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1994 KDX200....Finally got around to working on my KDX again, was going to put the Boyeson power reeds in.
Part #607
(I haven't done much work to this bike yet, so I hadn't laid eyes on the reed cage before just now.)

The pictures Ive googled make it seem like what I have is not the stock cage, there are 2 instead of 3 petals on each side, and none of the curved metal stops.

To make it worse, one site had a picture of #607 reeds with a 2 opening arrangement which WOULD make sense for my existing cage.

The boyesons I got have 3 openings and one petal so to say. They seem like they would make sense for the stock cage, but not for what Im looking at here on my bench. In the picture, there is one of the new boyeson units at the top, and one of the existing reeds pulled off and the cage etc.

There are no markings on the cage I pulled out. Any idea on what I have here?



Thanks in advance!

In looking at the existing reeds, there is a slight gap at rest, but no chipping or apparent wear.

Flipping the reeds does make the gap go away. Not sure if the gap is a big deal or not.
its about .008 inch or .23mm, maybe a little more on one side of one of them.

Yes, the gap is a big deal. Its how your engine builds intake pressure to force the fuel charge up through the transfer ports. Gaps can cause lean conditions, hard starting, etc.

Not the stock reed cage, kind of looks like an old Boyeson RAD valve, except the rad valves had the intake pipe as part of the cage. The Boyeson Pro reeds will probably fit, and are a 2 petal design with a similar mount hole pattern.

FMF Ram Valve

http://www.fmfracing.com/Product/Produc ... &Priority=

As with most everything you ask on the internet, there are many many debates about the gap in a reed valve. I think any opening may affect (a little) the fresh charge tending to back out, but as soon as theres more pressure after the cage, they will shut, at least with the tiny gap I have and the lack of force needed to put them against the block. My 465 is the only other reed valved member of my fleet, Ive never had to address those as it was all new when I got it, and it runs well enough. If that bike is down on power, I dont care, it has plenty more than I will ever use.


The KDX runs really well, its just that I was hoping to tune it back to having some low end. Im at a cross roads really..I have raced it in a 90s class MX race, and one cross country so far. Too much wheel spin for the CC...not enough grunt. Id like to have it right in the middle.Id love to ride on that is in stock form and see how that feels...I think that might be what Im after. Ive made that mistake in the past, taking a bike I loved and tuning it, making lots more power and hating it. Easier to ride a slow bike fast for me.

When I bought it, it had all KX plastics on it, and all the mods that I have found point to the previous owner trying to make the bike something its not. (well not the previous owner, he was a marketplace flipper--the owner BEFORE him. I had seen this bike on Marketplace and watched it for a while, then it sold. The guy I bought it from nearly doubled the price, and I watched the price go down over a period of weeks until he panicked and dropped it a little below what he paid. The relief in his voice when I said I was coming to look at it was palpable..as soon as he ripped it across his back yard, I said "SOLD". He was all smiles and so was I.

It may as well be a KX125 from the way it feels, a little less violent.
The boyeson reeds damn near bolt up.. I would have to egg out one of the holes in the reeds at one of the far edges by about 1/16th an inch.
The middle and one side lines up perfect.

It would cut the lower RPM intake cross sectional area a good bit with the three ports on the lower reed. I have a feeling it would run, and probably have the effect I want, but I also think Id be chasing the jetting. Of course, if I went back to a stock cage and put my new boyeson reeds on that...id have to change the jetting most likely. Not a big deal. As I write this, I may go that route.

KDXgarage, do you know the reeds you pointed me to are for the cage I have? I guess those are FMFs answer to 2 stage reeds for the ram valve.Its much appreciated, I just cant find those if I go thru their sites model search etc...(their site is a little clunky tho!)

That would be another way to go, if those FMF 2stagers will fit my ram valve.

If I need the bike before any of that, I may try flipping the valves over. It would be interesting to note the effects. Id bet that it might take me just a tiny bit in the direction I want to go...as at a given low pressure they would open a bit less, being stiffer due to having been flipped...I can feel the difference on the bench, having flipped them the other day....blowing thru the block takes more to open, (and they make a fun duck call sound. )

Yeah, Im not quite right in the head.

Flipping them over is generally the first thing most people due to get more life out of them. As long as they are sealing you likely won't feel a difference. The bigger issue is when they crack or break a portion off and then cant seal. Had forgotten that FMF even made a reed cage.

Hi 71. I asked this same question last Nov. nice to see KDXG still hanging in there. I have these FMF Ram in my ‘95 and have been very pleased with performance. But can’t say if Boysen might be better or not. But I am well pleased enough to keep using them, unless I find a problem.

Ps. I like to think about that comment of being able to ride a slow bike fast. I am just learning and experimenting with getting in the right gear with smoother throttle control to match. I think my bike is a hot rod but haven’t ridden enough other stuff to really know.

Hi. Sorry, but I am not sure on a part number. You may want to reach out to them and ask.

Just an update....
I made a spacer block for the reed cage and also put the lid back on the airbox. Put a hotter plug in as well.
I had it out today in a CC race and It did well.

Its odd....when snapping the throttle sitting still, I would get a bit of a "wooof"...a dead spot..but I mean a QUICK snap and back.
I was thinking that might be a lag from the spacer, or the distance taking it somewhat out of resonance. It wasnt idling though, so I played with the air screw and idle stop. Didnt have any more time to mess with It because it was go time, and I took it out.

I was thinking Id have to work around a potential dead spot right off idle, but it never showed up again.

I noticed that it tolerated lugging a little better....it is now more distinct when the KIPS opens up. I found I was able to accelerate moderately and get the RPMs up into some good power areas without breaking the wheel loose which was good because it was raining. It seems that there is a zone there I didnt have, or wasnt accessing...

(Of course, this might just be me getting used to the bike---Im not implying my spacer made some whizbang difference, although between that, the airbox lid going back on, and the hotter plug, I think it helped. when I first took the lid off of the airbox, it did definitely take what midrange it had away, but now it feels like it has more)

Im not able to actually test bike much here at home---when we finally moved out of the crappy neighborhood I wanted an old farmhouse and some land, but we landed in suburbia in all its glory. Dont get me wrong, I love it but my neighbors would hate me if I did too many passes up and down the street.

Anyway, Im liking the bike a whole lot more now, and again, it may just be Im learning how to ride it so to speak.
I was out there for an hour and 20 minutes and the bike never missed a beat and I did manage to win my class.

HECK YEAH! Congratulations on the win!

Congrats on the win! I saw three KDX's this weekend at the Pipsico VHSS race in Tidewater Virginia (besides mine) - all four were 2003's. Super nice guys riding them, all grinning ear to ear! I managed 9th out 18 with two DNFs and definitely had more bike than rider everywhere on the course - but I'm getting better!

MoonStomper, congrats on getting out there and mixing it up!

Way to go!