gazzaecowarrior Posted October 16, 2021 Report Share Posted October 16, 2021 (edited) I have tried everything to get my 2012 beta Evo 125 running well and I'm almost there. I'm just wondering if I need a hotter plug. My plug is always carbonised. It is dry black not oily wet. My previous evos all had perfect colour plugs and we're light tan whenever I checked them. Im now running 80:1 Castrol power 1 fully synthetic. Air screw is 2.5 turns out. Exhaust and silencer fully decarbonized, carb standard setting and air filter spotless. I run 99 octane petrol. My current plug is a ngk Br7es. I understand the higher the number the colder the plug with ngk. So I'm tempted to drop to br6es. I'm in the UK so it's seldom warm. Does anybody think a hotter plug will help it burn better and not carbonize ? Edited October 16, 2021 by gazzaecowarrior Changed it Quote Link to comment Share on other sites More sharing options...
carl ekblom Posted October 16, 2021 Report Share Posted October 16, 2021 A hotter plug will not change the combustion process but will change the temperature of the plug (hotter). Use plug accordingly to the manual and importer instructions. If you run Alkylat petrol like Aspen combustion would be cleaner. You may start with Aspen 4T and mix yourself, but give it some time to clean the engine https://aspenfuel.co.uk/ Quote Link to comment Share on other sites More sharing options...
gazzaecowarrior Posted October 16, 2021 Author Report Share Posted October 16, 2021 39 minutes ago, carl ekblom said: A hotter plug will not change the combustion process but will change the temperature of the plug (hotter). Use plug accordingly to the manual and importer instructions. If you run Alkylat petrol like Aspen combustion would be cleaner. You may start with Aspen 4T and mix yourself, but give it some time to clean the engine https://aspenfuel.co.uk/ Surely hotter the plug leaving less carbon on the plug will ultimately effect and improve combination? Quote Link to comment Share on other sites More sharing options...
ChrisCH Posted October 16, 2021 Report Share Posted October 16, 2021 21 minutes ago, gazzaecowarrior said: Surely hotter the plug leaving less carbon on the plug will ultimately effect and improve combination? https://www.ngkntk.in/importance-of-heat-range/ Quote Link to comment Share on other sites More sharing options...
gazzaecowarrior Posted October 16, 2021 Author Report Share Posted October 16, 2021 1 hour ago, ChrisCH said: https://www.ngkntk.in/importance-of-heat-range/ Will fit a br6es then and try that. My plug is exactly like the plug in the photo where the heat range is too high. One step down on the plug with all other variables such as fuel and carb kept the same will be an interesting experiment. Quote Link to comment Share on other sites More sharing options...
carl ekblom Posted October 16, 2021 Report Share Posted October 16, 2021 If plug is too hot it may cause pre ignition and pinking if very much too hot the plug may melt down. If too cold carbon will build up at electrodes and perhaps start to misfire. If very much too cold sparking will stop and engine stops. Combustion process and cylinder head temperature does not change until something bad happens. Lean mixture and retarded ignition may increase engine temperature. If very bad engine may melt down. Always start with manual specifications and importer instructions. If they say a hotter plug is needed. Use that plug This is after 4 years in my 199A. I crashed (dropped it at the floor) the plug some weeks ago when I for some reason had to take it out. Plug is Champion N11YC. Difficult to get a good photo Quote Link to comment Share on other sites More sharing options...
phiggs Posted October 16, 2021 Report Share Posted October 16, 2021 A lot depends on how long you run the engine. Some trials bikes just run 20 seconds in a section, then cool down in the 10 minutes waiting for the next section. Enduro bikes, or some moto-cross, run for up to an hour of full throttle action. I hope the NGK BR6ES works for you... ( Other brands of spark plug are available.) Quote Link to comment Share on other sites More sharing options...
ChrisCH Posted October 16, 2021 Report Share Posted October 16, 2021 4 hours ago, gazzaecowarrior said: Will fit a br6es then and try that. My plug is exactly like the plug in the photo where the heat range is too high. One step down on the plug with all other variables such as fuel and carb kept the same will be an interesting experiment. My missus' Evo 250 runs a BR5ES. It is what was in the bike when we bought it. I researched a bit on here as I also read the manual and it says a 7 heat value. I found a post that suggested 5 was better for a "cold climate". No idea if that is right or not. However the bike still has the same plug in it and has run 2 years without any issues at all. Never had the plug out to look at it if I am honest. It runs on V-Power 99 and Putoline TT Pro at a 80:1 mix or thereabouts. Starts first kick (well with me - wife takes a few more prods). Can't fault the engine (suspension is pants and the brakes not so hot either) I bought a spare plug and bought a 5 just in case the 7 made it harder to start. (After research it seems to me the starting has nothing to do with the heat value - so I have learned something in the process) Quote Link to comment Share on other sites More sharing options...
gazzaecowarrior Posted October 16, 2021 Author Report Share Posted October 16, 2021 3 hours ago, phiggs said: A lot depends on how long you run the engine. Some trials bikes just run 20 seconds in a section, then cool down in the 10 minutes waiting for the next section. Enduro bikes, or some moto-cross, run for up to an hour of full throttle action. I hope the NGK BR6ES works for you... ( Other brands of spark plug are available.) Thanks. I no longer compete so my riding consists of riding for no more than 5 mins at a time then stop for 5 then ride again and so on. It is typical low revs trials 1st and 2nd gear with blips of throttle. It will be interesting to see what difference 1 grade hotter plugs makes. Quote Link to comment Share on other sites More sharing options...
gazzaecowarrior Posted October 16, 2021 Author Report Share Posted October 16, 2021 2 hours ago, ChrisCH said: My missus' Evo 250 runs a BR5ES. It is what was in the bike when we bought it. I researched a bit on here as I also read the manual and it says a 7 heat value. I found a post that suggested 5 was better for a "cold climate". No idea if that is right or not. However the bike still has the same plug in it and has run 2 years without any issues at all. Never had the plug out to look at it if I am honest. It runs on V-Power 99 and Putoline TT Pro at a 80:1 mix or thereabouts. Starts first kick (well with me - wife takes a few more prods). Can't fault the engine (suspension is pants and the brakes not so hot either) I bought a spare plug and bought a 5 just in case the 7 made it harder to start. (After research it seems to me the starting has nothing to do with the heat value - so I have learned something in the process) Thanks for the info. Quote Link to comment Share on other sites More sharing options...
gazzaecowarrior Posted October 24, 2021 Author Report Share Posted October 24, 2021 Well I took the bike out yesterday. With exactly the same fuel all day. First hour I ran the Br7es. Took it out to check it. Black dry carbonized plug. Then fitted the br6es and rode the bike for another hour. Removed the plug and once again black dry carbonized. Im going to try 0.25 turns out in the air screw next and see if that helps. Bike is running really well though. Maybe even adjust the needle to run leaner ? Quote Link to comment Share on other sites More sharing options...
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