Steve Posted October 20, 2012 Share Posted October 20, 2012 I've rejetted my Thor several times (float bowl carb), with corresponding adjustments to the needle and air screw and got it running 100 percent better than it used to be. However, with the final tweak which has made it run the best yet, I am getting an orange plug. I've never come across this colour before and wondered what others thought. My first thought was to do with the oil (I use Motul 800) perhaps having some dyes which leave a residue which were invisible as it was oiled up previously on factory jetting. I don't have a CHT gauge but the flight which produced this colour plug had the engine sounding and running perfectly. Any thoughts on an orange plug would be appreciated. Edit: The porcelain is orange on 50 percent of it, the other half isn't. Sorry about the blurred shot, iPhone refused to focus after the first shot. Quote Link to comment Share on other sites More sharing options...
enzo200500 Posted October 20, 2012 Share Posted October 20, 2012 http://www.bcchapel.org/pages/0003/pg11.htm http://www.theultralightplace.com/sparkplugs.htm From the pics, plug does not look too bad. Was this achieved doing a correct plug chop or normal running? How it was achieved is very important!! Quote Link to comment Share on other sites More sharing options...
Steve Posted October 20, 2012 Author Share Posted October 20, 2012 This was normal running but also did an engine cut at 70 percent revs with the same result. Cheers for the links, I've searched so many pages about this but not found anything for 2 stroke orange plugs. Quote Link to comment Share on other sites More sharing options...
enzo200500 Posted October 20, 2012 Share Posted October 20, 2012 Plug chopping needs to be carried out on full throttle! Then cut the plug thread off to check the 'smoke ring' at the base of the porcelain! How far do you want to go?? If its 'digestive biscuit' colour, then generally its ok! Quote Link to comment Share on other sites More sharing options...
Steve Posted October 20, 2012 Author Share Posted October 20, 2012 Point taken, keeping it out of the danger zone without sawing plugs in half would be ideal. This is more jaffa cake than digestive. Quote Link to comment Share on other sites More sharing options...
enzo200500 Posted October 20, 2012 Share Posted October 20, 2012 Personally, I'd get mix slightly rich in winter then its good for all year. Unless you are chasing economy records!! CHT gauges are pretty good for long term checking, but they are slow to respond. EGT is faster to indicate 'issues'. AFR is really the only way to go, but lambda sensors and two stroke emissions do not happy bedfellows make...... Quote Link to comment Share on other sites More sharing options...
Steve Posted October 20, 2012 Author Share Posted October 20, 2012 Thanks for all that, certainly AFR and EGT just seems to impractical just for a bit of leisurely flying. CHT is easy and is on the shopping list, probably the Polini gauge. I will take a look at upping the main jet to be on the safe side, although I would still love to know what makes the plug porcelain orange. Any thoughts on why half the porcelain stays relatively clean? When a new plug goes in after the first flight half of it (and the rest of the plug) are pretty spotless. Quote Link to comment Share on other sites More sharing options...
enzo200500 Posted October 20, 2012 Share Posted October 20, 2012 Generally, when the AFR and plug heat range are correct, plugs are pretty much self cleaning. It makes me cringe when people start spouting off about 2T's oiling plugs at low revs, it just means they cannot sort the low speed circuit of the carb - heathens! Hence checking the base of the porcelain for correct mixture/jetting. Cutting plugs does get expensive though! Many factors can affect the colouring build up on the plug. The way the mix is introduced into the cylinder from the transfer ports, squish gap, piston/head shapes.....many variables! When we run cylinder heads with changeable volume inserts (VHM are things of beauty), even the direction of the earthing strap facing the exhaust port comes into play!! Another good check of mixtures is checking the flame/burn pattern on the piston crown (piston wash). OK, I admit it, I do have a thing for 2T's.........sorry! The Polini gauge looks very well made, but lots of wonga. There was an article from an American car racing site I found recently. It reall did go into much greater detail about mixtures etc and reading what the plugs were telling you. Even down to the different areas on the plug and what is affecting them, from timing, heat range, mixture.....geeky but very informative. The plug is basically a window into the heart of the engine. You just have to know what you are looking at. The good old days of leaded fuel were great for plug chops, this unleaded junk is a right PIA! Also, the choice of 2T oil has some small effect on the readings. Quote Link to comment Share on other sites More sharing options...
Steve Posted October 20, 2012 Author Share Posted October 20, 2012 Definitely a passion showing through, nothing wrong there. Thanks for all the ideas. Quote Link to comment Share on other sites More sharing options...
enzo200500 Posted October 20, 2012 Share Posted October 20, 2012 Or just buy a Koso AFR gauge kit!! http://www.startinglineproducts.com/ins ... /19-93.pdf http://www.exhaustgas.com/ProductDetail ... uctID=1787 I'm going into the garage now to caress my RG500. Theres 4 little 2T enginges all bolted together on that beastie..... Quote Link to comment Share on other sites More sharing options...
Hann__ Posted October 20, 2012 Share Posted October 20, 2012 If you can wield a soldering iron and make a basic circuit you can make an A/F ratio meter for a few quid: http://108.163.194.210/~dbbpcom/dbbp/tech-tips/mm.html Would it work on a 2T? Quote Link to comment Share on other sites More sharing options...
Steve Posted October 20, 2012 Author Share Posted October 20, 2012 Theres 4 little 2T enginges all bolted together on that beastie..... Interesting description. Quote Link to comment Share on other sites More sharing options...
enzo200500 Posted October 20, 2012 Share Posted October 20, 2012 Most lambda sensors should work on a 2T, but not for longterm due to the hydrocarbons expelled through exhaust! They coat the sensor and stop the residual Oxygen causing a chemical reaction between the different metals in the sensor. This generates an electrical current. The later types use a heating element in the sensor to speed up the reaction times on first startup. Quote Link to comment Share on other sites More sharing options...
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