react Posted May 18, 2009 Share Posted May 18, 2009 Hi Ive got a dt 125 1974 bike but the head has 2 spark plugs and going by the manual there should only be 1. Has anyone got any ideas. Thanks Nic Link to comment Share on other sites More sharing options...
Moderator Cynic Posted May 18, 2009 Moderator Share Posted May 18, 2009 Hi Ive got a dt 125 1974 bike but the head has 2 spark plugs and going by the manual there should only be 1. Has anyone got any ideas. Thanks Nic Chassis no/ engine no/ photo's needed. Link to comment Share on other sites More sharing options...
JimR Posted May 18, 2009 Share Posted May 18, 2009 Hi Ive got a dt 125 1974 bike but the head has 2 spark plugs and going by the manual there should only be 1. Has anyone got any ideas. Thanks Nic Hi React, the DT of that era had 2 plug mounts from the factory the one had a 'blanking' bolt in situ & the other had the spark plug ... take into account 1974 plugs would whisker at a moments notice so the extra plug thread was there for serious off roaders who had a plug failure and could swap the plug cap to another plug and get the bike running again in a short period of time .. tbh the one plug/plug hole is very close to the exhaust and may cause injury changing the cap over but it did work .... From memory I can only think of one person that removed the blanking plug and installed the second plug. I can guess people who didn't have plug problems (when 2 stroke oil got better) would never think that a dual plug cylinder head was a requirement ! Regards Jim Link to comment Share on other sites More sharing options...
react Posted May 20, 2009 Author Share Posted May 20, 2009 Thanks for the help guys. JimR Good bit info thanks mate. Link to comment Share on other sites More sharing options...
little dave Posted May 20, 2009 Share Posted May 20, 2009 thats the situation with my bike... one spark plug and one bolt. although i knew it was for a spare spark plug, I have always wondered: could one put both plugs in, split the plug wire and run a boot to both plugs? would two simultaneously firing plugs improve burn efficiency/fuel economy or give a boost in power? or would each plug merely work at 50% efficiency. or.... (the most likely of answers).... would one just burn out a perfectly good ignition coil? this question is in the spirit of learning....I dont have grand plans on trying it. Link to comment Share on other sites More sharing options...
Moderator Airhead Posted May 20, 2009 Moderator Share Posted May 20, 2009 In reality it would only ever spark to one of the plugs, electricity always follows the easiest path to earth, your two plugs will have different resistances to earth, so the one with the lower resistance will be the one that sparks. Link to comment Share on other sites More sharing options...
little dave Posted May 20, 2009 Share Posted May 20, 2009 In reality it would only ever spark to one of the plugs, electricity always follows the easiest path to earth, your two plugs will have different resistances to earth, so the one with the lower resistance will be the one that sparks. facepalm. I don't know why that didn't occur to me.... Link to comment Share on other sites More sharing options...
JimR Posted May 21, 2009 Share Posted May 21, 2009 In reality it would only ever spark to one of the plugs, electricity always follows the easiest path to earth, your two plugs will have different resistances to earth, so the one with the lower resistance will be the one that sparks. Hi Paul, There was only one HT lead & cap the secondary plug was just sat there as a get you going thing, to save taking out a red hot wiskered plug just switch the plug cap to the second plug & away the bike goes ( perhaps ). To the UK the second hole had a blanking plug & TBH when a plug was in there it was a pain to get the cap on to it ! Regards Jim Link to comment Share on other sites More sharing options...
Moderator Airhead Posted May 21, 2009 Moderator Share Posted May 21, 2009 Yes Jim, I was just replying to 'little dave' and his hypothetical question... I have always wondered: could one put both plugs in, split the plug wire and run a boot to both plugs? would two simultaneously firing plugs improve burn efficiency/fuel economy or give a boost in power? or would each plug merely work at 50% efficiency. or.... (the most likely of answers).... would one just burn out a perfectly good ignition coil? this question is in the spirit of learning....I dont have grand plans on trying it. Link to comment Share on other sites More sharing options...
JimR Posted May 21, 2009 Share Posted May 21, 2009 Yes Jim, I was just replying to 'little dave' and his hypothetical question... Hi Paul, I have had a long few days at work ... I had to work past 2:00pm and missed that post !!! Sorry, Regards Jim Link to comment Share on other sites More sharing options...
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