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To rejet or not to rejet, that is the question

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I recently purchased a 2001 DRZ 400 E. I really like this bike:ride: . The engine, exhaust, and carb are stock. I have stripped everything down but the engine and rebuilt it. Even in this stock condition, this bike is much more energetic than my son's 2006 DRZ S with 3x3 and Yoshi pipe.

The question is: should I rejet and modify my exhaust? Is it a big gain on this bike? What happens to fuel economy?

Pipe: stock

Carb: Keihin FCR39

Main Jet: #165

Needle: OBDXP-4th

Slow Jet: #45

Pilot Screw: 1-1/2 turns out

Thanks!

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It is always a good idea to make sure the jetting is optimized for your location. A freer flowing exhaust is also a nice improvement, but the tradeoff is increase noise. I'd definitely optimize the jetting, and if you can handle the noise add a pipe. Just be sure to decide on the pipe before jetting the carb!

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The reason is simple. Your '01 E has the 39mm FCR carb while your sons '06 S model has the anemic 36mm BSR carb. I think the E's also more or less alredy had the 3x3 done from the factory but I could be wrong about that part.

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ive got an 07 e all i did was derestrict the exshuast 3x3 178 main jet removed coast enricher has heaps more balls than stock

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Thanks all, but I was hoping that I would get an answer to the fuel economy question from someone with a DRZ E and FCR39?

I wouldn't get too crazy if your not in need for more power. A pipe and rejetting it will tune it correctly add more exhaust flow and more noise. Fuel economy won't probably change too much, are you doing long rides where fuel economy is an issue?

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I do go on long rides, and I usually rejet and repipe all of my bikes. I have an Acerbis desert tank on this bike, so fuel economy is not a huge issue. My question centers on this particular engine. With 12:1 compression, and the FCR flat slide carb, is it worth the rejet, exhaust and intake box mods? If it gives me a 20% increase in HP, and little difference in fuel economy, then I would do it. Most of the bikes I have rejetted, my fuel economy when down by at least 30%. What to do? Help me!

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Your fuel economy won't drop that much on the DRZ.....at least I haven't ever heard of anyone having that much of a drop.

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