Exhaust

[getagrp1k]

Opinions from the group.

Like my intro says I have been riding sportbikes my entire life and the cruiser thing is bugging me mentaly.

In your opinion would it be better for me to put a slip-on system on or a full system, with the full i would have a custom map made with a PC-3 usb. Does the FJ need to be tuned with slip-ons?

It is under sprung as well and am buying the race tech 1.0kg springs to match my weight and the comp/reb circuit as well.

Should I respring the rear 18.5 kg as reccomended by race tech or go with a new shock?

Your wise and knowledgeable input is greatly appreciated in the world of the FJR

curt

 

[Aasland]

To answer your questions ...

1. FJR's older than 2008 need to be tuned, even when stock.

2. Racetech is good. So is GP Suspension - they have lots of experience with FJR's.

3. Stock rear shock sucks for valving too, so bit hte bullet and get an Ohlins. Penske is good too, but you won't get the remote preload.

 

[dcarver]

I would think tuning is always good, assuming you have the dollars to throw, so full or just slippies, I'd tune anyway.

Of course, I'm riding stock motor but with full $uspension maintained regularly; for me the greater improvement is in handling, brakes, tires, not motor mods.

 

[happyPuppy]

I would do the suspension mods first, I think it is the best bang for the buck but both are not cheap. Slip-on's will change the sound but do not do much if anything for performance. The only way to really get any change is open the airbox, and due a full swap headers and all, mostly to get rid of the cat.

 

[UselessPickles]

1. FJR's older than 2008 need to be tuned, even when stock.

That's not true. There's nothing harmful about the stock tuning on a stock FJR. What you mean to say is that there is some hesitation with the stock tuning that can be fixed with a PCIII, and that many people believe it is a worthwhile investment for a stock bike.

Adjustment to fuel tuning is also not required for slip-on exhaust, but it is required for a full exhaust system.

There's only 2 options for full exhaust: Muzzy 4-2-1 (yup; you lose your awesome dual exhaust), or the Holeshot 4-2 system.

As for what would be "better" to do in terms of exhaust, only you can decide. What is "better"? Quieter? Louder? Looks better? More power? Not too expensive?

Slip-ons generally claim 3-5hp gain. Holeshot claims 6-9hp gain with their full system. An independent test showed ~7hp gain with the Muzzy full system.

Some people like the Holeshot header with stock mufflers because of the sound (a little meaner sounding, but not really louder). Someone did before/after dyno tests (with a custom PCIII map for the Holeshot header setup) and found that this setup actually causes a slight loss in HP.

I still haven't seen a before/after dyno chart comparison of a stock FJR compared to a full Holeshot system.

Personally, I have the Holeshot header + Remus Hexacone slip-ons (requires modification to the Remus connector pipe to fit):

Here's a couple samples of how it sounds:



And here's some dyno results (note that I also had a wildly modified air box): https://www.fjrforum.com/forum//index.php?showtopic=120164

It's an interesting reminder that peak HP/TQ numbers don't tell the whole story. Even though I show a loss of peak TQ and the same peak HP, my acceleration times improved quite a bit (10.98s @ 126mph 1/4 mile compared to my previous best of 11.36s @ 120mph, and 0-120mph in 9.7s compared to the previous 11.36s). I still think that my higher RPM loss may have been caused by over-oiled filters. Maybe I'll put it on the dyno again sometime now that I've gone back to a more stock-like air box setup.

 

[UselessPickles]

The only way to really get any change is open the airbox, and due a full swap headers and all, mostly to get rid of the cat.

Not quite true. Cats are not a big bottleneck (common misconception). Wicked Webby's air box mod results are evidence of this. He got significant gains with slip-on exhaust and a modded air box while keeping the stock header with cats. His air box mod is a bit excessive for most people, so we really need someone to get dyno results of a less insane air box mod with slip-ons compared to stock. I bet that would be worthwhile, especially since that air box mod is cheap and easy.

 

[Aasland]

1. FJR's older than 2008 need to be tuned, even when stock.

That's not true. There's nothing harmful about the stock tuning on a stock FJR. What you mean to say is that there is some hesitation with the stock tuning that can be fixed with a PCIII, and that many people believe it is a worthwhile investment for a stock bike.

True, it's not harmful, but on my 2006 it wasn't a hesitation but rather an off-idle lurch which, mid corner, is very disconcerting. Maybe some folks don't notice it, or get used to it, or are such awesome riders that they always get on the gas before leaned over. Comming from a sportier bike with impeccable fuel injection, it was bad enough that I would have had to get rid of the bike if I couldn't solve it (which the PC3 did).

 

[happyPuppy]

UselessPickles, I agree the best maybe a well done airbox mod. My concern is sucking in road debris if I did to radical of one. On another bike I used Uni Foam ( 2 types to get the right filtration & thickness) and it worked well. Removing the pipes and cat is mostly to save weight IMO. The stock pipes and some good cans should work as well. I would love to see a dyno of a well done one.