Couple of ?'s from a newbie

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Oct 15, 2007
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#1
How are you all doing today? Glad to hear..

I haven't owned a bike in about 15 years (91 CR125)I have ridden other people's toys once in awhile since then. I am unsure how to judge the performance of this particular bike.

I just bought a 1989 KDX200. Starts up first kick hot or cold. Brand new tires, plastic is decent. All in all seems to be in good shape. I have 2 questions.

1) The front shocks: They seem really soft. If i romp the throttle they jump alllll the way up. and go alllll the way down when applying the brakes or taking a corner. The rear end kicks out on soft sand when cornering. If i'm sitting on the bike and lean forward with weight, the shocks bottom out. Are the shocks gone or are they supposed to be that soft?

2) PowerBand: I know this bike isn't like a MX, but i am not sure how the bike is supposed to react. 1st gear take off it feels like it's loading up, shift get a burst of energy then feels like it's loading up, shift to 3rd get a burst then same thing. It's like you can't ride a gear. The sweet spot only seems to happen when in a low RPM. On a take-off i have the shift into 3rd before i start getting the power going a little and then in 4th it kicks in nice. Is this how it is supposed to be?
 
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Nov 22, 2006
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#2
You will love the bike. Hard to tell about your front forks but they are very soft. Go to KDX rider.net. You might want to consider getting USD\Inverted forks. Most guys get KX forks and then mount. Read on this website plus KDX rider.net for info on how to upgrage the forks.

As far as your power band is concerned - that is the nature of the KDX. Low end torque prettly flat upper power band. However, you can improve the power band by getting a FMF Rev Pipe. Also, read about Ron Black or RB Designs mods. He can port the top of your head for more performance. They are great bikes. Just need to do a few things to bring out its potential. I have 2 kdxs and love them both. Good luck
 

G. Gearloose

Pigment of ur imagination
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#4
Don't need a pipe yet. Open the airbox and research how to jet it.

my '91 was so factory rich it couldn't rev high enough to open the powervalve, long since remedied.


You need stiffer fork springs. '89 was one of the soggiest years, next to mine, .29 or so. Even some '95 -'06 take-offs .34's would be a marked improvement.

You can jet and replace the forks springs for under $100
 
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#5
Thanks for the pointers. After doing a lot of reading, it seems it's best for me to convert my forks. I found a set on **** from a 91 KX 125 . These will do the trick right? Has the forks,triple and stem. Will i need anything else?

I took off the seat and somebody already cut the top off the airbox :cool: I was fiddling around and noticed that the fuel line going from the valve to the carb was tucked under the overflow line, causing a kink right where it comes out of the valve. I took the line off and moved it over the overflow. It seems to have a little better response. The fuel line was dam near crimped.
 
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#6
To answer your points:
1) Although the kdx forks are soft and stiffer springs will help, maybe check oil levels and seals 1st, they shouldn't be bottoming out the way you explained.

2) If you have a std pipe, toss it away, fit an FMF desert Gnarly, toss away the airbox lid and rejet, next step is a decent set of reeds, this will immediately sharpen throttle response and let the bike rev out (MUCH) better.

cheers
 
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#7
AwfulSmokey, do you have any idea on when the forks were last rebuilt, oil changed, current spring rate?

I would suggest a full rebuild of the forks and shock, with fresh oil and install the correct rate (stiffness) springs for your weight / type of terrain you ride / skill level.

If you get the 1991 KX forks, you will need the complete front end, which means buying the front wheel, rotor, axle, brake caliper, brake line, master cylinder, fork guards, forks, triple clamps and all the bolts and such. Unless it is a miracle, your e-Bay purchase of used forks will need a full rebuild, fresh oil and the correct rate fork springs. Don't forget a revalve to make the MX forks into trail riding forks. 17 year old forks aren't going to be in much better shape than 19 year old forks.

On the power, check all the standard things (start with buying the service manual)

air filter in good condition, properly cleaned and oiled
reeds in good condition
timing set within normal range
correct spark plug (heat range and gap)
power valve system properly working
exhaust sytem not clogged, properly sealed
carburetor properly jetted
rings / piston / cylinder / crankshaft within service limits

For all the people recommending him to buy a new pipe, please consider that maybe more information is needed about the engine condition before slapping on a shiny new pipe??

Also, for the 1989 - 1994 KDX200's, there is only ONE model of FMF exhaust pipe, so no need to confuse him with Desert / Rev / Woods / Torque / Fatty / Gnarly.

His engine is not running properly, and slapping on a $225 new pipe on a poorly running engine won't be much help.
 
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#8
I have no idea what the bike has had done to it. I was playing around today in the backyard and noticed that the front isn't actually that bad. I live on 5 acres of sand (SW Florida)has grass and bumpy. The bike absorbs all the bumps nicely. I just don't like the feeling of cutting a corner in sand, especially when the elevation is going against you.

The forks don't bottom out as i originally thought. They just seem soft. Would it be worth re-doing the original forks for a temporary fix or just wait and get KX forks?
I have found a set of 95 KX250 forks for $50. Do the 250 forks work and does the year matter at all? Newer the better?

I just want to end up with a bike i can hop on and go riding whenever i feel like it. I don't need a brand new machine,just want one that works. I would fix the forks i have now. if they would still be sub-par, i would definitely want to do the switch.
 
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Oct 17, 2007
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#9
I have a question, i just recently recieved a KDX 175 from my neighbor and i am not sure what year the bike is, i know it is an 80,81, or 82 but i was wondering where i could go or how i could distinguish which year it is? (i'm in need of some parts)
 
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#10
KDXXX175 said:
I have a question, i just recently recieved a KDX 175 from my neighbor and i am not sure what year the bike is, i know it is an 80,81, or 82 but i was wondering where i could go or how i could distinguish which year it is? (i'm in need of some parts)
Start a new thread and someone will be glad to help, don't hijack this one.
 
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#11
AwfulSmokey said:
2) PowerBand: I know this bike isn't like a MX, but i am not sure how the bike is supposed to react. 1st gear take off it feels like it's loading up, shift get a burst of energy then feels like it's loading up, shift to 3rd get a burst then same thing. It's like you can't ride a gear. The sweet spot only seems to happen when in a low RPM. On a take-off i have the shift into 3rd before i start getting the power going a little and then in 4th it kicks in nice. Is this how it is supposed to be?
Sounds like your power valve is stuck closed. Order a manual, do a top end, clean the power valve etc., then start tearing up your 5 acres. You'll find a lot of people dissing these bikes but If they are tuned right you can have a lot of fun keeping the front wheel moving vertically.
 
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#12
These symptoms you describe... feeling like the bike wont really try to pull until 3rd or 4th gear... I have a silly question. Are you giving enough time for the engine to warm up before you're trying to honk on it to assess it's strength?

I'm only bothering to ask because virtually every other 2-stroke I've ever owned you needed to put around near campsite for a good 3-to-5 minutes getting up to like 3rd or so and letting her warm up before it would even let 1st or 2nd try to begin winding-out up high.

Only other reason I bother to ask is because you had said it's been awhile since you last rode.