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From the Service Manual... "the ignition timing can be adjusted for different power bands to suite the riders preference and ability"

Question: has anyone done this and what were the results?

The manual shows three lines of adjustment.

I learn something new about this bike every day. Thanks!

Do you have the online manual? It's got some details.

"Stator plate clockwise advances the timing, which brings the hit on quicker, but will cost you on overrev" (whatever that means...)

I re-tarted the timing and got great results on my test loop a 2000 ft vertical 1st and 2nd gear switch-back single-track trail.

I've still got that main seal leak so that should be fixed before any more "tuning" goes on.

i retarded the timing on my son's KX65 when he was still learning the clutch. It smoothed out the powerband, and allowed me to run 87 octane in the premix. I assume it would work the same way on any 2-stroke, esp peaky ones w/o powervalves similar the KX65 ;)

im looking to do this very shortly! anyone done it yet?

http://docs.google.com/viewer?a=v&q=cac ... G24g&pli=1


reading for anyone that is going to do it.

Yes. I check mine a few months ago. I like to go for as strong a top end I can get, but my timing was already as far advanced as it should go. IIRC, there is some kind of mechanical stop that prevents moving the plate any further...
This is not a "something for nothing" adjustment, though. If you retard the timing for better low end, you can expect similar sacrifice on the top end, and vice-versa.
On the 2 H series bikes I have owned, both were already set at (or very near) the advanced limit when I checked them. This leads me to believe that this is how they arrive on the showroom floor - but I could be wrong...

After reading Mr. Gore's document, I may, at 50 years old, still be learning. I will try retarding my timing and see if what he says holds true.
I usually like a strong "hit", but he says that retarding the timing will not only give me more over-rev, but will move more heat from the cylinder to the pipe. If I lose too much hit, I won't be happy though. Good thing this only takes 10 minutes or so to try out...

I posted awhile ago on thumpertalk about this. I found that retarding it gave a bit more over rev up top, but not much. Advancing it just a hair past stock suits my riding style a little better. More bottom end, smoother powerband.

I played with this last night, and took several test rides. There are 3 small marks on the stator plate (retarded - normal - advanced) that line up with one small mark on the case. I actually found that I had intentionally left my timing in the full retarded setting for the last several months. My bike was hard to start when cold, and not very exciting to ride. As Nick said, I guess you could say that there was more over-rev, but there was very little power accompanying it.
I reset my timing to the advanced mark, and the bike fired right up and felt much more alive. The "hit" is much more pronounced, and the bike is much more fun to ride.

problem with 2 strokes is that you can't just change 1 thing and have a better bike, if you want a revvy engine you need to adjust the timing, reed block, carb size / needle / jetting, squish band, and every other bloody thing to suit! im aiming to make mine a revvy bastard, so i will keep you people in the know as i continue on my quest

For a revvy KDX, I would guess that you would have to go for an FMF Desert pipe, and a V-force reed cage with the reeds on the high tension setting. And maybe run a longer muffler. That is about as far as I would go. Beyond that, I'd be looking at getting the carb bored, and maybe lowering compression a bit, but at that point, I would start to lose most of the benefits of starting out with a KDX to begin with.

In order to adjust the ignition timing, do you have to remove the flywheel, or can you access through the holes in the flywheel.

Thx !!! Michael

Never mind, got home and checked manual, yes flywheel has to be removed, however it does not state if turning it clockwise, or counterclockwise will advance the timing. I want to see if advancing the timing gives more bottom end that the PC I pipe took away. I have no problem trading up some bottom end for some top end. If that doesn't work, then the head mod is on the wish list, for more bottom.

Michael

This is the link that answered my question;

http://67.222.34.237/forums/viewtopic.p ... 10&p=24330

Michael

I tried the full on advance and could not feel much of a difference. Idling RPM's did not go up, which I expected, it felt like there was no loss of top end, bottom end, or mid range, no additional hit. The only thing I did notice was once it got warmed up, the kick starter wanted to kick back at me and the combustion seemed to burn cleaner. Now I am testing this down at sea level, but most of my riding is @ 3,000 feet+, which i believe would make a difference, albeit a small one as I lose about ~ 3 to 6% in power due to the elevation change(s). Less air & atmospheric pressure = less power.

Michael

Back in 86, my cousin got a new kx80. It had NO low end at all, and no hit. It was a razor thin, pro type powerband. We either advanced or retarded( whichever gives low end) the timing, and it gave it an unbelievable mid range hit-but took away all top end it had (and it had a lot for a mini if that time). I'm loathe to start fooling with my kdx timing, but if it's anything like that old kx it would reap all kinds of benefits.

Advancing the timing typically gives more bottom end and gives a bit more hit in the mid range and you lose some top end. Retarding typically does the exact opposite of trading up bottom end for top end. I was trying to see if would get rid of, or some portion of the popcorning, some I believe refer to as 4 stroking, but it sounds like a popcorn machine, hence my phrase. I am still on a quest for more bottom end, still think the head mod might be the next thing on the bucket list. If that does not it clean up, perhaps a torque pipe is in order, or a throttle slide #6 vs. #5, dunno, still researching.

The problem I see with over advancing is the kick back. Last thing you want is the motor to kick back on you when you are in tight situation. I know I used to have an XR 600 back in the day. If you touched the throttle to much on a start up, it would kick back with a huge force that if you weren't prepared could potentially break your leg, it was that intense. I used to call it the 1 cylinder Harley, or the lower body work out machine, as it was a bugger to start if you had a get off.

Michael

When I had only ever ridden a mini bike (84-87 at the time) a guy who lived next to the coal mine I rode at rode up on his xr600 almost brand new. I'd been hitting a small jump and getting about 8 feet height and 20 feet distance on my cr80. The guy says "try my 600" so I jump on his bike and hit the jump full speed in 4th. I'd be willing to bet I got 15 feet height and about 60ft distance. Lol. I landed accidentally hit the front brake and destroyed the handlebars, levers, and tweaked the forks. Moral to the story is I always wanted an xr600 lol.