thai-ty Posted December 27, 2017 Report Share Posted December 27, 2017 Don't know if plugs have a shelf life (doubt it) but my at least 15 y/o NOS plugs from the UK stock has dwindled to the last one. 'Ol Yeller has been eating them at a remarkable rate recently, NGK B6ES. The manual states the R version NGK BR6ES. I notice the TY350 Mono manual states NGK BP6EV which is a projector plug (different c/head chamber and bigger bore) but not a resistor plug. Now both bikes run the same CDI system which confuses me why Yamaha would specify an R plug for one and not the other. Ideas? Input? Whilst searching info , I came across BVM's website and their plug page shows a bunch of different plugs, none of which are resistor models. Surely some makes of the modern bikes specify R plugs? Or does the R just not affect spark/CDI performance in these models? Also had a helluva job locating any 6's over here, (pity because 14mm NGK plugs retail at 1.30 GBP or 11 quid a box of 10...) so have just ordered a box of 10 BR6ES from the UK. Quote Link to comment Share on other sites More sharing options...
scifi Posted December 27, 2017 Report Share Posted December 27, 2017 (edited) Quote I always thought that Resistor Plugs were used to reduce radio interference. So if you don't have a fitted radio, why use a resistor plug? The resistor used is about 5k Ohms, but as the current is so very small, there is not too much voltage drop. (V = I x R.) I wonder why your bike is going through plugs at a great rate? You may have a carburation problem. If they are burning out then the mixture could be too week, or if they are carboning up, then the mixture is too rich. If your bike is non standard in some way, then maybe you need to try changing the heat range of the plug, either up or down one number. Just seen your location, do you use leaded petrol. In the UK we don't have leaded any more, so wiskering of two stroke plugs is no longer a problem. However our Ethanol fuel now rots our fibre-glass petrol tanks ! . Edited December 27, 2017 by scifi Quote Link to comment Share on other sites More sharing options...
thai-ty Posted December 27, 2017 Author Report Share Posted December 27, 2017 Thanks for the reply. I've read certain CDI's like a resistor plug. If that's the case why did Yamaha specify a non R plug for the 350 (N. American and Australian markets only)? Fuel - it's leaded over here, but we still have a choice of ethanol 91 or 95 AND 95 octane "pure petrol" non ethanol. I always put the good stuff in with a 50:1 mix of semi synthetic. Carburation is good, bikes run really well, plugs look slightly rich, bar DEP silencer and Boyesen reeds they are pretty stock. Someone mentioned source coil, but I can remove the dead plug, remove the plug cap and get a decent spark jump to earth. Put another new plug in and away I go... However 'Ol Blu does not go thru plugs like 'Ol Yeller... Quote Link to comment Share on other sites More sharing options...
thai-ty Posted January 5, 2018 Author Report Share Posted January 5, 2018 So, no one can explain or answer the question as to why Yamaha would specify an R plug for one model and a non R plug for another model? Both bikes having the same cdi, and ignition component set up. Perhaps it's a legal thing for different markets? The 350 mono only ever being sold in Australasia and the N. American market? Quote Link to comment Share on other sites More sharing options...
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