Hi, just wondering my Dt first reg April 1980 has a rectangular section swing arm, im sure these had a tubular section arm, If this has been changed for the more modern design will I find that other bits have been changed to make it fit, ie the shock (Mainly curious but may be helpful if I need to overhaul the shock)

cheers

I doubt it isnt the original one

Different swing arm

different shock absorber

different chainguard

what side is the oil tank on?

what is the vin number?

Yeah oil tank on the left. Swing arm dosent look 30 years old, in fact its in better nick than the one on my 1999 GSXR

you sure the oil tank is on the left i dont see it?

1980 should be on right shouldnt it?

Oil tank is missing, but there is space for one

V5 states first reg April 1980

THE 1979 DT125MX I had defineately had a rectagular swinging arm and from what I remember as Airhead say's the oil tank was on the right hand side and the airbox on the left.

If its got the lh filter then it shouldn't have the round swinger. Maybe its an upgrade. Or the fellow doing the part rebuild fitted it. Who knows.

Wack the first part of the chassis number (leave the last 3 digits off for safety's sake) up and we will know for certain.

Frame number 2k40018***

So if its original 1980 with the air box on the right and oil tank on the left then the rectangular swing is correct ???

you had me confused saying its a 1980 bike, these did have the square sect swing arms

as i thought..its a 1979 model thats why the oil tank is on the left...someone fitted a later arm

Don't mean to spoil your fun but that 125 is a 175.

If it was a 125 the chassis number would start 2A8.

2K4-001 is the earliest of the 175 MX generation dating from feb 78 to very early 79 when the 2K4-010 took over.

It was the 2K4-020 that had the square swinger, LH airbox and 6 wire cdi

Thanks guys so.....

its a 1979 chassis 175 MX registered in 1980

with a 125 cc 1981 bottom end

with a 175 cc Head

with a later rectangular section swing arm fitted

I guess ordering parts could be interesting.

Is it likely that the shock was changed with the swing arm then or would it fit both styles.

so the engine# isnt also 2k4 then ?

No I contacted Yamaha, the engine is 2A815****

and got the following reply:

Thank you for your e-mail.

The engine number you have providedrelates to a 1981 model year Yamaha DT125 which was produced early in that year.

When ordering parts we would recommendthat you quote the Model Code 4J3 along with the Engine Number.

the shock will have been changed too unless the width of the original shock bottom pivot was reduced to suit the new arm

Seriously - A massive Thanks to you all

would have taken me ages and countles frustrations im sure to get all that figured out