This is just to show the tickover with TT carb and internal slide stop. Previous owner (the late Bernard Harding) fitted it.
Hi David, Does the long…
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I really don't know, Robert…
I really don't know, Robert. It's there because it came like that. I had more trouble with the banjo leaking at the bottom of the carb than with spitting back. I had to resort to Wellseal to stop fuel leaks from the banjo. Maybe I should try Dowty washers. The ugly looking foam filter sock should prevent spit back anyway. I was running it with the air filter (in the torrential rain!) late last year and it seemed to be fine.
As for performance - as far as I've read the benefits are marginal, and non existent except at maximum revs. So it's just decoration really (no harm in that of course...). I ran it without very briefly after I bought it, and didn't notice any difference with it at the revs and throttle openings I was using.
This is an early TT carb. The inlet throat of the carb body splays out more quickly within the body than on the later carbs, so the designers intended it to have a shorter, more splayed out inlet. The long inlet was fitted by a long time previous owner who made lots of updates to a 1932 motor, including head (hairspring valves), cam box (racing magnesium) and even a rev counter. When Bernard bought it, it had been thrashed into the ground and was a money pit that took over 10 years to get back on the road, by which time Bernard was almost too old to ride it, although he did take it up Brooklands test hill on one occasion.
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That's a real machine Dave...
...Lived with and modified with what was available at the time; the combination makes the "whole" so unique.
I spotted you had had banjo leaks, Dowty may well help but try another Banjo, it may be that.
I agree with your comment regarding the trumpet, but it also helps contain the fuel dribbles that blow back due to the cam overlap.
Hadn't recognised the throat difference on the earlier version TT . Mine is of 1934 vintage, its a bit sloppy and the jet block was well gummed in, but its apart now and ready for fettling.
Best regards
Jon
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Early TT carb
The picture shows the inlet. It has an outside thread, unlike the later ones. This is marked with 1932 date. I don't know if data are published somewhere but I think they changed in 33 or 34 at the latest.
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Looks like you have no air…
Looks like you have no air lever (or rather mixture enrichment device) . And the air slot blanked off?. Normally a usefull device on a TT carb ,not a choke , Perhaps this loss of air is compensating for the extra air these old carbs usually get and contributing to your unusualy good tickover !!. My SSI has the cable hole plugged and the slide removed but the air slot open. I did try blocking the slot but it ran badly.
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No...the air slide is there…
No...the air slide is there on the right. I close it to start and open it on the road. If closed it runs very rich. Incidentally I thought the Dellorto carb (which is near enough a copy of the TT , allegedly) has a tickover adjusted by means of a prong dropping down from the top of the carb and through the slide, and the slide hangs up on it? Or something like that.
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Hi David, Does the long trumpet make a difference to the running? I prefer the look of the orriginal but sometimes a longer trumpet helps with blowback .