killing a plug

[shepgs850]

my number 3 spark plug keeps dieing
i have put individual K+N filters on each carb and have up jetted them to 130 main jets
any idea why i am killing my number 3 plug after about 30 miles
will the carbs need to be rebalanced? cheers

[chef1366]

Is it fuel or oil? How is the compression on that cylinder?

[Tarbash 27]

do you have an aftermarket exhaust also? i think 130 mains is a bit high? what was the stock size?

[shepgs850]

compression on all the cylinders seems to be good
as for the exhaust i have a 4 into 4 system using standard harley exhaust end cans the standard size main jet is 115
don't want to change the exhaust as i have built the trike myself and the amount of work involved would be a pain in the arse not to mention the expence cheers

[Roy]

I had the same problem on 82 gs850gz, that had the airbox snorkel removed , I replaced snorkel, threw out the 130 jets,& changed for 122's to suit 4 into 1 exhuast.Also run some upper cylinder lubricant in case valve was sticking. Seems to have solved the problem. She runs much better now.

[shepgs850]

thanks for the help i'll give it a go this weekend cheers shep