I really wanted to know if they were any real difference between a

N100.604 Large Round and N102.221 Small Round. It just seem that the 604 is for the older carbs and the 221 is for the newer ones. Is there any real diff. The diameter of the hole the fuel passes through is going to be the same correct?

Bump. This is a good ?

Not sure in the older carbs, but the newer carbs are the small round main jets. I believe the older carbs are the same.

Well from al my searches its being stated that the large rounds are usually the one they put on the older carbs mains. The small rounds are people with the newer carbs. I just want to know if they is any REAL difference.

j87

Quote from: Wrecent_Wryder on August 19, 2006, 06:30:50 AM
The large round jets fit in a larger round hole- if you get the wrong size, they won't screw in. Doesn't affect the "jet" diameter, but, yeah, it's a real difference.

But the threads are the same on both. My thoughts on it is if the threads are the same and the actual hole for the jet is the right diameter then whats the BIG diff. Im just asking. I know you guys have experience here.

You can use the small round where a large round will fit, but you cannot use a large round  in place of the small round; the surface area where they butt up against may be different.    The only other thing that I can think of is the needle jet/emulsion tube that they screw into; too small and the main jet may not keep the tube seated in the carb body.

Quote from: scratch on August 19, 2006, 07:52:52 AM
You can use the small round where a large round will fit, but you cannot use a large round  in place of the small round; the surface area where they butt up against may be different.    The only other thing that I can think of is the needle jet/emulsion tube that they screw into; too small and the main jet may not keep the tube seated in the carb body.

Thats the samething i was thinking but i put them next to each other at the shop and the threads are exact same length and width.