Samurai Cag overhaul

This is another of the three repair bikes.

It's a Samurai type cag which are probably one of the worse ones you can get quality wise. the welding is especially bad and they are quite frustrating to work on compared to the other kinds due to some awkwardly placed bracketry! They are however the lightest type of Cag so perhaps good for the hardcore racer ;)

Typical of many Samurai's a few parts of the frame needed rewelding. the rear brake caliper bracket had sheared off a few mm above the weld (thats how bad the metal is) as had the top end mount. Both were remade from 3mm mild steel and TIG welded back on.

Another problem i see on alot of these bikes are seized chain links. Often caused by not using a good quality chain lube (or none at all) but also - and in this case -parts of the frame grinding on the chain. the chain cover bracket was actually grinding on the bottom of the chain. the cover is practically useless on these bikes so it was removed along with the offending bracket. Good quality BZM chain and regular lubrication fixes that issue.

The saving grace of these samurai bikes is that the engines are pretty good and generally bulletproof when left stock. They are just not highly tuned enough to kill themselves save a dodgy chinese bearing here and there.

This was a good one as it came with a 50cc engine from new where as most are 39cc. You can tell by the bore measurement (44mm vs 40mm) and also the bottom fins on the barrel dont join all the way around on the 50cc versions.

For a stock engine it ran surprisingly well. Upon dis-assembly everything was great inside so i put it back together only one piston ring this time (the two ring design is a relic from the motors original use in agricultural tools - it serves no real purpose that the single ring cannot do in this application) and also lowered the squish down to .5mm from over 1mm by using good quality liquid gasket and carefully milling the crankcases and bottom of the barrel flat. This part is essential or you will forever have air leaks!

The jetting was spot on from stock aside from lowering the clip down on the needle to make it a tad richer.

The performance increase was very noticeable after even this small FREE modification. The customer was very surprised at how much better it went considering it was all using the same parts! Just goes to show how important port timing is on 2 stroke engines.

The obligatory replacement of the very poor chinese parts like the spark plug, footpegs and fuel line + filter saw this job done.

*pics to be added soon*