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[Mark M]

The Mk1 Interceptor (1966 US export model,) has been running well, sorting out teething troubles over the last few months and enjoying the bike. One niggle has been a tendency to spit back when in the transition from pilot to slide, ie, just as you pull away, or throttle right back etc. Really annoying but not a big problem. Anyway, after a great weekend at the Interceptor Rally when the bike ran quite badly due to poor quality local fuel until I sussed the problem, I decided to look into it again. I changed the pilot jets from 25 (std) to 30, no change so I changed back. Did some research and found Pete Fletcher's article on the REOC Humber site about setting the float height on Monoblocs. While I didn't think this was my problem Pete's explanation showed how the fuel level fills the pilot jet well allowing an amount of fuel to be available to be drawn up quickly when the throttle is opened, acting a bit like an accelerator pump and ritchening the mixture as you come on to the slide. Pete had explained that the new Viton tipped float needles (which I had fitted when rebuilding the carbs,) are slightly longer than the old brass or nylon ones and as a result you need a fibre washer under the needle seat. Well I tried that and it didn't work, petrol just poured out of the tickler. I took the washers out and replaced the Viton needles with the original nylon ones which are indeed, a few thou shorter than the Vitons. This has really made a difference! A test ride this afternoon (we are near Silverstone so the roads are quiet while the racing is on,) shows the bike greatly improved. Really good throttle response and better tickover. I will need to do a carb balance session but looking good. Thanks Pete for the hint!
REgards, Mark

[PeteF]

Thanks for the Thanks Mark.