KDXRIDER.NET

Saw this tip pop up on another thread and decided to start a new one . . .

It apparently is possible to reduce the spring pressure on the detent spring and thereby change the rpm at which the power valve opens.

Anybody tried this?

I was wondering the same thing. Reduced pressure would be achieved by adding another washer,? Removing the ball altogether? CC started this, then left it vague, so I think it's his responsibility to tell us what the trick is.

What was the vague part?

Fredette's been doing it for years (pressure reduction). Well, so he has said, and I have no reason to doubt it.

It's unlikely the sort of thing that will get a, 'Wow!' response. A lot of things that add up to a good running bike are that way.

Kind'a like putting in an aftermarket lighting coil for better spark.

Yeah... kinda like Eddie Van Halen used to only use a volume knob on his guitars and every manufacturer of guitars followed this.

Years later... come to find out he only did this because he did not know how to wire in the tone pot. What a riot!

Don't know about the lighting coil deal or the detent ball.... but I do know that the KDX could use a bump in the sparky from the get go... I would be willing to try it if I needed the extra lighting power but that's 'spensive if not needed.

Detent deal would cost nothing to try ifn' you got a hair... so that is worth what you put into it just to see....

Expensive? $80? You're kidding, right?

Get a coil from rickystator if you can't find an Electrex (FRP still has those last I heard)..gap your new plug to .030", then try to wipe the grin off your face as you post a 'Not a big deal' thread.

Canyn, are you guys talking about replacing the lighting coil or ignition coil?

Indawoods wrote:Yeah... kinda like Eddie Van Halen used to only use a volume knob on his guitars and every manufacturer of guitars followed this.

Years later... come to find out he only did this because he did not know how to wire in the tone pot. What a riot!

Don't know about the lighting coil deal or the detent ball.... but I do know that the KDX could use a bump in the sparky from the get go... I would be willing to try it if I needed the extra lighting power but that's 'spensive if not needed.

Detent deal would cost nothing to try ifn' you got a hair... so that is worth what you put into it just to see....

Yeah, I definately got the "hair". When I was at the verge of choosing orange, of the many things that intrigued me about the exc, the ultra-smooth hydr clutch and the adjustable power valve were a couple of my favorite.

Turns out that Magura [sp?] makes a hydraulic setup for the KDX ($220).

And . . . it seemed reasonable that a weaker/stronger spring could change power valve opening RPM but I was too uneasy about what I DIDN'T know to go changing things - so the mention of it caught my interest. 'Seems like it'd be a kick making sort of study of it.

At a minimum I'd like to see how things change by both weaker and stronger springs (or washers or lack thereof). Be nice to also tweak the rate of opening when it does open, i.e. slow opening vs. snap, but just to look at the assembly my feeble mechanical skills can't visualize it (unless I just removed it).

Maybe I'll make a go of it during the Christmas holidays if it's not too cold. Then I would have some ideas of what to do after I get the RB work done.

BTW: You know EVH? I think everybody tried to emulate him in those days, I still got a Kramer from back then for crying out loud, used to play a bunch when I was in the service . . .

canyncarvr wrote:Expensive? $80? You're kidding, right?

Kidding? no.

When I can buy an entire DVD entertainment center for $50 that has surround sound with 5 speakers including the powered subwoofer. Who is ripping who off here?

I guess I may have to try it... sure wish I could wind my own though....

I've seen instructions on howto wind your own. All you need is a couple of pounds of magnet wire and some epoxy to coat the finalized coil with. I'll see if I can dig them up for you. A rewound stock coil while having more juice than a stock coil, will not provide the same level of output that an aftermarket coil would. The aftermarket coils use more plates and thicker wire to provide increased current as well as wattage.

Winding your own lighting coil isn't too big a deal. Nothing like winding your own exciter (sparky) coil.

The lighting coil doesn't need to be potted (epoxied). The wire is thick enough that it's not likely to get damaged by vibration and such...and the voltage is relatively low. A good coat of varnish would work to hold it together.

Nothing wrong with using epoxy..I'm not arguing that.

A $50 DVD 'entertainment center' with all that stuff? Now there is a unit I'm SURE would keep up with my Proton 1200!!

1500W into one ohm! No problem....right?

I've not been helping keeping threads centered lately. I will do better...

I'm just saying a wrapped magnet vs. an electronic nightmare and the cost. Someone is raking in the money!

I did some googling and found some info on . . . what was it we started discussing?

***edit***

Oh yeah, now I remember . . .

Two things:
1) CDI timing is mapped such that ignition advances as RPMs increase from idle to 6 grand, then ignition falls back. Impact? I don't know (yet!!!).
2) If you ADD another washer wouldn't it preload the spring more and result in valve opening at higher RPMs?

The word 'mapped' generally refers to computer driven control boxes that can be mapped. The KDX sparky box is a simple analog device. That's not to say that timing doesn't change...it does, and it does drop off considerably about KIPS time. Why? Because 2-smokes work better that way..less timing in upper RPM ranges. That puts heat in the PIPE and that improves the pressure wave effect that makes 2-smokes work.

Adding a washer=more length=less tension. You would be adding a washer on the OUTside, not the INside.

Again, referring only to the two FRP cylinders I have, they both have two washers, he said he reduces detent tension in that spot (that was second hand, but from a reliable source). I didn't look at the parts diagram until recently to see that the OEM cylinder has two washers...so that's not it.

canyncarvr wrote:
I've not been helping keeping threads centered lately. I will do better...

Brad - Please stay off your "Centering Meds" I enjoy your wit and humor and writing style - one of the prime reasons that I log onto this site!! I'm not kidding either!!

Get a room already!


Couldn't resist!

I talked to Jeff a few weeks ago about removing the spring and ball and he said he had worked with that a while ago and didn't find any real gains. I noticed without the ball and spring that the center power valve will not stay in place with the slop in the system so the ball and spring force it to stay closed until made open. I think you may give up some bottom end if you remove it.

You likely will give up some bottom end if the valve opens early.

For peeps thinking that the KDX has too much/or not enough - coming on the pipe hit, though; this may be worth fooling with.

Seems like it would be easy to remove a washer and retest and then install an additional washer and retest seeing if either change is better for you. I assume if you go with a earlier opening KIPS you may need to jet slightly richer in that particular range to compensate for the earlier opening of the power valve.

FWIW - On the KTMs changes in the power valve spring preload can make a noticeable difference.

No one said 'remove it'. I said do not remove it.

That may be somewhat of a btw, but the title of the thread refers to reduction in pressure, not removal of the spring/detent altogether.

A question I've asked but not gotten a reply to: For anyone that's looked, what is relationship of the spring to the 'holder' (bolt) when you take the bolt out? Even with end of the bolt? Somewhat inside? Outside?

..for anyone that checks...don't loose the detent ball! Best to take the slotted cover off to see what's going on if you take the detent bolt out.

Considering the spring that Kaw used in their kicker (useless..it coil binds with about two seconds of use), this spring may not be any better.

Another thing to consider. Instead of differently shimming the existing spring (if the spring is junk especially) replace the spring itself. Use differently tensioned springs (different spring rates) and see if you like it.

Just because the KIPS opens at 6K (advertised) doesn't mean the system won't work better at 5500..and that activation threshold does not necessarily mean you would lose a single bit of bottom end.

Another debunk maybe to the 'stock is always best' point of view of some..

IdahoCharley wrote:
. . . FWIW - On the KTMs changes in the power valve spring preload can make a noticeable difference.

There's quite a bit of discussion around the power valve adjustability with them orange bikes . . . that's why the comment about it being tried before on a KDX caught my eye.

I'd be just as interested in what adjusting the opening at a higher RPM would "feel" like - more BOOM maybe ?! And maybe with some needle changes just to see . . .