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

  react said:

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.

  react said:

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

Thanks for the help guys.

JimR Good bit info thanks mate.

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.

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.

  oldgitonabike said:

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....

  oldgitonabike said:

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

Yes Jim, I was just replying to 'little dave' and his hypothetical question...

  little dave said:

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.

  oldgitonabike said:

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