Paulwhite Posted July 8, 2009 Share Posted July 8, 2009 hi i need to sort out my carb jetting iv got a xv 125 4 stroke engine and i need to do plug chops to figure out whats happening now iv had a look on google and every picture iv seen is different to another (in relation to what color the plug should be) so could anyone point me in the right direction? i just need to know what it should look like if the fueling was bang on then i can tinker from there. cheers .Paul. Link to comment Share on other sites More sharing options...
yoda Posted July 8, 2009 Share Posted July 8, 2009 hi i need to sort out my carb jetting iv got a xv 125 4 stroke engine and i need to do plug chops to figure out whats happening now iv had a look on google and every picture iv seen is different to another (in relation to what color the plug should be) so could anyone point me in the right direction? i just need to know what it should look like if the fueling was bang on then i can tinker from there. cheers .Paul. Driven normally, the spark plug should be a straw colour. Black is too rich White is too weak Hope this helps. Link to comment Share on other sites More sharing options...
Paulwhite Posted July 8, 2009 Author Share Posted July 8, 2009 Driven normally, the spark plug should be a straw colour. Black is too rich White is too weak Hope this helps. a picture would help loads (iv seen many colors of straw from grey to orrange and all inbetween) Link to comment Share on other sites More sharing options...
sluggo Posted July 8, 2009 Share Posted July 8, 2009 Hi Unfortunately the days of looking at plug colour to assist tuning are gone with the advent of un-leaded petrol. A nice grey colour used to mean good tuning but now a plug will show a black colour when running well on un-leaded. The black needs to be free of any sooting effect which would show a rich mixture. If too lean it will burn to an almost white and the bike would be overheating and baulking at high speed and revs. As long as the plug looks black but clean it should be OK. Any lighter colours with un-leaded will mean a lean mixture. Your most reliable & accurate tuning method these days is a CO2 reading at the exhaust end (muffler). Also try higher octane un-leaded if you haven't already. This can make quite a difference to a high performance engine that requires it. See what octane rating is recommended before checking the tuning. Usage of a higher octane than required will give you no increase in performance but may give you slightly better MPG. Weigh up the advantages. Also be aware that un-leaded will varnish up in the carby bowls from heat. I became aware of this after suffering the problem. Most un-leaded fuels are now engineered for fuel injection so every 3 months I run some carby & injection cleaner through with a tank or two of fuel. Regards. Link to comment Share on other sites More sharing options...
scobri Posted July 18, 2009 Share Posted July 18, 2009 Hi Unfortunately the days of looking at plug colour to assist tuning are gone with the advent of un-leaded petrol. A nice grey colour used to mean good tuning but now a plug will show a black colour when running well on un-leaded. The black needs to be free of any sooting effect which would show a rich mixture. If too lean it will burn to an almost white and the bike would be overheating and baulking at high speed and revs. As long as the plug looks black but clean it should be OK. Any lighter colours with un-leaded will mean a lean mixture. Your most reliable & accurate tuning method these days is a CO2 reading at the exhaust end (muffler). Also try higher octane un-leaded if you haven't already. This can make quite a difference to a high performance engine that requires it. See what octane rating is recommended before checking the tuning. Usage of a higher octane than required will give you no increase in performance but may give you slightly better MPG. Weigh up the advantages. Also be aware that un-leaded will varnish up in the carby bowls from heat. I became aware of this after suffering the problem. Most un-leaded fuels are now engineered for fuel injection so every 3 months I run some carby & injection cleaner through with a tank or two of fuel. Regards. I`m gonna get real technical with you now,think biscuits. Ideally you will want a colour very similar to a rich tea biscuit that has been dunked in coffee,if you have a colour which is lighter than an undunked rich tea it`s runnig too weak,if you are heading up to a digestive or choccy digestive you are heading up the richer end,then if you have a triple chocolate cookie you are running far too rich,so moral is when carb tuning always put kettle on first grab you nearest box of family choice biccys & away you go. Link to comment Share on other sites More sharing options...
Moderator Cynic Posted July 18, 2009 Moderator Share Posted July 18, 2009 I`m gonna get real technical with you now,think biscuits. Ideally you will want a colour very similar to a rich tea biscuit that has been dunked in coffee,if you have a colour which is lighter than an undunked rich tea it`s runnig too weak,if you are heading up to a digestive or choccy digestive you are heading up the richer end,then if you have a triple chocolate cookie you are running far too rich,so moral is when carb tuning always put kettle on first grab you nearest box of family choice biccys & away you go. So you could call a Jaffa a quick reference guide, cake side ok and if lighter too weak, chocolate side too rich needing attention. Link to comment Share on other sites More sharing options...
Paulwhite Posted July 24, 2009 Author Share Posted July 24, 2009 sound! got it all sorted whilst enjoying a brew! Link to comment Share on other sites More sharing options...
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