I have rebuilt a 1982 Imola from a basket case, but it is now suffering from what I think is poor carburation. it was fitted with K&N filters and some mods to the jetting, namely: an E27 needle instead of the E26 standard one. The only difference is a slightly smaller shaft diameter (0.03mm), presumably giving a slightly richer mixture at small throttle openings. The only other difference is a 42, instead of standard 40 idle jet. The carbs are correct Dellorto VHBZ 26.
I don’t know if the bike ran well with this set up before being rebuilt. As the K&N filters were past their best, I bought similar S&B ones. The engine ticks over fine and pulls ok at above about 3000rpm, but gets bogged down and won’t pull at low revs. When stationary, it is a similar story, not being happy to rev between 1000 and 3000 rpm.
I plan to try raising the needle a notch and checking mixture with a colortune and also check compression, but would be grateful of any advice from anyone who has been there, done that. I’ve checked timing, changed condensers, checked float height, balanced the carbs with vacuum gauges and pretty sure there are no manifold leaks, so carburation seems the logical place to look. When rebuilding, all I needed to do to the top end was lap the valves and replace rings.
Yours, in hope!
Adrian Overs, member 415 Â Â