My MIVV exhaust plan - fail need help, advise.

[Saint aka ML]

So got the MIVV slip-on I love, the double gun.
Went to a mechanic today and it was in a line of:

"Yep we can fit it however your exhaust valves (or just valves do not recall) will eat them self ASAP."
Also if you do manage to make it work police will kill you on the spot, club first ask questions later due to noise.

Now I do know nothing about pipes except lighter/louder is better

The Mivv pipe is just a single pipe split in to two on exit. So in short it is like removing your slipons and running the bike like that.
Apparently if you do that there will be not enough pressure in exhaust and engine will start to eat itself.
My question is is that correct?
I mean my current pipes are big but at the end they are also straight through, TBH even more so then MIVV. MIVV has a bend in the pipe while current D&D are just straight and you can see through it. On top of that I was in believe that on a Monster it is the triangle shaped thing at the bottom of engine that regukated gasses pressure?

Help me out here, do want MIVV fitted but do not want engine to go boom?
Is what he said correct, they are mainly Jap specialists so might not know about L2.
If they are correct is there a way of increasing pressure in exhaust by fitting narrowings in link pipes to compensate, if so how do you calculate narrowing needed?

This is the pipe I want, only one the shorter one so other side if exhasut would be welded shut:

http://i261.photobucket.com/albums/ii70/Ruscik/Pipes%20and%20other/IMAG0005.jpg?t=1296686249

[Mr Gremlin]

all that will happen is that your fuelling will be very lean. this will be what eats your valves. once the fueling is set up they wont damage anything. your bike might be gutless though, exhausts are a science in their own right :( if they dont suit the tuning of the engine, they wont work. theres no point putting exhausts designed to make power at say 10k rpm when your engine wants to make it at 8k.

[Nickj]

Probably sound awesome.

My dogs can hear my cored standard pipes a mile plus away.... that's from the other side of a hill with forest on it

[Nickj]

What happens at the valves depends an a few things but with fairly open pipes like that it will run leaner across the range. The reason being you have less back pressure to stop all of the burnt gases escaping. There will be a little bit of resonant standing waves going on but that'll only be at a certain rev band and isn't really that significant on a 4T at the kind of revs mosters pull.
For a really clean set up you'll eother have to go old school and do umpteen plug chop runs, you need a small sack of jets, slides and needles to this properly, a mile or so stretch of road and an enormous ammount of patience.
Else get along to a specialist to reset it by a seat of the pants wild ass guess system OR some fuelling runs on a dyno.

[Saint aka ML]

What happens at the valves depends an a few things but with fairly open pipes like that it will run leaner across the range. The reason being you have less back pressure to stop all of the burnt gases escaping. There will be a little bit of resonant standing waves going on but that'll only be at a certain rev band and isn't really that significant on a 4T at the kind of revs mosters pull.
For a really clean set up you'll eother have to go old school and do umpteen plug chop runs, you need a small sack of jets, slides and needles to this properly, a mile or so stretch of road and an enormous ammount of patience.
Else get along to a specialist to reset it by a seat of the pants wild ass guess system OR some fuelling runs on a dyno.

For start it will do fitment and gas analyzer. I might even ask to put a narrowing (cone) in to the pipe to get a bit more pressure.

[Dookbob]

You really do need to understand the exhaust back pressure thingy in order to give yourself a start point for exhaust mods. The original system is designed to give you good torque in a rev band that is usable on the road. The back pressure is tuned to the valve overlap, so that the gas is coming into the cylinder before the exhaust valve has closed,( valve overlap), in order to get absolute cylinder scavenging the incoming gas overfills the cylinder to the point where gas passes momentarily into the exhaust pipe at top dead centre, it is the back pressure in the exhaust system that pushes this unburnt gas back into the cylinder just as the exhaust valve closes. So if you reduce the back pressure you loose this effect to some extent, which requires a richer mixture to compensate, which pushes the torque further up the rev range. You need to decide if this is going to suit the way you want to use your bike. (If I didn,t get all this correct to the letter, please someone point out the discrepances)

[Funkatronic]

i reckon you should take some photos of the mivvs and maybe make some drawings of how you want them to look and then sell the mivvs on ebay (or send them back if you can get away with it)

then call an exhaust specialist, there might be someone closer to london but this guy come highy reccomended

wayne @
J A C Stainless Steel Exhaust Specialists (http://www.jacexhausts.co.uk/). Unit 7, 1 Wigwam Lane, Nottingham, Nottinghamshire, NG15 7SZ
01159635556

he should be be able to make some exhausts that look how you want and are the correct size for your bike
dont know if he does titanium tho

[gary tompkins]

i reckon you should take some photos of the mivvs and maybe make some drawings of how you want them to look and then sell the mivvs on ebay (or send them back if you can get away with it)

then call an exhaust specialist, there might be someone closer to london but this guy come highy reccomended

wayne @
J A C Stainless Steel Exhaust Specialists (http://www.jacexhausts.co.uk/). Unit 7, 1 Wigwam Lane, Nottingham, Nottinghamshire, NG15 7SZ
01159635556

he should be be able to make some exhausts that look how you want and are the correct size for your bike
dont know if he does titanium tho

FWIW that would be my advice as well

[Saint aka ML]

Well I am fitting it, if it is **** as hell I can always go back, that is why I will not sell my current exhaust for a week or two.

[Albie]

Take a risk and try to see 1) what it looks like and 2) whether you can set it up when on.

No sweat no gain. But you know its your decision and may it be a good one. Look forward to some pics.:thumbsup:

[Mr Gremlin]

You really do need to understand the exhaust back pressure thingy in order to give yourself a start point for exhaust mods. The original system is designed to give you good torque in a rev band that is usable on the road. The back pressure is tuned to the valve overlap, so that the gas is coming into the cylinder before the exhaust valve has closed,( valve overlap), in order to get absolute cylinder scavenging the incoming gas overfills the cylinder to the point where gas passes momentarily into the exhaust pipe at top dead centre, it is the back pressure in the exhaust system that pushes this unburnt gas back into the cylinder just as the exhaust valve closes. So if you reduce the back pressure you loose this effect to some extent, which requires a richer mixture to compensate, which pushes the torque further up the rev range. You need to decide if this is going to suit the way you want to use your bike. (If I didn,t get all this correct to the letter, please someone point out the discrepances)

its a fair description of what goes on, but the term "back pressure" is misguiding. its a phrase that has been used since the dawn of time but is technically wrong (except with 2 strokes). there is a shock wave that bounces back up the exhaust which does what you discribe but the build up of any pressure within the exhaust system will be detrimental. this shock wave should reach the exhaust valve ideally the moment it closes so burnt gases dont return into the combustion chamber. as this shock wave travels at a set speed and bounces back when it meets a change in flow within the system (ie baffle, atmosphere), the return rate is dictated by the exhaust length (tuned length) this is why all exhausts work best at a specific rpm. Yamaha came up with an idea that if you put a valve in the exhaust and open and close it in sync with rpm you can effectivly change this tuned length so spread the power over a wider rev range. they called it EXUP. A well designed tapered exhaust system will work just as well. a common mis conception is that a big diameter exhaust must be better, but in reality a small header pipe exiting the barrel which tapers larger down to the collector at a specific angle will work far better as the gas velocity exiting the combustion chamber will be constantly high causing better scavenging and swirl and a better spread of power. the problem for manufacturers to make tapered systems is cost, they are very time consuming and so would generally make them too expensive for joe public , to put it into context, ive been designing and building a system for a customer in germany for his H2 (i know its a 2 stroke but the ideas the same ). weve tried every commercially available pipe for it from allspeeds to jolly motos. so we re-did the maths and realised they were all wrong. i have only made 1 prototype pipe for it so far but it gave an additional 10 bhp just on one cylinder with jollys on the other 2 , this one pipe has taken nealy 40 hrs work just to make to prove a point, and i didnt even bother making it to fit the bike as on the dyno, exhausts can hang out in any direction :) so now i am going to have to make 3 complete pipes that fit (Booooooo!!!) 120 hours of work.. ok there are 40 odd cones per pipe but you get the picture :) but we should have a good 110 bhp when they're done :)

[Nickj]

When Stan Stephens still did race tuning I had a 350 LC with a stage 3 which was a bit on the savage side.
The pipes made a huge difference. I looked at pipe design then for 2T's and it is hugely complex. You only need to look back at the technical lead MZ had after Walter Kaden used his rocket experience to produce some serious power that crucified the jap 2Ts. From what I read it's half hard science, half mysticism and half luck getting the design right

[Saint aka ML]

Well case is solved I am going to give it a go, minimum I get from it is single side pipe and pipe closer to centre.

Second option is I can always attach small carbon pipes at the end of MIVV.

[utopia]

...... shock wave travels at a set speed and bounces back when it meets a change in flow within the system (ie baffle, atmosphere), the return rate is dictated by the exhaust length (tuned length) this is why all exhausts work best at a specific rpm...

My current understanding is that, in practical terms....the longer the pipe, the lower the engine speed that it suits best. This would seem to have some backup from the accoustics of flutes and other pipes, where a longer pipe gives a lower note.....??
I did some calculations for the Ducati, using a method gleaned from a Piper Performance booklet that I picked up at a bike show in the dim and distant. For my chosen rev range it turned out that I needed a primary pipe 3 metres long !!!
I was wondering whether this would account for the way my 750 seems to run much better at low revs since I fitted high-level Termis, ie, due to the added length from the link-pipes. ......?

Also, if my H2 road bike special fantasy should ever materialise, might you knock me up a set of pipes, or let me know your wizard dimensions ? ...for an appropriate consideration, naturally.

[Dookbob]

Thanks for that Mr. Gremlin. for that interesting and easy to understand explanation, I dont need to spend the rest of my life re-educating myself in shockwave technology now. I am currently tidying up another M600 carb bike (2001) so i am going to do my usual dump the air box, fit pod filters, half race cans and stage two dynojet. Unless someone would care to suggest a better option. I,m always prepared to make use of the mine of information that this forum contains.

[crust]

So got the MIVV slip-on I love, the double gun.
Went to a mechanic today and it was in a line of:

on top of that I was in believe that on a Monster it is the triangle shaped thing at the bottom of engine that regukated gasses pressure?

This is the pipe I want, only one the shorter one so other side if exhasut would be welded shut:

http://i261.photobucket.com/albums/ii70/Ruscik/Pipes%20and%20other/IMAG0005.jpg?t=1296686249

No, that bit very efficiently splits the flow from each into two and diverts the two airstreams into the silencers.

Weld what up?

What front pipes do you have on it?

[Saint aka ML]

Crust, weld the left pipe exit shut. That apparently is a common mod for monsters as only one pipe is needed anyhow.

[crust]

Crust, weld the left pipe exit shut. That apparently is a common mod for monsters as only one pipe is needed anyhow.

Common where?

Welding up one side of a cross junction designed to split flow into two will cause a large Blockage resistance in the header pipe, why would anyone want to do that?

Who says only one pipe is needed?

The factory would disagree as they have fitted two pipes to all their twin race bikes but then they can afford to replace race cans.

If you're fitting a header (front pipe) system designed around a single pipe, fine, a good designer will be able to come up with a system that allows a single pipe.

[Saint aka ML]

Look at most DD bikes or L2 track day bikes. Second pipe is nothing but extra weight to them. Ghost's bike is a 600 DD that has one side blanked off and other side is running a single 1098 Pipe, less weight more power so it does work. Couple of dealers told me that I could easilly make with only one pipe so I can save extra weight. On a monster it does seem like a design feature.

[Gilps]

Look at most DD bikes or L2 track day bikes. Second pipe is nothing but extra weight to them. Ghost's bike is a 600 DD that has one side blanked off and other side is running a single 1098 Pipe, less weight more power so it does work. Couple of dealers told me that I could easilly make with only one pipe so I can save extra weight. On a monster it does seem like a design feature.

I may be wrong but I believe a couple of DD'ers have also realised that this mod (welding one side shut) causes problems. In my experience of playing around with the crucifix, leave it alone. I lost 1k from the top of the rev range and lost bhp too when we opened it up internally. It has been designed to do a job by professionals who understand exhaust gas flow.

[crust]

You're seriously using DD as an argument for welding the X junction on your 900 as a performance boost?

Seriously?

DD bikes are 600s with limiting rules for tuning, running small port heads and standard carbs that use the same X junction as a 900, so the restriction will be a hell of a lot less, so for them it may work.

Your bike flows 50% more exhaust gas, the factory designed the system to work as efficiently as possible, hence two cans. The same as the 888 race bikes that raced in World Superbike, the same as the old Bevel race bike, the same as present day World Superbikes.

Miguel Galuzzi designed the Monster as a stripped to the bones bike, no extras, no frills, so why would he stick an extra exhaust can on for fun?

[Saint aka ML]

Crap, when I make the call to go ahead and do the pipe there is always this one or two people who add something more to a now argument.

Hmmm

In regards of Galuzzi design, bear in mind he is a designer and they fit lots of things for looks over anytihng else.

If you look at S2R1000 and even S4R pipes they have two cans on one side but cans are significantly smaller then old style monster one's. On S2R pipe diameter is the same but baffle is smaller.

I do not know...... crap.

[gary tompkins]

Crap, when I make the call to go ahead and do the pipe there is always this one or two people who add something more to a now argument.

Hmmm

In regards of Galuzzi design, bear in mind he is a designer and they fit lots of things for looks over anytihng else.

If you look at S2R1000 and even S4R pipes they have two cans on one side but cans are significantly smaller then old style monster one's. On S2R pipe diameter is the same but baffle is smaller.I do not know...... crap.

That's because the S2R's have a CAT fitted as standard. THe CAT contributes significantly to the silencing effect, and means they can use a smaller silencer. This is vey noticable when fitting race spec Termi's (or similar) when leaving CAT in place. The noise is nowhere near as loud as when CAT bypass pipes are fitted as well. Earlier monsters didn't have CAT's and needed more silencing (bigger cans) to satisfy noise regs.

[Saint aka ML]

That's because the S2R's have a CAT fitted as standard. THe CAT contributes significantly to the silencing effect, and means they can use a smaller silencer. This is vey noticable when fitting race spec Termi's (or similar) when leaving CAT in place. The noise is nowhere near as loud as when CAT bypass pipes are fitted as well. Earlier monsters didn't have CAT's and needed more silencing (bigger cans) to satisfy noise regs.

I know that but if you do fit said termis and get rid of cat you endup with more noise but also less pressure as it is more free flowing, on top they do use one in to two pipes.

As said by some nothing ventured, nothing gained. I can always go back.

[Dukedesmo]

Surely blocking one of the outlets would increase back pressure anyway?

But if I was doing a single exhaust, I'd be looking at getting rid of the 'crucifix' and getting/making a proper 2 into 1, in fact even with twin pipes it is on my wishlist to get a 'spaghetti' style 2-1-2 setup as the standard setup must be restrictive.

[rac3r]

Why not try the place that did Littlejimmy's exhaust for him?