I have been doing initial shake-down rides on my 1955 Model 88. It seems to be basically OK - seems to be holding together, and only a small drip from the timing cover. Some issues:
1 - racing idle when really hot. I had to use the kill button to lower the idle speed. I don'[t think this is the throttle slide is failing to close properly. Could it be tired ATD springs not giving full retard?
2 - clutch lift reduces a lot. I keep thinking the clutch centre nut is coming loose, but the clutch lift returns when the bike is cold
Paul
Could be an air leak in th…
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When the bike was stinking…
When the bike was stinking hot yesterday, it would not drop down to idle, so I used the kill button. Having dropped to idle, it stayed there, but did it again next time, etc
The carb slide is a very new one. The issues are complicated by the fact that the slide and carb top parts are as the bike was previously in service, but the body is a replacement - the previous one was lost during the time the bike was in pieces. I did flat the carb joint face as part of the build.. I will look for inlet air leaks.
Are all Lucas ATD springs the same?
No, the clutch does not slip. The only part of the clutch which is not old Norton supplied is the clutch springs, which are mid '80s. Friction plates are all old style Ferodo inserts
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The very hot engine could…
The very hot engine could be vapourising some extra fuel and thus making the idling mixture too rich.
I would also suggest the timing is a few degrees over-advanced. This could be down to the points being open too much. I guess that your bike has a magneto in which case close the points gap down to 12 thou and see if this helps. You could also add some Octane improver to the fuel and see if this changes the engine idling.
Dominator clutches do not like getting too hot. All the plates and the main body expand resulting in a huge gap arising between the clutch pushrod and the pressure plate. This in turn makes the clutch lever go sloppy resulting in less clutch lift, crunchy gear changes and difficulty in finding neutral. All made worse if you have 7/8 centre levers.......which is the downside of fitting such.
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The magneto was set with p…
The magneto was set with points gap 12 thou one side and 13 thou the other. Timing set using a feeler gauge to detect opening, set fully advanced 29.5 degrees and 31 degrees BTDC. If timing is over advanced, that could be an ATD not retarding sufficiently.
I just remembered that when hot, it seems to kick back a bit when trying to start it. That adds to the idea that the ATD is not giving full retard
Paul
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The racing idle turns out…
The racing idle turns out to be a tag of insulation tape getting sucked into the open bell-mouth. Trimmed off, the problem is solved. There's also an off-idle snatch and occasional spit-back which suggests raising the needle one notch to richen.
More seriously, tonight on my way home from a NOC meeting, I suddenly noticed that the lights had gone out. There was a faint glow, so I think it's the dynamo not charging, and the batttery has gone flat. Could this be the dynamo needing 'flashing' to make it charge again? The bike was off the road for 30 years.....
Paul
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Could be an air leak in the carb / manifold, a worn slide, or even the slide hanging on the cable (not enough slack). Can you get the idle down to an acceptable level with the throttle stop when it's hot?
You're right that if it's too advanced it will probably idle too fast but even so you should be able to get it slow enough with the throttle stop.
WRT the clutch, is it slipping? That can make the plates swell.