Re: TommyGlides Plug Question - Harley Forum

evoKENevo · #1 02-28-2009, 09:40 AM

Tommy in one of the threads where a number of posts were lost due to the forum's tech malfunction (fixed) you inquired as to what plug and heat range was correct for your '85 Evo...and,that part was lost along with my reply. So here's the gist of things.

I double checked my chart...and the correct Champion plug for your and most stock Evos is their RN12YC...noting that the "12" indicates it's heat range.

As a rule American plug manufacturers number their plugs higher for hotter...vise-versa...the "foreign" manufactured are numbered in reverse of that...and you need a cross index chart to select a comparible plug from any company and go from there as far as hotter or colder...because, oddly enough, there seems to be NOTHING uniform in their coding/numbering from one company to another.

By the way,frisco had made a point to remind you that the "R" on the Champion's = resistor type....which you need with electronic ignitions

tommyglide · #2 02-28-2009, 01:45 PM

evoKen, thanks for the info as I was away and did not get to see the replies before they were deleted. So, if we have head work, increased CR and a performance cam we should be looking at a cooler plug, is that the idea?

aceharleywrench · #3 02-28-2009, 02:00 PM

A cooler plug shouldn't be neccesary and would be more prone to fouling.

evoKENevo · #4 02-28-2009, 05:52 PM

I'd have to go a little further and say it all depends on the extent of your combined engine modifications and just how much additional combustion chamber heat was or was not created,by them...noting that my original suggestion of considering hotter/colder plugs as a part of "proper-tuning" (not specifically mentioned by others) was in context with a thread concerning "big-bore" engines,etc...

tommyglide · #5 02-28-2009, 07:25 PM

Thanks very much, guys.

aceharleywrench · #6 02-28-2009, 08:20 PM

Quote:

Originally Posted by evoKENevo

I'd have to go a little further and say it all depends on the extent of your combined engine modifications and just how much additional combustion chamber heat was or was not created,by them...noting that my original suggestion of considering hotter/colder plugs as a part of "proper-tuning" (not specifically mentioned by others) was in context with a thread concerning "big-bore" engines,etc...

Sorry, I had to run out to a benefit for a 17 yr old girl & didn't have time to elaborate about the plug issue.Too buzzed now.

tommyglide · #7 03-01-2009, 12:19 AM

Ace Frehely, Aceharleywrench, one and the same?

frisco-rigid · #8 03-01-2009, 12:48 AM

Yeah jeeeeze

I also had some info for Rob too but that's gone...

Everytime they do something to "improve" the site Via servers and such it's like an Iranian Butt Plugging Party,,,,jeeeze..