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I've been looking at some dyno charts for EFI motors and almost all of them I've seen have a dip in the 2-3k range. What causes this? Didn't see this in the motors with carbs.
 

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jrehm said:
I've been looking at some dyno charts for EFI motors and almost all of them I've seen have a dip in the 2-3k range. What causes this? Didn't see this in the motors with carbs.
Not really an efi thing, it's generally the pipes that cause it. A bit of back pressure improves or cures it. I currently have a 5 lb dip that I know is from my LSR because it is low restriction but I'll eventually work on that and see if it can be minimized.

Here's an example of a properly tuned efi bike.......
http://www.deweyspegs.com/dyno_pages/dyno1.html
 

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jrehm said:
I've been looking at some dyno charts for EFI motors and almost all of them I've seen have a dip in the 2-3k range. What causes this? Didn't see this in the motors with carbs.
Yeah I dont think that it is a EFI thing either. It is something that I am constantly working on and the more I get rid of the dip the better the ride and the better that seat of the pants yank you off the seat feel. For me the key to a good ride is right in that area. I went with the Woods TW-5G and it helped in that area. The Thunderheader did too. I am still not where I want to be but it is like night and day from stock.
Note the difference in the 2000 to 4000 rpm tq curves in the two attached files. Hopefully you can see each curve is getting stronger in that range and I am still working on making it better again. To me that is where you can really feel the difference when you crank on the throttle
 

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I was just wondering if the original post is referring to an AFR dip or the dreaded torque dip. In some cases an AFR dip is apparent with a WOT dyno with no associated torque dip. I've got one, and believe it's just an artifact. I have no torque dip at all.
 
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