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?
Ignition Timing
- Thread starter cicone
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canyncarvr
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- Oct 14, 1999
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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!!
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!!
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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!!!
canyncarvr
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- Oct 14, 1999
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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.
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
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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
- Jul 24, 2000
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Yes, but the appendix in my service manual says for 90-94, indicates 19 degrees.
canyncarvr
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- Oct 14, 1999
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re: how one would check such a thing
First off, ftr the 'H' 200 is 21º 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.
First off, ftr the 'H' 200 is 21º 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
~SPONSOR~
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)
canyncarvr
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- Oct 14, 1999
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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.......;)
...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
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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?
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?
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(Oops! Sorry to throw another question in the line - and it was almost posted twice in a row!)
OK, this question will reveal my amount of experience and expertise on this subject! I have read a number of posts about the plusses and perils of timing changes...retard for more top end rev, advance for more bottom end (and maybe a hole in your piston??)
The question - There is a "jetting by feel" method. Is there also a "timing by feel" method? It seems like if you changed the timing incrementally, you'd get to the "sweet spot"...
OK, this question will reveal my amount of experience and expertise on this subject! I have read a number of posts about the plusses and perils of timing changes...retard for more top end rev, advance for more bottom end (and maybe a hole in your piston??)
The question - There is a "jetting by feel" method. Is there also a "timing by feel" method? It seems like if you changed the timing incrementally, you'd get to the "sweet spot"...
jaguar
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If your cooling system is working good, its summertime, and you advance your ignition too much, then you'll notice coolant boiling out of your radiator at places you've ridden where you didn't notice it before (sand runs, hill climbs, tight MX courses, etc)
I'll let you know what the idle timing should be after I figure it out once I receive my timing light in a couple weeks.
I'll let you know what the idle timing should be after I figure it out once I receive my timing light in a couple weeks.
farmerj, the 200H engine only has 7.9:1 compression so that gives a pretty good safety factor from the bad effects of advancing the timing A LITTLE too much. I have mine at a little more advanced than the most advanced mark (about 1/2 of a space past). I like the results of a snappier and cleaner running bottom end. Eric Gorr suggested I could go a little beyond this even. In addition I had my cyl. base shaved a little to increase compression (only enough to raise it 8 lbs. on the compression tester). I think it's now at 142 lbs. I still never overheat or detonate and my top end seems to rev as far as it did before. I run 91 octane pump gas and MX2T at 40:1. All in all I got the effects I was shooting for with no negative compromises.
jaguar
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It just occured to me that since the KIPS opens at 6000rpm, that one could take the cover off and rev till it opens and then mark where the timing is by using a regular automotive timing light. Then with the engine stopped you can measure how many degrees (mm on the circumference of the magneto) advanced it is.
G. Gearloose
Pigment of ur imagination
- Jul 24, 2000
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Perhaps, but thats a lot to look out for. Since the advance if full (the retard is fully removed) above 6K, just hold it pegged until you see the timing line stop moving, then voila, read it. I suspect 6000 is more of a minimum than an absolute. Actually, I more than suspect, I've done it, indexed the flywheel and everything.
As to a 'sweet spot', I hear they run pretty sweet right before they grenade... :yikes:
As to a 'sweet spot', I hear they run pretty sweet right before they grenade... :yikes:
jaguar
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Just looking at the schematic (see my other post on CDI repair) I'd say the basic design of this CDI tends to cause it to advance the spark timing more as revs go up until around 6000 when the timing capacitor doesn't have enough time to discharge completely before the next cycle and the effect is that above 6000 the spark timing starts to retard (or at least stop advancing) which is really needed. So essentially there is a spark "curve" when graphed out. I plan to diagnose the curve and present a graph for all to see. I also plan to change that capacitor and see how it affects the curve. With less capacitance the retard curve should happen sooner than 6000 which may allow me to set the system more advanced for low revs while still having the right timing for high revs. Basically more of a racing curve and less of a foof bike curve. (boy, that term dates me!)
Gearloose, tell me if my ideas are on the right track, since you've had a timing light on the system.
Yeah, I agree; I've ruined a few pistons by jetting the carb for the sweetest spot.
Gearloose, tell me if my ideas are on the right track, since you've had a timing light on the system.
Yeah, I agree; I've ruined a few pistons by jetting the carb for the sweetest spot.
G. Gearloose
Pigment of ur imagination
- Jul 24, 2000
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Your fairly accurate, me thinks..
After spending a few hours of 'quality time' with the light, I too have myself convinced that the stator plate is installed well advanced statically, and the CDI produces more retard at low speed than high.
Naturally,the CDI has no idea when the flywhel is expected to come around again, it only knows when it did. More retard at low speed, then reduces the retard at high RPMs, gives the illusion (and effect) the CDI is advancing the spark as RPMs increase.
Sounds like we're both saying the same thing. I concur, a little more advance (er, less retard!) at low revs could be exciting. I loved the way my bike would rip off idle with the plate advanced, but when I saw the way the highs were affected adversly, I knew I was on thin ice.
Please let us know how your anti-foof cdi works out.
After spending a few hours of 'quality time' with the light, I too have myself convinced that the stator plate is installed well advanced statically, and the CDI produces more retard at low speed than high.
Naturally,the CDI has no idea when the flywhel is expected to come around again, it only knows when it did. More retard at low speed, then reduces the retard at high RPMs, gives the illusion (and effect) the CDI is advancing the spark as RPMs increase.
Sounds like we're both saying the same thing. I concur, a little more advance (er, less retard!) at low revs could be exciting. I loved the way my bike would rip off idle with the plate advanced, but when I saw the way the highs were affected adversly, I knew I was on thin ice.
Please let us know how your anti-foof cdi works out.
jaguar
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I just Increased timing cap by 1uf to 5.7uf and advanced the stator plate 2.5mm (CW) since at 3000 rpm (50hz) on the bench it was retarding the spark .15msec which is 2.7 degrees. (The stator plate is slightly smaller in circumference than the magneto).
Man, I'm stoked! It ran so damn good all the way through the rev range I couldn't believe it.
Dudes I'm going practicing tomorrow. Hell with work!
I've got the years first race coming up on the 27th and now I've got a jet! I'll blow them all into the weeds!
Man, I'm stoked! It ran so damn good all the way through the rev range I couldn't believe it.
Dudes I'm going practicing tomorrow. Hell with work!
I've got the years first race coming up on the 27th and now I've got a jet! I'll blow them all into the weeds!
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