Bonus Question!
 

Does anyone out there in SH land know the difference between a #45 Pilot Jet and a #45S? I've measure, magnified, and searched and I'll be danged if I can find any difference. They are both Series 21 but no one I know, knows if there is a difference.

Are you sure it's an S and not the Keihin stamp?

"S"
 

Thanks for the response but, no, it is not the Keihin mark. It has that as well. Kind of weird Huh?
I has the K trade mark followed by 45S. I'll call Sudco in the AM as even the dealer has no clue.:confused:

I'm not sure that's what it is in your case, but "S" usually stands for "Slow jet" as in pilot circuit... The profile is different, so putting a jet meant for a pilot circuit in a smaller carb as main jet might not work well, hence the marking...

5 of my series 21 OEM Keihin 45's have an S (45S)
Some came out of the OEM carb set up from the factory, some bought as replacements from Sudco.
I have a 42, 43, two 48's, 50 series 21 OEM Keihin jest and none are marked with the S.
Some came out of the OEM carb set up from the factory, some bought as replacements from Sudco.
Sudco makes no distinction in the catalog?
and like you, visual, pin gauge and micrometer inspection shows no difference I can find .

If Sucdo has some thing to say please post up.

Tweety .. is the series 21 Keihin jet
http://i258.photobucket.com/albums/h...ps9cfa61dd.jpg

used as a main in another carb?

Just got off the line with SUDCO. The difference between the #45 and the #45S is that the latter (S) is a Honda proprietary part. There is a minute difference in the bleed hole configuration, so minute it can be compensated for with a 1/8 - 1/4 turn of the Fuel screws. And yes, the Honda part is considerably more expensive.

I wouldn't know actually... But that was the only instance I knew of where an "S" was used... Now we know another it seems...

Well done..
Though it brings upo a question for me.. The ONLY Honda carbs I have had apart that use this jet are the SH, so I should have at most 2 of them...... came out of Suzuki, Yamaha's, or a Harley .. Not the original jets to that bike I suppose.. I have source jets at Harley for non Harley bikes... no reason to think someone did not source OEM Honda jets for a non Honda.