OK, I'm bitching out loud again. So we did the dyno runs and assumed that would dial things in. NOT. I had a chance to today, and dammit, the bike started running rough between 4000 and 4300 @ 1/4 throttle. I had the same condition when I used the N1TC needle @ 4. So, here is what i'm thinking, when they run the dyno, they get into 4th, drop the rpms as low as they can go, and then gun it to red line. This essentially is running the bike on the main jet. Right? That makes the needle setting useless for this dyno test. Now i know that when i drop my needle back down to .050in from .110in lift, it will run great again. Therefore, this is how i read my dyno lean readings. The Muzzy has little to no back pressure, which relates to a very lean low end. As the rpm's reach mid range the bike is in a normal/more restricted flow, as i hit the top-end, the air box lid restricts the the flow and i get richer @ 8-9k. Scat and I both went rich after 9000rpm, which leads me to believe the lid and snorkel flow best up to 9k @ full load. For you guys with a floating idle rpm's...the air/fuel mixture is too rich if your running the 40 pilot @ 2 turns.

I also noticed, my 130mj(first dyno) a/f is almost identicle to the first 128mj dyno(20 minute cool down @ 50deg). Now the best/last run on the 128mj is much leaner and the bike was definatley hotter after five runs. Now I beleve I should go back to the 130mj, which would run cooler in the summer time heat.

Since I am not of higher education, can you engineer types comment on my pipe vs jetting vs air box theory. dyno link

 

Yeah, that's the bad thing about most of the common dynos being used. They don't have a variable load were you can let the engine stabilize at the same RPM with various throttle openings. Rather they used a inertia drum which can only arrive at power readings via the time it takes to accelerate the drum. This makes them even worse for A/F ratio readings because there is no way to stabilize the RPM at various throttle openings. With a load type dyno the RPM is stabilized in 1000rpm increments and the full range of throttle openings are checked at each 1000RPM increment. The A/F ratio changes once the speed has stabilized at any given throttle opening...you can't see that on an inertia drum dyno. Most places can't afford to purchase and maintain a variable load dyno, such as the eddy current type, so they're stuck with the various inertia drum models made primarily by Dyno Jet and a few other manufacturers.

 

I do believe Tony we need to make you a new insert for your muzzy and see if we can restrict it down abit.... Just a thought...I am game.

 

I have definitely considered that. I think a 1inch diameter core would be a benefit.

 

Unfortunately I was not able to hang around when the shop dyno'd my bike so I was not able to watch the procedure. I guess I somehow thought the machine would load the bike at the various RPM values and gears across the range and develop the curve over many samples. Sounds like the test is not nearly so sophisticated, at least not on these simpler inertial dynos like dynojet makes.

And now, Eddie Sisnoro's comment (the jetting guy over at TT) about my air/fuel mixture graph that I posted there now makes perfect sense:

"The main jet is rich. That's pretty much all that graph shows."

Well, I'm far from a carb expert as I've said before but your assessment sounds reasonable to me. I think it is also reasonable to concluded that, at least on an inertial dyno like the dynojet, about the most one can conclude from the air/fuel mixture readout is whether or not the main jet is sized appropriately, i.e., the carb settings at WOT. It doesn't tell you much if anything about lower throttle settings.

I believe the more advanced eddy current dyno's can gather a whole lot more information about the engine and fuel mixture characteristics. Unfortuanately few shops have those because they are so much more expensive. The FAQ on the Muzzy site talks about that a little bit:

http://www.muzzys.com/support/faqs.html#dyno