Dyno Runs with 2007 Newer Bikes

[Bagger]

Can we generally think that 2007 newer 6th speed bikes in the dyno section were done in 6th gear?

[PoorUB]

No. They will often say what gear they run it in, but many are done in 5th.

[kd]

I think it sometimes also depends on the build and capability to reach top RPM in top gear.  Tire ratings can be  prohibitive and it may be too dangerous to hit the limiter in 6th gear with the high OEM ratios.

[Ohio HD]

Both of mine in the dyno section are in 6th gear. I'd venture that 80% are 6th gear pulls.

[kd]

The numbers are generally better in 6th gear. 

[Ohio HD]

I think it varies a little. Here are these two pulls from the same bike, same day, same dyno. This was a 107" with stock heads before dyno tuned.

The 4th gear pull has more HP, but less torque. The 6th gear pull has more torque, a little less HP. In any event, it's not a huge difference.


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[kd]

There's been lots of debate about that phenomena even on here. We have had a couple of decent ones.  I don't know if it's relevant to the OP's question. It appears to be the way the dyno does it's calculations (based on speed and time) and of course depends on the ability of the engine to produce power and torque usefully.  It's real easy to get into the weeds and find yourself falling down the rabbit hole. It doesn't seem to be a lot but it does show up as your graphs indicate.  It also often clouds over the real reason for being on a dyno. Tuning.

[kd]

 More to the OP's question, I do believe that most dyno operators try to use the gear closest to 1:1 ratio for consistency.   OEM 6 speeds of that vintage are 1:1 in 6th gear.  In the 6 spd GrudgeBox it's 5th gear. The other gears have ratio changes that may rob power.  I suspect and hope a tuner or more will see this and set the record straight.

[No Cents]

  all my dyno runs that I've had done on my 08 FLHX by Jim Kennedy were done in sixth gear.

[Don D]

The loss is really comparing 99-06 5 speed equipped bikes VS 6 speed bikes. It is just parasitic drivetrain losses from the helical VS straight cut gears, IMO. Many years ago I remember Mike Stegman stating it was close to 5%.

[Bagger]

No. They will often say what gear they run it in, but many are done in 5th.

I must be missing where to look on dyno sheet for gear run was done in.  I reviewed 15 dynos and saw no indication of what gear used.

I always assume when looking at 6 speed bikes they were 6th gear runs.  I figured the dyno operator would use 1:1 gear ratio.

A friend of mine believed majority of posted dynos on HTT are 5th gear.

[kd]

I did a little personal research on it myself about 3 years ago when it was debated in a little depth here.  I found the general consensus among those that seemed to be credible to be in that 3-5% range.  That from Dyno operators and manufacturers.  One of the problems I found was the ability of a dyno operator to skew the results by using creative settings and methods.  The bottom line is the dyno is a tool, not a scale of true measure.  It shows trends that are being converted into numbers.  Those numbers can be adjusted for weather and other atmospheric conditions.  Lots of room for "error".  I believe that's one of the reasons this site has posting rules respecting the format of graphs.

[Bagger]

I've confirmed with Durwood (Sheffer's Tuning), Fuel Moto and LA Harley that they do final dyno runs in gear that is 1:1 ratio.  If 5 speed, then 5th gear.  If 6th speed then 6th gear.  If bike has an 6peed OD transmission, then 5th gear is 1:1 ratio.

I agree a dyno is a tool and if one knows the details of the run, then a person can see the potential that a particular combo may produce.

So I'm going to assume unless noted on dyno sheet, final runs are done in gear that is 1:1 ratio

[kd]

That's a decent assumption if the dyno operator is as good as Durwood or the others.  It is also what many other chassis dyno operators claim they do. 

[PoorUB]

Perhaps dyno operators finally settled on a standard.  It wasn't many years ago there was a big discussion whether to run in 5th or 6th.

[04 SE Deuce]

The loss is really comparing 99-06 5 speed equipped bikes VS 6 speed bikes. It is just parasitic drivetrain losses from the helical VS straight cut gears, IMO. Many years ago I remember Mike Stegman stating it was close to 5%.

Mike Roland was one of the first to mention parasitic loss of the 6 speed vs 5 speed with same build...but not many were listening back then.   IIRC he stated 6-8hp in the HP range they were measuring...so approx. 5%