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DR 650 - Air Box Mod - Is it worth it?

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Hi all,

I'm just working through some mods on my '01 DR 650 and have some questions regarding the air box modification that is recommended by Keintech....

I bought the Dynojet Kit (not installed yet) and have plans to pick up an FMF Q2 pipe once I can free up some cash....

So - my question is.... Is it worth butchering the air box? Is there a definite performance gain realized from the modification? :thumbsup:

I would hate the cut the airbox up for no good reason...

Any thoughts/ Comments?

Thanks in advance

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It's either that or take the side cover off

After the DJ kit it will need all the air it can get, or it won't run for she-it

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Is it worth it, hell yes. Will it make a definite performance improvement? Yes it will if done with a DJ kit and pipe (even without a pipe it'll make a big difference), and the jetting is right. I've yet to come across anyone who has done this mod properly who hasn't raved about it. I've seen enough dyno charts on this and other forums to know these three mods can be worth up to 20% extra bhp + torque over stock, and yes you will definitely notice that.....

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I started with the 'poor man's dyno kit' ie shimming the needle with washers and a 155 main jet, cut two 1 1/2" holes in the top of the box. Finally broke down and got the DJ kit for their needle, threw in their jet (155) and removed the box side cover as well. Wow!! It's a different bike now, well worth the noise increase IMHO.

Ed T.

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Thanks for the fast responses!! :ride:

Looks like I'm going to make the mods when I put in the jet kit... :thumbsup:

I can't wait to see the difference!

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Don't cut it, the sound increase is literally in the seat of your pants. Feels hella louder.

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I started with the 'poor man's dyno kit' ie shimming the needle with washers and a 155 main jet, cut two 1 1/2" holes in the top of the box. Finally broke down and got the DJ kit for their needle, threw in their jet (155) and removed the box side cover as well. Wow!! It's a different bike now, well worth the noise increase IMHO.

Ed T.

Hey Ed, just remember that DJ and Mikuni use a different system to size their jets. One is on flow, the other is on diameter, so that a 155 DJ is smaller than a 155 Mik. There are conversion charts available on the net, just do a google search. I'm running a Mik 155, which is equivalent in flow to a DJ 165.

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Do it all at the same time. Cut the box, get a K&N Filter,Jet and drill the slide in your Carb, and get an exhaust system that is tuneable (ie. Super Trapp with diffuser discs). With a tunable exhaust and your air box correctly cut you will probably run160 main. I have a 1990 DR 650 that is running 17 discs

in the Trapp, 160 main, drilled slide, and a seriously modded air box with a K&N filter...my bike is a rocket. I highly recommend that you find someone in your area that has a DYNO machine that can totally dial your bikes cardio vascular. I am pushing 56 HP to my back wheel (couldn't have dialed it that well with out the Dyno).As well, the 1990-1992 DR650's came with 3.5 more horse power than the following years (go figure).

Rock and Roll

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I have a 1990 DR 650 that is running 17 discs

That must sound wonderful :thumbsup:

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Yep,,, I think it is part of the 'Whole Package' of power ups...

I don't like the removing the cover thing 'cause it way close to the back tire and will suck up tons of dirt into the filter........

Don't need to go ape shi$ on the hole,,, remember it'll rain on you......

As far as the noise,,, no big deal,,you pick up some 'Waaaaaa' sound but &%$#@!?

Here is what I did......

garage.php?do=viewattachment&attachmentid=13322

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I drilled 12 one inch holes in the top of mine

Originally I had those little Uni Filter vents in it but it would not pass enough air with them so I popped them out

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I cut my airbox and put in a k&N and it increased air flow so much it would not even run over idle.At least not without the jet kit.If you dont like it you can duct tape over the hole and never know it was there,unless you take off youre seat.I love the sound of every motor,intake and exhaust mod I do.

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It is only worth it if you don't mind the noise. Certainly you will get use to the noise but everyone else may not like it.

I am still debating this mod. My friend has done the mod but mine is still stock, and his bike is considerably louder. The other morning, I heard him coming from 2-3 miles away, and he still has a stock muffler. I like how quiet my DR is mainly because I like to explore places unheard.

Another consideration is fuel consumption. We rode together 2 weeks ago, riding at the same pace. He got 38 mpg, and I got 54 mpg.

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