Diameter Of Collector On Kerkers

[79XS11F]

For anyone who has a 78 - 79 Standard of special model bike with a Kerker Exhaust. What is the Diameter of the Collector.
I am Asking because I have 2 sets of Kerker pipes but the collectors on them are different diameters. One was listed as off a 79 standard (small collector)and the other a 78 standard (large collector).
So which one do you have?
Rob

[bikerphil]

My Kerker collector is 2 1/2 OD. It's at least 25 yrs. old. The megaphone is chrome with no emblems like the newer ones. It's stamped Kerker below the hanger bolt hole. All the other ones I've seen in person have the smaller collector OD.

[79XS11F]

My Kerker collector is 2 1/2 OD. It's at least 25 yrs. old. The megaphone is chrome with no emblems like the newer ones. It's stamped Kerker below the hanger bolt hole. All the other ones I've seen in person have the smaller collector OD.

Ya, back in 1981 my Kerker was all black without a name plate and was also the large DIA collector. So I must wonder, why was it changed?, and which will deliver the best overall performance? Maybe the collector size was changed to meet noise or emission regulations?
Rob

[yamahansolo]

if you look in the dennis kirk catalog it talks about the different sizes they don't list the exhaust anymore for our bikes but they still sell the baffles, they tell you to look at the number stamped on it and it will tell you. i'll measure mine in a few while i work on the headlight issue.
i currently have no baffle.. it's loud!