sempergumby Posted October 9, 2011 Report Share Posted October 9, 2011 HI Guys, I apologise in advance for all the dumb questions. I'm told that its not if I foul a plug but when I foul a plug. I'm running a NGK B6HS plug. I've done two AHRMA Vintage trials (Sesquhatchee and Barber) plus practice in between and this afternoon coming back fromt the Swap meet at Barber to the Lot D parking (where all the dirt track people hang out) the bike rapidly lost power. When I got home I pulled the plug and checked that there was no spark when I kicked it over. I poped a new NGK into the plug cap and WALLA I got spark and the bike starts. So what should I do? 1) I'm running the needle all the way down although I don't know what needle jet the DPO has in the 27mm AMAL. 2) It has a 2.5 slide when the book call for 3. The doner Montesa Cota I got recently also had a 2.5 slide in it but a 3 slide would be leaner as the side opens off idle. 3) I'm runnin PJ1 silverline oil (a synthetic blend) in the bike at a 28:1 ratio. Should I bump this up to 32:1 or 40:1? The oil says its rated at 50:1. 4) Should I try a BR6HIX Iridium? The serial number is a 21M6600+ number. Is this just the way it is? Should I just plan on putting new B6HS in the bike before every trials? Should the gap really be set at .015? Would this help in the anti-fouling effort? Quote Link to comment Share on other sites More sharing options...
feetupfun Posted October 9, 2011 Report Share Posted October 9, 2011 Ok a 6 heat range NGK plug is a good choice in an air cooled trials bike for trials type riding and gentle trail riding. Changing to a fancy plug will make no difference to any fouling that is occurring. Iridium plugs wear slower than a standard plug but it is vanishingly rare for a sparkplug to wear out on a trials bike unless it sees many thousands of km per year. You do have quite a lot of oil in the fuel mix but it more likely that your problem with plug fouling is in the fuel/air ratio. If you still have the standard 27mm Amal they are notorious for wearing the throttle slide, the throttle slide needle and the throttle slide needle jet and being generally crude in their air/fuel ratio control. It is very likely that those parts require replacement and if you do that it will solve your sparkplug fouling problem till they wear out again - and it will run nicer too. Yes a 0.015" gap is OK but I would recommend a sparkplug gap of 0.020" or 0.5mm in my language if you are running the standard points type ignition. Sparkplugs usually come standard set with a 0.040" gap but that does not mean it is correct for every bike. If you fit a fancy modern electronic ignition then I would suggest setting the gap wider than 0.020" to take advantage of the higher performance ignition. The gap makes no difference to the fouling rate, but a narrower gap will keep sparking longer with a fouled plug because it takes less voltage to jump a smaller gap, and fouling reduces the available voltage by leaking current through the conductive fouling. Quote Link to comment Share on other sites More sharing options...
sempergumby Posted October 9, 2011 Author Report Share Posted October 9, 2011 Thanks. I'll bump up the fuel to oil to 40:1 and replace the needle jet and needle. Later this winter I send the slide and body to Lund for sleeving. And thanks for the confirm on the gap. I'm new to this two stroke stuff. One more trials in November at Aonia GA for me. Quote Link to comment Share on other sites More sharing options...
copemech Posted October 10, 2011 Report Share Posted October 10, 2011 I thought most were running 50:1 in the air cooled(trials) motors. Others may chime in here. Quote Link to comment Share on other sites More sharing options...
vintagecota Posted October 10, 2011 Report Share Posted October 10, 2011 use 50:1 synthetic. Quote Link to comment Share on other sites More sharing options...
sempergumby Posted October 14, 2011 Author Report Share Posted October 14, 2011 (edited) use 50:1 synthetic. Motul? Ester based? ..again thanks for the replys!!! Edited October 14, 2011 by sempergumby Quote Link to comment Share on other sites More sharing options...
sempergumby Posted October 31, 2011 Author Report Share Posted October 31, 2011 (edited) Well thanks guys for the reply. Things done: New needle and needle jet for the AMAL from Jared at Southwest Montesa. Switching to Motul Synthetic at 50:1. Hey it doesn't smoke anymore! Got a Montesa 247 Silencer from Sammy Miller. Hey I can hear myself think now! Got some weld on footpads from B & J products in Tennessee so now I can stand. Also got a Domino long throw throttle and cable and some pro taper bars also from B & J. I have practiced for two days now and WALLA the NGK B6HS is a nice medium tan with the clip on the needle in the middle position (I had it in the top slot before). I've got more low end power and it is more fun to ride with no sign of fouling! It doesn't bog down now when I go up a long set of stairs. I'm still waiting on shocks and a new red rear fender to replace the abortion that is on there now. So the bike is ready again and I'm off to Aonia GA for the Nov 5th Atlanta Motorcycle Club/ AHRMA regional trials. Thanks again guys! Edited October 31, 2011 by sempergumby Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.