Spark Plug Gap?

5 replies to this topic
  • goalpostcasualty

Posted May 16, 2007 - 12:39 PM


I have an 04 yz450 and I was wondering what the spark plugs should be gapped to? And does it matter what brand plug you put in it?

  • 642MX

Posted May 16, 2007 - 12:46 PM


0.028 inches

  • grayracer513

Posted May 16, 2007 - 12:56 PM


The manual calls for a minimum of 6mm (0.24") Pretty much anything between that and 0.35 is good.

No manual?

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  • 642MX

Posted May 16, 2007 - 01:45 PM


My answer came out of the NGK book.....

  • goalpostcasualty

Posted May 16, 2007 - 04:35 PM


No the guy I bought the bike from ruined the manual... or so he said. But I was just checking. I recently had a post on here and I was having problems all of a sudden on how it was running. One day I was riding and it ran like a champ and the next day it was popping and backfiring when I would get on the gas and when I would get off the gas. So I cleaned the carb, jets, etc right and it still didn't help... So I changed the plug out but couldn't get a NGK so I bought a Autolite instead. It ran fine the next time I took it out. I rode it for probably 1.5 to 2 hours and then put it up thinking everything was fine. Ok its been 3 days since and I went to ride it today and it cranks fine and idles fine but when I get on the gas it backfires again! NO FREAKIN IDEA WHATS GOING ON! It couldnt have fouled the plug that quick could it? If you want the whole story look up "YZ450 REVVING PROBLEMS". Thats my post. Any ideas on how to fix it or what might be the problem?

  • grayracer513

Posted May 16, 2007 - 05:06 PM


My answer came out of the NGK book.....

No, I meant GPC on the book question. 0.28 fits right in with what the Yamaha manual says. I bought a Autolite instead. I

Autolites are barely adequate for cars. Use the right NGK and you should have better luck.

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