Ignition Timing

Joined
Sep 29, 2003
Messages
310
Likes
0
#1
Succesfully installed new ignition stator coil last week and test rode yesterday. The bike is running stronger than ever, but I'm afraid my next job will be the main bearings as slight amount of in/out and side-to-side play was noted upon flywheel installation :whiner: . I was very careful to set the timing exactly where in was prior to this repair. However, now I notice that if I give the bike a half hearted kick it kicks back at me. It never did that before. I'm positive that I didn't advance the timing---it's a tad to the right of the center mark. Is it possible with the spark being much stronger that a weak kick will give a good enough spark to kick back, as the weak kick doesn't have the momentum to push the piston through the cycle effectively?
 
Joined
Oct 14, 1999
Messages
4,005
Likes
0
#2
Possible? Sure! Why not?

There can be a timing change with the r/r of the coil. Presumeably electrex did it right.

Figuring that out is a bit tough, cuz I've yet to see a timing spec ('x'mm piston movement BTDC) for the bike. That just takes a dial indicator once you know 'where' the spark hits. Otherwise, you're stuck with a degree wheel to figger it out.

So...the coil fixed your problem? That's great!!
 
Joined
Sep 29, 2003
Messages
310
Likes
0
#3
thanx cc, it's rockin'. Coil did the trick. Looking forward to changing the mains and possible replacement of the crank. hope it holds out a while longer---guess i'll be doing a few things at once to keep off time to a minimum. strangely---braahp---i find myself looking for one more shift on the top end, seems that close to wide open at 60 or so mph i'm looking for an upshift. could rev it out, but there seemd plenty left. go figure---bottom end kicks butt and the top end seems plenty strong to run a 14 tooth counter sprock. if you don't believe me, come take a ride!!!!!!!! :yeehaw: and as mentioned earlier--Wibby seems in need of the twelve step program!!!
 
Joined
Mar 15, 2003
Messages
997
Likes
0
#4
Wibby seems in need of the twelve step program
Me?:eek:

Hey, I just checked, it takes exactly 12 steps to the refigerator to grab a BEER and back
 
Joined
Sep 29, 2003
Messages
310
Likes
0
#5
Hey, I just checked, it takes exactly 12 steps to the refigerator to grab a BEER and back


:eek: coincidence?? I think not!
 
Joined
Oct 14, 1999
Messages
4,005
Likes
0
#6
refigerator?

Is that a tool used to figger something over because it wasn't figgered right the first time?

Glad to hear the coil straightened things out.
 

jaguar

Subscriber
Joined
Jul 29, 2000
Messages
1,450
Likes
76
Location
South America
#7
Yes, a higher voltage from a replacement coil can advance the spark a tad. (I'd explain why but it would take a chapter). I'd experiment with retarding the spark (by moving the stator plate CCW) a half millimeter at a time until the tendency to kick back goes away.
 

G. Gearloose

Pigment of ur imagination
Joined
Jul 24, 2000
Messages
709
Likes
0
#9
Yes, but the appendix in my service manual says for 90-94, indicates 19 degrees.
 

canyncarvr

Subscriber
Joined
Oct 14, 1999
Messages
4,005
Likes
0
#11
re: how one would check such a thing

First off, ftr the 'H' 200 is 21ยบ BTDC @ 6000rpm. Most interesting though, is the correlation to piston travel. In the case of the 'H' 200 that figure is 2mm BTDC.

First, find TDC. Use the positive stop method for best results. Thread something into the sparkplug hole that will prevent the piston from reaching TDC. Make a mark someplace on the flywheel. It doesn't matter where. Rotate the engine (by hand of course) CCW until the piston stops by virtue of hitting the stop you installed. Mark a spot on the case corresponding to the mark you made on the FW. Now turn the engine the opposite direction until the piston is stopped. Make another mark.

The spot smack inbetween the two marks you just made is TDC (I don't have to say between them which way, do I? ;) )

Remove your stop from the sparkplug hole. Install a dial indicator thru the hole. Rotate the piston to the TDC mark you have determined. Zero your dial indicator. Move the engine CW until your dial indicator reads 2mm+ a good bit, reverse direction-CCW (now going the same way the engine runs) until you just reach 2mm. Or just move it thru a piston cycle in the direction of travel. The important thing is to not find that 2mm mark when the engine is moving backwards.

Make another mark. That's where you can expect to see an alignment (your mark on the FW and the 2mm mark on the case) when you attach a timing light. Adjust the stator to suit.

You can use a degree wheel to the same end....find TDC the same way. Using a dial indicator to try to 'measure' TDC isn't effective. You will see a lot of rotation happening with the piston barely moving.

Used to be a lot easier with points. A meter would tell you when the points opened. You won't see that sort of thing with a magneto. I don't know of a mechanical method to determine spark time with a mag/cdi setup. That's what you need a timing light for.

Well...and a tach. Unless you have an RPM sensitive ear? ;)

An o'scope will work...look for 167usec cycle.
 

jaguar

Subscriber
Joined
Jul 29, 2000
Messages
1,450
Likes
76
Location
South America
#12
There are timing lights that have digital readouts of the rpm also. I am bidding on one now and hope to receive it in a couple weeks. Then I will find TDC, mark it on the flywheel, then put the timing light on (using an external 12v adaptor to supply the thing), rev it up to 6000 and mark on the case where the TDC mark is, then measure on the magneto the millimeters from one mark to the next. (luckily the magneto is just a hair more than 360mm around it which makes things easy). So then I would move the stator plate accordingly so that the next readout at 6000rpm would give me 21 degrees BTDC. (for my '89)
 
Joined
Oct 14, 1999
Messages
4,005
Likes
0
#13
360mm circumference? Wow. It would be really impressive if it was planned that way. What foresight and intelligence applied to engineering!!

...but, it was probably more a matter of chance. ;)

Jag: I hope you post a thread about your results. I'm interested in the method for one, and the results for another.

I've worked on bikes in the past that did not have enough 'oomph' in the high tension lead to trigger my clamp-on (parallel) timing light (no, it didn't have 'r' plugs). I had to use a series light (yeah...grab ahold of this!) on them. I haven't put my light on my kdx to know if it works or not.

A light with a tach! I think I see a new tool in my future.......;)
 

jaguar

Subscriber
Joined
Jul 29, 2000
Messages
1,450
Likes
76
Location
South America
#14
of course I will post the results. can't let all this hard work not be used to advance the do-it-yourself KDX technology!
You know, what is really throwing a stick into the spokes (so to speak) is that in the CDI timing circuit, there is a thermister which lowers value as it gets hot which would retard the spark timing some. So the question is : set it at the specified timing at 6000rpm when it is just fired up, or when it is good and hot?
 
Last edited: