Replacing your stock muffler on the KLR can achieve two goals. One measurable output is shredding weight from your motorcycle. As the stock exhaust system weights exactly 1 zillion tons (5.5kg), a FMF Q4 pipe (2.5kg), for example, can save you 3kg.
You can go even further in weight saving if you replacing the stock header pipe with an aftermarket one. Sticking with the FMF Q4 example, investment in a “PowerBomb” header will reduce the weight of the KLR further. See all FMF KLR650 products here.
The harder to measure result of replacing the exhaust system is some extra power. To gain some measureable extra horse power requires further works on the air system, adjusting and jetting your carburetor and some other tweaking around the engine.
You can find a couple of well documented KLR650 tuning project around the Internet. Even the claimed ~3-3.5Hp is an impressive 10% improvement in power, the overall power output is still in the lightweight, under 40Hp range.
But hey, if the modest power of the KLR 650 isn’t enough for you, you can turn to the new Husqvarna 701 which will soon get the strongest single cylinder engine available commercially these days. The 690cc KTM engine is producing a whooping 74Hp (71Nm). You will be still welcomed on our KLR Ramblers rides and tours, we are not holding you back. :-)
An aftermarket muffler is always louder than the stock one. This is a fact. Be mindful in your choice because VTNZ stations are not equipped with sound meters, and as it is stated on the NZTA website: “The WoF inspector uses their experience to assess the noise output of the vehicle”, which does not sound neither accurate nor fair.
My own measurements resulted a 3dB difference between the stock and the FMF Q4 pipe (with the spark arrester and quiet insert). Max 83dB and max 86dB respectively.
How much is 3dB change in a sound level? Very likely if your loved one will ask you to crank up the volume on the TV or lower the volume of the Hi-Fi, you will change it with 3dB by instinct.
As we know, there is no meat without bones, so let’s talk about the expected downside/complications.
WoF. Yes, you have a chance for an argument with the WoF inspector at a VTNZ testing station. Have your WoF done by your motorcycle mechanic for you.
During deceleration/engine breaking the bike maybe will “backfire”. It can be corrected with the adjustment of the air/fuel ratio at the carburetor.
Re-packing the muffler. It will be necessary once a year, at least. No going around with this one.