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Dyno tuning

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scottly:
Hey folks, I've made a few pulls on the dyno lately, trying to sort my carb out. All numbers are with a large-by-huge K&N filter, a free-flowing muffler, and a 60 idle jet, which has proved to be too rich. The next pull will be with a 58 idle and a 160 main.

147.5 main: 25.7 HP, 23.09 ft/lbs
152.5 main: 25.835 HP, 23.815 ft/lbs
157*  main: 27.4 HP, 24.95 ft/lbs


*Drilled jets are like a box of chocolates: you never know what you get. ;)

J6G1Z:
Looks like she wants more fuel. You are very fortunate to have a dyno available.

Do you have an exhaust sniffer or exhaust gas temperature gauge to help tune with?

Good luck & please keep posting up your jetting & tuning info.

Thanks
J.

scottly:
Yes, I do have a sniffer, but found that it didn't work well with the stock muffler, hence the swap to the Muzzy. I had the best pull yet, today, with a main drilled to "167": 28.81 HP, and 27.47 ft/lbs. More importantly, the A/F graph stayed within the readable range, instead of mostly flat-lining on the lean side (top of the bottom graph).

J6G1Z:
Here is a larger copy of the graph. It's a bit fuzzy, but still readable for the most part.

Do you think that 30HP is possible?

scottly:
I was hoping to report 30HP tonight, but it didn't happen. :( Even with the main drilled to "178", the sniffer was still leaner than optimum for max power. The next step is to modify the slide needle height, which, as I'd already looked into a while back, is a major PITA, compared to changing idle and main jets. I can drain, drop the bowl, swap both jets, reattach and prime the bowl in about 15 minutes these days.  ;D

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