pilot jet size question..........

[oldnortonrider]

I'm in the process of rebuilding my carbs ~~ 3rd time in about 20 years ~~ 10 years since last rebuild. The carb kits that I've got are from georgefix (eBay), and are the best quality out there IMO (K&L). I wasn't able to find the K&Ls available, and for the right price, for the 78 or 79 carb types with the 42.5 pilots; so these came with the "45" size. They're 6 hole and the ones that are still in my carbs before rebuild and disassembly start, are 42.5 size (also 6 hole type) pilot. The machine that I've had for 21 years (daily ride) is an 81 Special; the set of carbs that are the "earlier type" with the brass floats et al, had been installed by PO. I have a separate , extra set of carbs; also 79 year; same type carbs as the ones I'm about to rebuild. My question is ~~ if I install the new "45" size pilots, instead of re-installing the "42.5" size pilots ~~ wondering what performance change I might expect? Curious if there's anybody out there , riding around with the "45 pilots" I am also installing new carb boots; they definitely look top OEM type quality; that I also got from georgefix. I'm going to get the Morgan Carbtune to synchonize with this time, although I still have the MotionPro "mercury-type" (hadn't used it since last carb rebuild on this machine)..................

[natemoen]

The '78 came with 45 pilots and 210 air jets.

[oldnortonrider]

The '78 came with 45 pilots and 210 air jets.

Ok; thanks for the input ~~ reminded me to look here~~>http://www.xs11.com/forum/showthread.php?t=73

[natemoen]

That table is not correct though because it does not show the 210 air jet along with it.. I think you probably need the 210 air jet along with the 45 pilot jet.

[bikerphil]

I run the 45 PJ with the 180 air jet in my 79, no problems, bike runs strong, 40 mpg. YMMV. I have 4-1 exhaust and drilled airbox/K&N.

[oldnortonrider]

I run the 45 PJ with the 180 air jet in my 79, no problems, bike runs strong, 40 mpg. YMMV. I have 4-1 exhaust and drilled airbox/K&N.

These new K&L kits that have the 45.0 pilot, came with new 180 air jet.

[bikerphil]

The 45's should be fine, worst case scenario, switch back to the 42.5's.

[MPittma100]

Pilots

I went to the 45 pilot and 210 main jets in a 79 Special that had the smaller 42.5 and 180. I like the performance of the bigger jets. I agree with bikerphil that the 45 pilot and 180 jets would be just fine as well.

I lost maybe 3 mpg after the swap, but like I said, the performance/throttle response is better. If I were to change again I would likely go back to the 180 mains and keep the 45 pilots.

The later smaller jets were mainly considerations for less "better" emissions required by the US.

MP