four 220's set up the same---one doesn't pull

[Deseret Rider]

Grandpa, son and grandsons ---we have 4 220's all '04 and '05 models. 'They are all jetting similarly. All have had the Wiseco piston installed. All have the KIPS claw and gear setup to where the port is fully closed when the engine is shut down. Three of the bikes have the FMF Gnarly gold fat pipe and turbine core muffler ---the forth bike has the Pro Circuit fat pipe with the FMF turbine core muffler. All the bikes---except one--(of the FMF machines) -pull strongly off the very bottom--- the Pro Circuit bike---it pulls OK) . We don't know why but we suspect that the KIPS is already starting to open the port on that bike that doesn't pull as soon as the engine is started and at very low RPM. We don't really know what governs the engine RPM at which the KIPS starts to open---we think it must have some sort of centrifugal mechanism down in the engine block?----and perhaps that has a weak spring on the one bike--which is allowing the KIPS to start to open the port before the proper engine RPM is reached??? We don't have a shop manual and we don't know where to start --------We seek advise and information:
Are we on the right track in looking at the KIPS?
What is the procedure for adjusting the KIPS---(we know that the nut on the claw is a left hand thread---and we know to support the shaft when removing the nut)
Is there something internal within the engine case that we need to know about and/or adjust ?
PS----the bike that doesn't pull strongly off the bottom runs perfectly once the RPM comes up a little---but it gives up quickly on tough single track when the low end pulling power is needed.

Advice requested---what to do?

[KDXohio]

May sound stupid but have you tried swapping the pro circuit pipe with one of the fmf's it could just be the different pipe design

[Deseret Rider]

May sound stupid but have you tried swapping the pro circuit pipe with one of the fmf's it could just be the different pipe design

You know----the Pro circuit pipe pulls really strong---especially since I swapped the fiberglass blanket out for 8 stainless steel 'donuts' in the muffler----but it doesn't pull any better than two of the FMF equipped machines-------So excluding the Pro Circuit bike what I have is two FMF piped bikes that pull really strong and one that doesn't. Since everything is pretty much the same setup as between those three bikes I am puzzled as to why one of them doesn't pull like the other two----and I'm tending to blame something in the KIPS setup simply because I don't really understand the KIPS----specifically, how the Kips knows what RPM it needs to start opening the port? I'm only guessing that the bike that don't pull is opening the exhaust port too soon?????? I know there are guys on this forum that can educate me on the KIPS ------

[diymirage]

between 4 bikes you should have at least one manual (you can download one from the main page on our website)


first of, here is some info on the KIPS
http://www.justkdx.dirtrider.net/kips.html


going with your assumption that it is in fact the KIPS and not something else that's causing the difference (sprockets maybe?) here is something to consider...KIPS can be tuned
as a matter of fact, there are 3 ways to tune your KIPS, and if you did not buy all 4 of these bikes brand new it could pay off to see if the one bike has had any of these mods done different from the others

the first way (if I remember correctly) is to remove the round cap with the slot that sits on front of the KIPS cover on the left hand side of the bike
below that you will find a 10 MM bolt (if I remember correctly) which has 2 copper washers, a spring and a ball underneath it
this is a pre-tension mechanism
if you remove one washer (leaving only one) the valve will stay shut longer giving you a more mellow powerband (good for tight single track or beginners)
or, if you want it to hit harder, you can remove the spring and ball altogether

if it were my issue between the 4 bikes I would start there because it takes about 30 seconds and it will make it obvious if the KIPS is working or not)

the other two ways to tune the KIPS are a little more involved, for starters you can adjust the resonator chamber volume by adding a spacer (not sure who makes them but they are out there) this should give you more low end torque but lower maximum RPM
it should be easy enough to spot if any of the bikes have a spacer like this installed by looking at the resonator cover and seeing if there is anything other then a regular gasket between there and the cylinder (the resonator cover is on the left hand side of the bike, just behind the slotted cap we mentioned before)

the third way to adjust them is a little more involved
moose racing makes a KIPS tuning kit that basically just consists of 2 different KIPS springs one softer for a quicker, harder hitting opening of the valves and one stiffer for a later, smoother opening of the valves

having said all that, im gonna say one more thing again, if they were mine, I would start by counting teeth on the sprockets to ensure all 4 bikes has the same final drive
in order to install these (or see if they have been installed you need to remove the inner clutch cover

[bufftester]

Pulling off the bottom isn't going to involve a properly operating KIPS at all, it doesn't really become a player until 5k+ rpm. First thing I would check is the KIPS governor which is attached to the other end of the KIPS shaft. You have to remove the right case cover (not just the clutch cover) and you will see the mechanism. Basically its a rod at the end of the shaft that rides in a centrifugally operated drum (similar to the clutch on a snowmobile). Not unusual for the pin at the end to be bent or missing (part number 13236-1260 you can look at the whole thing at http://www.motosport.com/dirtbike/oem-p ... VER%28S%29. Assuming that is ok, your problem is likely not in the KIPS. A good carb cleaning, readjustment, check your reeds/reed block, a leak down test on the motor.

A manual is a must (especially with 4 bikes)

[adam728]

Don't rule out ignition timing either. The marks arent always 100% accurate, and a degree or two can be felt. Proper setup requires a dial indicator to set timing when the piston is a certain distance from TDC. This translates to a degree setting.

I also agree that carbs and reed block swappong should be tried, and even the "same" pipes. I once read about a kart guy buying something like a dozen pipes and dynoing them. All 1 model, but production tolerances made a difference in the amount of power and the rpm in which it occured.

Sent via morse code

[Deseret Rider]

Oh---this is great! Thanks guys----now I have something to sink my teeth into---- Really good info to get me started. I'll get started as soon as I can get the bike transported here. I'm really appreciative to get that information. I do have an owners manual that came with one of the bikes but not a shop manual. There are several things to think about here and I'll get back to you guys with some findings and results as soon as I can. Thanks so much !

[pumpguy]

A bit OT perhaps, but until I read DIY's link about KIPS operation, I wasn't aware there was an ignition timing change going on as well.

Just curious if anyone has actually checked with a strobe timing light to see if this timing change is actually happening? If it is, could different CDIs cause different timing changes, and different engine performance as well? An RPM/timing advance chart would be some interesting information.

[bufftester]

The timing change is generated within the CDI unit and is the reason that E, H, A models can share CDIs, but earlier bikes can't (KIPS equipped bikes can share but not with non-KIPS). The timing change is integral to the KIPS proper operation, and a normal non-KIPS CDI doesn't advance the ignition at 6k but keeps retarding it since non-KIPS effective stroke doesn't change. Basically the KIPS is like riding with 2 engines with the same bore but different strokes and operating ranges. You can take the flywheel cover off, mark the flywheel and case at TDC, use a protractor or degree wheel to set up some timing marks, and watch it with a timing gun. A chart would have a sawtooth shape as the timing walks from 6 to 21 degrees as RPMs increase, then at 6k drops back to 6 and starts climbing again until you redline. It really is an engineering masterpiece. I shared some of this same info with an engineering prof I had years ago, it intrigued him so much he started riding, and using the KIPS data/operation in his teaching. Sorry for the thread hijack

[Deseret Rider]

Sorry for the thread hijack

Not to be sorry----I found that most interesting and answered the questions that have been going through my mind since reading about the timing issue. Let me pose a question now: Suppose that I have an spare CDI unit which came off a non KIPS machine----and I install it now on a KIPS machine----will it fire the bike? and if it does will I notice any difference in the performance of the bike if I keep the RPM's under 6000 RPM's ? I am anticipating that you will tell me that the non KIPS CDI does not have the capacity to advance timing based on RPM and therefore while the bike might run normally at very low RPMS it will suffer in the mid rpm ranges below 6000 RPM? Or am I misunderstanding this issue?

[pumpguy]

Hmmm... So, if we changed the KIPS timing with a different centrifugal spring, carbide balls, or some other way, would the CDI be smart enough to change the ignition timing to match the new KIPS timing, or does it change only in response to RPM?

[adam728]

Hmmm... So, if we changed the KIPS timing with a different centrifugal spring, carbide balls, or some other way, would the CDI be smart enough to change the ignition timing to match the new KIPS timing, or does it change only in response to RPM?

Only changes with rpm.

Generally on 2 strokes timing is retarded more as rpm increases.

Sent via morse code

[bufftester]

Yes only changes with RPM as it uses the trigger pulses from the stator. Retarded is correct, I always get them mixed up since in my head going from 6 to 21 is increasing and my simple mind defaults to "plus=advance" lol. If you did monkey with the KIPS by using different balls/springs/etc there would be a slight difference, though likely you might not notice it, or it might fell like the bike is loading up or stumbling a little in the midrange before the valve and the rpms sync. The CDIs also all vary a little from one to another, but there is such a small window between the valve opening and the ignition being advanced that you normally won't notice it unless you happen to hold right at the right RPMs.

To answer your other question I have never done it (sounds like a good science experiment though ), but from looking at ignition curves likely what you would see is below 6k the bike would run normally (timing might be slightly off, but it would run), but as soon as the KIPS opens the CDI is still retarding ignition, but now you have a shorter effective stroke so it will feel like the ignition was retarded even more and would start running like crap. Drop back below KIPS actuation and it would run. Hmmmm....there was a guy on here who was talking about riding with his daughters boyfriend who was on a KTM and he wanted to get quicker....he could drop a KDX CDI in the KTM ...might help him keep up a little easier lol

[diymirage]

Hmmmm....there was a guy on here who was talking about riding with his daughters boyfriend who was on a KTM and he wanted to get quicker....

I thought we banned him for letting his daughter associate with "those people"

[Deseret Rider]

Now that i've digested some of the excellent information that you guys have provided I am less inclined to blame the KIPS system ----but I will check to make sure that the main port linkage is fully closed and that the sub ports are closed and that the linkage is correct. If the KIPS doesn't kick in until 6k (give or take) RPMs and if those items mentioned are OK then I'll move on to check ignition timing and maybe experiment by exchanging parts--CDI's, pipes, reed cages---etc.
Also----I'need to confirm now that all the bikes are running the same 13:47 sprocket ratios and are all jetted alike---but I will take the time now to remove, clean and double check the jets and needle positions. I expect to get the bike sometime this weekend . I'll get back with with a followup as to what I find when my work is complete. thanks for the help guys. lynn

[Deseret Rider]

Let's talk about ignition timing---how to determine?----I have a timing gauge which will allow me to find top dead center---and can measure in .01mm ---to 5mm increments before top dead center (piston position). That measurement would be in distance---not degrees. I also have an automotive type timing light which will strobe with each ignition pulse. If I mark the flywheel to show the TDC position then what distance on the flywheel would I place my mark to show where 6 degrees before TDC should be? If I had those two marks could I then not interpolate to show other degrees of advance? As I understand what has been written the CDI will automatically advance the timing as the rpm's increase. I will be trying to verify that my CDI timing is within those accepted parameters.

As I have noted I am trying to determine why this one machine doesn't pull well at low rpm in comparison to other machines similarly set up-----I want to rule out ignition timing as a possible cause before moving on to other possibilities.

[diymirage]

if you want to rule out ignition I would swap CDI boxes between that bike and another one
seems like the easiest way to get that part marked off the list of possible suspects

I take it you went and counted the sprockets?

[bufftester]

To accurately set the timing marks you would need to use a degree wheel. Easier is to pop the flywheels off the bikes and note the location of the stator plate. Factory is the mark on the case lined up with the middle mark on the plate. I don't think your issue is in timing, but it will be an interesting exercise.

[rbates9]

It seems that lately there is a lot of interest in finding out the exact degrees of timing on the KDX for some reason. Why not just pop the flywheel off and turn the stator a bit and see what it does? Sounds easier then devising a way to determine a specific degree that, to me, seems a bit irrelevant. How the bike runs seems a little more important.

[diymirage]

Sounds easier then devising a way to determine a specific degree that, to me, seems a bit irrelevant. How the bike runs seems a little more important.

you know, that reminds me of a bike I had aaages ago
I was 16 at the time
I cant remember what the occasion was but for some reason I had pulled the flywheel off and wouldn't you know it , I misplaced that darn woodruff key
I looked and looked and I couldn't find it anywhere and it was getting late and I was supposed to be at a bar soon (legal drinking age growing up was 16)
eventually I said "forget it, ill just eyeball it"
so I slapped the flywheel back on, eyeballed it and torqued her down
got everything buttoned back up and it fired right up on the very first kick
allright, put on my helmet and off to the bar I went...kicked her in first, rolled on the throttle and eased off the clutch and over the handlebars I went as the bike lurched backwards

apparently the timing wasn't quite right, it was so far advanced that as it detonated on the compression stroke it actually kicked the piston back down causing the engine to run backwards

I guess I really should have fixed it at that point but now I was getting really thirsty so I rode her backwards to the bar...you should have seen the looks on their faces




(not sure what the point is though...if the engine turns the right way the timing must be close?)