Yoshimura R77 Slip Ons

[JOCK]

Hey Buhjones, I fitted my R77's last week and the bike is performing fine, not even popping back on overrun.

[bazman]

That looks nice, JOCK........VERY nice!!!!

[tickedo]

Sorry to wake up an old thread. I've just installed some R77's on my gen2. I reckon it's lost lots of torque! Anyone else think this or do I need to get it mapped to suit.

[Batfink]

you got the silencers in or out?

I kept mine out when I put them on and found the bike ran/runs great

[Shordy]

What do these silencers look like?

[tickedo]

They are out. I'm also finding that it runs hotter..........!

[Batfink]

@Shordy they are a 125-150mm long s/s tube that sits in the end of the can. The easiest way to tell is when you look inside the end of your can if you see a smooth long tube then you have silencer in, if your see a short tube then the mesh of the baffles then you haven't LOL

[DjPete]

tickedo are you sure it's not the psuedo effect?
Don't mean to be rude but it's worth considering.
I doubt very much that a diff exhaust would do what you are experiencing

[BUSGO]

When I fitted my R77s, I noticed improved torque with stock air filter. I was told to disconnect the battery and reconnect which was supposed to reset the ECU O2 sensor. It might have worked but who's to know.
A definite improvement for me.

Sent from my SM-G360G using Tapatalk

[Shordy]

I read the Yoshi web site when I fitted my R77's and it said that it would lose 2hp but have the same torque as standard.
I accepted this small loss as I like to hear my bike when I'm riding it, and since then the ECU's been flashed which has more than made up for any small losses.
I didn't receive any silencers separately with my R77's Batty, but it's not too quiet so I guess they aren't installed.
It does give me a reason to go up the shed (read have a couple of stubs) and uncover the white one tonight and have a look.

[DjPete]

heres a pic of the silencers.

I had to slip mine in for RWC a while back. Just made rw with them in

[tickedo]

I wondered if I'm dreaming it......
Another thing is it is going through heaps more fuel.
BUT it is so worth it

[Batfink]

This last bit of info has clinched it for me...

Here is my theory
You have just put on your new R77's and really, REALLY love the new sound of the bike, lets face it the stock cans make it sound like a sewing machine LOL
And to get the best sound out of them you are now riding the bike in the medium to high rev range (rather than the low to medium range you did with stock cans). This change in rev range will make the bike feel like it has less torque, run hotter AND use more fuel. These things I found out when I went for a Learner ride with a mate.... by taking it a lot easier and slower I saw/felt that my '13 busa
1. had a lot more available torque with every extra twist of the wrist
2. stayed cooler by the gauge
3. used a massive amount LESS fuel (a tank could do me 400+ klm compared to my ususal 250-300 klm )

You can get a little more out of your busa by getting it correctly mapped and dyno tuned but not sure if the expence is worth the results with such a minor change as slip-on R77's.

BTW.. Zooki does offer R77's as a Manufacturers option so I would think they require minimal, or no, adjustments

[Huls]

I've always been told that by removing the stock exhaust on any bike and replacing it with a freer flowing system will impact upon torque, power and air/fuel ratios. Stock exhausts are fitted with lost of baffles etc to reduce noise, emissions and this obviously slows down exhaust gases exiting. The back pressure from the stock system helps with torque which is why Yamaha patented their EXUP exhaust valves years ago. The EXUP valve would be in place below say 5000rpm to assist with noise, emissions and torque, then rotate out of the way as revs rise in order to take advantage of freer flowing exhaust gases as faster exiting gases assist with improving engine performance. By fitting R77's you have achieved the same things. Downsides are loss of back pressure and therefore torque at lower revs and potential changes in air/fuel ratio causing flatspots and leaner/richer running at certain revs. Change the air filter to a K & N or similar and get the bike dynoed to take advantage of the changes you've made.

[Batfink]

Isn't the catalytic converter the biggest restriction point on a modern exhaust system these days? I always thought it was and if you are just changing cans then you are effectively not changing the flow that much. However, if you remove the catalytic converter (by complete new system or just hacking it out) then you will definitely need to adjust the bikes ignition to compensate.