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Tech. Advice: Series 'B' / 'C' 500cc/1000cc Bikes
Ignition Timing & modern Fuel
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<blockquote data-quote="greg brillus" data-source="post: 47237" data-attributes="member: 597"><p>Hi Derek, When these bikes were being manufactured the fuel available had an octane rating of about 80. A vacuum advance unit would have been perhaps a bit complicated for engines with only one or two cylinders....remember that the vacuum advance assists with a flat spot just off idle which multi cylinder engines with only one centrally mounted carburretor need, as well as an accellerator pump to enrichen the off idle mixture. And also the fact that most all car engines were/ are liquid cooled verses a bikes air cooled engines which run much hoter. The fuel available now burns much faster, so if the original timing figure is used, the engine will most certainly detonate.....I run twins at around 34 deg and singles 30/32 deg at full advance and around 4 deg in the retarded possition or else the engine will run hot and be a little harder to start. As an aside.....I did a run this Sunday just gone on my Rapide, this being a fairly hot 34/35 deg celcuis day, and when i got home after a couple of minuts i checked the temp at the top of the crank cases with a digital thermometer and it read 137 degrees celcius..........Cheers......Greg.</p></blockquote><p></p>
[QUOTE="greg brillus, post: 47237, member: 597"] Hi Derek, When these bikes were being manufactured the fuel available had an octane rating of about 80. A vacuum advance unit would have been perhaps a bit complicated for engines with only one or two cylinders....remember that the vacuum advance assists with a flat spot just off idle which multi cylinder engines with only one centrally mounted carburretor need, as well as an accellerator pump to enrichen the off idle mixture. And also the fact that most all car engines were/ are liquid cooled verses a bikes air cooled engines which run much hoter. The fuel available now burns much faster, so if the original timing figure is used, the engine will most certainly detonate.....I run twins at around 34 deg and singles 30/32 deg at full advance and around 4 deg in the retarded possition or else the engine will run hot and be a little harder to start. As an aside.....I did a run this Sunday just gone on my Rapide, this being a fairly hot 34/35 deg celcuis day, and when i got home after a couple of minuts i checked the temp at the top of the crank cases with a digital thermometer and it read 137 degrees celcius..........Cheers......Greg. [/QUOTE]
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Tech. Advice: Series 'B' / 'C' 500cc/1000cc Bikes
Ignition Timing & modern Fuel
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