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post #31 of 34 (permalink) Old 07-09-2020, 07:21 PM Thread Starter
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Originally Posted by passx View Post
Originally Posted by AtlRiderrr View Post
So weird, because on every performance car I’ve seen, the headers add like 10/12hp and 8ft/lbs. Maybe it’s because they have those honkin’ cat converters in the stock ones. *shrug*
Alt, a couple of things, was that h-power claim from an actual dyno test or just a manufacturers claims to sell product ?

On automotive exhaust they are typically waaaay more restrictive than a motorcycle, mostly due to the exhaust manifolds themselves which is caused by simply packaging trying to make things fit and nothing more. Bikes really don’t have the same issues and 99% of the dyno testing I’ve seen the stock bike exhaust is better than the aftermarket. Performance gains in the aftermarket exhaust is simply due to being much lighter, typically 50% or more lighter. Also a lot of the claimed gains is by the increased noise levels (Harley factor) if it’s louder it has to be faster, right ? Also the “butt” dyno is a big liar ! Not at all accurate.

Catalytic converters, claims of big power gains there are quite simply pure internet myth, it ain’t there, past the early GM pellet type converter the current honey comb brick type simply is not a restriction, the pipe diameter creates more of a restriction than the converter.

An example I’ll give is that I have a 94 Dakota that I used to drag race and all the internet “expert” gear heads convinced me that there was an easy 25rwhp by removing the stock 2.5” cat so I fashioned up a straight through test pipe and removed the cat, it produced not 1 mores-power, zero, nada, nothing ! It used a lot more fuel (screwed with the O2 sensor a little) which made it slower in 60 ft.

I called an aftermarket performance cat company to talk to them (MorFlow) about the results, the head guy there just laughed, he said he sells a lot of converters because the mistaken belief is that there’s this huge restriction and he told me that past the oe GM pellet type (highly restrictive) the new honey comb converters literally provide zero restriction and that the pipe diameter creates more restriction than the converter. I did reinstall a converter on my dakota with zero negative results. Quite frankly there is very little to no benefit gained by removing any of the “emissions” equipment on a vehicle these days, it just ain’t there, as I say, “pure internet bs” nothing more.

Now all that said, I have learned that quite frankly there’s very little to be gained in the fjr past improving the sound and removing a little weight, maybe,,, ,,,, ride more, worry less,,, just enjoy what you have ! If you need more speed, buy an R1! My .02
It was tested with dyno runs. This was with my 2002 Manual IS300 back in the day. Headers, intake mods, cat back, and SAFCII brought me something like 15ft/lbs and 12hp. It was totally noticeable. But then again it wasn’t the cheapest endeavor.

1994 Honda VFR750 custom streetfighter
2015 Yamaha FJR1300A
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post #32 of 34 (permalink) Old 07-10-2020, 08:52 AM
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Alt, glad it worked but from what you listed it had to be an expensive proposition for the results gained. Iíve learned over the years that Typically it takes about 20hp or more to make a noticeable/ feelable difference, doing exhaust usually makes the brain think that thereís a lot more simply because of the noise, itís the old Harley thing where itís felt that because itís loud it has to be fast.

And usually after any modifications to the engines breathing it should be run on a dyno to have the a/f settings optimized but of all the bikes I seen ran on the dyno they all ran extremely lean at idle (15-16 to 1 a/f) and then went pig rich once off idle, typically in the 10-11 to 1 a/f which is why you can add a pipe & air filter and not need to rejet.

The reasoning behind those factory settings is that all the manufacturers self certify for emissions and the guidelines mandate it be done in the 1000 to 2200 rpm range (think automotive) so the idle & maybe the mid jetting are set very lean to make the emissions regís. Once past the emissions band they go really rich for several reasons, mostly because it reduces the warranty issues because the engine tends to run cooler and is much less sensitive to weather & barometer variations as it always runs the same. If you get close to the optimum 14.7-1 a/f ratio youíll make the most power but will be very sensitive to weather changes.

Myself on a carbíd bike Iíll leave the idle/midrange jetting in its lean state which helps make it run cleaner (easier on the plugs) maybe bump the mid-range jetting a little to fix any flat spots and then even with full headers and a high flow intake filter Iíve found dropping the main jetting about 4-5 sizes works best, this pattern is common across most of the manufacturers.

Fuel injection is a little different but they tend to run similar patterns but isnít as easy to fix unless you have the ability to reprogram the PC, which is why the Ivanís reflash is popular where he is more aggressive with the timing maps which tend to lean things out, anyway a very long winded response that I hope may help some to understand a very complex deal. Good luck in your endeavor, hope it works great and please let us know how it works out.

As a side note your weight reduction plan is the best possible means to increase the performance and handling, no bad side effects from that path.

Steve P
Red 2014A, the fastest color !
Ride more,, worry less !
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post #33 of 34 (permalink) Old 07-10-2020, 10:09 AM
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I put the same mufflers on my 2014 FJR.
Only difference is I did not go with the carbon.
I just love em
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post #34 of 34 (permalink) Old 07-10-2020, 10:26 AM Thread Starter
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Originally Posted by Zendmanmarc View Post
I put the same mufflers on my 2014 FJR.
Only difference is I did not go with the carbon.
I just love em
So mine didn’t stay put which i figured would happen. I ended up using the extensions they gave me after all. I was perhaps overthinking it too much, it just places the cans in a similar location to the stock ones. They look good. I’m experimenting with just leaving hard cases on... so far I’ve already used them a few times haha. Go figure
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1994 Honda VFR750 custom streetfighter
2015 Yamaha FJR1300A

Last edited by AtlRiderrr; 07-11-2020 at 12:22 AM.
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