KDXRIDER.NET

I have to start by telling you that I know nothing about two cycle engines. I agreed to help my boss get his 2004 KDX 220R running after it sat in a shed for five years. I started by draining the bad gas from the fuel tank. I then clean the carb (it was surprisingly clean), checked the fuel line, cleaned the petcock, replaced air filter, changed the spark plug, refilled with fresh pre-mix (32:1), and the bike started with 3 to 4 kicks. The bike starts and idles fine but it doesn't have any power. It won't pull the front wheel off the ground no matter what. It feels very very lazy. My boss came over and rode the bike and it was very very obvious that it isn't right.
I have since checked and the compression. (140 cold) I then removed the power core 2 silencer and verified that it is not plugged. The packing is in fair condition.
I have spent days searching the internet and many hours trying to track down the gremlins. The KIPS seems to raise my eyebrows. With the round inspection cover removed on the left side, I can see the gear actuate as I increase the RPMS. There is one tooth missing from the gear but this doesn't seem to affect operation. With the exhaust removed, I can see the main valve is very dirt hand covered in carbon.
Under the KIPS cover, I see that the valve doesn't close completely when allowed to close under its own pressure. (See photos)

I'm really pulling my hair out in trying to figure this thing out. It seems very flat all through the rpm range. Please let me know if you have any advice.

Brian

Letsgofast wrote:...it sat in a shed for five years.

Did it run well before he put it into storage? If so, I'd say it's probably something in the fuel system.

I think that you should pull the jug off and clean the kips out and replace any worn out parts. While your in there, make 100% sure that that isn't the stock piston and if it is, replace it. Stock 220 pistons are known to loose the bottom skirt, which could have already happened.
As far as being flat, check that the silencer isn't plugged .

The top end has been done at some point. He bought it from another guy we work with that had is gone through. It ran great the last time he rode it but had loaned it to his nephew and didn't ride it when it came back and went into the shed.

6 Riders wrote:As far as being flat, check that the silencer isn't plugged .

Letsgofast wrote:I then removed the power core 2 silencer and verified that it is not plugged.

Reading comprehension, it's a very important thing.

Letsgofast wrote:It ran great the last time he rode it but had loaned it to his nephew and didn't ride it when it came back and went into the shed.

Ouch...

Jim B wrote:

Letsgofast wrote:...it sat in a shed for five years.

Did it run well before he put it into storage? If so, I'd say it's probably something in the fuel system.

+1 I would clean the carb/jets again

That missing tooth on the gear would concern me. That isnt soft metal and teeth just dont fall off for no reason. My guess is something jammed and broke the tooth.

I agree on pulling the head and cleaning the KIPS out. At the very least you need to find and remove the missing tooth.

spl383 wrote:

Jim B wrote:

Letsgofast wrote:...it sat in a shed for five years.

Did it run well before he put it into storage? If so, I'd say it's probably something in the fuel system.

+1 I would clean the carb/jets again

I've had the carb off and cleaned 3 times. I have thought about a 4th but that seems like overkill.

Tedh98 wrote:That missing tooth on the gear would concern me. That isnt soft metal and teeth just dont fall off for no reason. My guess is something jammed and broke the tooth.

I agree on pulling the head and cleaning the KIPS out. At the very least you need to find and remove the missing tooth.

That's a really good point.

Letsgofast wrote:.....

I've had the carb off and cleaned 3 times. I have thought about a 4th but that seems like overkill.[/quote]

while seeing a chipped tooth on the rotating shaft's gear isn't good, it shouldn't matter so long as you've verified the kips is actually changing with RPM increases/decreases. it's definitely a sign of something going wrong at some point, but the actuation of the system today should prove that it's in working order. verify that the subvalves open and close as you turn the shaft (disconnect the vertical shaft FIRST) and know that the nut on the VERTICAL SHAFT's END is a left hand thread. support the shaft while removing that LEFT HAND THREADED nut, or it will break in process.


pull the reed box-> it's between the carb and head, about six 8mm bolts hold it in place. my kdx ran very poorly once, and one of the reeds was actually laying in the reed box, along with it's phillips head screws. it would start, idle poorly, and pull enough to get me up/down the driveway, but it was extremely weak with that one reed petal missing ;-)

replaced the reed, loctited the screws, and it pulled great again.

you've verified the arrestor and carb are clean, check the next points as mentioned above. :)

I have had the reeds out. They looked great.

ohgood wrote:

Letsgofast wrote:.....

I've had the carb off and cleaned 3 times. I have thought about a 4th but that seems like overkill.

while seeing a chipped tooth on the rotating shaft's gear isn't good, it shouldn't matter so long as you've verified the kips is actually changing with RPM increases/decreases. it's definitely a sign of something going wrong at some point, but the actuation of the system today should prove that it's in working order. verify that the subvalves open and close as you turn the shaft (disconnect the vertical shaft FIRST) and know that the nut on the VERTICAL SHAFT's END is a left hand thread. support the shaft while removing that LEFT HAND THREADED nut, or it will break in process.


pull the reed box-> it's between the carb and head, about six 8mm bolts hold it in place. my kdx ran very poorly once, and one of the reeds was actually laying in the reed box, along with it's phillips head screws. it would start, idle poorly, and pull enough to get me up/down the driveway, but it was extremely weak with that one reed petal missing ;-)

replaced the reed, loctited the screws, and it pulled great again.

you've verified the arrestor and carb are clean, check the next points as mentioned above. :)[/quote]

What are you referring to by "sub valves"?

Letsgofast wrote:What are you referring to by "sub valves"?

These:

They move freely but do not return to fully closed as seen here. Could this be the issue?

Letsgofast wrote:They move freely but do not return to fully closed as seen here. Could this be the issue?

can't tell from the photo which way they are turned, but yes, you want full open/close action on the subs. it will impact low (and high) power of the bike dramatically.

it would be a good idea to pull the cyilnder off, seperate the head, and clean everything thoroughly. i know it sounds like a PITA, but it's really only a few hours work the first time, after that, two hours tops. it will help you verify that everything is moving FREELY and not about to grenade.

the subvalves need to move freely, and FULLY.

Letsgofast wrote:The top end has been done at some point. He bought it from another guy we work with that had is gone through.

Aside from getting the KIPS cleaned and working correctly, I would want to pull the head/cylinder to verify that a Wiseco piston was installed.

Pulled it apart tonight. Took about 30 minutes as I already had the tank off. Looks like a stock piston. Main valve is so covered in carbon that it barely moves. I'm going to order a service manual, clean it up, and throw a piston at it.

She is up and running. I have to say that a service manual is very valuable in putting the top end and KIPS back together.
Come to find out, the KIPS valves were installed backwards by the dealership(see photo above) that did the last top end. I gave it a good cleaning, installed a wiseco piston, and reassembled. It runs great. I would have to say that there is no way that the bike ran properly when parked. Iboearned quite a little bit about 2 strokes and really like the KDX after working on it and riding it around a little bit. I don't know that I would give up my KTM to have one but the KDX appears to be a serious weapon in the woods.

Letsgofast wrote:I have to say that a service manual is very valuable in putting the top end and KIPS back together.
Come to find out, the KIPS valves were installed backwards by the dealership(see photo above) that did the last top end.

IIRC, the manual is wrong and if you follow the directions in the manual they'll be backward.