September 2012: Frustration !!!!!

The first test ride after the Olympic fornight spannering sessions went really well. The bike started up and ran on both cylinders, the clutch did not slip and the brakes were much improved. I was very happy, job done !

Later that week I decided to take it out for an after work ride. Damm thing took over half an hour to start and would not run on both cylinders all the time. When I rode it at high speeds it kept cutting out and would not start again without lots of swearing and kicking (by me). Back in the garage, carbs off revealed dirt in them. Despite having a fuel filter some fine particles were getting in to the floatbowls. Looks like the rusty tank needs sealing. Checking the plugs for sparks showed a weak orange spark so maybe I had an electrical problem too. It would be difficult to find out what was causing it without spare parts to swap out and test. I checked out all the connections and measured all the resistances of the coils etc. Everything was as the manual says it should be. I sourced a complete igintion system from a later bike. The CDI unit I had was well known for breaking down after about 10 mins running, so the later unit would be more reliable in the long run. I needed to modify the wiring loom to fit the CDI as the wire connections and colours were different. Now I had a much better spark, a fat blue spark and the engine starts easier.

However the bike still has problems, when I ride gently and don’t use full throttle everything is fine, but as soon as i give it a long burst of wide open throttle (like acclerating quickly through the gears) the engine dies on the right cylinder again. Its like fuiel starvation, but even running with the fuel tap on prime to give a good flow it made no difference. Very frustrating and despite several carb/electrical strips and checks I still can’t get it right. My thinking is that I have a bad crankseal that leaks air and weakens the mixture. Looks like an engine strip to replace that, so time to SORN the bike and start the resto.

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