seem to get the tuning right on the sliders. Someone more experienced might not have these problems as this is our first year racing.

As far as your bogg, I'd guess the rollers are too heavy or your spring is too weak. The Dr. Pulley variator will not act the same as the one you took out. One change affects everything. As said on here a hundred times. Adjust one thing at a time.
About the Hit Clutch, You really need the pillow springs. They will not affect the "hit". I use Green bigger springs with red pillow springs. Just fyi.

[jerkyboy]

You said you checked everything but you left out that you changed the variator. They clutch can make it sound like a carb or
electrical issue. I tried this on one of our motors and had no luck with it, seens to shift to fast. Try putting it back in and use lighter rollers.

[kpnone]

My rambling does make it sound like I changed a bunch of stuff, but I didn't mess with the clutch until after the breaking up problem and then a very obvious clutch problem during this weekends racing. I blew out a reed two weeks ago and wrongly assumed that if I replaced them I would be back at square-one. I'm starting to believe that I have several problems (incuding the clutch) contributing to one symptom.

Thanks for all the great suggestions and thanks to Wes at G-Force for the call this morning. We have state series races at Kenai this weekend and I hope I can have my son's quad back in top running condition by then. His mechanic (ME) let him down this last week, your suggstions will help me redeem myself. Thanks again to all who helped.

[rmuscle]

had my teather wires crossed , and bike ran for 2 races for no prob , then started braking up , went to pull it in trailer and i got shocked , thats when i realized i had them backwards, also we had an issue with plug looking rich no matter what i did plug was rich , pulled cylinder and found i was missing three orings and was blowing coolant into cylinder , and thats why my plug was comming out that way .

[kpnone]

I just put a new tether on. I changed it because my old one started causing problems, i.e. wouldn't start unless I pulled the plunger all the way out and gingerly reset it.

My understanding is the wire coming off the metal side goes to ground. Is that right? Can I assume you're running an aftermarket (normally open) tether?