* Power Delivery System, fuel, exhaust, air & timing *

I want a new exhaust is very often the first thing that a perspective modifier thinks! Well lets look at a few of the pro's, cons and things to be considered when you start that journey. Why do I call it a journey, well thats because there are so many things to consider when you first make that decision & because one mod very often leads to another!

If you do decide to make changes

......Do you really need a new exhaust or just want louder pipes?
......What modifications are commonly done to the stock exhausts?
......Will modified stock exhausts have any other affects that need to be considered?
......Will a new set of aftermarket exhaust have any other affects that need to be considered?
......If you do buy a set of exhausts are you going to stop there or is this the first in a series of fuel, air & timing modifications?
......What modifications are done to the fuel, air & timing?

These are just some of the questions that need to be asked or considered before you start to modify your new baby. I will try to answer these questions for you as best I can but I would like to point out that I am not a mechanic or engineer and the following info is just my opinion based on modifications that I have either done myself or learnt from others.

One main thing that needs to be taken in to consideration when any modification or change is made to the air intake or exhaust is fuel. These bikes run lean from the moment they leave the factory due to EU rulings on emissions, so any increase in air flow either in or out will make the bike leaner.

A single change or modification to either the exhaust or air-filter

Most people are in agreement that if changes are not made to both the exhaust and air-filter but to only one of them, that no adjustment is required to either the jetting (2005 onwards) or fuel injection (post 2005). The question we have to ask ourselves is, are they right or not? If we think that they are wrong then we should either leave the initial modification alone unless accompanied by changes to fuelling. If we believe them, and they are many, then we can go for it in the knowledge that they proclaim to many tens of thousands of miles without any detrimental affect.



Stock Exhaust Here are just a couple of ways that these are modded.

Modifying the stock exhaust is very often the first modification that people do and can be done by anyone that has the most basic of tool kits. There are numerous modifications that can be done including completely gutting them but we will cover just a couple here.
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The first one is to drill between 8 & 12 holes in both backplates of between 10 & 12mm. This is the most common mod as it is extremely easy to do and will give a little bit of extra rumble and decibels to the exhaust.

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The next exhaust mod is to almost the same as above except in this case only 4 holes are drilled but also to punch a hole through the two plates that are further up the exhaust. This is done by placing a 3/4" pole down through the center of the baffle port and hitting it until you have gone through it. The 1st of these plates it 9" down and the 2nd is at 13". This will give a deeper tone and increase the decibels further. Some modifiers will keep going at this point and punch all the way through the catalytic converter, further increasing the tone (possibly) & decibels.



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The next exhaust mod is to de-baffle the pipes. The easiest way to do this is with a drill attached metal hole saw. The guy in the video below cuts around the center of the baffle and then around the outer edge of the backplate. It is easier and will save time to have both attachments fitted at once and in so only one attempt at cutting is required per exhaust.




After-Market Exhaust What do I need to consider.

Style and finish

Firstly would be the style of exhaust that you like & there are many different styles. Short exhausts, long exhausts. thin exhaust, fat exhausts, Curved exhausts and variety of every combination of those combined. Very loud exhausts, quiet exhausts, exhausts that can be easily de-baffled, exhaust that can be easily quietened down. Exhaust with a highly polished finish, exhausts that are brush finished, exhausts that are black and every combination of those combined. Am I going to bobber the bike at some stage and will the exhausts that I have picked lend themselves to that type of styling as well as the current styling.
Does it have a fitment for a lambda (o2) sensor


Lambda (o2) sensor (2005 to current)

Do I need to buy an exhaust with the lambda sensor? Well the answer to that is no! I shall explain.
The lambda sensor is bolted on to the exhaust and reads the environment within it, to ensure that under all conditions and in real time the air fuel mixture is held in the predetermined lean state for the first 15-20% of throttle position / power delivery. This is great for the environment but has a detrimental effect on power!
If you do decide you want to keep the lambda sensor and buy an exhaust that has no boss for you to screw them in to, then all that is required is to have a boss welded on. This is a very cheap add on and should not put you off buying an exhaust that you have decided is the dogs googlies or you have secured at a really good price.
The lambda sensor is easily disabled by either buying a couple of "lambda sensor eliminators" or by cutting the wire in port #23 of the ECU. If you do not either cut the wire at port #23 to bypass the sensor or add the eliminators the fuel injection error light will come on. I personally just cut the wire as all the eliminators do is loop the 2 wires around to each other to create a circuit.
One consideration is that if you later decide to add a fuel processor, you will gain nothing in the first 15-20% of the power delivery if the lambda sensor is in place.


Hi-Flo air filters

The initial concerns with this one are detailed above under the heading " A single change or modification to either the exhaust or air-filter Although there are numerous modifications that owners make to air filtration, there are three that stand out as the most popular. The first two are K&N filters & Hyper Chargers. The third one is the Nekkid jugs mod which usually involves the removal of both the air filter and pair valve and in doing so puts those lovely chromed v-twin heads on full display (we will cover the pair valve in the next section)

K&N Filters are the one that most bikers will know of and is a tried and tested method. Sadly at present the newer shaped air filter (2009 - present) is still not catered for, however if you are set on a K&N then there are a couple of ways around this issue. The first way is to revert back to a pre 2009 air box, which is still a direct fit & then fit the K&N. The other option is a bit more drastic and is the route that I took when I first bought my bike not knowing that there was any differences between any of the air filters. For this I modified the 2010 air filter to take a pre 2009 K&N filter. I won't go in to all the details here but will give a link to the modification LINK

Hyper Chargers are also a favourite but rather an expensive option. In reality is the extra cost of a hyper charger worth any possible gain they may offer when scaled against the cost of the cheapest hi-flo filters? The answer to that has without a doubt got to be a resounding no! However if you are after a descent hi-flo filter that has more than a descent measure of bling factor and really impresses Joe Public, then your on to a real winner with one of these.

Nekkid Jugs really do show off the heads in all their glory and is a very popular modification. It involves removal or the pair valve, air box (see picture) & relocation of the air filter using a uni-filter under the tank (See Picture)


Pair Valve What is it & do I need it

First of all before we start, the question we must ask is do we need a pair valve? Well the answer to that in the UK at least is NO! Complete removal of of the entire pair valve system is very common, you will find this LINK to Moccasin Mike very useful. The pair valve is there for emissions only and injects air so that any un-burned fuel can be ignited in the exhaust. I have read a lot over the years about disabling the pair valve on bikes & this seems to be an extremely common practice on our bikes. Some do the complete removal of the pair valve & others modify it by blocking the tube with a golf tee. Now I can kind of understand it for the guys that are doing the Nekkid Jugs mod because the pair valve housing although not as big as the air box is still slightly blocking the view of the jugs and although chromed is not all that aesthetically pleasing. I was considering doing this mod simply because I was thinking like a lemming in sheep clothing but whilst out riding today suddenly thought no! I actually like the burble that the exhaust gives because the pair valve is in operation. When the bike was totally stock there was no burble in the exhaust on deceleration that I noticed at the time but as I went through each air flow mod I noticed it slightly more & more. From drilling the exhaust ends to de-baffling to K&N's to the V&H Cruzer install. I think some people get confused with the difference between a deceleration burble and a full on backfire, mine has never done what I would describe as a proper backfire, even after all the mod's that I have done. I like the burble that we get with the pair valve in operation & mine is staying where Mr Suzuki put it.


Fuel Injection Processors & Jetting

I will keep this short and simple, 2005-onwards have fuel injection & pre-2005 bikes have have a Carb.
As already discussed if you make changes to either just the air filter or just the exhaust you will get away with not adding a fuel processor to fuel injected models or up jetting the carbed models. This is a very controversial area though and on these already fuel lean bikes. If however you decide to make modification to both the exhaust and add a hi-flo air filter you must either re-jet the carb or on 2005-present models add a fuel injection processor.
Carb up-jetting for the very first time is an extremely daunting process but in reality you will be shocked at how simple it really is. When I have up-jetted carbs I always take my time whilst doing it and work over a nice clean white sheet so that I can lay everything out in its own space in a methodical manner. However if you are not the type of person that researches properly how do do things then leave it alone and get a competent person to do it.
Fuel Injection Processors are in comparison to a carb a dream, these can be fitted in an extremely short time. There are more processors out there than you can throw a stick at and they will all claim to be the dogs danglies. Most of them are plug and play to a large degree and require very little input from the fitter. Most of them nowadays (not all) will connect to your laptop when fitted and you will send pre-determined maps to it for your type of setup. To give you an idea of how mine fitted have a look at the video below, at the time of fitting I only fitted the TRE and Air Filter but had no fitted the Cruzers.
It's not the best video but it will give you an idea of what could be involved.



Timing Retard Eliminator (TRE) For fuel Injected bikes

The timing on our fuel injected bikes is programmed in a retarded state, again this all about emissions and as such effects the available power and its delivery. What the TRE does is correct the timing to its optimum state, therefore improving throttle response and acceleration. The TRE uses a resistor circuit to create a voltage drop equal to that of 4th gear which fools the ECU to think its in 4th gear all of the time, regardless of what gear you are actually in. The reason it does this is because the timing is retarded in gears 1-3 with gear 4 left alone and gear 5 has a limiter on it. The TRE also automatically uses the stock map while the bike is in neutral (typically warming up), and then it switches to the timing retard eliminator mode after you put the bike into gear. As the TRE has now partially bypassed the ECU this removes the top speed limiter, smooths out throttle response & increases torque. The TRE is advised on our bikes at all points of modification from stock bike to the heavily modified beasty.

Excellent read Mr I very useful to have all that info in one place

Useful for all but especially for the newbies as you have answered in one place a lot of the questions that are first asked

That answers all.

Excellant read Dave very imformative.

Thanks for the info brill this ironed out alot of questions

a much appreciated and informative read

How did I miss this post orginally! Wish I had seen this before getting new exhausts. Great info dave, thanks for taking the time out to help

It's these comments that make it worth taking the time out to write threads like this & if it helps even 1 person then alls good.

I too must have missed the original post. So somewhat belatedly I think the order of honourary degree in motorcycle science should be bestowed on Dave who perhaps could now be known as Dr.Intruder! A truly excellent write up and a valuable site port-of-call for any member interested in not only modifying the 800's power delivery but, perhaps more importantly, understanding the fundamentals involved.

Here Here well put John.

I enjoyed reading this the first time around and enjoyed reading it as much again this time. It's nice sometimes when members trawl through stuff that was written a while ago and dig out the little gems such as this one. Maybe it should be turned in to a sticky so it stays at the top, it would be a shame for a newbie to miss threads like this.

captain crash wrote:

Maybe it should be turned in to a sticky so it stays at the top, it would be a shame for a newbie to miss threads like this.

Good idea, done

captain crash wrote:

...... it would be a shame for a newbie to miss threads like this.

Not to mention an oldie!!

Bluesman wrote:

I too must have missed the original post. So somewhat belatedly I think the order of honourary degree in motorcycle science should be bestowed on Dave who perhaps could now be known as Dr.Intruder! A truly excellent write up and a valuable site port-of-call for any member interested in not only modifying the 800's power delivery but, perhaps more importantly, understanding the fundamentals involved.

Excellent article ... I nominate Dave to be Dr. Intruder as well .... Professor of Suzuki 800 modifications dept !! Well done Dave .. !

Yeah "Doctor Intruder" has got a ring to it but if I remember right when I first joined "Mr Intruder" was actually called "The Intruder" but when we all kept calling Dave "Mr I" he changed it to "Mr Intruder". Might be a name change again soon then

Nice work Dave.

Very usefull info that cheers, i was a bit concerned about the lambda sensor as a friend of mine told me it would damage the bike, however mine is still connected to the wiring, just tie wraped up out of the way and it seems to be running fine, i cant compare with what it was like before the aftermarket pipes cos i never had the bike then, but to be honest i dont care, it sounds loud as f**k and turns a few heads

E


Evening everyone, found this video on the Virago tech forum, this was comissioned by S and S
but by using a Dyno has give quite an unbiased view of the workings of an exhaust system, hope you enjoy it regards Doc Cox

That was an extremely informative video, thanks Doc. One thing it taught me is, if it isn't broke then don't fix it. My bike was dyno tuned some time ago and I have since removed the baffles for a different sound, they are now going back in.

Great video Doc, a good contribution to this thread. 

Interesting vid 

  Very useful info thanks