Help please,map2 and open exhausts

The map that I put on was for open exhausts,aftermarket air filter,ecu switched to map2..and yeah I'm goin to get some dyno time booked very soon just to finish off the tweaking.
But yeah must keep up the mods to stay with my dads super duke lol.

Exhausts are not simple tubes, they are designed to expel air in certain way across variety of engine speeds. So shockwaves come out as air pluses from expanding gas, get this wrong and you can get your pulses actually restricting air flow. Get it wrong the other way, and they will actually suck air of of the egine as the valves open"¦
It's not as simple as removing baffles/air flow restrictions. Other wise your bike would be fastest with no exhaust pipe or headers what so ever (baring the noise of course) and Moto GP bikes would have open headers. You need certain back pressure, shock wave pattern for swirl/burn pattern in cyclinder. Even dragsters have stubby pipes
Tuning two strokes, you'll know you need to re-jet whan changing cans. Listen to morris minor and the exhaust notes sound "messy" but on modern cars, they are clean (make sense"¦.hmmm"¦)
anyway
So Mivv/Akaroprovic cans are £800 a pop, after only using £50 of materials, so they can research this. This is why the "same" can won't work on a 1000cc GSXR, but will work on a 600cc GSXR, they look the same but inside the diameter will differ, as the engines have different exhaust signatures
Sysems like EXUP/YPVS all take this into account, they tried to giveback pressure/ good air flow(not the same as fast air flow!!!) at low revs, opening up to give better/faster flow at high revs
When you cored your cans, you messed with exhaust length and inside diameter, and a hot exaust will behave diffently to cold exhaust. So you may have done nothing wrong, other than use a certain can to do something it's not designed to do.

Hope the above (2nd attempt) makes sense.

El Liamo said:

When you cored your cans, you messed with exhaust length and inside diameter, and a hot exaust will behave diffently to cold exhaust. So you may have done nothing wrong, other than use a certain can to do something it’s not designed to do.

Click to expand...

I think you may have hit the nail on the head there chap.Most aftermarket race cans have a 50mm internal diameter baffle,...the cored cans I have are 63mm i.d.The bike definitely runs rougher and is a lot louder with 'em on.I went back to the Arrows.
I might open up the cored cans over the winter and experiment with a 50mm baffle tube.

well done El Liamo i actually understood what you were on about for a change

Excellent explanation El Liamo.:thumbup

Makes a lot of sense that,I will stick with what I've got at the min,until I get fed up of the noise lol.

Excellent explanation mucker, all engines need a given amount of back pressure, my mivv suono's have a carbon cap at the link pipe end, it has 4no slash cuts in it to allow any excess back pressure to vent from and to allow additional air flow at speed to help evacuate the exhaust gases.

Very clever and as yer said that's why they cost a bit more than yer wrap round a perforated tube ones.

Have a look at this and watch the link pipe end of the can, this might explain better than me.

http://youtu.be/f8LP1j4GpnY

bike **** :thumbup

I might make that my ring tone....

ah think yiv mibbe nailed it there Gav min....even if def was on map 2 different cans will re-act differently. The difference between the Akras ah originally had on mine and the MIVV GPs on it noo is quite distinct. Seems tae run smoother through out the range on the MIVVs. On the Akras there was a fair bit o backfire and poppin particularly on the over run, which totally disappeared wi the MIVVs.