I factor in the cost of a brand new Carb and ignition with every rebuild
Good point Slakey. When I built my Champion framed Honda XL350 back in the early 90's I fitted what I thought was a good 34mm Mikuni off some unknown Yamaha MXer. Try as I might, I couldn't get the engine to pull cleanly from bottom to mid range, I tried everything in the pilot and main, 3 or 4 different slides and needles, fiddled with two or three different ignitions, and even fitted a softer camshaft profile, all with varying effects but still not clearing up the "blubberyness". One day I was over at Jonesy's place and I spotted a NOS 34mm Amal Concentric methanol carb from a Weslake speedway bike on his bench and I managed to talk him into donating it to the cause. I'd been wanting to put the bike on methanol anyway so with no changes whatsoever to the jetting I fitted the Amal to the Honda and Voila!! the bike ran as clean and smooth as a Holden Kingswood right from the get go. I ran the bike for the next two years without touching anything inside the carby at all, still with the factory stock jets for a Weslake speedway bike! Anyone who remembers that bike will tell you that it was damn fast and pretty reliable and was docile enough to be abe to ride it in traffic. When I later checked the Mikuni I found the body to be microscopically worn to an oval shape contributing to the inability to jet it correctly.
Ever since that lesson I've tried to use new or newish carbys and good ignitions on all of my bikes. If a new carb is out of the question I try and build a carby as close to factory tolerances as I can. I used parts from half a dozen different carbs and checked another dozen more to build the 34mm flange mount Mikuni on my Cheney. The hard part was finding a body and slide combo that wasn't worn beyond usable limits. I've got a brand new methanol jetted type 54 Bing from a Jawa speedway bike in my carby stash waiting for a project worthy of its presence.
