WHY not valid? Both V-twins. Both similar displacement. Both operate in similar rpm range.

Besides, I am using the Honda as one example for which I have recent muscle memory. The Breakout is my 40th motorcycle. After 40 bikes, it strikes me as being surprisingly low in engine braking.

Jim G

 

Just a theory:
Maybe the ECM is giving the engine a little "throttle" to keep the emissions down. When intake manifold vacuum gets too high on decel, cylinder compression gets so low that the cylinder won't fire reliably, and unburned fuel goes out the exhaust.

 

Jim,
Your the one that told me yourself that the BO has extremely tall gears, that alone will cause engine braking to be less even though it has noting really to do with the motor.

 

With extremely tall gears, one would be expected to downshift sooner, or be in a lower gear to start with, so that part is kind of a wash.

 

I dont really know what Jim is looking for in regards to a real answer. But it might be time to just use...maybe a little bit of brake now to simulate your engine breaking from the Honda. LOL

 

THAT's something that had not even occurred to me. Good question to ask. I'm not sure who can answer it though. Maybe a pro tuner? Even a pro indy tuner might not know, as an indy tuner has no reason to be concerned with emissions certification.

Jim G

 

Sure, we can just use more brake, but I think Jim is clearly looking for a technical answer to a technical question.
I didn't notice much difference between my Harleys and the Breakout, when I test-drove one. And I've only spent maybe twenty minutes on a Honda VTX, and that was something like 5 years ago, so I'm under-qualified to comment on whether the decel differences are real or imagined.

Water-cooled engines can inherently maintain closer mechanical tolerances, so they may not need to rely as much on tuning workarounds to be emission compliant, to the extent that the air cooled engines do. It could make perfect sense to have the computer introduce a little throttle on decel (through the idle air control valve, or through "throttle by wire") to reduce emissions.

 

One thing I wonder is if he is the highest gear for his speed when he lets off? If you shift conservatively like the owners manual recommends, the act of letting off of the throttle won't have as much an effect on engine braking.

That was the case for me when I first started riding. Now I tend to wind out the gears a little more and lifting off of the throttle usually results in immediate engine braking because I am usually at >2600 RPM when I lift.

 

I usually keep the bike in the 2200 to 2700 rpm range when cruising, and that is also the range that I cruised the VTX in.

Heck, I recall my HD Sportster 1200 having much more impressive engine braking than my Breakout.

And my Ducati S4 Monster (916cc V-twin engine) was an absolute engine braking demon compared to the Breakout, although it did not surpass the Honda VTX 1800.

Jim G

 

A quick search on the internet shows

Breakout 710 pounds
VTX 734 pounds

According to my math that is not 75 lbs difference...much less a hundred...The Harley has about the heaviest flywheels of any modern motorcycle...that and the gearing is the difference...downshift one gear and you will get all the engine braking you want.