From dc to ac

[Triesandluth]

When I thought I had one in town,  both dealers were out of stock of my dc cdi.  So,  while deciding to order one or not,  a buddy with a totaled super 9 ac with the ac cdi offered to sell me the stator,  wiring harness and cdi for 100 bucks.  So I'm gonna do it,  set the other stuff aside,  and wait until I can find another cdi for it or the other mess to burn up. 
Any thing I need to keep in mind with the whole swap? 

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[Triesandluth]

Done,  and running.  Only thing that I noticed different was my bike backfired once after riding 1/4 throttle for a good bit in traffic then dumping on it to wot.  I can say that it could have something to do with it sitting for a week,  the endless rain,  dirty silence packing,  or something else.  Time will tell.
The harness came off an air cooled bike with no tach. Now to figure out how to wire up the thermostat and tach.  The thermostat should be easy enough once I find what wire is connected to the light in the harness.  The tach may be a lost cause.  I want to think that I would hook it to the pickup wire,  but I'm not sure. 

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[TheAmishSasquatch]

Glad to hear its back on the streets.  Now mine isnt working right. We keep alternating whos bike is broken and when. Im not sure both our bike have been running at the same time since weve had em lol.

[Triesandluth]

Lol,  possibly before we got balls deep in tuning.

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[TheAmishSasquatch]

Turned out to be a fouled plug from an over rich condition. Bought 2 new plugs, adjusted the card, rode it, after fired, plug chopped, rode WOT again, soft seized, after-fired through the exhaust again, pushed home, gonna do plug read tomorrow. :\

[Triesandluth]

Holy smokes,  did you wildly adjust it?  Like many size jet difference? 
I need to change my rollers now,  got some wicked flat spots going on.  I may lighten the torque spring and try lighter weights to see if I can use my sliders and help acceleration without throwing my rpms through the roof. 
Also,  the pickup was altered to allow it to be adjusted either direction.  It seems like it tried to bog whenever I go from a low speed to wot.  I'm thinking,  since it didn't do that before the swap,  that the timing may need advanced a touch.  I'm also using a minerelli cdi,  the guy I got the harness etc from had an extremely ported engine with a 24mm carb that wouldn't run right with the Kymco cdi.  I'm looking into a cdi that has adjustable timing advance. 

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[TheAmishSasquatch]

No not really. The temps and humid have changed drastically over the last few weeks and the bike is just very sensitive to it. Upon cold start with the choke pulled it was just too rich. Fouled the plug. Seeing as I had the idle mix turned out 2.5 - 3 turns, I readjusted it very lean..or very rich still unsure. Out (left) = rich or lean on the Dell? I pulled the plug and looks pretty clean. So...??

[chaz35]

Instead of adjustable CDI, could you just re-install stator flywheel slightly rotated to advance or retard timing?  I know stator has woodruff key, but probably doesn't need woodruff key to hold flywheel in position, if properly lapped and torqued.  I have mounted many flywheels and sprockets (2 cycle and 4 cycle engines) without keys in the past with no problems.

Also, I plan to make a cheap stator flywheel holder to properly torque back on.  Should be able to make one out of the piece of wood with a couple of swag bolts screwed into it at the proper locations to hold the flywheel (after screwed in, cut of the bolt head), with hole drilled in wood at center (use spade drill bit) to access the nut to tighten and torque.

Cheers

[Triesandluth]

No not really. The temps and humid have changed drastically over the last few weeks and the bike is just very sensitive to it. Upon cold start with the choke pulled it was just too rich. Fouled the plug. Seeing as I had the idle mix turned out 2.5 - 3 turns, I readjusted it very lean..or very rich still unsure. Out (left) = rich or lean on the Dell? I pulled the plug and looks pretty clean. So...??

Man,  I STILL have problems with my carb tuning.  And the weather change hadn't helped.  Then with the flywheel/stator/cdi swap I'm going to have to find a starting point again. 

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[Triesandluth]

Instead of adjustable CDI, could you just re-install stator flywheel slightly rotated to advance or retard timing?  I know stator has woodruff key, but probably doesn't need woodruff key to hold flywheel in position, if properly lapped and torqued.  I have mounted many flywheels and sprockets (2 cycle and 4 cycle engines) without keys in the past with no problems.

Also, I plan to make a cheap stator flywheel holder to properly torque back on.  Should be able to make one out of the piece of wood with a couple of swag bolts screwed into it at the proper locations to hold the flywheel (after screwed in, cut of the bolt head), with hole drilled in wood at center (use spade drill bit) to access the nut to tighten and torque.

Cheers

I'm not sure if my key is removable,  didn't check.  And I only have half the threads on my crank to attach the nut that holds the flywheel and turns the water pump from when that nut came loose in the past and stripped the threads on the end, almost ruining my bike. 
The pickup coil was altered where it bolts to the case,  allowing it to be shifted a few millimeters either direction.  I moved it up,  which I assume by my limited knowledge, is advancing it.  The ride to work tonight after was really smooth,  no previous bog issues,  and a possible new top speed.  That may have been wind in my favor and drafting,  but I'll know that when I leave in the morning.  It also seems to idle smoother.
Now to fix that damn suspected oil pump leaking into the case

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[chaz35]

I am 99% sure the woodruff key comes out.  Your stripped threads could be a problem.  I recently saw a crankshaft on CL for $25, I think in S Carolina, but you know have to split the case to change it out.  I am working on my People AC engine, but should be similar to S9 LC?  After I made my post, I thought about maybe the pickup coil being adjustable.  If it's easy to get to, you can just try some different settings to find the sweet spot for timing.  When you change the position of the flywheel, it gets to be a lot of work mounting and remounting trying different settings.  Do you have a timing light, degree wheel, piston stop?

I haven't done a search, but I bet there is some good info about timing for the S9 engine.  The maintenance manual says to check timing and there are marks on the flywheel and case to check with a timing light, so it must be adjustable somewhere?  I would stay close to stock timing, unless you were want to make HP at high revs, have large carb, higher ports.  Cheers

[TheAmishSasquatch]

He and I have the same ignition pick-up coil mod. All that's done, is the 2 mounting holes for the pickup to mount to the case have been elongated on the left side to allow the pickup to be physically slide forward, advancing the timing slightly. Then tightened down at desired position. From my understanding the best power here should actually be with a slightly colder or mid plug and base or slightly retarded timing. I will tinker with this and a few other things again next fall when temps and weather permitting. Next week will be in the upper 60-mid 70 here as an indian summer and might try then instead of waiting.

[Triesandluth]

I already have that done to mine,  the holes that bolt the pickup are cut out to allow adjustment.  I moved mine up/left/whatever, which I want to say is advance () and it helped tremendously,  with my slight bog whenever I go from a low speed to wot and I might have a bit better performance overall.  I think the demon I have to work with is that the cdi is for a minerelli,  the engine all my electrical just came from was extremely tuned and wouldn't run right with a Kymco cdi.  I'll either have to mimic his build and port my stuff and add a giant carb and intake,  or tune to what I have. 
In reality,  I will buy a 90 dollar cdi when I have spare cash and put the dc setup back on.  Until then,  I get some new tinkering to do

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[TheAmishSasquatch]

That's what I was sayin to the other fellow, not you. You and I have the same mod done because we both troll the tech section on 49ccscoot.proboards.com 

[chaz35]

If you know the diameter or circumference of the flywheel and how far you move the pickup counterclockwise, you can compute the additional advance?  That flywheel is pretty small, I didn't measure it, but let's says it's 5" diameter.  So, 5" X Pi (3.14) = 15.7" circumference divided by 360 = .044" distance for each degree.  So, if you move the pickup 1/8" or .125" divided by .044" = approx 2.8 degrees additional advance.

If you are moving the flywheel instead of the pickup, you move it clockwise to get advance.  This is all very confusing and I usually have to think about it awhile before I know which way to move what.  Cheers