Jetting at 3000 ft.

I have been pondering whether to jet my bike or not. It is a K model (kicker) with the FCR39 carb. The only mod is i have a homemade endcap on my exhaust, no spark arrestor. I have stock jetting and was wondering is a rejet would give me much more performance at my altitude. Is it worth it or not.

IMHO, Yes! Pull the snorkle on the thing and rejet, it'll be worth it!

Yes! Rejet!

Yes, Yes, Yes, lots of hidden performance for little money spent. It is a little hastle, but will pay off for the rest of your ownership of your bike. Check out the Taffy mod too!

Can someone tell me the best setup I can use to rejet at my altitude, pulled snorkle, and the homemade endcap with stock exhaust

Icedog,

You said 3000 ft. Is that the highest you ride? What's the highest point you usually ride to?

-Matt

thats about the highest

That's great! If you ride 0-3000ft the "advanced" jetting will be perfect for you.

158-160MJ

38PJ

70-73 PAS (use the adjustible pilot air screw)

EMM needle on 4th clip

remove airbox lid

remove coast enricher

Check out my website www.drz.info for more information.

All items can be purchased from www.sudco.com for www.carbparts.com

-Matt

Matt,

How high have you ridden with your jetting?

I ride 0-3000ft most of the time, but it is not unusual for me to hit 7000ft in the mountains.

Will the "Advanced" jetting perform better or worse under these conditions?

(I'm currently running 45 pj, 165mj, stock needle raised one clip, opened up airbox and Yosh full system (med tec)).

Thanks,

The highest I've been is around 4000 ft. At that elevation it ran fine, but I have heard from many others that the EMM needle is too rich much above 4000 ft. Maybe someone else can comment...

-Matt

I wanted to do basic jetting. Keep my needle and keep the coast enrichner on. Is that a problem still be gains or not. What should I do to set it up then.

You will see improvements over stock. Anything is better than stock!

165 MJ

48 PJ

airbox opened up

needle on 5th clip

Fuel screw out 2.5 turns from closed (I think)

Should work great. You should be able to get those jets at your local dealer.

It will not be as good as the advanced jetting though.

-Matt

I've gone to 6,500' with the advanced jetting and it ran a little fat on top and I lost just a little bit of the snapp on throttle response. Being that I have the kicker, there is gobs of room under the carb and I can change the main in about 3 minutes. I adjusted the fuel screw when we got up to that altitude and the throttle response got better. Being that we go from 2,200 to 6,500 in the same ride, I don't change any of my jetting. It just runs good. 38/73, 158 main, 180 main air (soon to be 200 main air) EMM C-4, on coast crap, 2.5 fuel screw, full Yoshi, and Taffy mod at .5 second fuel squirt. If you run at 4,000'+ all the time then you would want a leaner needle and main.

matt:

did you leave the screen between the airbox and carb in? do you know if there is any improvement by removing it?

I left my screen on. I heard it was to prevent fire. Don't know if that's true or not, but I imagine any performance gain would be minimal if any, and didn't want to take a chance.

-Matt

OK. Thanks. I don't think the purpose is to prevent fire. I think it is to make the flow from the airbox more uniform rather than a vortex. That's what it is for in the machines we manufacture at work anyhow. Our engine engineers tell me it is a restriction but without it the fuel may not vaporize completely. It is more crucial in multi-cylinder engines so that the distribution is even. I was just wondering if anyone tried to remove it on the DRZ.

I ride at 4,500 feet and the following is spot-on perfect:

165 main Jet

48 Pilot Jet

Clip dropped 1 spot on stock needle

Snorkel Removed

White Brothers E-Series with 8 discs*

*I ran this jetting combo before the pipe and it was fine too.

I never had to mess with the fuel screw, coast enricher, or most importantly...the backfire screen. This set-up is easy, cheap and makes a HUGE difference in power. Keep it simple and have fun. :)

I also ran with the clip one down from stock and a 162 main and the bike ran very good and I was happy. The advanced jetting made the bike just run a little better overall and much better throttle response. It is a little bit of a hastle to rejet but in my opinion well worth it. Once you do it once, then it is done for life. I don't have time to do testing, so I have to give thanks to the guys like Matt (and others on TT too) who did all the up front jetting work and testing, so guys like me could just piggyback their knowledge and do it right on the first try. Thanks Matt, Burned, Ballistic, and the whole TT crew. My ride is better because of you!! Oh ya, don't forget the Taffy mod.

Thanks for the good words, but much/most of the credit should go to Taffy and James Dean over on the Yamaha side. They spent months trying different needles, PJ, PAJ, MJ, MAJ, clip positions etc. If you want to see the history of the EMM needle read a post on the WR forum called "Jetting Q's" The "Advanced jetting" on my website is very very close to what they came up with. For example, they suggest 40 PJ, 70 PAJ. I (along with others independently) found out that 38/70 or 38/73 works better for the DRZ.

-Matt

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