So I went to a new (to me) indy' the other day to see about getting some engine work done. As he's showing me a dyno tune being performed I see they've removed the A/C and have the cooling fan blowing at a 45 degree angle across the opening. Is this how a dyno is normally performed? I thought a dyno would be performed under 'riding conditions' with the air cleaner on. Is this done to improve the numbers on the dyno chart? Should I be suspicious?

 

I have seen several dynos done before, including my own, and have never seen them do it with the ac removed. I would be suspicious of this one. Probably trying to fudge the numbers to make his look better than everyone's else. I bet he uses the STD instead of SAE settings also

 

https://www.hdforums.com/forum/touri...no-how-to.html

 

No that is not the way it is done. period. Ask him why he does it that way and let us know, i'm real curious to hear the answer.

 

Curious to know who that is. You do remove the horn and have your fan on a 45 degree angle on the rear cylinder.

 

If it was a carbed bike and he was doing jet changes he likely left the A/C off to make the jet swaps easier. You guys do remember that motorcycles did have carburetors back in the dark ages.
And the fans are the only way to keep the bike from overheating while it's sitting still on the dyno.

 

I tune carbed bikes all the time, if I have to remove an air filter to get to a jet I put the air filter back on before making a run. What good would it due to tune a bike that isn't in the state it will be ridden in? Tune a bike with the air filter off (carb or FI) then install the filter and ride, it will run Richer than it was tuned for, plain and simple.

 

There is some good dyno info in the last couple editions of American Iron mag.

 

do you mind sharing what shop this was? PM me if you wish.

 

You should be asking the shop this question. There could be some odd reason for what you saw.