I have an 01 KDX 200, FMF Gnarly Pipe and FMF Silencer, jetted to specs from fredette's site. The bike starts easy, pulls fine through low to mid RPMs and just as powerband begins to come on at higher RPMs, the bike begins to break up. I initially thought this was a carb issue - so I confirmed that it was clean, and that jetting was to specs - which had worked fine. I then pulled top end, verified piston was within specs and put new rings in a did a thorough powervalve cleaning....I suspected that the powervalve was gummed up and sticking closed, however once bike was back together - the problem still persisted. A friend of mine suggested it was my ignition and that I should buy a new black box - the ignitor is over $300 so before I buy the box, anybody have any ideas? OR every had a similar experience? Thanks!
2001 KDX 200 breaks up at higher RPMS
- Thread starter nickyd
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motorider200
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- Nov 11, 2002
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Try a new plug, use fresh gas, and make sure the airfilter is clean. Does it seem to run rich or lean? You can check the powervalves operation by removing the slotted cap on the left hand side of the engine, and reving it up and see if the nut is turning.
- Thread starter
- #3
Bike has fresh gas - fresh plug went in with new rings as did clean filter - I will confirm that the powervalve is being actuated...I initially suspected water in the float bowl but I drained the bowl to no avail. As far as running rich/lean - I'd say its a tad rich - some smoke from the pipe when running but nothing out of the ordinary. Guy I asked claimed "I hear people having problems with KDX ignitions all the time and they say the same thing about the revs"....not sure if he is full of it or what.
motorider200
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- Nov 11, 2002
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If the power valve checks out the next thing I might suspect would be the ignition. You might try and search to find more info about that.
G. Gearloose
Pigment of ur imagination
- Jul 24, 2000
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And your airbox lid is......un-modified perhaps?
- Thread starter
- #11
air box is lid is off. will do on the buddy's bike and for sure will post results.....sucks that when I first got the bike only tested in really tight woods, bought it and then took a trip to the mountains and rode tight woods....so in essence I put 200 miles on it before coming home and noticing something was wrong b/c it was my first chance to open it up.
motorider200
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- Nov 11, 2002
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Test and make sure the kips system is working properly before you put much more time on it. I had the pin in the right crank cover that activates the kips system break off. I lucked out and it didn't damage anything else.
If the KIPS checks out and the silencer is properly packed I'd be sure to look at being too rich on the main jet as a possibility. I don't know what your elevation and temperature is, but I'd try the next size or two leaner on the main in a quick test run to see if the top end cleans up and comes alive. Also, how's the condition of your choke circuit? Is your fuel petcock good and clean (does gas freely run out of the gas line to the carb when it's disconnected)? If all of that checks out then ignition is the next step I'd go after. Are you running a fresh plug?
My 01 did the same thing. I found it was loading up on oil. if you get out on open flat area, and pin it briefly, and then off, and do it a few more times, it would clear up. I blamed it on oil in the air boot. when running at low rpm, it was fine, butr when i demmanded throttle, it would garbble. have you ever ran a 2-stroke with the air boot off? you will see a mist of fuel and oil "pulse "out of the inlet of the carb. this would collect in that low portion of the air boot. when you pinned the throttle after woods riding, it would pull this puddle up, and thus, was running rich.At least, this is what was going on with mine anyway. Give it a look.
canyncarvr
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- Oct 14, 1999
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re: '..you will see a mist of fuel and oil "pulse "out of the inlet of the carb.'
and..
'and check reeds.'
Yeah. A bad case of #1 leads to doing #2.
When is the last time they were changed? And...what type of reeds are they?
This is under load with a lot of throttle? Light throttle, no load?
I 'spose the term 'breaking up' could be applied to your average everyday 4-stroking no-load 2-smoke. You're not talking about that, right?
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This afternoon I replaced my FMF forest approved spark arrestor (after 5 years of use and 3 recent repackings with short lived success) with the (still new) stock KDX spark arrestor. I rode 18 pretty hard trail miles tonight without the engine cutting out once. I believe the Issue is resolved. :cool: It rips again!
The prior symptoms were gradually started cutting out wide open and then migrating gradually to cutting out midrange. Repacking helped for about 20-40 riding hours and then start over. :bang:
*******
BTW...20-40 riding hours is well within reason for having to repack an S/A. Depending on the jetting situation, that could well be WAY overdue!
and..
'and check reeds.'
Yeah. A bad case of #1 leads to doing #2.
When is the last time they were changed? And...what type of reeds are they?
This is under load with a lot of throttle? Light throttle, no load?
I 'spose the term 'breaking up' could be applied to your average everyday 4-stroking no-load 2-smoke. You're not talking about that, right?
***edit***
Just got this post notification. Apply to you?
This thread is located at:
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Here is the message that has just been posted:
***************
This afternoon I replaced my FMF forest approved spark arrestor (after 5 years of use and 3 recent repackings with short lived success) with the (still new) stock KDX spark arrestor. I rode 18 pretty hard trail miles tonight without the engine cutting out once. I believe the Issue is resolved. :cool: It rips again!
The prior symptoms were gradually started cutting out wide open and then migrating gradually to cutting out midrange. Repacking helped for about 20-40 riding hours and then start over. :bang:
*******
BTW...20-40 riding hours is well within reason for having to repack an S/A. Depending on the jetting situation, that could well be WAY overdue!
- Thread starter
- #18
that's helpful - thanks. I rode today - tried different air screw combos (quick and easy on the trail) to no avail. I am going to repack silencer for sure (spooge now running out of the back). I did pull the kips cover and confirm that p-valve was working. I've got a borrowed ignition lined up so in the meantime I am going to check all of the minor stuff. Reeds were inspected w/top end - that was only 1 tank of fuel ago.
canyncarvr
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- Oct 14, 1999
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Taking the KIPS cover off doesn't show you anything.
Well...that is kind of a smarty answer 'cuz it's easy to infer you are referring to the cover that says KIPS on it. But under there you will find nothing to look at.
So....what DID you look at? If you took off the slotted cover on the LH side of the cylinder in-line with the main rod and saw that it moved, you don't know if your KIPS is working.
If you took off the actuating rod cover from the RH side of the cylinder and saw it move, you STILL don't know if your KIPS is working.
To determine if the KIPS is working as it should, it is not enough to see the actuator rod move. It's still possible for the subport drums to be stuck and their activating racks could be broken or stripped.
It's still possible for the drums to be out of time, for the main valve to me stuck or otherwise non-operable.
You have to look up into the exhaust port (pipe out, 'eh?) and with the engine running at 6000+ RPM,
.
.
.
.
just kidding!.
Don't start it of course. Manually activate the KIPS using the nut under that slotted LH cover and observe the drums and main valve to be working as they should. If you don't know what 'as they should' means take a look at CDave's site to see an animation of it. If you have any questions after that, feel free to ask.
Well...that is kind of a smarty answer 'cuz it's easy to infer you are referring to the cover that says KIPS on it. But under there you will find nothing to look at.
So....what DID you look at? If you took off the slotted cover on the LH side of the cylinder in-line with the main rod and saw that it moved, you don't know if your KIPS is working.
If you took off the actuating rod cover from the RH side of the cylinder and saw it move, you STILL don't know if your KIPS is working.
To determine if the KIPS is working as it should, it is not enough to see the actuator rod move. It's still possible for the subport drums to be stuck and their activating racks could be broken or stripped.
It's still possible for the drums to be out of time, for the main valve to me stuck or otherwise non-operable.
You have to look up into the exhaust port (pipe out, 'eh?) and with the engine running at 6000+ RPM,
.
.
.
.
just kidding!.
Don't start it of course. Manually activate the KIPS using the nut under that slotted LH cover and observe the drums and main valve to be working as they should. If you don't know what 'as they should' means take a look at CDave's site to see an animation of it. If you have any questions after that, feel free to ask.
- Thread starter
- #20
just for the record, taking off the KIPS cover (LH side) while the bike is running lets you see the resonator chamber being closed off or opened to exhaust gases. Step back to the start - all of your advice is sound - in my case, I'm positive that the valve is not stuck - its clean - timed correctly and has no stripped gears. I noticed this one thing yesterday - sitting at idle I was trying to rev the bike and see if it would clear out....as I opened the throttle, the motor would break up and then clear itself out and rev hard....however, once in gear with a load, the bike had no power.
canyncarvr
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- Oct 14, 1999
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re: taking off the LH cover to see......
That doesn't show you the RH drum...and that is the one that usually has the problem. Well...to be truthful, more often on earlier models, but the point is that looking at the LH side doesn't tell you what the RH drum is doing.
Dont' misunderstand. I'm not picking at what you know or what you've done. I've seen a thread go on for days with a guy that couldn't adjust his idle....come to find out he was adjusting the BRASS screw...he didn't know the difference between the air screw and the idle screw.
Please go back to what I asked earlier. Is this break-up thing something that happens under light load or heavy load. Do you know what a 4-stroking 2-stroke sounds like? Is that what you're describing as 'breaking up?'
By the way...spooge out the back is NOT an indication necessarily of anything wrong jet-wise. It may be due to a soggy silencer. Oh, you'll also get spooge with a too-lean condition, too. It happened with my bike. Dripped all over the place and a lean-roll stick to go with it!
Don't jet by spooge!!
One more thing...an 'inspection' of the reeds doesn't tell you what they do under pressure. Just because they aren't frayed, cracked and split doesn't mean they are any good.
That doesn't show you the RH drum...and that is the one that usually has the problem. Well...to be truthful, more often on earlier models, but the point is that looking at the LH side doesn't tell you what the RH drum is doing.
Dont' misunderstand. I'm not picking at what you know or what you've done. I've seen a thread go on for days with a guy that couldn't adjust his idle....come to find out he was adjusting the BRASS screw...he didn't know the difference between the air screw and the idle screw.
Please go back to what I asked earlier. Is this break-up thing something that happens under light load or heavy load. Do you know what a 4-stroking 2-stroke sounds like? Is that what you're describing as 'breaking up?'
By the way...spooge out the back is NOT an indication necessarily of anything wrong jet-wise. It may be due to a soggy silencer. Oh, you'll also get spooge with a too-lean condition, too. It happened with my bike. Dripped all over the place and a lean-roll stick to go with it!
Don't jet by spooge!!
One more thing...an 'inspection' of the reeds doesn't tell you what they do under pressure. Just because they aren't frayed, cracked and split doesn't mean they are any good.
motorider200
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- Nov 11, 2002
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What jets are you currently running? If it is spooging it is most likely a little on the rich side.
KAY DEE EXER
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- Mar 3, 2003
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motorider200 said:
canyncarvr said:
motorider200
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- Nov 11, 2002
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So if that is the case why does the silencer get soggy? I might be wrong but from my experience running rich jetting contibutes to spooge. As for as the lean spooge thing that makes no sense to me mabye somebody will enlighten me.
KAY DEE EXER
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- Mar 3, 2003
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I'm not trying to start an argument or anything just pointing out a differing view on this. I too am a bit baffled as to how a lean bike can spooge but Im sure the ol' wise one will set us straight. Oh CC where are you ??? :worship: :worship:
