Well I replaced the Muzzy with the originals,incidently no apparent loss of power ;definite improvement in fuel consumption; but;since the great difference on the exhaust noise I have noticed severe klunk in engaging 1st and through the gears at lower revs either up or down,More drag on the starter motor than the Concours had when starting with clutch in when in 1st.I am aware there is a multiplate oil clutch, but it seems more drag than expected.is it a sign of heavier oil, damaged plates,incorrect adjustment of the lever , or? I am not sure but there could be a slight improvement when warmed up.As a matter of interest earlier fuel consumption was 6.4 litres per 100 kms,since exhaust change has registered 5.8 and 6.05 . I will continue to monitor usage.The higher rate was after a ride that included a few 120/140 kph runs.

* Last updated by: donfre on 2/6/2017 @ 7:32 PM *

I believe I have heard of this happening after installing an aftermarket exhaust but I dismissed it because I do not see how the exhaust and gear box could be related.

I have noticed severe klunk in engaging 1st and through the gears at lower revs either up or down,More drag on the starter motor than the Concours had when starting with clutch in when in 1st.I am aware there is a multiplate oil clutch, but it seems more drag than expected.is it a sign of heavier oil, damaged plates,incorrect adjustment of the lever , or? I am not sure but there could be a slight improvement when warmed up.

The klunk into 1st is normal as you must know but if it's severe, something is up. Have a look at your idle speed. the clunk is worse if it's high. Yes, cold oil or thicker oil would make the clunk worse. There's nothing wrong with your clutch plates if this happened all the sudden. If anything, I would think worn clutch plates would soften the clunk not make it worse.

Are you sure it's not just time to change oil? Old oil is klunkier than fresh.

Clunk possibilities:
1. Old oil thickens up = clunks while dragging the plates with it.
2. Cold out and this thickens the oil when first starting a cold engine.
3. Ever so slight clutch plates warp, where it drags the clutch pack and won't stop when clutch lever is pulled in.

Clunk eliminations:
a. Start the bike in 1st gear.
b. Hold clutch lever in longer so the pack stops spinning before stepping into 1st.
c. Run thinner oil.

Pipe vs. fuel economy:
I. The faster the event, the more gas used, meaning, no air cleaner, no bumps in the ports so you polish them for less friction, which relates to a speedier event happening. Like pushing a bubble straight out of a tube, as opposed to sending it into one tube, then to a chamber where the next tube is being used as an out, but takes longer for the (bubble) event to happen.
II. The faster out the pipe changes up the back-pressure and moves the unspent out of the chamber and into the port.
III. The stock pipe slows the event so the unspent is not pulled from the port as much, meaning, seat of the pants performance is still there, but for every stroke times 4, there is you slight change in fuel economy... is how I explain the fuel differential.

yes, I knew I heard someone else claim aftermarket exhaust made the bike shift rougher. Never would have thought better flow would impact the gear box but I guess it could. Not sure why fuel mileage would improve unless you changed maps.

Juat had a 200 km ride and noticed the klunk is less obvious,that leads one to favour hot ,therefore thinner oil could be the reason.A service is due in 1000 kms time so will check on the viscosity of the oil going in. The bike has done nearly 60k kms and is new to me so the viscosity and quality of the last oil change is unknown.A previous bike a Concours ,completely standard,was almost always 6 litres per 100 kms.

Hi donfre,

As Rook mentioned, 1st gear "clunk" is entirely normal, make sure your idle speed (RPM) is set correctly, should be 1,000RPM +/- 100RPM. The only time I've ever noticed any kind of a clunk into gears other than 1st is typically the 1st to 2nd change as the gear ratio difference is the greatest and is typically when I don't time the gear shift sequence properly. Usually I roll off the throttle too soon when it happens, ideally the input shaft rotation should be rotating at the same rate as the next primary gear rotation. If you know anyone else with a ZX14 would be worth your while to trade bikes to see if the sound/feeling is normal as it might be as simple as the sound is more noticeable with a quieter exhaust and its entirely normal.

Regarding fuel economy, I actually noticed the opposite of what you saw, went from 6.8L/100km down to as low as 5L/100km with my modifications. But as Hub pointed out, the stock exhaust provides more back pressure, with an engine tuned for performance the valves will be open for longer and wider to provide more top end power but at the expense of low end power and efficiency. Back pressure from the exhaust can actually help improve the low end (think <4,000RPM) performance by stopping/slowing the air/fuel from the intake stroke from being sucked out the exhaust valve due to valve overlap, where both the intake and exhaust valves are open at the same time. If the ECU wasn't flashed or a piggy back fuel unit added (ie power commander) good chance your fuel economy was mostly due to a poor air to fuel ratio.

As you pointed out, the other major contributor to fuel economy is the speed, road conditions and aggressiveness in which you ride. That being said, as much as I enjoy getting better fuel economy than my car, I did buy a high-power sports bike for fun more than economy... the better fuel economy helps me justify the cost of tires, insurance, oil, etc.

If the ECU wasn't flashed or a piggy back fuel unit added (ie power commander) good chance your fuel economy was mostly due to a poor air to fuel ratio.

Seems to me if the stock fueling was not changed, the same amount of fuel is spraying no matter what exhaust you put on. Yes, the AFR might run a bit leaner with an aftermarket exhaust but that's because the amount of air taken in has increased, not because anything about the amount of fuel changed.

Just completed a 225 km ride with a group(less spirited riding) with two observations,the klunk is mostly obvious in first four gears both up or down.It is less changing down if I maintain the revs to perfectly match lower gear. I know that is to be expected,but I have never had to be so careful on other bikes.I believe there is an existing fault somewhere,wear perhaps because the lower gears with the quieter exhaust seem to be noisier, that decreases when revs exceed 4000.The quieter ride today gave me a fuel consumption of 5.65 litres per km.

1. Loose chain.
2. Oil plays out around 4300km and the shift quality deteriorates.
3. It's all about hand-timing; if the oil is fresh and the chain is up to spec.

I've swapped out some pipes in my day and the shift to back-pressure is some wives tale someone tries to pawn that off on you. I've never shifted a more plush transmission; call the gen. I have a habit of using the clutch at dead stops and then for second gear only. I also hold whatever gear I'm in until I coast to a stop and then shift down to 1st so as not to cause a clunk or mismatch some lame downshift if not in a more spirited mode, then sure.

I believe there is an existing fault somewhere

I dont mean a fundamental fault Hub,I wonder whether the PO may have abused the lower gears,they seem noisier than expected.I have had 10 125/150 HP bikes in the last 10 years with the current Ninja 1000 that has gears like a hot knife thro butter.I have a feeling not all is right.Chain / sprockets nearly new and adjusted correctly.

Got it... Possible previous owner abuse. Then again, the search for a fault may be to drop the sump cover, inspect for gear debris, i.e., slivers that are magnetic. The next inspect is to look up at the gears and forks for 'bluing.' Here again, we have severe damage, we'd be missing gears and/or popping out of gear under loads.

Do we have any gears coming out of robust throttle applications? No? Then it would more be like finding another 14 owner and let h/er assess the ride that may or may not notice anything different. We are talking about big clunky gears in a big bore bike to handle the power made.

Thanks Hub,a comparison is probably the way to go. Unfortunately the zx is a rare beast locally.