in communication with the shop now. He agrees something is off. When I receive a call back I will get the cam info and get head flow numbers.

 

not sure what those are. Got a standard ness big sucker

 

no step, which through my searching I need.

ID on collector is pretty small. Not sure off top of my head but I think around 2.25. Ill check length and diameters this evening. Didnt do a run with muffler off.

 

I would try running a different exhaust system as a litmus test,,,,doesn't need to be anything crazy, just something that is a known and proven performer. bolt it up and run it again and compare the results. I know that a some dyno shops often have systems laying around just for test purposes. run it without re- jetting it first to see what difference the pipe alone makes.
m

 

I am really thinking the exhaust has a lot to do with it. Weather turned bad this afternoon so it looks like I wont be able to see if its sumping until tomorrow.

My thought process is, the bike draws more fuel the higher it revs. If the exhaust pipe cant move the spent gas out of the engine fast enough, it will only get more rich the higher it revs, leading to power loss. (Dyno shows this)

Cam specs for those that were curious.
.610 lift
Intake open = 23
intake close = 45
Exhaust open = 55
Exhaust close = 17
overlap of 40

 

right now i would not be worrying about AFR/mixture strength as they have little to do with the bike not continuing to make power past the rpm point in play. that is definitely a flow issue, not afr. the pipe is the easiest to start with. for what it's worth, with a build like this you could probably throw a set of drag pipes on it just to see if the upper rpm power comes on. i'm not saying keep them installed, just as a test.

m

 

I have to agree with Marco. I would see if the shop you used to tune had another pipe on the wall you could try like maybe a thunder header or something. The cam should carry out...

 

I'm curious what intake manifold was used on the two bikes, same port size etc.

 

Or, has hrdtail78 suggested, just pull the mufflers and see how the motor responds. I recently ran three different pipes on a freshly built 98" motor, one of which was the venerable D&D Fatcat. Both the tuner and I were dumbfounded when we saw the D&D pipe perform way below the other two. We changed cams for another reason, ran the three pipes again and the D&D did much better but was still not the best performer. What this revealed was that just because the D&D pipe works well on most builds, it is not the do all/end all for all builds and that cam and exhaust do have a relation ship that can make/break a build. Having said that testing pipes will be an endless and mind numbing experience. Making a pull or two without mufflers should indicate whether or not the exhaust is the bottle neck at higher rpms.

 

Yeah- your dyno sheet looks very similar to what a motor with a supertrapp exhaust with an end cap on. Very torquey but low to midrange powerband. Thats where alot of 2 into 1 exhausts excel at. I think you need more flow out of the exhaust. Just my opinion- but thats what i see.