Depressing day today.
Had my son around to start the project for me, as my hip ain’t great and this bike needs a mighty kick to get her over. After several attempts with only the occasional pop from the rear cylinder we discovered the carbs had flooded. I have 34mm Mikunis on this bike, which I bought because they were way more compact than Mk2 Amals and relatively cheap (£400 the pair with cable choke). All my bikes have Amal carbs (except the Weslake with a Dellorto) and they must be the most trouble-free and easy to tune carburettors ever made (I mean starting from scratch on an unknown engine as opposed to a ‘tune up’). If only you could say the same for Mikunis. But at the time I didn’t fancy splashing out too much before even knowing if the engine was a runner.
I was aware before I started that they are a nightmare to tune because of their crazy assortment of jets, but foolishly hoped I’d at least get somewhere close. Well, I haven’t even got that far because I’ve now discovered they won’t tolerate ANY downdraft / updraft angle without flooding. Great. My carbs are mounted athwartships, so even leaving the bike on its sidestand means the carbs flood. In contrast, the Dellorto on my Weslake is mounted at 45* downdraft with no issue.
Another hassle with Mikunis is getting to the float valve. On the project, that’s the best part of an hour per carb because removing the pin holding the valve flap requires the carb on the bench and a special tool to support the legs holding that pin. Try and drive it out without and you’ll likely break the pillars supporting it, and that means a new carb body. And getting a carb off on the project means dismantling the twistgrip and pulling cables out etc.
So am well peed off. Was intending putting the bike on the lift next week to start designing the exhaust, but now I’m going backwards. A brand new set of carburettors are about to go in the bin and I’ll need to fork out another £400 plus for some decent ones. No doubt that’ll mean making new throttle and choke cables - and the latter were a real pain. I’ve been pressing on with this bike for around a year now, realising the need to get it finished whilst still physically able to do so, but sometimes I feel like just giving up. I hate Mikunis!