Loss in Top Speed

[RiderFZ]

Currently my my 2017 fz07 has the EJK, removed snorkel, cheap after market exhaust modeled after the m4/yoshi r77 and no 02 sensor. The bike stops right around 130. But before all this i had welded a m4 slip on to my stock header. With ejk, tune or snorkel mod the bike did 139 before i let off bc cars came up. Any ideas as to why? i was told running the bike with basically a straight pipe and no "tune" at all would would effect the bike but now its slower. I rented the AFR tool and talked with the reps from the EJK and my bikes fuel is perfect now, i just wanna know why its slower.  

[mossrider]

Just now, RiderFZ said:

, cheap after market exhaust modeled after the m4/yoshi r77 

First off you can't go by the stock speedo if that's what you've been using since your numbers are optimistic. Use a GPS app on your phone or similar. Then do some scientific testing. Same day, road, weather, traffic, same, same for comparison.  Anecdotal #'s are suspect at best.

Second that quoted statement above speaks volumes. Get it properly tuned on a dyno and see what that pipe makes for power, hopefully you had same done before so you know where you stand.  A quality exhaust will get you much of the way back to 139 but I doubt you'd ever truly get there without more motor or aero work. Just not enough umpf. 

You are correct, the mods did effect your bike. Negatively. It happens, personally I discount 10mph variances all the time as statistically irrelevant.  

[Beemer]

From everything I've read just running a straight pipe alone allows for gasses to escape quicker which in turn increases top speed but from you described you haven't done that yet. You said you ran an M4 exhaust muffler which gave you 139 mph. and are now running a muffler "modeled after an M4/Yosh R77" I can see where a different muffler like what you have on now can affect top speed (made differently) but it's not a straight pipe, it's a muffler or am I missing something?

[randy2100]

Wind direction and speed has a big effect at 130 mph.

[peteinpa]

Lots of variables. Tire pressure, any drag, different jacket, brakes, wind direction, gas from different station, etc.

[RiderFZ]

On 3/22/2020 at 9:14 AM, Beemer said:

From everything I've read just running a straight pipe alone allows for gasses to escape quicker which in turn increases top speed but from you described you haven't done that yet. You said you ran an M4 exhaust muffler which gave you 139 mph. and are now running a muffler "modeled after an M4/Yosh R77" I can see where a different muffler like what you have on now can affect top speed (made differently) but it's not a straight pipe, it's a muffler or am I missing something?

The the first M4 slip on i had was just a generic M4 blast pipe. Just a foot long pipe shaped like a cone. It was every definition of straight pipe. The exhaust i have now is the Anodize Racing amazon special thats looks like the yoshi r77 or the actual M4 thats made for the FZ.    

[RiderFZ]

On 3/23/2020 at 8:45 AM, peteinpa said:

Lots of variables. Tire pressure, any drag, different jacket, brakes, wind direction, gas from different station, etc.

i did it on the same section of mexico highway before and after the new exhaust and EJK. only difference was the 139 run was made in a t shirt in 90 degree weather  and after the mods i was wearing a race jacket at around 70 degrees. I only get gas from a station in town whenever possible.  i guess that drag really does change things. 

[RiderFZ]

On 3/21/2020 at 1:24 PM, mossrider said:

First off you can't go by the stock speedo if that's what you've been using since your numbers are optimistic. Use a GPS app on your phone or similar. Then do some scientific testing. Same day, road, weather, traffic, same, same for comparison.  Anecdotal #'s are suspect at best.

Second that quoted statement above speaks volumes. Get it properly tuned on a dyno and see what that pipe makes for power, hopefully you had same done before so you know where you stand.  A quality exhaust will get you much of the way back to 139 but I doubt you'd ever truly get there without more motor or aero work. Just not enough umpf. 

You are correct, the mods did effect your bike. Negatively. It happens, personally I discount 10mph variances all the time as statistically irrelevant.  

i have a video of the speedo reading 139 and a screenshot of the gps app that says my max speed was 138. im not saying you are wrong because ive read that the speedos are off and my app could be funky as well. Truly the bike was never ment for top speed and does wheelies just like it was intended to i was just more curious than anything.