More Bottom end for a KDX200

NCFRC · May 20, 2009

Any suggestions how to get better bottom end out of a 200 ?

Even with a torque pipe , torque ring and higher compression ratio
it has only good midrange and topend.

Maybe the KIPS isn't working properly ?

The 220 we have runs great low , mid and top ,,,, if I could get a 220 top end reasonable I'd swap it over in a heartbeat.

Thanks for any suggestions

sr5bidder · May 20, 2009

yeah maybe you can check it out..the kips

julien_d · May 20, 2009

220 is even more torquey than the 200 just by design, but the 200 has legendary torque anyway. I would try removing the torque ring. I found it killed the performance on my 200. And yes, definitely check the kips for proper operation.

porterdog · May 20, 2009

If you're too rich on your pilot you could be sacrificing power.

I came to the KDX from an XR400 (tractor) and an XR650R (100 mph tractor), and the only time I could complain about the KDX's torque (mine's an '06) was after I put the Rev pipe on. (Fredette torque ring took care of that)

Agree with the others, either there's something wrong with your bike, or your expectations are unreasonable :)

G. Gearloose · May 20, 2009

Set the air screw for best off-idle response under load, not highest idle.
Jet the bike right and consider a different needle.
After that, learn to slip the clutch.

NCFRC · May 20, 2009

julien_d said:
220 is even more torquey than the 200 just by design, but the 200 has legendary torque anyway. I would try removing the torque ring. I found it killed the performance on my 200. And yes, definitely check the kips for proper operation.

Were you using the torque ring with an FMF woods " torque pipe "

That's what we're running.

I'll take the kips apart this weekend ,,, I think it runs more like a 125 on the bottom and it hits hard at mid-throttle .

julien_d · May 20, 2009

I was using a modified stock pipe. Performance wise it should be pretty close to a woods pipe. I switched to a DG but have not tried the torque ring since switching. I don't want to change anything, it's perfect :D.

Have you checked on the reeds? If they are stock and you haven't replaced them, throw some boyesen 607's in. That will help the low end response considerably and you won't lose any top.

What do you mean by "higher compression ratio"? What have you done to increase compression?

NCFRC · May 20, 2009

Yes , it has 607 reeds .

The head was planed .015 to up the compression 1 ratio .

I hope I find something in the Kips is broken

glad2ride · May 21, 2009

Did you have the head combustion shape changed any, or just had it lowered?

Did you do any other changes when you modified the head?

julien_d · May 21, 2009

If the kips were staying open you would have good mid/top and no low end, much like a 125. I hope you find your problem there. If not, then I would double check the compression and make sure it's where you think it is. It could be a jetting issue as well. Either too rich or too lean on the pilot/needle jet.

theckeler · May 21, 2009

Little off topic, but how does one check to make sure your KIPS is working correctly. I cleaned mine all out and checked it when I did my top end, of course it wasn't running, but wondering if your able to check it when running?

julien_d · May 21, 2009

Pull the plastic cover on the RH side and watch the actuating rod get pulled out when you throttle it. If anything is broken or not moving that arm will quite likely get hung up.

theckeler · May 21, 2009

julien_d said:
Pull the plastic cover on the RH side and watch the actuating rod get pulled out when you throttle it. If anything is broken or not moving that arm will quite likely get hung up.

Cool thanks, guess I could have figured that out, makes sense... just didn't know if you could pull covers like that while running.

julien_d · May 21, 2009

The engine can be ran with the RH cover removed. It's just a dust shield really. It's a pain to get off with the pipe in the way though.

NCFRC · May 21, 2009

julien_d said:
If the kips were staying open you would have good mid/top and no low end, much like a 125. I hope you find your problem there. If not, then I would double check the compression and make sure it's where you think it is. It could be a jetting issue as well. Either too rich or too lean on the pilot/needle jet.

I had some time this afternoon and pulled the cover off where the Kips shaft gear contacts the exhaust port shaft . Yes , I removed the exhaust to make it easier. What I found was the shaft tension wasn't holding the exhaust port completely closed. I gently twisted the shaft with a pair of pliers and it had good spring tension so I assume the lower part of the shaft is connected properly.

I moved the shaft half moon gear one tooth ahead on the port shaft and it now holds the exhaust port nice and tightly closed.

I had the top end off this winter and I thought it was tight but maybe I didn't check it close enough. The other strange think is I don't think it had this bad a low end when we first got it out.

After reassembling , the bottom is back and the power is much smoother , no abrupt hit , which made it terrible for trail riding.

Is there any way the shaft can be slipping on the bottom ?

NCFRC · May 21, 2009

glad2ride said:
Did you have the head combustion shape changed any, or just had it lowered?

Did you do any other changes when you modified the head?

Maybe not textbook correct but I polished the combustion chamber for better flame travel and had a machine shop friend plane .015 off it. Yes , I just lowered it and didn't reshape the squish chamber

mudpack · May 22, 2009

NCFRC said:
Maybe not textbook correct but I polished the combustion chamber for better flame travel

Interesting. In what way is it better than it was pre-polish?

Mud

NCFRC · May 22, 2009

NCFRC said:
I had some time this afternoon and pulled the cover off where the Kips shaft gear contacts the exhaust port shaft . Yes , I removed the exhaust to make it easier. What I found was the shaft tension wasn't holding the exhaust port completely closed. I gently turned the shaft with a pair of pliers and it had good spring tension so I assume the lower part of the shaft is connected properly.

I moved the shaft half moon gear one tooth ahead on the port shaft and it now holds the exhaust port nice and tightly closed.

I had the top end off this winter and I thought it was tight but maybe I didn't check it close enough. The other strange think is I don't think it had this bad a low end when we first got it out.

After reassembling , the bottom is back and the power is much smoother , no abrupt hit , which made it terrible for trail riding.

Is there any way the shaft can be slipping on the bottom ?

Any thoughts on this ?

NCFRC · May 22, 2009

mudpack said:
Interesting. In what way is it better than it was pre-polish?

Mud

A couple things ,,, pre-polish the combustion chamber is fairly rough like it was sand cast ,, so polishing it with emery paper prevents any carbon build up and the flame travel from the ignition point is more efficient.

Just a small thing that adds to much bigger overall increase .

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