Hey folks,

I know I've only driven my '93 Ultra around 80 miles since the rebuild, but I was wondering why the rear plug (the one on the right) has some carbon deposits on it. Is the back pressure different on that head due to the header y-pipe?

-Dave

 

I always thought because the rear cylinder runs hotter (not as much air flow)

 

pulse the rear cylinder will run a bit richer to help keep it cool

 

Actually guys it is a proven fact, that the rear cylinder runs cooler, under normal operating conditions [going down the road]
Due to Splash Oil...

 

Touring exhaust (2 into 3) will always run the rear plug a bit darker on the rear with a carburetor.
Your plugs look normal for low mileage / just knocking around.
No worries Dave.

 

I don't see anything to be worried about put them back in and get a good 500 mi on them then take a look.. and no putting around....

 

Oh, I wasn't worried. The question was more one of technical curiosity. Thanks!

 

Didn't know they came out with new pipes.. 2-3. Did they do that to help with reversion?

 

They did it just to look good

I just call it that. Front into 1, rear into 2... = 3. But it's more like front into 1 and rear into 1 and 1/8, so far as exhaust flow volume since the left is a short 90 degree at the head. (unless you use my $6 trick to make it true duals)
Probably 2 into 1 and 1/8 would be more accurate. I've been on decaf for nearly a year - gimme a break hotrod

 

Did they do that to help with reversion? [/QUOTE]


Thats funny stuff!!