Hi All.

I've just done a deal on ebay for what I understood was a 1980 Yamaha DT125 Trials bike.

After picking up the bike and a bit of investigation it turns out to be a DT175 engine in a hand made frame possibly WES Powys? There are some trick aluminium parts, air filter and exhaust expansion box and fuel tank. Marchoni forks

Engine starts easily so I'm happy I've got a good deal.

I'm trying to identify the frame  builder.

Anyone know anything about it? Any info would be useful.

Thanks Peter

Edited June 7, 20242 yr by Pete_engineer

That monoshock configuration is reminiscent of mid-1970s Yamaha MX bikes.

Some interesting backstory here: https://motocrossactionmag.com/classic-motocross-iron-1974-yamaha-yz360b-monoshock/

 

What you have there is a Chapman BSA.

One of the 1st mono shock trials bikes, built by a chap called Mike Chapman.

Based on a DT175, hence why you thought it was a DT

Well that is pretty cool.  I Googled "chapman bsa trials" and the first hit is here: 

Looks like the original builder was a member here (mick_99) and replied, "...20 production bikes and there were 3 prototype made:..."

I've got No 20!

Any idea if Mick is still around. He's not posted since 2012.

I just got the bike in the garage.

Tried to start it but the mains had siezed. Looks like there was water in the crankcase. 

Rebuild is in progress.  I was going to fit lights and get it road legal.  Not sure if this one was ever registered. 

Edited October 19, 20241 yr by Pete_engineer