Old Brown

Neat! I figured, with those tires, it did more duty on the street, than the trail. 40-50mph is about it, for an adult rider, on a 100cc. I wouldn't want to go any faster anyways. I've heard of a "Taco Chaser". Tacos at the mini-mart? Perfect! Put a basket on the back for your "groceries", and have fun with it! Cheers! :cheers:
 
A college student bought it 4 months ago with 764 miles on it. He commuted to class on it until his parents found out about it and was told it had to go. He mentioned that his next bike would not go on his debt card that his dad could monitor. Smart kid.

When I pulled up and saw it for the first time the front tire was pause for thought. WTF , it's a XS tire. How did it fit between those tiny forks. It "do". The back tire is sized about the same as the street version of the 100 that Kawasaki sold in other parts of the world.

I assume that the scooter shop he bought from was the source for the tires and the "New Carb".

Got it home and fired it first kick. Idles great. Noticed I had not shut the petcock when I loaded in the truck the night before. Was on reserve and was reluctant to move. I suspect he turned it to reserve when he bought it and never moved it .

The "New Carb " must be leaking gas so got a good plug run in to see how bad the jetting is off.
 
I think upwards of 7hp at the moment. It's supposed to make 11. Wish it had a tachometer.

I think it may need the crank seal and the rotary valve seals replaced. There is a leak test but I'm looking for how to do it out there on the web.

If I do end up doing the rotary valve seal then the valve will get some minor trimming to boost the power up a bit. There are mods to the carb cover to increase air flow and foam filter.
It's a 99 model so well into the crap gas era so should be ok on Exxon or Shell premium pump gas
I'm thinking the OEM carb is EPA lean.

The street tires are a vast improvement over the "trials tires" that they came on. 40 mph no sweat. I'm hoping for bursts to 60 on level and downhills.
 
Jim asked today about my progress on replacing the TCI box.
Old Brown has a 1986 XJ700 igniter box grafted in. She starts and idles great but I'm not getting any advance.

The 650 uses a small round magnet on the side of the stator. Most later electronic ignition systems use a longer bar magnet. Also the polarity of the pickup coil on the 650 is reversed from what the later Yamahas use.

I think the advance is not working because the coil pulse is too short with the small magnet.

My thought is to use the stock small magnet with a rewound pickup coil that is elongated along the path of the magnet to lengthen the pulse to the igniter box.


Jim. Ever look inside the pickup coil to see whats in there?
 
A single pickup.
I want to make a armature for the pickup that spans the retarded to advance arc on the stator. I think the newer boxes use a long pulse that goes from retarded to advanced. pure speculation on my part by looking at the span of the magnet on the newer flywheels.
xj700 magnet.jpg
 
That piece is attached to the left end of crankshaft. The alternator is similar to the 650 but mounted on a jackshaft above and behind the crankshaft.

Screen Shot 2020-02-15 at 3.13.19 AM.png
Notice how the arc of magnet looks to be same as the range of advance. I think the leading edge of the magnet is full advance and the trailing edge would be the retarded timing spot.

Right now I have the XJ igniter box hooked up to the the XS650 retarded pickup coil. I get spark at the fire mark at idle. When I rev the bike the spark actually retards about 5 degrees.
If I hook up to the advanced coil the bike is really hard to start but it fires at the fully advance mark. I have been afraid to rev it above idle because I'm fear that it might advance the spark even more.

So my thought is to extend the arc of the pickup coil to get the same range of pulse with the 650 small magnet that the longer magnet gives with spot coil on the XJ.

The Virago 535 uses a similar rotor to the XJ. The igniter box for the Virago is ~ $30.00 on Amazon.

So

Stock XS650 TCI stator and round magnet.
Stock XS650 Charging coil

Rewound XS650 TCI pickup coil that covers the retarded to advanced range.
Virago 535 TCI igniter box.

Thoughts of a mad man in his recliner at 3am.
 
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I plan on trying this when I get moved into the new building.

Disclaimer

I have not tried this yet so I take no responsibility for any of the following.

The Suzuki GN250 must have sold a butload someplace in the world from 1983-2001.Commuter bike. 50/35 12v headlight and 10 Ah battery

The "CDI" igniter box,regulator,stators etc are dirt cheap.

They call it a cdi but I think it is a TCI box. The coils are powered through the kill switch All stock.Pretty easy to wire into stock TCI harness connector.

Still working on the phasing for the pickup coil.



out orange wire to coil

gnd . black to good ground

vdc red/white to kill switch

in+to pickup coil

in- pickup coil

gn250-tci-wiring-2-1.jpg
 
The GN250 PMI stator and regulator look like they are good candidates for a "Bubba" PMA TCI system.

HHB banshee adapter plate.
Banshee adjustable banshee mount
Banshee rotor.
GN250 Stator with pulsar coil
GN250 TCI box
GN250 regulator

The battery and lighting are similar to the 650 so should be sized to keep the battery charged
 
Interesting. So... if I'm reading this right (questionable), all the magneto is used for is the trigger... system power is still supplied by the battery... correct?
If so, before you go all banshee on it ( ;) ), what are the chances the existing TCI pickup would supply a strong enough signal to trigger the box? Perhaps even a small amplifier circuit to make the trigger signal strong enough?
 
I think the signal level will be ok. My main concern is the length of the pulse because of the small arc that the small stock TCI magnet covers.

I'm going to try hooking both the advanced and retarded coils in series to get a longer pulse.
I'm wondering if the 2 pick up coils are out of phase because this didn't work with the XJ TCI box. May have to drag 2many over with his handheld scope to see what the waveform on the pickup coil looks like.

But yes

stock TCI rotor and stator and regulator.

Hopefully stock TCI pickup and dual output coil.

Working on the last wall section on new building and hoping to be weathered in tonight and can start testing the Suzuki box.

I have a spare coil so I'm planning on a test rig that only hooks up to the TCI pickup on the bike.

Just hope the smoke doesn't escape from any where.

BTW amazon has these for $9.00 plus free shipping.

https://www.amazon.com/Motorcycle-I..._1_1?keywords=gn250+cdi&qid=1581966261&sr=8-1
 
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Sure wish I had a scope... and the brain cells to remember how to use one.... :rolleyes:
Looking at the trace above from the pickup coil signal, it goes positive when it reaches the magnet and falls off negative at the end of the magnet... advance and retard signals. So... the SG uses 2 trigger outputs with a center tap to feed 'em. What if we dropped the center tap and just tied 'em in series.... end to end? Think the trace would resemble above?

Untitled.png
 
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