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Rex, I measured the engine temperatures after a run using a touch digital thermometer and got 55 Deg C on the timing cover at the pressure connection point and 135 Deg C at the third fin from the top on the cylinder head.

I noted the Amal Premier I received from Burlen was fitted with a #4 throttle slide and when running port throttle the plugs are a greyish colour after a plug chop - running lean? Would a move to a #2 or #2.5 throttle slide be too much of a change to richen up the mixture when running at part throttle?

Appreciate any comments.

As a quick update, I fitted a new Amal carb from Burlen including 4 Cutaway Slide Hard Anodised, 180 Main Jet, 106 Needle jet and Size 17 Premier Pilot Jet. I ran the bike last week end and the plugs were a very light brown - see pictures. I plan to drop the circlip to richen up the mixture and get a darker plug colour.

The engine still seems to be running hot but I do appreciate other comments which suggest the engine is not running but the right hand pipe of the 2 into 1 is well blue! I did try to measure the head and timing cover temperatures with a touch thermometer but the test was inconclusive - I'll have to invest in the optical device from Maplin as suggested.

Does anyone think the coil could be causing some of the issues? The coil is a single unit with two HT leads made by EMGO. Would it be worthwhile changing the coil for another unit?

Again, any comments appreciated - I am planning to take the bike to France for a rally in two weeks and will cover approximately 100 miles. Time is running out to fix the "overheat" issue if there is really one. I will cover 30-40 gentle miles before going to France.

Thanks for all your comments.

The plugs are Champion N4C (when I acquired the bike, it was fitted with NGK B7ES plugs).
The timing has been set with a strobe and the timing mark checked using the slot in the flywheel accessed through the inspection plug behind the cylinder barrel.
Th engine is running Morris 20w50 oil and I will change this to Morris SAE40 at the next oil change.

The re-bore was completed due to the scuffing of the bores - I only think it is running hot based on comments from the guy who rebuilt the engine following the re-bore saying it may scuff again if I was not careful and the right hand cover feels hot (as opposed to warm). Maybe this is the way they all are and I am unduly worrying? Any drip of oil from the rocker box does  quickly burn off with a "wisp" of smoke.

Thanks for your comments.

There is the genuine "thick" paxolin gasket between the carb and cylinder head.

Looks like pulling the timing cover will be time well spent.

The engine has a Pazon ignition system with the timing set at 38 degrees (as per recommendations). Is it worthwhile advancing (or retarding) the timing to see if the heat generation can be reduced (there is one comment in the thread to advance the timing which I will try).

In terms of dimensional checks, the engine was rebuilt by a reputable bike restorer so I am not aware of any piston-bore and ring gap dimensions.

Appreciate the comments in the replies.

Help needed….. I have a 1969 Triumph T100R in a Rickman frame with a single Amal 626 carb and 2 into 1 exhaust. The engine has just been re-bored to 0.020 oversize after the previous owner scuffed the pistons/bores. The engine runs well and starts very easily with the ignition timing set with a strobe, but the engine runs very hot. To ensure the carburation is OK (currently running with 190 main jet), I am about to replace the carb with a new one to be sure there are no air leaks between the throttle slide and body. I will also remove the “slip on” style silencer to see if that is increasing exhaust restriction (and retaining heat in the engine). Beyond that, I have run out of ideas!

Has anyone else experienced similar over heating issues and what was the solution? Any comments welcomed.

Thanks,