Took the Bonnie out to Pacific Harbour to see Colin Head and borrow some of his Classic Bike magazines. Under wide throttle openings the engine would run rough and not throttle off. I was forced to pull in the clutch, let the revs rise, and then it would come right again. Low throttle openings caused no problem.
At home in the workshop, removal of the RH air cleaner revealed what I had suspected. The throttle side is jamming in the carb bore. Again.
This carb has never been right since I first installed it and over-tightened the stub nuts. I thought I had gotten away with it by slackening the nuts off, but apparently not! The carb body must be permanently distorted. Now when it is tight, the slide is really tight.
I sanded the scuff-marks on the slide with wet&dry to ease it down, my aim being to keep on sanding until the slide could drop back down the bore by its own volition. Problem is, this took a lot of sanding. I’ve probably put about 25,000 miles of wear on this slide. And these carbs are reckoned to only last for 20,000 miles before they are so worn that they need replacement anyway.
A lot of people go for Mikuni conversions these days, but I don’t myself feel moved to do so. I think Amals are the right carb for this bike. Mikunis have endless permutations of tuning possibilities, so offer the potential to either dial the carb in to 99% of its capability (if you know what you are doing) or get horribly confused (if you don’t). Amals have only a limited range of possible adjustments, which means that a dumbo like me can relatively quickly dial it in to about 90% of its capability.
This is not necessarily a consideration if you buy your Mikunis already set-up for your particular model of bike from one of the specialists like Allens. But I suspect a lot of the hype about Mikunis giving such a dramatic improvement over Amals stems from people who have just junked their clapped-out old Amals for a brand spanking new set of Mikunis. Not exactly a fair comparison.
Also, Amal Concentrics look so nice, simple and elegant. Just a pity they are made of such shit metal, and don’t have the threaded top-ring for reinforcement like on Monoblocs.
Went for a test run out to our shrimp farm on Sunday to feed the shrimp. Bike runs okay without the slide jamming, but the engine is not running as smoothly as before.
I might as well face facts and accept that I have to buy (another) new RH carb. Let’s just call it a NZ$200 “Stupidity Tax”.
