After having an Audi TT driven through my right tib and fib, I feared that I would not be able to start my '74 MKIII 450, with manual decompressor, or Yamaha SRX600 twin shock single that has an auto-decompressor. However, after a successful op, with a titanium pin screwed in place through the length of my tibia and 6 weeks after the incident I was able to kick start my SRX600!
The surgeon would have preferred that I hadn't, but I had to prove to myself that I could, or else my 450 rebuild was going to be less enthusiastic!With 12v, points ignition, a decompressor and new Amal MKII 32mm carb what could possibly go wrong? Twenty (20) months later, 2 cam changes, 3 complete checks of both valve and ignition timing, 3 carburettors, 1 new Amal MKII, ! rebuilt MKII and 1 rebuilt MKI, using different slides, pilot jets, main jets, needle jets and needles in all 3 carbs, 3 sets of points, 3 different spark plugs. Blowing 3 inlet rubbers to smithereens, blowing the carburettor off the inlet stub over 50 times. 2 different exhaust pipes and 3 different exhausts, in combination with the different carbs and their settings!
I had numerous kickbacks, some of which really made me feel the pin and at times kicked the engine over for 30 minutes trying to get it to start or re-start after dying.
Finally, I purchased a Electrex Hall Effect EI from Nigel Lacey, fitted it, timed it ( far easier than the points set up as the whole job can be done from the right-hand side of the bike) and the engine started 1st kick, no effort, no backfiring, no blowing the carb off, taking chips out of the frame webs and carb bellmouth!
There was rejoicing in the glens! Yes, the carb needed some fine tuning, because I was at last able to take the bike out for a run, without worrying if it would blow the carb off and split the inlet rubber in the middle of nowhere.
The AAU was the item that appeared to be the cause of my problems. Why? I am not sure; the AAU pivots and springs all appeared in good condition and it was suggested that the 450 crankshaft harmonics were causing the problem. Who knows?
What I do know is that after fitting the Electrex EI, even with the carb settings being "ballpark", the engine settled to a steady 1,200rpm tick over and no kicking or spitting back. Now, after fettling, the old bird has 3,500 miles under the wheels in 2021, with more to come in the years ahead.
Also, your "bionic bits" are probably stronger than you think and as long as you haven't raised the compression to 12:1 and everything else is standard, in good working order, you should be fine to keep on pogoing a Duke into life!
Good health, Bill
P.S. If you haven't read the saga of the 450 carb then here is the link: 450_Desmo_carb_Pages_3-24 BR