mk1 rd125lc identification

[budwasmedog]

hi, I've just bought a mk1 rd125lc, it's on a Y plate, and appears unmolested having been off the road from '87 to '14!

The lad I got it off bought it last year and rebuilt it, when he got it the motor was dead, the reason it had been taken off the road way back when. 

It has frame and motor numbers beginning 10w.

The only decent exhaust he could get hold of however has a 11.. part number stamped on it. 

I haven't done any research yet and aren't familiar with mk1 125 model part numbers / ID's etc so can anyone help me out please.

Is the 10w the standard mk1 UK market model and if so what is the 11 model.

Thanks Ray..    

[looey]

10w is the unrestricted 21hp model (not learner legal), 12A is the UK specific learner legal restricted model.

If the steering lock works from the ignition, it's a UK bike, if it's on the left hand side of the headstock, it's an import.

11Y is German or French I think (someone better informed may confirm).

My Mk1 10W is an import and has an 11Y carb and is not restricted.

Hope that helps a bit

[budwasmedog]

Looey, thanks for the help.
Only just starting to have a bit of a better look at the machine now.
Frame and engine 10w, no signs of tampering with ID on either, steering lock is from the ignition so presumably UK machine from new.
Engine was replaced by previous owner due to it being wrecked way back when, both motors 10w.
Original carb' was suspected shot so replaced but last owner could only get hold of a 12A-00 carb' so this was rebuilt with 10w spec' main jet, needle etc.
Are 12A and 10w carbs' otherwise the same??
The exhaust is stamped Yamaha 11Y-14711, does anyone know if this is restricted or not, I'm hoping not, that way I should have a full power machine??
Thanks again for the help and advice..

[looey]

If you're running a 12A carb, I'd be careful running a 10W spec main jet. The 12A carb has a 185 main jet standard standard and the 10w a 155.

It could be that the 10w needle jet will pull the extra fuel through the smaller main jet as it immulsifies the fuel but if it doesn't you'll risk holeing the piston

If I were you I would run the 12A carb exactly as it should be (unless you start changing filters and pipes) cos despite popular belief, the bike will go just as well with a 12A carb (I have every combination of bike and carb combination and they all go pretty much the same).

You should be ok with an 11Y pipe, as they weren't restricted anywhere but the UK (12A).

If it doesn't squirt up to 90mph pretty quick (depending on your weight obviously ) then something is holding it back.

[budwasmedog]

Hi again,

So are you saying that the 10w motor with a non restricted exhaust runs properly and makes full power with a standard 12a carb? I would have thought it would run weak?

Are there any other differences between a 10w full power bike (motor / carb'/exhaust etc) and a restricted 12a bike?

It does seem to run well with the current set up but I haven't been able to take it down the lane and plug chop it yet so don't know whether it's set up ok or not.

The more information I can get the better..

Thanks again

[looey]

Yes the 12A carb on standard setup will give full power with an unrestricted exhaust.

The motors are identical (there is only a 10W engine) but the 12A exhaust is restricted by a tube welded in at the top of the downpipe

If it runs ok as is, then maybe just be careful until you know it's not running lean

Like I said, maybe the 10W needle jet (emulsion tube) works with the 155 main jet in the 12A carb (never tried that).

[budwasmedog]

Cheers for that..

[museumman]

I can sell you 10W carb and exhaust. If your frame is 10W and sure it started life in the UK back in the 80s, they are quite desirable