My old school teachings were to go up a few sizes until you feel the engine slow down then put it back one step. I did that with my current set up, then I took my carb to C & J Engineering to have them go through it.

I think the old guys name is John, he put together a formula based on my engine specs, made my head hurt looking at it. Then he looked at me and told me he would use the exact jets I had in place already. I felt good about that one.

How do your plugs look? Yea to get a good reading you'll have to shut down at WOT for the top end.

Thanks, the plugs look perfect, just figured if I richen up the top end a bit, maybe it would give me a little more mph, but I will try  your method and see how that works out, thanks again

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Fat is safe, lean is mean.

You're better off staying on the fat side. Less horsepower, but safe.

We normally err on fat side and do what was previously said.

In more cases than not, we find that up one jet larger on all for corners and a lower number power valve is really close to the sweet spot. You will seldom need a power valve higher than a 5".

With a 750, I would say a 5.5" is a good start, depending on quite a few things.  RPM, compression ratio, displacement and cam grind for starters.

Just an honest opinion based on trial and error.

GT

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It has 65 p.v. 72/77 jets. The engine is .030 over with old trw  pistons with eagle rods. The cam is a comp cam xm288h Flat tappet .570/ .575 lift, 781 heads with upgraded valves that are standard size. Edelbrock performer 2.0 dual plane intake, this set up runs 5k rpm wot at Gps 63mph. Berkeley pump with a impeller, drop shoot and place diverter

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What the list#on the carb?

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Carb

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Someone at some point leaned it down a bit.

If you have no idea where you're at jetting wise, I'd try this.

Primary jets to 73 (factory is 72)
Secondary jets to 81 (factory is 80)
Power valve down to 5" (factory is 6.5")

Should run like is scared and be pretty safe.

Bring a fresh set of plugs and read them After a hard shut down.

JMO.

GT

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1 more quick question, on the power valve. Do I need single stage, two stage, or high flow? Just want to make sure I get the right shit, thanks

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Ok thank you

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