Dear Gents,
If you ever break an ignition shaft, there is a way to fix it. One day i broke this by accident. Usually i dont use much force with such things, but some time ago I was installing new rings. As I was lowering the barrels, one of the oil control retainer rings snagged in the cylinder. It snagged so bad, nothing could free it. I used both the kick starter and an attempt to free it by turning the ignition shaft left with me with a broken one. (I used a few too many herbs on it). I ended up rubber malleting the piston back out of the barrels to fix my original issue. I've since installed the barrel on just fine and replaced the bent oil controller retainer ring (the thin one), but it left me with a broken ignition shaft and it broke way up in the threaded section.
I actually have a spare crank with a spare ignition shaft in it, but it was almost impossible to remove and so was the one on my bike (honda must have used green locktite or something similar in the day) & i was reluctant to use propane on it due to the oil seal and O-ring behind the shaft that you cant see. So i decided to fix it in situ. I thought i'd document a procedure i used, with the hope of helping someone else who has had this dilemna. There is hope.
By the way, forget about using JBWeld to join bolts together, it just wont work and will not have the strength when used on a small bolt like we have here.
Basically, what I ended up doing was the following, pretty much in the following order.
(1) Find a spare bolt to use to extend the existing shaft on the bike. I think is a M6. Cut off a small length off the bolt, I used about 25mm.
(2) Make half moon sections on both the bolt and also the shaft on your bike. All I did here was use a hacksaw & go half way, then take out the remainder of the metal (half of the bolts diameter) using a small angle grinder. Then touch up any fine work with a small file. Be gentle and patient and it will come good. Cover your bike well to you dont get naked sparks on it & use your grinder in a way to direct sparks away from the bike. I used an old sheet.
(3) Keep working the shape of both half moons on both the bolt and ignition shaft so they marry well together. Use a vernier to check your measurements how how deep you have cut to make the half moon. Keep filing until the measurements are half of the diameter of the bolt. This way the two halves should come together faily closely.
(4) Spin a nut on and try to catch a few threads on the ignition shaft if possible, mainly for the reason of keeping it fastened for the next step (which is to drill a hole through it). On the inside of the shaft, use a cable tie as shown in the pictures. This way both the nut and cable tie will act in keeping the bolt true with the ignition shaft.
(5) Now that you have the shaft and bolt true against each other and held together with a nut and cable tie, drill a small 2mm hole directly through both halves.
(6) Find a 2mm diameter nail, or old bicycle spoke that is 2mm (I used a spoke), cut a short length but slightly longer that the bolts diameter, perhaps cut it 7mm or so in length. This becomes the pin that will keep the two halves together.
(7) Push the 2mm pin through the 2 halves and use vice grips to progressively squeeze the pin onto the two halves. Take your time and progressively get the vice grips tighter. The purpose of using the vice grips here is to keep the ignition shaft straight (by not using hammers). The vice grips have the effect of peening over both ends of the pin, keeping things secure.
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Before removing the nut or cable tie, heat up the area with a small blow torch (again keep the bike protected from open flames) and dont use any more heat than necessary and keep the heat localised on the two halves. Apply lead or solder (I used lead) and fill in such that the lead penetrates right through the joint properly. Using lead is not the strongest solution, but the end result is certainly strong enough and allows you to use minimum heat only, which is important.
(9) Use a file to round the shaft off neatly and to a point that you can slide the advancer unit over the end and position it in the crank dowl. Note, it doesn't matter if the advancer is slightly tight due to the new joint you have made because the advancer plate center spins with the crank anyway. I was patient and kept filing to make the end result neat anyway.
(10) Congratulations, you have successfully enlargened your shaft
Check for trueness with a dial gauge if your've got one. If you don't then just eyeball it and check the final result by testing for timing consistency (using a timing light) of 1.4 against 2.3 and that both are firing consistently without timing jitter (nothing jumping around) and that they are 180 degrees apart as you would expect. I.e. if the timing is correct, then this is what the bike sees anyway, so if you end result is confirmed as mentioned with a timing light, then that should be good enough, it was for me.
If your timing does jitter as HondaMan has mentioned that can happen on 2.3 due to bent shaft issues, then you will have to do some alignment to get it straight as he suggests on one of his threads.
(11) Before fitting your advancer unit, clean the ignition case with soapy water and a rag. Get all the little shavings out so its spick and span by the time you are finished. I put a small smear of grease around the seal.
(12) Fit your advancer unit and reassemble your ignition points or pamco or whatever you have. You might now have to much length extended with your bolt that you have added to your shaft, and this might prevent you from being able to put the points cover back on. Install the small nut on the end, and gently hack saw off any extra length that needs to come off.
(13) Start your bike and time it using your timing light. Check that your advancer is working as expected and while its running, gently press your points cover back on to check that the end of the shaft is not going to rub against it. This will tell you whether your shaft length is ok or if you need to take more off it.
Make sure you put some locktite (blue) on the end nut so it doesn't come off (and no need to overtighten it). It won't go anywhere. Test ride and enjoy.
The pictures are pretty much in the same order. First picture is how they look if you were to buy one (which i think is now impossible brand new).
cheers
Alex
