It Takes A Lot of Work…

It takes a lot of work to get to the stage of putting a bike project back together. Media blasting, sanding, de-greasing & ordering new parts. It can be tempting to rush but taking care in assembly will make sure everything works. It took a few trial assemblies to get the shims right on the QA-50 engine & transmission. Everything was fitting together nicely with minimal end-play. Then this happened…

This is the kick-starter shaft. A common problem with older motorbikes is that the kick starter lever can become loose on the splined shaft and if not fixed the spline can be stripped or damaged. Some unscrupulous mechanics will try to repair this by welding the lever to the shaft (often damaging the oil seal & making it impossible to split the case), drilling and pinning the lever (half in the shaft & half in the lever) or cross drilling thru the shaft (removes a lot of material from the shaft cross-section which leaves it quite weak). This bike had seen the latter and the end of the shaft broke off. This left the bike unable to be started and as a result it sat in a shed for decades.

Now the Honda QA-50 can be described as the poor cousin of the much more popular Z-50. It was less popular and not manufactured anywhere near as long. This means that there are less old parts available and less aftermarket parts. Finding a kick-start shaft was proving difficult. That drove me to try a not so typical repair to the old shaft. Since it was already damaged and ready for the scrap heap there was nothing to lose.

This is the other end of the shaft. It was sourced from a cheap “pit-bike” style engine, which are close copies of the CT-110 engine, and had the right sized spline. The old shaft and new donor were cut and mated together with a turned spigot to help alignment before being welded. The weld was turned down to suit the hole in the crankcase and polished.

As you can see from the photos this did not hold up use. The breakage occurred after just a few kicks but at least the motor did fire. What can also be seen from the images is that the weld was very thin around the outer circumference. This gives me confidence that with a better weld prep & deeper penetration the repair should work…

Find out in a future update.

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