classic motorcycle forum

Some very good advice so far, one other thing with the Thunderbird clutch is that over the years the handlebar lever gets replaced and sometimes with the wrong one, the Thunderbird lever should measure 7/8 inch between the pivot bolt centre and the nipple hole centre, if yours measures 1 1/8 inch which is the more common lever change it to the correct one the difference is vast.

Hi Wetdog

I haven't measured the compression ratio on this bike but  with the bigger piston and the dome top I would estimate it to be nearer 8-1 than 7.15-1 but certainly wouldn't argue about it.

The bike you have is as you say far too high a compression for petrol and needs dropping down, also the problem you have with the little end bush makes me wonder what else the dopey PO has done to the bike, personally I would do a complete strip and carefully check everything in there, as I said previously a compression plate is easy to make, get a piece of 3/16 soft alloy sheet from your local supplier and spend about an hour making one. I used a cylinder base gasket as a template.

Yes I have one in my B31 together with a pair of Goldie clubmans cams starts first kick every time and goes like a good un.

EDIT
I forgot to say when I first did it I made a compression plate to fit under the barrel from 3/16 alloy sheet, I have now removed this plate and can't really notice any difference. If you want to drop the compression it only took about an hour to cut drill and file the plate to shape not a big job at all.

I wish you luck Bomber, But don't hold your breath.

Hi again Wetdog.

Indeed you do seem to have "racked him off", I have used these valves on a B32, a 500 Goldie and a 350 Goldie without problem a friend also has them fitted to a 350 Goldie and a 350 AJS (in line type from same supplier) without any problem.

About three years ago my brother fitted one to an A7 which had recently had the engine rebuilt by the previous owner, it had only done around 200 miles since the rebuild and one bright but freezing winters day he took it for a run, about half a mile out he felt the engine tightening up and stopped, the engine  then would not kick over and he pushed it back cursing the anti drain valve as the culprit, when he went to the bike again the engine had freed off and turned over OK, the offending valve was removed and he rang me complaining about it, I went along to check it out for him and the valve was working as it should but turning the engine over had no oil returning.

I am not saying the same happened with yours, but on the twins they can suffer a "cold seize" this had happened on my brothers bike. the freezing weather shrinks the alloy case which compresses the timing side bush onto the crankshaft, if you ride off straight away the wind cools the case even more whilst the shaft is beginning to warm, if the bush is a very close fit the shaft can force it round cutting off the oil supply to the bottom end, after sorting the main bearing bush the bike has been running without problem with the valve refitted ever since.

I hope  the damage to your bike was not too bad.

Where are you buying the plugs?, I had a similar problem, Google fake NGK spark plugs for info.

Pretty much as R says, but some Triumph engines are prone to melting the piston if you use hotter plugs, so I would not advise that, also how long is it since the bike was running?, is the petrol stale?.