Harri Posted December 18, 2014 Share Posted December 18, 2014 Looking at the petrol valve positions, On = on. obviously. Res = reserve. Pri - ?Barcud Quote Link to comment Share on other sites More sharing options...
Tango Posted December 18, 2014 Share Posted December 18, 2014 Prime.......opens the fuel flow without the engine running to prime the fuel line and carbs.... Quote Link to comment Share on other sites More sharing options...
Harri Posted December 18, 2014 Author Share Posted December 18, 2014 Right, so -Prime - before you start the engine. Then - on - when the engine is running?Would it make a noticeable difference if you kept it on prime when you were riding the bike?And so, no 'off' position?Barcud Quote Link to comment Share on other sites More sharing options...
Mr Fro Posted December 18, 2014 Share Posted December 18, 2014 Can't say I ever needed to use the prime position in normal operation - only if I'd left the bike for a couple of weeks outside in the summer and the fuel had evaporated. Quote Link to comment Share on other sites More sharing options...
Tango Posted December 18, 2014 Share Posted December 18, 2014 Yeah.....as Mr Fro says, Prime is only used if there's no fuel in the lines or carbs (if you run out, for instance). Normally in the On position the fuel flow is controlled by a vacuum pipe from one of the inlet stubs......so the fuel only flows when this vacuum is present........but, if you run out, it could take a fair bit of cranking on the starter to prime the system up, so that's when you'd use the prime position..... Quote Link to comment Share on other sites More sharing options...
Harri Posted December 18, 2014 Author Share Posted December 18, 2014 Thanks guys.The last run out I had all seemed fine with the idle at junctions. This time out the idle ran too low and the engine cut! I thought maybe I had the prime position on the petrol and the mix was rich? If not I'll have to adjust the idle tomorrow. 2 carbs, could be interesting Barcud Quote Link to comment Share on other sites More sharing options...
eastanglianbiker Posted December 19, 2014 Share Posted December 19, 2014 if you had the fuel tap in the prime position then you would of flooded the engine while at the lights causing it to cut out Quote Link to comment Share on other sites More sharing options...
Mr Fro Posted December 19, 2014 Share Posted December 19, 2014 if you had the fuel tap in the prime position then you would of flooded the engine while at the lights causing it to cut outErm... No. The fuel would still have to navigate it's way round the float valve. Prime position just bypasses the vacuum operated part of the fuel tap. Quote Link to comment Share on other sites More sharing options...
Tankbag Posted December 19, 2014 Share Posted December 19, 2014 I thought it was for ' Optimus Prime ' mode Quote Link to comment Share on other sites More sharing options...
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