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DRZ erratic idle settings

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Got a DRZ125 that either won't idle OR it idles way too high.

 

Thought maybe dirty carb. Took it off, cleaned, blew it out, held jets up to light, looks clean. No green guck anywhere in the carb. Cleaning it didn't change symptoms at all.

 

The confusing part. To me anyway.

 

If it's idling too low, choke raises the idle, except sometimes it'll kill it. If it's idling high, choke kills it or lowers it to acceptable, except sometimes it'll make it idle even higher.

 

The screw on the left side of the carb seems extremely finicky. I'll adjust it in, one mm at a time. Blip throttle, let it settle for thirty seconds, make an adjustment. Most of the time the bike just wants to die but then it seems there is one point of no return with that screw where it'll just suddenly jump the idle up and it will not come down.

 

You'd think you could just turn it back that same amount and it'd come back down but it doesn't, you actually have to back it out quite a bit before it'll return back to idle for five seconds and die. Again, making small adjustments and waiting before making another adjustment.

 

I did have it idling decently for about a minute or two and then suddenly it just climbed up again and wouldn't come down, not with the choke or using the kill switch to drop it down. You can shut it off, kick it over and sometimes it idles right where it was just before you shut it off, other times it's back to idling and dying?

 

Any help appreciated. At this point wondering if I should just find a new carb for it and call it a day.

 

 

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If that is a 2 stroke, you may have a vacuum leak somewhere between the carb and cylinder.  I had an old Suzuki that did that, and it was a bad crankshaft seal.  The entire lower end of the engine is part of the intake circuit. 

Or a vacuum leak on a 4 stroke can also be a problem.  But usually easier to find, and repair.  GOOD LUCK.

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4 stroke. Went for a ride, idle kept getting lower and lower. Screw on side turned all the way in, still died. But at one point after a long grid road, stopped and it was revving high again. Good points weezerthegeezer thanks for your input.

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4 stroke. Went for a ride, idle kept getting lower and lower. Screw on side turned all the way in, still died. But at one point after a long grid road, stopped and it was revving high again. Good points weezerthegeezer thanks for your input.

Hmmm I remember a similar problem with a klx 125 maybe 5 years back. Did you check your valve timing? Also your bike doesn’t have to be a two stroke to have a vacuum leak check for cracks in the air boots between the carb and head and the carb and airbox
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Is your choke on or stuck on? Did you hold the pilot up to the light?  Did you adjust the fuel screw?  Pull the airboot off the carb: does it run better or worse?  Put your hand over the back of the carb: does it run better or worse?  Check for a air leak. 

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Also take the fuel mixture screw out and squirt carb cleaner through the hole.  Then use compressed air to blow through it.  Replace screw and readjust.  

But it really sounds more like a vacuum leak.

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Set valve clearances earlier, but come to think of it the spark plug looked fairly black when I had it out doing that...maybe the choke IS stuck even though the lever is down. I'll check for vacuum leak as well and maybe give that carb one more clean, I didn't have carb cleaner to use so I was just looking at everything holding up to the light and blowing out the jets etc with compressed air. But I guess it could be gunked up INSIDE the carb. Thanks for the tips everyone, I'll check it all asap and report back.

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Thanks guys. Took the entire carb apart, jets etc, used half a can of carb cleaner cleaned it inside and out, blew out with compressed air, set the idle screw and pilot screw back to factory settings, reassembled, one kick, started and idled for five minutes. I let it idle that long because last time it'd just suddenly ramp up out of nowhere.

The choke looked like it has some debris or something down there, I'm thinking that was it because it felt like it was running rich and the plug looked pretty black and sooty too.

Appreciate the help, lesson learned carb cleaner!

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