Rough idle with M4 slip-on exhaust

Hey guys and gals! Thanks for the warm welcome (esp appreciated after the crap Sydney weather these last few days).

Sorry if this has been asked before but I traipsed the forum and couldn't find an answer.

Specifically has anyone with a 250r fitted an M4 slip-on pipe and found it really rough on idle?

Going out on a limb, I'd say the new straight through, wider opening is the cause. Doesn't seem to be idling any lower (about 1200rpm) which is the same as the stock pipe.

But I can no longer roll forward by slipping the clutch. With the M4 pipe I have to give it about another 1000 revs before engaging or the damn thing will stall.

Also it doesn't seem to take off as cleanly and acceleration on first 4-5k revs don't seem as crisp. But it seems to be OK higher up.

I haven't pushed it past 8k revs as the bike is still new and hasn't done it's 1000 kays yet.

Checked for leaks and loose hose clamps along the exhaust and can find anything.

Does it need a retune/rejet?

Link to M4 pipe here (not trying to flog them, just for reference)

is it really idling rough? or is it just that you can acually hear it now??

they are a twin, so dont expect anything too smooth.

maybe up the idle a touch so it doesnt sounf to rough, i dont think you'd need a tune.

just a quick note here once you remove the stock pipe and replace with an after market unit you should have the bike at the mechanics and have all the setting adjusted and retuned to the new pipe .

i found this out on my busa but i think that stands for any bike you moderfy

most pipes (not full systems) are designed to be "plug and play"
Akropovic for example state that their pipes are designed to go on a bike with no changes at all.

the M4's are normally pretty loud, i think it just sounds rough because its a little twin.

any less restricion normally equates to less torque, and more hP.

lower revs they normally loose out. its probably amplified as your little beastie didnt have much torque to start with.

Even a 'plug'n'play' pipe will exacerbate any tuning issues. I put a Staintune on the Sprint (very happy, incidentally), and with the baffle out the bike would simply die at 2500 rpm - as in, almost stall. Get the bike tuned, and enjoy the result.

Thanks for the replies all.

I initially bought it for the exhaust note, plus I figured the louder pipe could only help the cagers notice me..and believe me, some of them need all the help they can get! But being a newbie going for my L's, the last thing I need is to keep stalling in front of the instructor so I'll probably stick with the OEM pipe until I can ride it back to the dealers and get them to check it out.

Incidentally, I found out later that the full system is only an extra $300 for the mid and front pipes so I might go for that.
Anyone had the full M4 system put in? Being a 2-banger I'm not expecting any real gains.

i dont think anyone has been interested in flushing 300 bucks down the toilet. tough times and all that jazz.

save your 300, thats almost a set of tyres when you wear the sides out on yours carving up Gixxers

A mate ran a full system on his little lady... Got a bit of extra kick out of her... The remember if you run a full system you will definatly need to tune/jet etc to make it opperate the way it should....

I agree... Save the coin... $300 will do nicely for an advanced rider course which could have a greater effect on performance than spending it on the exhaust.

My zook went from purring to sounding like a ported Rotary at idle after putting on an M4 (Replaced both pipes and the cat/muffler box)however there was no real change to idle rpm or power delivery, its just because its louder, straight through and hardly muffled now.

Did you say you are stalling it more with the pipe fitted?

hi Mero. Yes, theres no other mods. The bigger pipe sounds great but when I try to roll forward from a stand still it will stall if I don't give it more throttle than with the stock pipe. This is on level ground. With the original pipe I can just slowly release the clutch while easing the throttle and it will roll by itself.