95 KDX 200 hits the rev limiter about half way FIXED!!!

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tommyd
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95 KDX 200 hits the rev limiter about half way FIXED!!!

Post by tommyd »

I rode my KDX out in the desert for the first time yesterday! Whoo hoo! Fun bike!

Once it was warmed up it would run just like I was on the rev limiter right about the time I hit the sweet spot where the engine would normally make the best power. I've never hit the limiter on a KDX but I have on other bikes and that's exactly what it seems like. It will really rip until it gets good and warm and it's still rideable after that as long as you like putting on boring fire roads at low RPMs. I have a KLR so I already have one machine for that kind of nonsense...

I bought this bike from a friend who told me about this problem. I need to call him to find out what he's done to try and figure it out since I've had it in storage for three years and can't remember.

Has anyone ever experienced this? Any ideas?

I was telling a friend of mine about this who was a bike mechanic for many years. Before I finished my story he interrupted and said that KDXs are known for that and many had bad stators. I did a search on here and couldn't find a single thread about this problem. He is kinda old. Maybe it was an old air cooled model that no one talks about any more?
Last edited by tommyd on 11:46 pm Aug 05 2009, edited 1 time in total.
IdahoCharley
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Post by IdahoCharley »

No rev limiter on the KDX 2 stroke bikes. If it does not rev "out" it could be main jetting too rich, power valve not opening like it should (stripped teeth problems or crud not allowing subports to open), or a choked (plugged with carbon) up sliencer, or obstructions in exhaust pipe. Or it may simply be down on compression or timing incorrect and needs some TLC.

Suggest you check the compression, check for activation of your power valve and take a look at your what jetting is currently in the carburator.

Then let us know what you have found and also let us know if you are running a stock pipe or a aftermarket pipe . (Stock pipes do limit the upper rpm range to a lower rpm than do aftermarket pipes.) If you perform these initial actions we can likely help you better.

Performing a search of this site using terms such as 'power valve" cleaning or problem or activation or 'jetting' or 'exhaust' or should get you started. 'Compression reading' or such will likely yield some helpful hits.

P.S. Don't knock the old guys ".... He is kinda old...." or you will not much help from some of us on this board :evil: :twisted: :roll: . Think of them as guys will years of knowledge and always remember you may just be getting what you paid for.... :lol: :mrgreen: Plus one day if you are lucky someone may refer to you as ... he's a old fart but knowledgable... or something similar.. :wink:
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Post by tommyd »

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IdahoCharley wrote:
P.S. Don't knock the old guys ".... He is kinda old...." or you will not much help from some of us on this board :evil: :twisted: :roll: . Think of them as guys will years of knowledge and always remember you may just be getting what you paid for.... :lol: :mrgreen: Plus one day if you are lucky someone may refer to you as ... he's a old fart but knowledgable... or something similar.. :wink:
I shoulda said he's been around a long time but hasn't worked as a bike mechanic for some time and might not be familiar with newer bikes. I'm not exactly a kid myself so I should have known better...

Yeah, I have some sorting to do on this bike but that's ok. It's was a lot of fun not running right so I won't take it for granted when I get it figure it out.
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Post by tommyd »

I talked to the previous owner and our knowledgeable friend who did most of the work to it after he bought it. They took the KIPS apart, cleaned, and retimed it. I guess someone had it apart and put it back together wrong. They rebuilt the carb (I cleaned it too) and it runs great until just past 1/3 to 1/2 of it's RPM range once it's good and warm.

MY friend who worked on it thinks it's definitely ignition and I think so too. I read up in the shop manual and everything seems easy to test with a multimeter except the CDI has a warning about certain multimeters. Has anyone blown one up testing it or successfully tested one with a multimeter?

I want to change the plug wire because it's old and cheap. Should I use an OEM one or is there something better in the aftermarket?
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Post by canyncarvr »

Caveat emptor. I'm an old fart.

KDXs don't generally fail in the spark generation (exciter coil) control (so-called CDI box) or output (ignition coil) areas. I'm not sayin' never...but rarely. They are NOT 'known' for having 'many bad stators'.

Comments like, 'Once it was warmed up it would run just like I was on the rev limiter..' and 'It will really rip until it gets good and warm..' do sound symptomatic of an exciter coil...or may be just too rich like IC already said.

Does it start from cold-iron (dead cold...overnight cold) without the choke? Once started, does pulling the choke make a difference? The choke plunger might be leaking fuel.

I don't read that you changed the plug. Certainly that's the first step..cheap and easy.

I don't know the PO..and I'm not bashing anybody, but the way to know that <something> is right is for you to check it...considering that YOU know what's right.

I know of no instance that a multimeter blew up a KDX ignition box...but that's 'cuz riders don't generally mess with 'em. They work fine for a long time. The BEST way to 'test' an ignition box is to swap it out with a known good one, or put YOURs into another KDX.

There are a good number of things that might be at the root of the problem. An overoiled air filter is one. A cracked main jet from someone getting too rowdy with a wrench is another.

Replacement plug wires? There's another item that isn't replaced very often. I don't have an opinion on that matter...having never replaced a KDX wire/cap, but I'd lean toward an OEM part because I know it's worked well for me..and I know some aftermarket stuff is problematic (not too good a fit with the existing stuff) on other machines I've replaced wires on.

Start with the basics (replace the plug, check the air filter), go from there.

To be clear...'hits the rev limiter' means you have the throttle open, but the bike is blubbering? As opposed to being at cruising speed in high gear with the throttle just cracked?

Those are two completely different issues.

I recall awhile back a KDX-er had a problem with the bike running similar to what you have. He found a mouse nest in the exhaust!

'Scuse me...but it's time for my medication and a nap. Ooopsie! :oops: I need a new Depends, too..........

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Post by tommyd »

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canyncarvr wrote: KDXs don't generally fail in the spark generation (exciter coil) control (so-called CDI box) or output (ignition coil) areas. I'm not sayin' never...but rarely. They are NOT 'known' for having 'many bad stators'.
Yeah that's the conclusion I came to after the multiple searches I did with different key words.
canyncarvr wrote: Does it start from cold-iron (dead cold...overnight cold) without the choke? Once started, does pulling the choke make a difference? The choke plunger might be leaking fuel.
Even in 108o temps it needs the choke but not for very long. If I pull the choke while it's running it will stall immediately.
canyncarvr wrote:I don't read that you changed the plug. Certainly that's the first step..cheap and easy.
The PO changed the plug and it looked very new/clean. I cleaned and gapped it anyway. I live in a small town and I couldn't locate one on a Saturday afternoon. It runs very good before it acts up.
canyncarvr wrote:I don't know the PO..and I'm not bashing anybody, but the way to know that <something> is right is for you to check it...considering that YOU know what's right.
I trust the POs abilities but especially the friend who helped him. They are both professional mechanics and the friend has a lot of bike experience.
canyncarvr wrote: The BEST way to 'test' an ignition box is to swap it out with a known good one, or put YOURs into another KDX.
Yeah I need to find someone willing to let me do that. The ignition coil and wire are reasonably cheap and I wouldn't mind having the old ones as spares since breaking down in the desert is sometimes fatal. The CDI is a bit pricey so I'm not quite ready to throw parts at it in that price range just yet.
canyncarvr wrote:There are a good number of things that might be at the root of the problem. An overoiled air filter is one. A cracked main jet from someone getting too rowdy with a wrench is another.
I checked the air filter when I first got this bike some years ago. Strangely enough it fell apart in the areas that were glued. I started it like that before I noticed it. I replaced it with a Uni Filter.
canyncarvr wrote: I don't have an opinion on that matter, but I'd lean toward an OEM part because I know it's worked well for me..and I know some aftermarket stuff is problematic (not too good a fit with the existing stuff) on other machines I've replaced wires on.
Good...OEM it is then!

canyncarvr wrote:To be clear...'hits the rev limiter' means you have the throttle open, but the bike is blubbering? As opposed to being at cruising speed in high gear with the throttle just cracked?
It runs fine at cruising speed with the throttle cracked. If you then hit the throttle it just does nothing. It doesn't blubber , bog, or anything. I think being in gear is the only thing keeping it running. And then it makes that steady PANG PANG PANG like a bike does when it has nothing left or like a street bike does when it hits the rev limiter. Even if you give it light throttle up to the same RPM it does the same thing.


canyncarvr wrote:I recall awhile back a KDX-er had a problem with the bike running similar to what you have. He found a mouse nest in the exhaust!
I've checked the exhaust (trying to find the rattle I mentioned in another post) and all the basic stuff. I might look at the carb again just to make double sure everything looks good and to see what jets are in it.

The PO and friend tried all of the basics and then he ordered a manual. By the time the manual came in he already put the bike away and started messing with some jet skis he bought at auction around the same time. Summer arrived and he lost interest so he never tested any of the electrical components other than checking for obvious wiring problems/connections. I think I will start with that and a new plug/wire. It is very hot and dry here so things like plug wires have a short life.
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Post by canyncarvr »

Re: 'And then it makes that steady PANG PANG PANG like a bike does when it has nothing left or like a street bike does when it hits the rev limiter.'

A decent rev-limiter won't misfire..which is what my guess is you're 'splaining. It will simply drop plug fires evenly..the bike will blubber/bobble..no backfires. I don't unnerstan how '..It doesn't blubber , bog, or anything.' relates to a rev limit function.

There is an old rule (I know it 'cuz...why? Yeah..I'm old): Fix what you know is broke.

That rule will hold you in good stead a whole lott'a times. Especially true when you're dealing with something odd (PANG PANG PANG), when you find something not right, take care of it. You will be surprised how often thing 'A' being wrong will effect/cause thing '2' to show up...the 'A' and the '2' not seeming to have ANYthing to do with each other.

You know the silencer is broke. You know you're going to get another one..so GET one. If the bike still acts up after you get a working unit bolted up, then fuss with what's left.

Good luck!

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Post by zz3gmc »

I had a similar problem with my old 92 KDX200, it ran ok off of the bottom but was weak in the mid to top. After replacing the stator and CDI, both with no results, I found that the silencer core broke and dropped down, blocking the flow of exhaust. I fixed the core and fixed the problem. Had the same problem on my fiance' 00 CR250, it would overheat quickly while racing a enduro. It still had good lowend but was very muted in the midrange on up. Core broke. Put your hand behind the silencer and rev it, you should feel a pretty good pulse or blast of exhaust, if not, take a look at the silencer, especially since its rattling.
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Post by canyncarvr »

If this problem is the silencer...I want a Kewpie doll or sumthin'.... :wink:

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Post by JimmyB »

Could it be whatever is rattling around(either the core or other object)in the silencer at higher rpm is restricting the output flow or creating to much backpressure.
Any chance you can test(borrow)a different silencer for a test run..
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Post by canyncarvr »

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Indawoods wrote:I will make you a "Golden Years Member" :wink:
Does that come with a box of 'extended wear' diapers? :neutral:

Re: 'Could it be whatever is rattling around(either the core or other object)in the silencer at higher rpm is restricting the output flow or creating to much backpressure.'

That's the subject de'joor...under the 'Fix what you know is broke.' axiom.

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Post by bcdonyo »

Hey Tom, if you want me to pull off my silencer for you to try let me know. At least it could rule out that possibility-Don
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Post by canyncarvr »

Well th'ar 'ya go. The KDX community in action.

Good deal!

:pop:

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Post by tommyd »

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bcdonyo wrote:Hey Tom, if you want me to pull off my silencer for you to try let me know. At least it could rule out that possibility-Don
Don, that would be awesome! I'll get your number from Kelly if that's alright.

Now that you mention it, it seems like I got it past that point a couple times, both times leaned over on a berm. Maybe whatever is broken in there moved out of the way just enough to let it blow through...

I just rode my KLR in the sand and gravel and it's got me ready for something nimble and light.


If I didn't think it would piss off the whole neighborhood that me and my dad grew up in I would be out there revvin it with my hand behind it right now!

CC, I wouldn't know where to get a Kewpie doll in this day and age but I would owe you fer sure!
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Post by canyncarvr »

If I didn't think it would piss off the whole neighborhood that me and my dad grew up in I would be out there revvin it with my hand behind it right now!
HIT IT!!

..I can't hear a thing! (but...that's because I'm...what? Oh yeah. I rememmer!!! OLD!!!) It ain't even midnight, yet!

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Re: '..wouldn't know where...'

:hmm:

Let Google be your guide:
Google wrote:Results 1 - 10 of about 186,000 for kewpie dolls for sale. (0.21 seconds)

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Post by tommyd »

Bought a stock silencer on the Bay...

Like you said I need one anyway. I won't get to mess with this until the weekend at the earliest. It's supposed to be 111o today anyway.
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Post by KarlP »

I hope it is your silencer. I had a plugged one once, and I'm not very old.

I had been getting faster and faster on my bike until even at full throttle it could not keep up with my abilities. I decided I needed to send my head and carb off to this well known fella who could fix them up so I could get more power to go along with my new abilities. When I got the carb and head back I put them on the bike.

It did not run very well. It just would not rev out.

I got that fine fella on the phone on a Sunday afternoon. He asked a few questions, listened to it run over the phone, had me pull the seat off for some reason, and asked about the smoke coming out the exhaust. I told him it looked about like cigarette smoke coming off the end of a cigarette.

I think we both came to the same conclusion at the same time. Luckily I had a spare silencer.

All I got to offer is my experience. I have no idea what is wrong with YOUR bike. :lol:
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Post by tommyd »

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canyncarvr wrote:If this problem is the silencer...I want a Kewpie doll or sumthin'.... :wink:
I owe you one Kewpie Doll AND Sumthin...

I rode it around with no silencer today and she ran like a bat out of hell!

Thanks for all the help everyone! I was thinking I would spend a bunch of money on electronics getting this thing running. The price of one slightly used silencer and I'm riding this SUCKA!!!

Thanks again! If any of ya come through Vegas the beers are on me!
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