Another bit of data: I queried Draganfly, who make their 4G pipes with the small one to the rockers, but Mark I pipes with the large one to the rockers.
They replied "we are confident the parts are correct to OEM specifications"

I'm a bit reluctant to re-open this controversy, but it seems not to have been settled. I came across the issue while looking for insight on the abnormally low oil pressure my 1952 Mk I Square Four exhibits. Apparently several owners have had inexplicable low pressure, and solved it by switching the...

Nick, According to the Amal documentation for 1936, 89/14 is the correct carb for the VH. Specifications are 200 main jet, 29/3 slide and needle clip in slot 3. The 289 carb is a later model, very similar to the 89 but lacking the separate air intake holes in the body that are visible in your pic. I...

I like the results of using a fine stainless steel rotary wire brush.

Hello all, Thought I'd pass along my latest adventure with the '52 Square Four. I was riding along peaceably in fourth gear when I felt a skip - a momentary interruption in power, but with no misfire or change in engine sound. Very brief, and sudden - not a slipping clutch. Normally this would have ...

Yes, I see - the photo is a bit dark there. Should work reasonably well, then.

It looks like the feed tube still comes from the original upper tank, rather than the lower converted toolbox. So, how would oil in the lower tank ever circulate to the engine?

Yes, it looks to be an advertising brochure. But we're told on the back page that colloidal graphite "is so fine that it is used for injection into the breathing tubes of mosquitos". Irrelevant trivia to be sure, but does anyone know why someone would bother injecting graphite into the bre...

The front brake on my '52 Square Four was completely ineffective, even though I'd sent the shoes off for relining. The handlebar lever would go all the way to the bar with hardly any actual braking. There turned out to be several problems: - The exchange relined shoes were wrong, 1" wide not 1....

Hello all, This afternoon I took a pleasant ride on my newly-restored 1952 Square Four Mk I. That is, it was pleasant until around 30 miles in, at which point pain set in due to the very uncomfortable saddle. This was a legacy of the previous owner, and is clearly wrong. It requires setback adapters...