Power loss in the middle - '05 KDX220

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Power loss in the middle - '05 KDX220

Post by ack »

I'm pretty new to all this and not very technical, but I've been trying to figure out a problem I have with my KDX220. I am losing power in the middle of the throttle range (that might not make much technical sense, but I'll try to explain).

Off the line, the pull is good. If I stay on the throttle, the power flattens out, then once it gets up in the high rev range, it seems to come to life again. It doesn't bog in the middle, it just stays flat.

Specs:
2005 KDX220R - bone stock.
I put a new Wiseco Std. Bore Piston Kit (all gaskets, rings, pistons, etc.) about 20 hours ago. Since then, it starts 1st or 2nd kick every time.

Carb: Keihin PWK33 (stock)
Main Jet: 145
Pilot: 42
Needle: R1173L (#5 slide) - Clip at 3rd position
Air Mixture Screw: -1.5 turns out
Airbox Snorkel is removed.

Spark Plug: NGK BR8ES (gapped @ .7-.8)
Gearing: 13/49
PreMix: Redline @ 40:1 or AmsOil Dominator @ 50:1
I ride mostly trails at Sea Level - 2000 ft.

This issue happens regardless of altitude.
New mods (today): FMF Gnarly "Desert"/PowerCore2 (sounds great and has a bit more low-end torque).

If anyone can steer me in the right direction to get this flat spot out, that would be greatly appreciated. For a while I was thinking that this issue might be Jetting Needle/Clip related, but I'd like to read more to better understand.

Thanks!
Steve
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'05 KDX 220, '00 KTM 200 MXC, '04 KLR 650, '03 WR450
Just learnin' and looking to have fun.
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rbates9
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Post by rbates9 »

Try jetting. Might be something screwy with the ignition also.
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gsa102
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Post by gsa102 »

Try adjusting the carb needle down, meaning put the clip one notch higher on the needle so the needle is in a lower position in the carb. Try a couple different settings. The needle is supposed to control the jetting at medium throttle openings, but the pilot could affect it somewhat, too. If it is good on top, the main should be pretty close. Read the jetting guide. :wink:
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Post by Deseret Rider »

I think gsa 102 is on the right track----With a 145 main jet I would try the needle in the first or second notch-----
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Post by ack »

>|<>QBB<
gsa102 wrote:Try adjusting the carb needle down, meaning put the clip one notch higher on the needle so the needle is in a lower position in the carb. Try a couple different settings. The needle is supposed to control the jetting at medium throttle openings, but the pilot could affect it somewhat, too. If it is good on top, the main should be pretty close. Read the jetting guide. :wink:
Thanks for the reply - I'll try this first thing today.
IF moving the clip up helps some, I'll then increase the Main to a 148 and see what happens then.

Thanks.
Steve
Raleigh, NC
'05 KDX 220, '00 KTM 200 MXC, '04 KLR 650, '03 WR450
Just learnin' and looking to have fun.
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Post by ack »

>|<>QBB<
Deseret Rider wrote:I think gsa 102 is on the right track----With a 145 main jet I would try the needle in the first or second notch-----
I will try this step first, thanks.
Steve
Raleigh, NC
'05 KDX 220, '00 KTM 200 MXC, '04 KLR 650, '03 WR450
Just learnin' and looking to have fun.
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Post by Deseret Rider »

Raising the clip leans the mixture across the span of the needles influence----if the bike runs cleanly at open throttle you probably won't need to go to the 148 Main----It doesn't hurt to experiment but that 'flat' spot is probably an indication of too rich a mixture at those throttle positions.
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Post by Deseret Rider »

Raising the clip leans the mixture across the span of the needles influence----if the bike runs cleanly at open throttle you probably won't need to go to the 148 Main----It doesn't hurt to experiment but that 'flat' spot is probably an indication of too rich a mixture at those throttle positions.
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Post by grump99 »

Check your KIPS too. If its sticking, you will get a flat spot before it opens up.
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Post by ack »

OK, here's what I've done, and the results:

- Took the carb off/apart and cleaned it.
- Moved the Clip on the Needle up 1 slot (to #4 - 2nd highest pos)
- Buttoned it back up and rode around
Results: No real discernible change - same flat spot

- Swapped out original 145 Main for a 148 Main
Results: More smoke, same flat spot

- Swapped the 148 Main for the original 145 Main
Results: Doesn't smoke excessively, and still has the flat spot

To me (a complete novice), this is what I've noticed: Off the line (2nd gear), the bike is great...for about 30 feet, then it runs out of ass. It doesn't sputter, but it sounds weak in that mid range.

I just saw a post from grump99 about checking the KIPS - I'll see if I can find some dumbed-down instructions for checking that bad boy.

Thanks again for all the responses.
Steve
Raleigh, NC
'05 KDX 220, '00 KTM 200 MXC, '04 KLR 650, '03 WR450
Just learnin' and looking to have fun.
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Post by Julien D »

There are a couple things to think of when you say "mid range". Is this the middle of the RPM range, or the middle positions on the throttle? If it has a flat feeling at a certain throttle position then it's the jetting. If the flat spot is at a specific spot in the RPM range, regardless of throttle position, then it is likely something else. Clogged silencer, electronics, timing, KIPS, reeds, etc. A good way to test is to make a mark on your throttle housing, and then corrospding marks on the throttle side grip so you can visually identify 1/4, 1/2 and 3/4 throttle. Make thos emarks, and ride keeping the throttle between 0 and the 1/4 mark, then between the 1/4 - 3/4 mark, and finally between the 3/4 to full. If it's jetting, your flat spot will be evident in one of those area's much more so than the others.
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Post by Oregon Trail »

When did this problem start; after the new mods or before that? :hmm:
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Post by ack »

>|<>QBB<
Oregon Trail wrote:When did this problem start; after the new mods or before that? :hmm:
Before.
I guess it's been like this since I picked this up early last year, and I've just been putting around in the woods with it.

The only mod to this bike is the Gnarly/PowerCore2, which was put on yesterday. The new exhaust really accentuates the flat spot.

++++++++++++++++++++++++++++++++
I THINK I may have found an issue.

I unscrewed the PowerValve Cover (circular cover next to the KIPS Cover). With the bike revving, I'm not seeing the PowerValve (if that's what it is) moving at all. On my KTM, I can see the PV moving as I get the motor into the higher revs.
Steve
Raleigh, NC
'05 KDX 220, '00 KTM 200 MXC, '04 KLR 650, '03 WR450
Just learnin' and looking to have fun.
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Post by ack »

Is there a way to check the KIPS and Exhaust Valve assembly for proper movement BEFORE I disassemble it?

I have the CP Manual and it shows how to disassemble the Exhaust Valve, but it doesn't show how to check for proper movement (while it's assembled) or how to troubleshoot the KIPS/EV (unless I missed it somewhere).
Steve
Raleigh, NC
'05 KDX 220, '00 KTM 200 MXC, '04 KLR 650, '03 WR450
Just learnin' and looking to have fun.
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Post by Deseret Rider »

Good question.! Can't you just pull the cover on the right side of the motor and watch the gearing movement ?

When you installed the Wiseco piston did you check to make sure the teeth engagement between the claw gear the the Kips drive went back in the same way as when you took it down? I wonder if that could be the problem? Easy fix if that turns out to be the case.
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Post by rbates9 »

When you changed the piston did you support the KIPS shaft while removing the left hand nut? If you remove the right side cover can you move the shaft the goes into the transmission? Or does it feel like it is still on the governor?

With the right side off you could take the paw looking gear off and look thru the exhaust port and see if things are moving when you turn the gear.
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Post by KarlP »

I unscrewed the PowerValve Cover (circular cover next to the KIPS Cover). With the bike revving, I'm not seeing the PowerValve (if that's what it is) moving at all. On my KTM, I can see the PV moving as I get the motor into the higher revs.
With the motor off you can use 10mm nut driver and the mechanism should move easy.

If you remove the cover on the right side you can see if the claw gear is engaged, as rbates9 said.
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Post by ack »

Thanks to all for the quick and helpful responses - I'll try to look at it today.
To be honest, I remember very little about the KDX when I did the top-end.

I was doing the KDX at the same time I was fighting with the top/bottom ends of the KTM, which gave (and is still giving) me fits.

To make all this worse, my other bike (WR450) just blew a valve cover gasket last weekend (in the mud). Now I have 3 sick bikes.

Ahhh, the joys of ownership!
Steve
Raleigh, NC
'05 KDX 220, '00 KTM 200 MXC, '04 KLR 650, '03 WR450
Just learnin' and looking to have fun.
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Post by paulkdx220 »

Image

refer to item 220 and 92043A on the parts fiche. make sure those are installed... they retain the KIPS shaft and prevent it from migrating upwards and disengaging from the governor. they are easy to miss or lose when doing a top end on the bike because they are so tiny.

item 13236 may be broken as well, happens when nut 92015A is wrenched on and all the force is transmitted to 13236 causing it to snap.

p
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Post by ack »

I went out this morning and opened the EV cover again. I put a nut driver on it and gently rocked it. It resisted a bit, then it broke free (it felt like it was hung up on crud, not like it has a mechanical/structural issue). Revved the bike, and now I see the movement that I wasn't seeing before.
I put the cover back on (without doing anything other than breaking it free).

I'm assuming that mechanically, all is well, but the EV & KIPS need a thorough cleaning. Not sure if there's an interim cleaning I can perform before I do a thorough one (I might as well do a top-end while I go everything disassembled).

I rode it around the backyard and it feels much, much better. Only got into 2nd & 3rd gear, but that's where I was feeling the flat spot before.

I'd be interested to know if there's anything I can do to prevent it from sticking again before I get to the complete cleaning. I'd love to ride it this weekend.
Steve
Raleigh, NC
'05 KDX 220, '00 KTM 200 MXC, '04 KLR 650, '03 WR450
Just learnin' and looking to have fun.
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