Been lurking, commenting, and criticising in roughly equal ammounts on here for a few years, finaly couldnt put it off any longer and bought one of the few 250cc 2 stroke race repicas I haven't yet owned.

Anyway here she is, as always pictures make it look better than it is and it's seized, the chassis looks clean and straight, bodywork needs some attention but it's all there.



Anyway first bit of help I need, there is a White multi pin connector under the tank with six light green wires with different colour traces on them, coming from the same stand alone bit of loom and exiting near the white connector is another light green wire with a red trace. The loom section comes out of the gearbox sprocket cover area and terminates under the tank above the carbs.

Thanks in advance.

It's connected to nothing and there is nothing to connect it to, what's missing please? All the obvious electrical boxes are present and correct, coils, servo motor, PGM, reg/rect etc.

Sounds like a MC21 GPS (Gear Position Switch) lead. At a guess your bike may have an MC21 engine, or at least a bottom end.

Thanks, sounds interesting. Any idea how I go about proving that via the engine number?

Thanks

my r5k has one in the box next to the servo under the tank that connects to nothing. what shape are your cylinders? hex or round?
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it wouldn't be fun if it was easy!

They are round mate, this plug is too big to fit into the box by the servo. Given the number of wires I think the gear position sensor sounds about right.

MC18 has hexagon shaped cylinders.
MC21 has round shaped cylinders.
I've always liked your type of MC18. Will have to get one at some point!
From what I've been told the '18 doesn't use a gear position switch. I guess you've already checked the wiring diagrams?

Thanks. Not checked the wiring diagram, I will tomorrow but I think you are right given the cylinder shape and the plug has no home to go to. Thats the great thing about 20 year old project bikes, you never know what you will find!

Do you have the neutral light working? I put an MC21 motor into an MC18R2 chassis and had to hook up the neutral wire out of the GPS.

It does sound as though you have the complete motor if you have round bores and a GPS.

This is a pic of 3 bottom ends and the MC21 on the left has a hole for the GPS cable where the other two just have the neutral connection.

More pics of the internals of the knackered motor if you can be arsed.

Hmmmm, 6 light green wires doesn't sound like the GPS to me (should be three wires, yellow/red, yellow/blue blue/green) though the green wire with a red trace should be for the neutral light.

***EDIT***
Ignore the advice above, it couldn't be more wrong if it tried
***EDIT***


Roy's right though, only the mc21 uses a gear position switch, you can see where it is really clearly here on RichG's trackbike, that wire running between the flywheel and the sprocket down to the little black thing held in with one little bolt. Though why it's still there on his trackbike I don't know, there's nothing for it to plug into and nothing to be lit up.

On the mc18 it does nothing other that light the neutral light the mc18 has no different maps for different gears or side stand cut out so the easy test is does the neutral light work?
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Last edited by fontyyy on Fri Dec 10, 2010 11:07 pm; edited 3 times in total

geezagillard wrote:
It does sound as though you have the complete motor if you have round bores...

I would hope the bores are round, irrespective of what model they come from!

I think the only motor not to have round bores is the NR, isn't it?!
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Mmmmmmmm the thick plotens, pictures with her clothes off later.

"thick plotens" wtf

Just a variation on "the plot thickens" from Black Adder. Breath

Pictures tomorrow as I am off out to get very drunk with my wife, have a picture of the RS125 I keep in the house until then

With all due respect, Fontyyy, according to the wiring diagram (which I have in front of me as I type this), and the 4 GPS switches that I have sitting on the bench in the shed, there are 6 wires to the main connector, all light green, with thin coloured traces W, Bk, Y, Gn, Br & P (6th to 1st gear resp), and a single light green wire with a red trace for neutral.