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Uncorking the 450X

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To all of my friends out there with jetting issues or questions:

When I bought my 2005 450X 6 months ago a friend gave me a copy of “The Wrench” by Honda. Which is a document published by Honda for dealers, with the steps to modify a 450X for “Competition Use Only.” Basically it uncorks it and it is no longer stock and does not conform to EPA standards, but it actually runs how it was designed.

I went ahead and made most of these modifications after my first ride and I have NEVER had any problems nor did I have to spend any time “dialing” my ride in.

If you PM me (WITH YOUR EMAIL ADDRESS) I will email you a .pdf copy of the complete instructions; the instructions have diagrams that can be helpful.

The following is a condensed version of the process:

4. Replace the standard carburetor parts.

• Main Jet (from #142 to #162)

P/N: 99101-357-1620, H/C: 0419200

• Jet Needle

Change the clip position from #2 to #5

Leak Jet (from #70 to #65)

P/N: 99108-KSC-0650, H/C: 7660558

5. Set the pilot screw to 1 ¾ turns out.

6. Remove the diffuser pipe from the muffler

7. Increase the Airbox opening as follows:

• Remove the subframe and airbox

• Drill out the two pop rivets holding on the air snorkel and remove it

• Cut the section shown inside the raised cut line while wearing eye protection.

• Reinstall the air box and the subframe.

8. Cut out the left side cover as shown.

9. Behind the left side cover there is a “natural” color main coupler. On the ECU side of this natural coupler there is a pink wire. Underneath the pink wire is a blank terminal plugged with a rubber cap.

Swap the positions of the pink wire and the rubber cap. Reconnect the coupler to the wiring harness. (In modified form, the pink wire is NOT connected to any other wire.)

Tips from my experience:

This whole process is rather cheap, basically the cost of 2 jets. So go ahead and get an aftermarket T-handle pilot screw for 20 bucks or whatever, so you can make adjustments to that more easily. Another thing to modify while you are at it is Remove the smog pump, another 20 bucks. Also, the Boysen Accel. Pump cover added more instant power, but at $80-$90 I waited until 2 weeks ago to get it and I never had a problem with out it.

The last thing, the same buddy of mine who passed these instructions on to me ordered allen head screws in bulk for the bottom of the carb and angled allen wrenches. If you change out the screws while you have everything taken apart, it will make future jet changes or accelerator pump cover changes easier. I did and I know it made it easier to swap my accelerator pump cover a couple weeks ago when I finally had the cash for that mod. So if you want my buddy sells the kit for the screws with the allen wrench for rather cheap, I think 10 bucks. If you PM me I can get you his, so you can do that too.

ANYWAYS, if you are actually still reading this GOOD LUCK and have fun.

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Good post, I've done all that in one form or another except removing the muffler baffle, I want to be as quiet as possible. I understand the bike is still legal without the insert, has anyone ever been tested without it? I'm curious to know how much louder it actually is. I removed it in the driveway and could tell it was louder but I ddin't ride it.

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Thank you for info, just bought leftover 05 and looking forward to making it run, closed course of course.

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It's freaking loud. And it sounds like a delapidated '67 Impala with blown-out glass packs. Or bovine flatulance, which ever sounds tackier. :thumbsup:

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Good post, I've done all that in one form or another except removing the muffler baffle, I want to be as quiet as possible. I understand the bike is still legal without the insert, has anyone ever been tested without it? I'm curious to know how much louder it actually is. I removed it in the driveway and could tell it was louder but I ddin't ride it.

I believe TT member Shadyatbest's modded 450x (head work, high comp piston) blew 96 and change db with the stock pipe with the baffle out. PM him for the specifics.

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Hey neighbor, I'm from Green Valley. Just got my 450x and am in desperate need of your uncorking info. Thanks

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I guess I went the more expensive route, but am very happy with the results!

TwinAir Powerflow air filter

Removed airbox snorkel and opened up the side vents

JD Jet Kit

Applied Racing smog removal kit

White Bros E2 exhaust with quiet tip

I now run a 170 main jet, stock was a 142.

Z4

PS - don't forget to ditch the stock front tire for a better one.

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Great post. I am looking at a new left over 05 right now and will need the info. if I get the bike. If my local dealer jacks me off on it I'll buy a newer model year later on and somewhere else:)

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I've done everything that you've done as well, including the pink wire modification. The only thing that I haven't done is any type of exhaust modification. Are you happy with the white brothers exhaust? Did the change of the muffler make a pretty signifigant improvement? The other question I was wondering was what settings you are using with the JD kit. I'm assuming the red needle, what I was wondering what clip setting and aprox. how many turns out on the air screw?

thanks in advance.

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It's freaking loud. And it sounds like a delapidated '67 Impala with blown-out glass packs. Or bovine flatulance, which ever sounds tackier. :thumbsup:

:applause::applause::applause::ride::applause:

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Bubba, Thank you very much for the article on Uncorking the 450x. That was very nice of you to send it out.

I was wondering if you also did step 1....replacing the cam with the 450R cam,

or did you just stick with the stock cam.

Thanks again

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