Kawasaki Sportsbike Riders Club - Australia - Online Forum

I fitted a yoshi RS5 to my bike a while back.
i did notice a little flat spot at low revs but havent worried about it cause its not too bad
Was planning on sooner or later fitting a power commander but at the moment would rather use that money for better tyres or suspension upgrades.
as its not that big a deal.

before i fitted the pipe i had put a K&N filter. Im wondering now if i still had the standard filter in it would the flat spots go away?
Im thinking maybe its breathing a little too easy now and the standard mapping dont know what to do with all that air...

if i still had the standard one i would just whack it back in and try it out but I dont so i thought i would see here if anyone else as any experience with these issues. Dont really want to go buy a standard one if it isnt going to make a difference - but if it would make a difference i will give it a go.
any ideas?

Thanks.

I have been told that on these bikes cause they have no airflow sensor you can usually get away with an aftermarket pipe or a K&N but not both at the same time, they tend to lean out too much and run like shit with the lack of an airflow sensor you really need a PCIII so that you can tune it properly, thats the only reason why i have held off on getting a k&n.

ozten wrote:I have been told that on these bikes cause they have no airflow sensor you can usually get away with an aftermarket pipe or a K&N but not both at the same time, they tend to lean out too much and run like shit with the lack of an airflow sensor you really need a PCIII so that you can tune it properly, thats the only reason why i have held off on getting a k&n.

i have heard similar on most bikes ive considered doing this to (cbr929 and zed)....

i was told, its one or the other..or all 3 !!

my zx6 had a k&N and yoshi pipe and it ran fine

the zed with the K&n and pipes runs really badly, and is really lean.

my suggestion is you get a dyno run (no mapping) it will show you what your air fuel ratio's are,and work out what you want to do from there.

Its not something that you wanna risk cause you dont know how much your bike will be leaning out so you risk detonation your bike will be running hotter, so who knows whether youll start burning piston rings and shit...

ozten wrote:Its not something that you wanna risk cause you dont know how much your bike will be leaning out so you risk detonation your bike will be running hotter, so who knows whether youll start burning piston rings and shit...

yea..it could become an expensive stuff up...

thanks alot for the feedback.

im abit worried now about damaging it..

i think i will buy a standard filter and put it back in it for the short term till i can get a PCIII and mapping for it.

I've got a K&N and an Akra slip-on on the 10 and the fuel/air is fine. Like Tanya said, get it checked on the dyno if you are concerned, but often the K&N don't flow any better than stock filters, they just give you the advantage of being able to clean them.

just out of curiosity how do they check the air/fuel mix???

With a probe stuck in the exhaust while they do the dyno run

Mick C wrote:With a probe stuck in the exhaust while they do the dyno run

ohhhh probes!!....YAY!!

MrStompy wrote:thanks alot for the feedback.

im abit worried now about damaging it..

i think i will buy a standard filter and put it back in it for the short term till i can get a PCIII and mapping for it.

I will bet my house and all 4 kids that you *will not* damage your bike / melt pistons / burn rings / have any detonation etc etc from running a K&N and a Yoshi, without a PCIII......

Its just an air filter that can be cleaned, as MickC has pointed out, and in a lot of cases the standard air-filter can actually flow *more* than an aftermarket filter ! depends on the make/model......the only problem you are likely to experience is a flat-spot down low, which can be tuned out with the PCIII........

Spend the money on a dyno run.......without the PCIII - then you will have a baseline to work from when you fit the PC, and then get the mapping done properly.

Gosling1 wrote:

MrStompy wrote:thanks alot for the feedback.

im abit worried now about damaging it..

i think i will buy a standard filter and put it back in it for the short term till i can get a PCIII and mapping for it.

I will bet my house and all 4 kids that you *will not* damage your bike / melt pistons / burn rings / have any detonation etc etc from running a K&N and a Yoshi, without a PCIII......

Its just an air filter that can be cleaned, as MickC has pointed out, and in a lot of cases the standard air-filter can actually flow *more* than an aftermarket filter ! depends on the make/model......the only problem you are likely to experience is a flat-spot down low, which can be tuned out with the PCIII........

Spend the money on a dyno run.......without the PCIII - then you will have a baseline to work from when you fit the PC, and then get the mapping done properly.

Im glad you cleared that up i was convinced he was going to destroy his engine melt rings and then be up for the cost of a new engine...

I was merely pointing out a worst case scenario for an engine that is leaned out too much.
Odds are that with an aftermarket can and k&n air filter your bike will be running lean and to wat extent you wouldnt have a clue so why continue to ride with it without getting a dyno run to be sure.

Without the power commander, top dyno run, air fuel ration starts at 17 to 1 and goes all over the place

it's been remapped again since the bottom one, air fuel ratio is a steady 12.5 across the rev range now.

Places here do power runs for about $30, which is all you need to see the air fuel mixture.

ozten wrote:......Im glad you cleared that up i was convinced he was going to destroy his engine melt rings and then be up for the cost of a new engine... .....

So was I - based on your observation that ....

.....you risk detonation your bike will be running hotter, so who knows whether youll start burning piston rings and shit...

The facts are that these 2 simple mods *will not* cause detonation, or hotter running, to the extent that the engine will start burning piston rings and 'shit'....they will create some minor tuning issues and a slight loss of power down low, but thats it. Modern bikes are 'jetted' Way rich from the factory, for all sorts of reasons.....poor fuel, easier riding, owners putting on aftermarket pipes / air filters etc......

...I was merely pointing out a worst case scenario for an engine that is leaned out too much.
Odds are that with an aftermarket can and k&n air filter your bike will be running lean and to wat extent you wouldnt have a clue so why continue to ride with it without getting a dyno run to be sure.

He'll have to ride it to the dyno to get it dyno'ed !!! Putting an aftermarket muffler on, and 'another' air filter will never cause the type of damage you have indicated - ever. Modern bike engines are way tougher than that. Perhaps if you advanced the ignition timing to 55deg, you might get some detonation and a noticeable reduction in horsepower.

I just thought you were being way too pessimistic about this - a lot of people out there will take everything they read as *gospel*, when it just ain't so.

When my ZX12R was dynoe'd last year, the owner asked me what mods I had done - I told him just a Yoshi RS3 can, and a set of DNA filters, with no PCIII. He said that these mods were great, and should bring the a/f ratio down to just about *perfect*, from the stock factory *rich* setting. He was dead right, the a/f ratio did not need touching at all.