Thanks for the info. We too have a couple of machines running obsolete operating systems to support ancient hardware and software which won't run on anything more modern but is still indispensable. Just don't connect it to the internet . . . I've a couple of projects to finish before I can realistic...

Thanks Pete for an exceptional job with the scanning. I've just found time to look closer at what you've achieved. I'd expected a collection of scanned page images in a PDF wrapper and I was partly correct. What I hadn't expected was the embedded text. It looks like extremely good OCR. These PDFs (o...

Thanks for the photos and the number. The crankcase is right for the year and the head and barrel are the later sort of iron ones. You'll need quite a number of fixing bolts - 4 for the head and 8 for the rocker boxes that aren't the same as the later ones. The rocker boxes too aren't the same but t...

Firstly, some photos always make things easier. A 1959 NH would have had an alloy head on an iron barrel. In my experience all alloy heads had barrels with integral pushrod tubes. The NH alloy head had 4 bolts and the VH head had 5 - actually studs and sleeve nuts. Both VH and NH iron heads had barr...

Having had to do this under other circumstances - Yamaha SR125 many years ago - do make sure
that there isn't anything still attached to the guide that's going to fall off under the effect of the
moving inlet valve. A secondhand SR125 top end was available if not exactly cheap.

I can't help with where it is now but it's a lovely photograph. It looks professional and what struck me was just how clean everything is. Was this taken right at the start of the trial while all the competitors were still running? The 'bike has acquired a later alloy top yoke so wasn't new at the t...

I looked in the literature - the alloy pushrods don't seem to have been listed for all-iron engines, only those with alloy heads. I'm not sure just how hardened, if at all, the ends were - I've got some badly worn examples. I've also got some NOS ends somewhere which I'll look out and test. While it...

I've got to ask the question: why use alloy pushrods? I did it once, by mistake and wasn't able to correct it for a while. i ran the thing 'til it stopped, opened out the clearances 'til it ran again, and repeated until it kept going. From cold the clatter was horrible and it took quite a while to w...

Oops! I must read the posts more carefully. NH is, as Pete so completely describes, a 276 and not a 289.

It would have been a sidefloat Amal 289 but mine has a 376 monobloc modified
to help prevent surge on cornering - it's a trials sidecar.

Many years ago when they first came out I tried a concentric but I just couldn't
get it to work as well as the modified 376.