Dirt Bike idiot

I just purchased an 08 Suzuki DRZ 400S in Tucson, Az. but brought it to New Mexico to a higher altitude (7200ft).

Will start with choke but won't run without. Dies when cranked.

Since I have to work on the carb anyway I would like to rejet this stock Mikuni for 7200ft altitude. Bike is stock in every way.

I know nothing about this bike and have not worked on a bike carb in 10 years since my XR500R.

I have read the following:


Eddie Sisneros

03-19-2002, 05:12 AM

im at 5500 ft elevation.im running a 25 pilot,dynojet needle(for the drz)position 4,and a 128 main.most every body at sea level is runnin a 140 main with the dyno jet needle.the fact that your runnin th 27.5 pilot with that needle your usin shows that the root diameter of that needle is still wrong.get the real needle! :bonk:

My fuel screw is 2 turns out.


I am willing to do this with a DJ kit but can't find where to get a 25 pilot.

I want to ride up in Silverton, Colo. over Cinnamon and Engineer without bogging.

What pilot/main/needle notch/fuel screw combination will give me the greatest + - range about 7200ft?

Where can I find a 25 pilot?

Are there any step-by-step Mikuni rejetting instructions for idiots?

TIA to all,



the jetting isnt the issue.it has a pluuged pilot jet.

did the bike sit unused for a period of time?

Thanks for your reply. Great! Yes, I bought it a month ago in a pawn shop in Tucson and the guy said it had been in storage for 6 months.

So what steps are necessary to unplug the pilot? And I am a little confused with the "pilot" term. I have been reading and see references to pilot air jet and pilot fuel jet??

Eddie has a better link for fcr carbs. But carb theory is the same no matter what. So here's the link i have found most helpful. Hope this is helpful to you!


-BIG DAN:thumbsup:

Thanks for the carb tutorial link. It helps.

Its pilot fuel that is plugged. Is this a Kehein FCR carb? I think that is what your bike uses, if so I would expect a larger pilot that 25, most use 38- 40, 42 or 45. Problem with real small sizes is they are much more prone to plug, a 30 will plug if you get gas with water in it!

On the FCR this jet is in the bottom just forward of the main jet, on most bikes you can rotate the carb top to the right, remove the 17mm plug in the bottom, that jet is to the engine side of the main jet reseesed up a hole, you need a screw driver less than 1/4" wide, soak the jet in lacquer thinner, acetone or fingernail poliish remover overnight

bsr 36mm cv.

Yes BSR 36mm CV.

And I found a source ( http://www.rockymountainmc.com ) for a 25 pilot. So when I take the carb off I will clean it good and do the rejet.

Tks to all you guys for replying.

Hi Dave,

I think this post will help me with my problem too,,, I can get my 03 yzf 450 to idle with the choke on , but as soon as I take the choke off , it dies. Ive played with the pilot jet- turned it out to three turns out , but it doesn't seem to make a difference. And the pipe glows red hot, and when I take the choke off and rev the engine , it pop alot. Thanks for your help,,,,,,,,,,, Larry

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