I spent an hour on the dyno today trying to jet a stage 3 with a stock carb and pipe with end cap and to get the air fuel to 13:1 it made it loose about 6 hp from 15:1 air fuel, whats to lean for the air fuel mixture????

 

I don't know precisely because you're not stock but it's my understanding you don't want to go beyond 15:1...ever.
However I'm sure there are people who are more knowledgeable in that field then I am.

 

Optimum Air / Fuel or "Stoich" is 14.1 if I remember correctly.

I wouldnt go below 14 if I were you just to be safe! I cant say just how low you can go before you start to cause excessive conditions heat comes to mind first which in turn will lend to other problems.

Perhaps Im stating the obvious for you but why keep tunning down when your loosing HP as apposed to going the other way... or were you just calling out your observations of the days runs??

 

the leaner I jet the more hp it makes

 

Stoichiometric is 14.7 parts air to 1 part fuel. 13 to 1 is pretty rich. It doesn't suprize me that you lost that much HP. 15 to one is not bad. It is just on the lean side, but in reality it is proboly as close as you will get it. If you could get it to 14 or 14.5 to 1 you would be right on.

Remember guys, the HIGHER the first number the leaner the mixture. The LOWER the first number the richer the mixture.

 

Thanks for knocking the dust off that one for me clshortt. I knew it was 14 something ....

 

Where's the A/F meter?

Do you have any leaks in your exhaust?

If your head pipe is sucking air you could show much higher A/F ratios but, you could actually be lean.

But hey. . . that's just me. . . I could be wrong.

 

I run leaner for flat riding than for hill racing. The dyno presents a flat race situation where as the sand hill presents a heavy load and runs better with more fuel. I jet 13.2:1 on sand, 14.5:1 for flat riding.


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Something is up. I would try a new sensor. Maybe you have an air leak like DuneMe has asked?
Stoichiometric is 14.7 like clshortt has stated. You should find your most power right at 12.5. Why are you finding it at 15? I don't know, but something is not right here.
I don't know what compression your running but if your running any race fuel with lead in it the lead will foul the sensor very quickly.

 

I am running a 14:1 piston with 112 octane fuel with lead, the tech put the sensor in the end of the silencer and how would I know if I had any leaks, I can't hear or feel any leaks around the joints in the exhaust.