2007 DRZ400SM idles high

OK I have trolled and trolled on this site for a while and now I have finally registered because I don't know what to do.  My DRZ has this issue with idling now.  The engine can be cold or warm and you can ride it for hours... still does the same thing.  It seems to put itself on a high idle while I am riding but if I bump the clutch it drops it down to normal.  Sometimes when idling at a light it will jump back up and I bump the clutch and it drops back down.  I thought it was something with the cables hanging until I noticed it doing it just sitting and not touching the throttle.  Thought it may be a vacuum problem so while it was running I sprayed starting fluid all around the boots and hoses but it didn't do a thing.  When it does it, the RPM's are probably comparable to a cold start with the choke on.  Seems like everything is fine EXCEPT for this idle issue. 


I have the following done to the motor...

K&N air filter


TT FCR39MX kit (installed new this summer according to the FAQ on here)

Extended screw

FMF pipe and power bomb header 

Hot Cams stage 1 intake and exhaust 



Clean the carb , replace the pilot jet .

Lean idle condition.  Is this something new? Or always done it since install the FCR?


Adjust the fuel screw.


What pilot jet size?  You may want to replace it.  Is there a pilot air jet?  If not, try a 100 pilot air jet

...adjust the idle control knob? :)

The carb has less than 1000 miles on it and it was running fine before and after install.


Adjust the fuel screw... Out?


It has the jets in it that it was supplied with from the TT store.  The instructions on the FAQ said to remove the slow air, which I did.


Carb comes standard with the following:
- 200 Main Air Jet
- 160 Main Jet
- 45 Pilot Jet
- 100 Pliot Air Jet
- EMR Needle

zeeno, I dont think the problem is in the idle knob.  Idles where it is supposed to... most of the time lol.  The "low side" of the idle is fine, after I bump the clutch to make it drop down to where it is actually idling where it is supposed to be.  It's hard to explain, imagine you just started your bike with the choke on and it idles high for warm up or whatever then you push the choke in and it drops to regular idle where it is supposed to be.  Mine does that and then it also does it with the choke in but I bump the clutch and it drops it down to where it is supposed to be.  I don't know I feel like an idiot trying to explain it.

OK I just burned the tank down to nothing and filled it up with premium, screwed with the mixture screw until the point that its running as smooth as it can as "normal" idle. Its a pain bumping this clutch to drop the idle. What jet would you guys recommend? Should I put the jet back in that the FAQ said to remove and leave out?

Edited by FYYFFKY

1. Don't use premium in this motorcycle


2. What do you mean by "bump the clutch" ?

Zeeno - DRZ does not care what octane fuel is used.  May not need premium but no harm to use it. "Bump the clutch" means to use the clutch as a friction brake to slow the motor.


FYYFFKY--- The 45 pilot jet is correct.  It possibly could be restricted with dirt or varnish.  Clean or replace.  If no joy, then yes I would replace the 100 air jet.

When you get it corrected you will need to readjust the fuel screw and the idle speed.


An EMR needle is quite a lean needle.  You might need EMN or EMP.  Needle should not affect curb idle but there is overlap in the fuel circuits.


Sorry it does have the EMN needle in it. I copied and pasted that. In that kit was the EMN needle as well.

OK, then I think the problem is in the pilot air and/or the pilot fuel jets.

Well I guess I know what I'm doing tomorrow. Man, that carb is a pain in the arse to get in and out.

I happen to have bought a 2011 DRZ-400s today with 800 miles and didn't notice an issue with the idle until I was riding later this evening.  I am having the exact same issue.  The only difference is mine idles high most of the time.  If I let the clutch engage enough to get the bike moving and pull the engine RPM down and then disengage it, the idle stays low in the normal audible range.  But as soon as I give a little throttle(just a little flick of the wrist), it revs back up.  It sounds about like it does when it idles with the choke pulled out.  I read through the posts but I don't understand how dirty jets could cause a higher fuel input but the clutch engaging would lower the fuel input.  I think either I am missing something or something else could be the issue.  Any thoughts? 


Also, the fan on the radiator was still on when I killed the engine.  I am guessing running at high idle put added heat on the engine maybe. 


No mods that I am aware of.

Edited by deadpieface

Well I guess I know what I'm doing tomorrow. Man, that carb is a pain in the arse to get in and out.

I am curious if you cleaned the carburator.  I am still having that problem with my bike and I have noticed that the longer I ride the less of an effect the clutch bump has.  It will slow it down but when I squeeze it in again it revs back up.  After it has cooled off, it idles as long as I slow the engine with the clutch.  My brain can't quite understand how slowing the engine with the clutch, thus reducing the idle speed, would have an effect on the carburator at idle speed.

bump.  any updates on the issue?


my bike is doing the exact same thing. Idles high until you "bump" the clutch then the idle drops back down.

Almost sounds like a hanging slide inside the carb. When lugging the engine just a bit the vaccum in the carb changes a little and allows the slide to drop down. It also sounds like two diff carbs are having the same problem. I hate these little gremlins. I wish you both luck on finding a resolution.

It also sounds like two diff carbs are having the same problem. I hate these little gremlins. I wish you both luck on finding a resolution.




FYYFFKY:  curious if your bike idles after the carb clean. 

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