Pipe advice for newbie to the site

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DeSoto Flyer
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Pipe advice for newbie to the site

Post by DeSoto Flyer »

Hi folks! Just found this site the other day. I bought a new 2006 KDX last Apr after 20 years without a dirt bike. (I'm 48 years old). Great bike!! Now, after about 60 hours on the trusty steed, I am ready for a little more power, but don't want to give up reliability and the (almost) maintenance free nature of the KDX. In the very short time I've known about this site, it seems the FMF Gnarly Woods pipe is for me. Question - does the pipe come with gasket and springs? Do I need new gasket and springs from my dealer? Sound is a BIG issue, as I have 12 miles of trails right behind my neighborhood and don't want to irritate the neighbors. Question - will the FMF pipe work with the stock silencer? Does the stock silencer negate any power advantage of the pipe? Last question - will I need to rejet after installing the pipe?
I can fly jets, but my computer and maintenance skills are less than optimum.
Thanks for your time
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Jeb
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Post by Jeb »

Welcome to the site!!

I believe a new FMF pipe comes with 2 o-rings. Check to make sure you have the copper washer that should reside between the butt end of the pipe and the cylinder, have your dealer order one if you don't. Along with some springs, they don't come with the pipe unless you get some Ebay package deal or similar.

Stock silencer will fit fine and I haven't yet read where someone found a quieter unit. Some keep 'em, some replace 'em with the aftermarket spark arrestors. 'Seems to be a consensus that there's not a lot of gain from the aftermarket versions. I noticed a little more midrange with my PC version. Stock version doesn't require packing changes.

A free mod is removing the airbox lid OR drilling holes in the lid to increase air flow. Drilling the holes is quieter.

The FMF pipe will sound a little louder, not much, but it's there. And it sounds different, sort of "tinny".

Boyesen Power Reeds are an excellent way to enhance the FMF and airbox mod. They're $35. Some like the DeltaForce reeds (DF3) and claim additional gains over the Boyesens; they're a bit pricier so take your pick.

Rejetting? After installing the reeds, the pipe, and modifying the airbox do a "wide open throttle chop" (do some searches on the site, plenty of threads on this, and feel free to ask questions). The chop will show you where you stand with the jetting. If you have stock jetting you'll likely need to lean things up (which was the case BEFORE the mods).

Keep asking questions as you go about this stuff; I can vouch for the case that you don't have to be a mechanic to be able to do this stuff. Mechanics are just quicker. And greasier. :lol:
"No farmer ever plowed a field by turning it over in his mind" -George E. Woodbury

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skipro3
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Post by skipro3 »

Welcome. I'm not going to read Jeb's reply. If he said it, then he answered it better than I could. If he didn't say so, keep asking away and keep searching the site for info. LOTS of good stuff posted here.

BTW, aren't most jet cockpits computer controlled? You frighten me!!
Jerry

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DeSoto Flyer
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Post by DeSoto Flyer »

Thanks for the replies. Great advice! I have drilled holes in the airbox lid and installed some foam inserts. Lots of mud and water holes here. I am working the search function, but it seems there is SO MUCH information, I searched FMF pipe and got 42 pages. Not complaining, though. My bike "appears" to be jetted perfectly now. Always starts first kick, never fouled a plug, and throttle response is outstanding (no matter how slow I am). Dealer recommended Motul at 50:1, and it has worked just fine.
As for jet cockpits, the more modern ones have nice computers, but the company trains you to use them. No need for you to worry, I fly boxes instead of people!
Thanks again for the responses, I appreciate it!
jowens66
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Post by jowens66 »

Jeb pretty much hit it on the head. New pipe will make alot of diff. Remove your airbox lid. I wouldn't drill holes in it due to trashing the lid. When you just remove it, you can put it back on for wet rides or for washing the bike.

New reeds will give a nice gain too. I would get the boysen's. 35 dollars compared to 135, and the difference to me wasn't enough to justify the extra 100 dollars.

Wide open throttle chops are fine and dandy, but they only test the mj circuit, they don't test what your jetting is doing at slow tight singletrack speeds.

Motul is a fine oil, but there are other choices for less money imo. I really liked the Motul 800 premix. Quality oil that burns nice and clean, but not light on the wallet.

The stock silencer should be suffecient. Gains are almost non existing when it comes to silencers. The stocker is nice and quiet too. If you do choose to get an aftermarket and want to get the DB's down, look at a product called the DB Snorkel.

After those mods, you can go the RB route. I did it on my KDX and man what a difference the mods made for a couple hundred bucks.
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Jeb
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Post by Jeb »

I've removed my airbox lid vs. drilling holes because it seemed to make a little more difference (it does result in more airflow afterall), but it will make things noisier. Give it a try; if it's too noisy reinstall your "holey" lid.

A BTW - this doesn't apply to DeSoto 'cause he's already drilled his lid, but generally performance will suffer when reinstalling an unmodified lid for wet rides; the whole point is increasing airflow - right? Reinstall it and you're back to where you were, and if you were well-jetted you won't be anymore. I've not encountered a problem with water getting to the air filter. Just something to think about . . .

Indeed the throttle chop addresses only the main jet (MJ) and thus only a part of jetting. The pilot jet (PJ) is chosen to provide good throttle response along with some adjustment of the airscrew. Do some searches and read all about it! Generally speaking, though, most end up with 42PJ, 40PJ, or even 38PJ for both the 200 and 220, modified and unmodified I believe (note: I'm not sure about the Stryker carb on this).
"No farmer ever plowed a field by turning it over in his mind" -George E. Woodbury

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DeSoto Flyer
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Post by DeSoto Flyer »

Thanks for all the advice! Ordered a FMF Woods pipe, needle and some jets today. Dealer (who I ride with) recommended I try that and see if I am happy. Can always do reeds and other stuff later. I'll let you know how it turns out next week.
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