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

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Deseret Rider
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Re: four 220's set up the same---one doesn't pull

Post by Deseret Rider »

diymirage wrote:did we ever double check the gearing?
The gearing is 13:47 front to back--which I think must be standard---same on all my bikes.

Also----I did check the timing as I finished putting the bike back together. I used a micrometer to find top dead center---marked the flywheel in relation to the pointer at TDC------then started the bike and used an automotive timing light to see if I could determine the Degree before top dead center where it was firing. In that process I came to find a factory scribed line on the flywheel and saw that it was firing exactly on that line----at idle or wrapped up a little---no difference. I then took as accurate as I could--a measurement of the diameter of the flywheel (4.375 inches) and translated this to be a 13.744 inch circumference. I then measured the distance around the flywheel from my TDC mark and the Factory timing mark---to be .875 inches From this I calculate that it's firing 22.9 degrees BTDC---this is probably very rough---but close enough to what I expected that I don't think I'll try to change anything there.

The bike now seems to run strong---but then it did before until you put it to the test at altitude (7000 + feet) on a slow and steep single track------When we get a chance to do that I will be able to evaluate it's performance----the only thing we have changed then is the jetting. It had 138 / 40 main / pilot before---now has 140 / 42.
The Duck of Deseret (Deseret was Utah's first name)
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diymirage
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Re: four 220's set up the same---one doesn't pull

Post by diymirage »

diymirage wrote: 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
newbbewb wrote:DIYmirage has it right.


-1996 KDX 200 woods weapon (converted to 99 green body)
-1996 KDX 200 plated street toy (barney edition)
-2003 Yamaha TTR125-L (wifeys bike)
-1997 KDX 220 project bike
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diymirage
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Re: four 220's set up the same---one doesn't pull

Post by diymirage »

scheckaet wrote:3 WAYS TO TUNE YOUR KIPS: get the kips to activate later / smooth out the powerband or get it to hit harder/sooner

1: Kips ball and spring.

this is the KIPS pre-tension mechanism.
Removing one or even 2 of the copper washer (compressing the spring) (same if you used a stiffer spring) under the 10 mm nut holding spring and ball will activate the KIPS LATER and get a more mellow powerband (good for tight single track or beginners).

Removing spring and ball will let the kips activate much EARLIER, harder hit.

It s easy enough you can even try on the trail! (And lose said spring and ball in the dirt :roll: :mrgreen: )
I stuff grease in there myself to keep everything operating smooth and together when I take it apart.

2: KIPS cover spacer
thanks to Brock@BDK

http://www.kdxrider.net/forums/viewtopi ... 77&t=12800

yes a spacer plate on the KIPS expansion bottle should make a performance improvement to the water cooled as well as the air-cooled models.

Essentially the resonator bottle or expansion bottle is lengthening the exhaust pipe when open, so that you now have two different length pipes depending on revs.

Exhaust pipes are designed to only one rev range (for example 7000rpm) where they will perform best and everywhere else is a compromise. The longer the pipe the lower in the rev range it is tuned to. Typically road pipes are tuned to perform best well below the red line where the manufacturer deems most riders will be cruising (and to discourage you from holding it next to the redline where longevity is compromised). Performance pipes are typically shorter and work best closer to the redline (more rpm, more bhp).

Having an expansion bottle allows you to have two rpm's where the pipe is close to ideal, giving you a boost in mid-range performance.

In fact for whatever reason on a few models (the KDX and KMX notably) the bottle was not quite big enough to produce best spread of power and this becomes more pronounced with a shorter performance pipe. Quite why they did this is anyone's guess, but reducing the visual 'barnacle' effect may have had an influence.

The above is not a thorough technical rendition, there is a lot going on there but it gives those that don't know a good grip on the situation. As mentioned by someone else before on a previous thread; once the KIPS resonator is closed you are back to normal so there is no compromise of top end power for this low to mid 'boost'.

In bhp terms the improvement will not be astounding (at low revs the engine isn't making much power anyway), but in terms of percentage it is significant for the cost and ease of fit and makes the bike more forgiving and flexible.

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.
(the resonator cover is on the left hand side of the bike, just behind the slotted cap we mentioned before)

I can recall 2 different threads about making a spacer ranging from 250 thousands of an inch (or 6.35 mm) to 10 mm.
Another member (frenche200) mentioned using a spare kips cover, cut the top and get a spacer to the desired thickness for cheap ;)

3: change springs in the kips

http://www.kdxrider.net/forums/viewtopi ... 77&t=12425
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
newbbewb wrote:DIYmirage has it right.


-1996 KDX 200 woods weapon (converted to 99 green body)
-1996 KDX 200 plated street toy (barney edition)
-2003 Yamaha TTR125-L (wifeys bike)
-1997 KDX 220 project bike
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KDXohio
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Re: four 220's set up the same---one doesn't pull

Post by KDXohio »

Did you check compression and the reed condition?
1990 KDX200 FMF Fatty, Answer VFC silencer, VForce 3 Cage, Wiseco Piston, KX125-J series KYB USD fork conversion, Race tech goldvalves, J series front brake assembly, air-box snorkel removed, Acerbis Headlight, KX450F Front fender, Pro Taper RM bend bars, ASV front Brake lever, MSR Clutch perch and lever, RB Head mod, 36mm PWK carb, Trail Tech Kickstand.
The Duck of Deseret
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four 220's set up the same---one doesn't pull

Post by The Duck of Deseret »

Wow----a lot of excellent information from some very knowledgable guys about tuning the KIPS----thank you!
It's been quite some time since I had the boys bike here and was trying to determine where the problem with it was-----I had ruled out timing as a factor. I suspected the KIPS but without much knowledge or experience in how KIPS works. Some of the information that I received on this forum helped me there----but in the end I really didn't change anything unless it was simply by accident in the disassembly or reassembly of those components. The one thing that I did that produced a noticeable change was that I had changed the jetting and throughly cleaned the carb and was pleased with those results here at this 5800 foot elevation but I did not know how it was going to run at 7000 feet ---to 10,000 feet. Since that time I have had only one occasion to ride with my son and the grand kids at those elevations and they report that the bike now runs fine---as good as the others---and, in fact, that bike is now among the fastest of the bunch----maybe more to the credit of the rider than to anything I did. I guess ----from my point of view at least----all is well that ends well.

However I think this thread has brought a lot of knowledge and experience to the fore---and I invite any additional comment or information that any of you may want to add.
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Re: four 220's set up the same---one doesn't pull

Post by The Duck of Deseret »

KDXohio wrote:Did you check compression and the reed condition?

Yes---those were checked---I forget now what the Compression readings were (I may have reported that number earlier in the thread?). Both compression and reed condition were excellent .
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