Alan The bike in the photo is/was owned by Eric Parker from Nuriootpa South Australia. Eric has a very large collection of Ariels (Australia’s largest, as well as a large collection of Chevs). Eric had pictures of a prototype mk4 swing arm 4 and claims the bike in the photo was original. The frame c...

Look at how the piston ring gap opens up and how the lip develops at the top of the cylinder bore. That is a lot of magnetic particles.
David

Vincent
When Ariel went from the 1.5” base circle cams to the 1” base circle A7/642, they did not change the followers. But you will need longer pushrods.
David

Paul My mk2 is exactly the same as your 4g. I set 8mm or 5/16” fully advanced which is tdc fully retarded on my 4. I always set the fully advanced figure as it is quicker. To accurately set tdc means setting a piston stop and fitting a degree wheel. I did that the first time and then measured what f...

Paul
Hope you and the bike are on the mend shortly.
David

When a .060” oversize piston is fitted the piston will be heavier than std size and the engine will vibrate more. JP pistons are generally a bit heavier than originals. With the JP 9 to 1 piston for a VH/HS, I reduced the weight by scalloping the piston skirt at the sides a little more, as well as r...

During our hot summers I had a couple of oil brands clearly fail (black and thick) when overheated in my 4, although I did not experience sticking valves. Mobil 1 V-twin was recommended to me by a fellow historic vehicle club member and Harley dealer/mechanic. He spoke about the very high heat of so...

I do think that overoiling in this case is at least part of the problem. And the inlet valves are the ones that are most affected due to the very strong suction of the induction stroke. The exhaust valve stems generally only show signs of carbon when there is excessive wear and are not affected by t...

The original rocker box gaskets were very thick and hard, and never any problems. I had a stock of them until recently but had not used them after I found that they were mostly asbestos. I eventually dumped them. Many of the replacements are thinner and softer and they leak as they compress. I now u...

Gary The brand new carburettor could be the problem. While I don’t know of any reports of problems with the new VB 276, there are plenty of stories about problems with drill swarf still in some of the small passages on new purchased concentric and monoblock carbs. It might be an idea to remove the j...