Sanity Check

[ConnerVT]

OK, please be kind.

Thinking of replacing the stock Needle Jets on my '71 T500. As 188 Series are no longer available, going with 159 Series.

Question: Is the 275 4/042 Hex Main Jet is equivalent to the 150 N100.604 Large Round Main Jet?

(I know that 275 is a half size, and unavailable. If this is the correct sizing, I'll likely pick up a pair of 280 jets.)

Thanks.

[tz375]

Yes. That's what all the charts show.

Large Round jets are diameter rated and their flow increases with changes in diameter, so double the jet and 4x the area and flow. Keihin are the same way IIRC.

[ConnerVT]

Thanks for the confirmation.

I had seen the write up from H2Rick (which I figured was correct), but just wanted to get some positive feedback that I was going in the right direction.