KDXRIDER.NET

How far has anyone advanced the Ignition timing on a KDX-200 ?

I've been complaining about the lack of torque " pull " on my sons 200
for years.

A customer who raced snowmobiles told me to advance the timing.
Tonight I came home and advanced the stator plate roughly an 1/8"
past the factory advanced mark and did that wake it up.

Idles with more authority and pulls much stronger.

Zero detonation with 96 octane non-e fuel.

Any thoughts on this ??

" DISCLAIMER ! DO NOT TRY THIS ON YOUR MOTORCYCLE ! COULD CAUSE SEVERE ENGINE DAMAGE !

Flirting with disaster. Yes more timing will make a motor lots more responsive, and will also melt the tops off of pistons. You can get a few degrees but without a degree wheel there is no way I would chance it.

I've played with it a little, but always using the factory marks on the stator plate as the boundaries. Currently running just a tad ahead of the center mark, which gives best performance for my area/style. Not sure how much past the factory marks I'd go, but as long as you're keeping tabs on it and don't go crazy it should be fine.

ecojbr wrote:Flirting with disaster. Yes more timing will make a motor lots more responsive, and will also melt the tops off of pistons. You can get a few degrees but without a degree wheel there is no way I would chance it.

I understand and would by NO means reccomend anyone to do this.
These bikes are far from stock and even though I mix my fuel to get
the 96 octane , it's virtually the same as running race gas.

I've got to do some plug checks as I just picked up a new box of B8EGV plugs.

I recently had my 220 tuned...head milled, squished & all the ports matched, flowed & polished. The engineer who did all the work knows his stuff & told me he also advanced the timing slightly ( almost to 1 mark on the stator ) to allow for a little more top end rpm pull.

I just did this on my KDX220 and felt very little difference either way.

Advancing the timing will not get you additional top end, it's actually the opposite, it theoretically gives you more bottom end and less top end.

Retarding will give you more top end and less bottom end.

I settled on full retard to reduce the hit my bike has with the PC1 pipe, it has also slightly helped with the 4 stroking on the first 1/16th of the throttle, not much, just a little.

All "full" advance did for me was make it harder to start, it wanted to kick back on me, very negligible difference in performance.

Could be the 220 reacts differently than the 200, dunno, but was surprised how little the performance difference was.

I was chasing my 1/16th of throttle 4 stroking issue and went this direction to see if it helped and it did ever so slightly, (full retard).

I have just come to learn to live with the slight 4 stroking that I have.

Michael

My mistake!....I looked at the bill for my engine work today & in there it states the timing had been `retarded` & not advanced as I first thought....I even removed the stator cover & I could just see where the plate has been moved from its factory middle mark to just below & in front of the next.

The 200 and 220 do react very differently to tuning changes.

And by no means does it have that GREAT 220 torque.

I'm going to back it off to a 1/16th beyond the advanced mark . Plug chop looked a little too hot.

bufftester wrote:I've played with it a little, but always using the factory marks on the stator plate as the boundaries. Currently running just a tad ahead of the center mark, which gives best performance for my area/style. Not sure how much past the factory marks I'd go, but as long as you're keeping tabs on it and don't go crazy it should be fine.

Same here. Just a little bit past the center mark makes a noticeable difference. BTW, no problems running it with 91 octane 10% ethanol with the RB head mod.

I don't want to sway this thread BUT 10% ethanol is enough to dry out your crank seals , carb needles and
every other rubber part it comes in contact with. Oil in the gas does very little to keep this from happening.
STAY AWAY FROM ETHANOL FUELS !

And the bike runs very good at one notch width past the factory advanced mark. " Good Fuel " I'll boroscope it after a few hours
riding.

SS109 wrote:

bufftester wrote:I've played with it a little, but always using the factory marks on the stator plate as the boundaries. Currently running just a tad ahead of the center mark, which gives best performance for my area/style. Not sure how much past the factory marks I'd go, but as long as you're keeping tabs on it and don't go crazy it should be fine.

Same here. Just a little bit past the center mark makes a noticeable difference. BTW, no problems running it with 91 octane 10% ethanol with the RB head mod.

My RB head is an " experimental " version made for 95 or higher octane fuel.

C George wrote:I'm going to back it off to a 1/16th beyond the advanced mark . Plug chop looked a little too hot.

The same as if there was a forth timing mark.
It still pulls very good at this setting.

C George wrote:I don't want to sway this thread BUT 10% ethanol is enough to dry out your crank seals , carb needles and
every other rubber part it comes in contact with. Oil in the gas does very little to keep this from happening.
STAY AWAY FROM ETHANOL FUELS !

And the bike runs very good at one notch width past the factory advanced mark. " Good Fuel " I'll boroscope it after a few hours
riding.

Well, getting non-ethanol fuel here in AZ is impossible unless I buy race gas ($7+/gallon here) or aircraft fuel (even more $$$). However, considering my bike is only two years in to a fresh rebuild, I don't think I have to worry about it for quite some time.

Jeff Fredette said he's going to dig out his KDX and do some testing. Dyno ?

I'll let you know what his thoughts are on this.

Of course you have to be willing to commit to running a race quality fuel.

Turning the stator basically slides the power curve up or down in RPM on a 2 stroke. Generally you might get maybe +/- 3 degrees out of the slots provided, enough to move power maybe +/-300 rpm or so, depending on about a trillion variables from fuel used to jetting to head shape, etc etc.

Stolen from another thread, dyno of a KTM 250XC with timing advanced and retarded. How much? I don't know, maybe 4-5 degrees if I had to guess. The graph is sort of confusing as the red and pink look similar. Red hp and green torque is advanced. Blue hp and pink tq is retarded. You can see the shape of the power curve is nearly the same, just shifted one way or the other.

If one could change the curve of the cdi map and not just shift the whole thing one way or another then the bike dyno'd below would benefit from the advanced map up to 7000 rpm, then having the timing curve changed to match the retarded map above that. You'd end up with with stronger low/mid/high rpm power of advancing the timing, as well as the improved over-rev of retarding it.



If you are really picky then you don't run the same pipe for different ignition timings, as it effects the pipe temperature and changes tuning.


As for ethanol, good luck finding it many places. Until this last fall the closest station with an ethanol-free pump near me was 80 miles away. While it's not the greatest thing, there is a LOT of false accusations thrown it's way. For instance, crank seals are generally Viton, which handles ethanol without any issue, whether E10, E85, or even E100.

I'm not going to dispute the chart above at all , my only guess would be that stock KDX ign. timing
is MUCH milder than a stock KTM 250SX.

XC, not SX. The XC is really mild.

Hard to do on my phone while feeding baby, but Google image KDX ignition timing. Some charts showing the timing curve. I'm sure it's been posted here before.

That's a good graph...showing that basically the curve shift on a 2-cycle is basically the opposite of a 4-cycle when it comes to effects of timing.

http://en.wikipedia.org/wiki/Four-stroking

Good article in Wikipedia, hence why I retarded my timing, again, my objective was to eliminate four stroking, just above idle, which it did slightly.

The other benefit for me given the Pro Circuit I, or PCI pipe has such an abrupt motocross type hit, that it mellowed out this hit, which is beneificial for trail riding. If I was on a motocross track, or similar type terrain, then exact opposite would apply. I can't say what the benefit or detriment would be for other set ups, just mine.

Michael