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KDX power flat.

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So, the SIL bought a '97 KDX220 and after tire replacement, levers, skid plate, etc., we finally got it running tonight.  I rode it around the neighborhood to test it out  I thought the power felt fine until between 5k & 6k rpm and REALLY flattened out.  Since I've never ridden a KDX before and know nothing about them, I'm not sure if it's a problem or not.  I was thinking maybe I'm used to my YZ giving a kick in the pants at those rpm's so I'm not sure if it's normal or not.  I was even thinking maybe it's really a gnarly pipe on it and not the OE.  That's kind of the way my YZ felt with a gnarly.  I didn't like it!  Power valve not working correctly?  Anyone got any ideas?

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I would bet the KIPS valves are gummed up. Cleaning will involve taking the top end apart. Do you know if the bike still has the stock piston? If it hasn't been changed out for a Wiseco, it will be a ticking time bomb waiting to grenade itself into little pieces. My stock piston had cracks on the skirt that looked like it could go at any time. Might be a good excuse to do a top end rebuild and clean the KIPS real well. 

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Too lean on the main? 

 

Edited by crypto666
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I don't think the PO did any changes to the bike.  And the pipe on it IS a Kawasaki pipe with that little note they have on the side about noise levels, etc.  I suspect it IS the stock piston too.  Yes, it could be time for a top end job and cleaning the power valve.  I'm sure he will be thrilled to hear that.  Is it a plated bore?

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Yes, it has a plated cylinder. If it has the stock piston please replace it ASAP.

The 220 doesn't have the kick typical of most 2T's. It is a much flatter power delivery. Stock jetting was very rich. You should definitely find out what's in there and jet it accordingly. That alone can make a very noticeable difference in power and fuel economy. Upgrading to an FMF desert pipe, a 35mm PWK (or RB 36mm!), an RB modified head, along with air box mods, and it will wake the bike up significantly.

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The 220 is a torqu monster when tuned right. Pull the pipe off take the power cover off. And check the power valve arm. Also after that put the pipe back on and leave the cover off. Go on the left side of the cylinder. Look and u will c a flat way cap. Take that out and start the bike. And give her a rev and u should c the the dots on the gear move. If not there either stuck or the power valve paw behind the inner clutch cover is broke. If your good there. Remove the fly wheel cover and remove the mag and look at the stator. The mag has 3 marks. There are 3 marks on the stator plate for timing. Check those first and 2nd mark is mild 3rd mark is for wild. Also inspect the reeds. The kdx is a bitch to get the jetting right. I run a 42 pilot and 148 main. Just right for me at 40:1 mix. Also check your needle clip position. If your running stick pipe and silencer. Ditch that boat anchor.

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9 hours ago, SS109 said:

Yes, it has a plated cylinder. If it has the stock piston please replace it ASAP.

The 220 doesn't have the kick typical of most 2T's. It is a much flatter power delivery. Stock jetting was very rich. You should definitely find out what's in there and jet it accordingly. That alone can make a very noticeable difference in power and fuel economy. Upgrading to an FMF desert pipe, a 35mm PWK (or RB 36mm!), an RB modified head, along with air box mods, and it will wake the bike up significantly.

I'm sure it could use a top end job.  I'm still not positive the "hit" is normal or not, especially after reading your comment.  I had never ridden one before so I didn't know what to expect from it.  I KNOW what a YZ feels like for that seat of the pants feel.  I think we'll pull that small cover off the side and see if it rotates when revved up.

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Yea it's not goin to hit like a yz or cr. But it should pull power wheelie in 3rd at least.

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It will never hit like a yz.

It should be very noticeable when the power valve opens though. If the power valve is stuck (carbon) it will run poorly at the top or the bottom, but not both.

Burn your pipe out also

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Pitch the stock pipe, clean power valves, remove the air lid under the seat and re-jet. Huge difference, I used to smoke guys on a newer KX250's in the tight trees and sand washes. That was on a KDX200.

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Ok, we all put some time on the KDX.  I also checked out that inspection cover for the power valve shaft to see if it's moving.  Yup, it was turning although it seemed to need a lot of revs before it started to turn.  It still seems a little soft with the power.  He even had trouble making it up some smaller hills. This situation may have 2 causes.  One, the power valve linkage may be working but sluggish because of carbon.  Next, I'm thinking it may be top end time.  Does anyone have a ballpark of what the compression should be? I'll check it and see where we are.  Other than that, the SIL enjoyed riding it,  although it spooged like crazy.  He mixed it at 32-1 like the manual says with Amsoil Interceptor.  I think I''ll suggest 36-1.

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Run Interceptor at 50:1 and jet it correctly. The power will be much improved.

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On 5/30/2017 at 3:41 PM, motoxvet said:

Ok, we all put some time on the KDX.  I also checked out that inspection cover for the power valve shaft to see if it's moving.  Yup, it was turning although it seemed to need a lot of revs before it started to turn.  It still seems a little soft with the power.  He even had trouble making it up some smaller hills. This situation may have 2 causes.  One, the power valve linkage may be working but sluggish because of carbon.  Next, I'm thinking it may be top end time.  Does anyone have a ballpark of what the compression should be? I'll check it and see where we are.  Other than that, the SIL enjoyed riding it,  although it spooged like crazy.  He mixed it at 32-1 like the manual says with Amsoil Interceptor.  I think I''ll suggest 36-1.

the manual is PDF format and will give you service limits for piston/cylinder size along with compression numbers. 

 

the oil you're sending out the tail pipe doesnt matter, but the jetting sure does

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16 minutes ago, ohgood said:

the manual is PDF format and will give you service limits for piston/cylinder size along with compression numbers. 

 

the oil you're sending out the tail pipe doesnt matter, but the jetting sure does

It actually spooged enough to spit down on the rear rotor and get a little on the pads.  Not sure if he was able to save the pads or not.  I was kind of surprised at this because I'm sure it's stock jetting and he was riding it moderately hard.

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Stock jetting on those is way too rich.

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On 5/30/2017 at 1:41 PM, motoxvet said:

Ok, we all put some time on the KDX.  I also checked out that inspection cover for the power valve shaft to see if it's moving.  Yup, it was turning although it seemed to need a lot of revs before it started to turn.  It still seems a little soft with the power.  He even had trouble making it up some smaller hills. This situation may have 2 causes.  One, the power valve linkage may be working but sluggish because of carbon.  Next, I'm thinking it may be top end time.  Does anyone have a ballpark of what the compression should be? I'll check it and see where we are.  Other than that, the SIL enjoyed riding it,  although it spooged like crazy.  He mixed it at 32-1 like the manual says with Amsoil Interceptor.  I think I''ll suggest 36-1.

Definitely get the service manual. It states 95 to 151psi is normal.

Don't try to fix spooge my changing mix ratio. You can run 16:1 and not spooge if the jetting is right. Your lack of power could very likely be nothing more than pig rich jetting.

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13 hours ago, motoxvet said:

It actually spooged enough to spit down on the rear rotor and get a little on the pads.  Not sure if he was able to save the pads or not.  I was kind of surprised at this because I'm sure it's stock jetting and he was riding it moderately hard.

rejet it. it will run much better and have no excess oil out the pipe. oil ratio has nothing to do with spooge

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Just now, ohgood said:

rejet it. it will run much better and have no excess oil out the pipe. oil ratio has nothing to do with spooge

Yeah, I know that's the way it works.  Just frustration.  This has happened to me before after recommending Amsoil Interceptor for a pre-mix oil.  Even on my YZ, that never had the problem before, all of a sudden is spitting out oil and under identical conditions and use.  I have no doubt it's a good oil.  I just wish I remembered all those spooge threads I've read in the past.  The designed in oil characteristics are involved in spooging too, not just jetting - Correct?

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The silencer packing might need to be replaced. And, like mentioned above, yank that air box lid off.

The 220 has a smaller carburetor bore than the 200, supposedly to aid in bottom end. They like to be short shifted.

You can also send the carb to Jeff Fredette, the KDX guru, and have it bored 3mm larger, and have him port the cylinder, to give it more top end pull.

http://www.frpoffroad.com/

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I could tell when I first the first test ride, it liked to be short shifted.  It really flattened out which is why I wondered about the power valve but apparently it IS working.  Regarding the silencer, I just glanced at the OE silencer but I didn't see a way to take the thing apart !?!?!?

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