courtesy of Jens Lyck

Technical : The complex stuff - exciting but heavy reading, take your time.

How to get the best from your stock-ish 8V Griso

Author: Pete Roper


First let me put a few disclaimers into this message. Most of the experimentation has been carried out on one bike, mine and some of my observations are subjective and based on my own prejudices, likes and dislikes. I am NOT claiming that this is any sort of 'Definitive Guide' simply that the laws of physics and engineering will tend to agree with my observations and finding.

Secondly this is not a guide on how to radically improve the fuelling or performance of your bike. It is simply the results of a series of experiments I've carried out over the last year and a half on my bike and a couple of others belonging to customers. If you wish to radically alter the performance of your machine you will need to have some means of re-mapping the ECU. There are several options available and Todd Eagan's PCV-Autotune package certainly seems to be the most highly developed and dedicated currently available. Many people though can't or are unwilling or unable to justify the expense of such a unit and what I am trying to do here is to just offer some advice on how to get the best from your 'stock' machine with nothing more than basic modifications such as an aftermarket pipe and alterations to the airbox.

When they are delivered from the factory I have generally found that the set-up of things like the TB ballance and TPS setting are pretty good which is different to the older pushrod CARC bikes with the W5AM controller which all seemed to come with the TPS set at 3.5 degrees or thereabouts rather than 4.6. Whether this was intentional or not I have no idea but the 8V seems to generally be set up accurately. That having been said it is important that before you embark on ANY changes you should ensure that the bike is correctly tuned and serviced. While this may seem obvious to most I know from bitter experience that many shops, either through laziness or ignorance simply don't perform the alloted tasks in the service schedule beyond changing the oil and perhaps the oil filter at the first service. If the bike ISN'T tuned and serviced fully nothing that is changed is going to be of much help. It will still be a munter and I'm sorry, that isn't the bike's fault!

The very best first step you can take with an 8V Griso is to ensure it has the latest map upgrade from the factory in it. I believe the code for this is GRS8V068, I think the original was GRS8V054. Why the obtuse numbering? Don't ask me! This in itself makes a substantial difference to the running of the bike usually elliminating the rough running on a light throttle which I think is what people reffer to as 'surging' but since I've never experienced what I'd call 'Surging' I can't be sure. What in fact is happening is that at certain revs and light throttle openings the mixture goes critically lean so the cylinders don't fire every stroke. This uneven running results in a jerkiness and alot of lash in the driveline causing clattering and banging that anybody with 1/4 of a brain will realize can't be good for the bits that are bashing against each other. The good news is that if everything else is right on a stock bike the new bike not only deals with this very effectively but it also elliminates the power 'Step' at about 4,750-5,000RPM. This was the first thing that a customer I loaded it up on the other day said, the delivery was now linear with no pronounced dips or steps in the rev range.

After this the next step in most peoples' 'to Do' list is a new pipe to get rid of the very bulky and heavy original and this, more than anything else, is a very important choice if you wish to get the best from your machine. To start off with I'll upset all the 'Loud Pipes Save Lives' brigade by telling you that if you put on anything remotely 'Open' or 'Un-baffled' it is going to run like a hairy goat. Even with the 068 map in an open pipe will simply lean the mixture out to a point where the engine looses its smoothness and begins to feel 'Harsh' and vibratory.

To digress for a moment it is worth giving a short and simple explanation of why this is so critical. An engine is simply a self propelling air pump. Air is pushed into the cylinder where it is heated by burning fuel with the oxygen in the air. The heat expands the gas in the cylinder and this forces the piston down the bore turning the heat into mechanical work. To do this optimally the amount of air and fuel combined, the air/fuel ratio or AFR has to be at a certain proportion one to the other and this is governed by a number of factors that we don't need to delve in to but if it is wrong, or the further it is from correct the greater the chance of mechanical damage and the less useable energy is produced that can be turned into mechanical work. There are times when a poorly tuned engine will make MORE heat, the problem is that the heat won't be useable to turn into work.

Before the days of computer controlled fuel injection fuel delivery was by carburetor and if changes were made to how an engine breathed it was fairly easy for your average 'everyman' to swap components in a carb and get the machine to produce the correct AFR, the controlling factors were manifold depression and gas velocity with atmospheric pressure as a constant. It was very much a two dimensional image, rather like a graph. With the advent of EFI many other factors could be taken into acount, hence the number of sensors feeding data to the ECU and the fuel delivery along with spark advance are all combined with several other factor to produce a far more three dimensional model of how the fuel is delivered. Hence it's description as a 'Map' because one of the commonest ways to show diagaramatically what is happening with the signals from the ECU is by means of a three dimensional relief image that looks for all the world like a relief map of a block of land. The thing is that to alter the parameters of the map, (Which in most ECU's is encrypted by the programmer.) one needs the tooling to break into what is loaded in there and alter it. Not many of us have the equipment, skills or knowledge to do it. I don't for one. I'm sure its an open book to some but lets be realistic. Most of us haven't got a clue! That is the reason why full tuning options, especially for small volume machines like Guzzis, are going to be expensive and it is also why I'm trying to explain how to get the best out of what we are stuck with with the factory map.

While far from perfect if we accept that what we have is what we've got what we have to do is try and make any modifications we do either use the map to our advantage or, as a minimum, not do anything that will make things worse anywhere. The first thing I found was that when I fitted an open, unbaffled pipe the already lean nature of the map was exacerbated to the point where the bike not only behaved like a pig anywhere below 3,500 RPM, 8-stroking and clattering as well as backfiring, (Popping.) on the over-run to such a degree that it was actually tiring to ride, especially in traffic. Loading up the second, now superceeded, map from Guzzi helped a bit and at least made riding the bike fun again but it was still plagued by lean-ness and a general malaise of lean-ness exemplified by a harsh, vibratory feel to the whole machine, (You'll find me harking back to this description a lot!). Fitting a Fat-Duc O2 sensor fooler certainly helped this in the closed loop area of the map where it was most apparent but it wasn't without it's downside. At certain points the mixture would go critically rich and throw up the 'Service' icon on the dash. It didn't effect the running but it was a serious pain in the bum. The plugs never showed any signs of excessive lean-ness or richness but it was obviously going far enough outside the parrameters that the ECU would accept as 'Normal', at least the progarmme doesn't seem to have a 'Limp' home' mode when this happens as performance didn't seem unduly effected. More on the Fat-Duc later.

Eventually I couldn't stand it any more. Much though I loved the look of the pipe the fact was it simply didn't work. I toyed with the idea of making a *proper* dB killer for it but at the end of the day I found out that I was owed some dosh by Moto International so I got them to send me the 'Factory' Termi pipe and slipped that on. Not being able to get the dB killer out of the Termi due to the loving attentions of the TSA at LA airport, (The pipe was bought over from the USA for me by a friend who was coming to borrow the Griso.) who had managed to dent and bend it a bit I ran it with it in and the difference was immediately noticeable and a huge improvement in terms of vibration dimunition and smoother running in the closed loop area. Shortly after my mate had returned I downloaded the latest upgrades from the factory to my axone and discovered that there was yet another map upgrade, the 068 map, available so I uploaded that and I have to say that obviously someone at the factory had finally taken the time to do what should of been done in the first place because the new map, combined with the restricted pipe transformed the way the bike behaved. Gone was the stuttery, 8 strokey ,gearbox-chattering, final drive hammering behavior at low load/rpm, gone was the step in the power delivery in the midrange, it was now pretty much seamless from 2,500 all the way through to the 'Going too fast' area!

Knowing at this point that it was seemingly fuelling well everywhere I decided to tackle the one problem I knew it was hampered by severe richness at the top end. This is an almost universal feature of all motorbike and car maps and is probably a result of the litigious societies we live in. By richening them up unduly at the top end the can calim in any court that they have limited the engine's power because they could of made it make more! Daft but true! So it was out with the hole-saw and I very un-scientifically started cutting holes in the airbox lid. I continued to do so until it felt 'Right' and took the snorkel off the back of the box for good measure. In tat itteration it stillv fueled up well in the closed loop area and throughout the midrange regardless of throttle opening and would now pull to the rev limiter in top on the flat! Neither I or the Griso are lightweights! I was happy and it stayed there for several months.

Last week for the first time I had a bog-stock 8V in for a head swap under warranty. It had never been serviced properly so i did that too and uploaded the 068 map. It ran very nicely so I decided it was about time I pulled off the Fat Duc to see if it was needed with the Termi. The straightforward answer is no. It made no difference. In fact it may even of run a bit better without it so it won't be going back on. Spurred on by this I decided to finally tackle the dB killer in the Termi. Not because I wanted more noise, I hate loud pipes, but just to see what would happen and how it would behave. getting it out was a pain and I had to damage the cat to do it which was a pain but i didn't harm it severely, just a 10mm hole for the long punch to go through to get to the back of the dB killer.

Immediately the harshness, the popping on the over-run and a host of other silly little glitches showed up again. Nothing serious or un-nerving but irritating because I knew exactly how good it could be. Because I'd damaged the dB killer getting it out and I've given oit to a welder mate to 'remanufacture' I decided to see if restricting the intake side would have any effect so it was off with the drilled airbox lid and back on with the full lid and snorkel. Result? In open loop it was very nice. In closed loop it would sometimes hesitate when the throttle was cracked open and the popping on the over-run was still there.

As soon as I get the repaired dB killer back it'll be going in and staying in. I'll see how she goes with the stock airbox lid but I reckon it's best itteration so far has been 068 map, restrictive pipe with dB killer in, no Fat Duc and drilled airbox lid. By far the most critical factor in ALL of the experiments has been the pipe fitted. As soon as the exhaust is un-baffled the mixture gores critically lean in most of the range and it is readily apparent by the way the bike feels and behaves.

So there you have it. By all means you can fit an open pipe, if you enjoy being deafened, but your 'Stock-ish' bike will run like a pig. at the end of the day you CAN have a pipe as open as you like, but you WILL need to stump up for an expensive map modifier to make it work. A catalytic converter in the pipe will act as a baffle of sorts but it is obvious from me experience with mine that the cat alone is not baffling enough, to get the best of the stock maps to work to the best of its ability you NEED more restriction to the flow of gas through the engine and the critical point on an otherwise stock bike would seem to be the exhaust pipe.

I have the full PCV/Autotune option but because I misunderstood how it worked I did't get the ECU re-flash so it wouldn't work on my Oz bike. What I'm going to do with it is take it over to the US and put it on and tune it with Todd's assistance on my US 8V. I have few doubts that with the full package it will run better than my Oz bike does but as I said at the beginning, this is not about striving for perfection, its about getting the best you can with what we have.

So in summary.

The GRS8V068 map is a must.

An open pipe is a disaster. when choosing make sure that the pipe you purchase has a decent and fairly restrictive dB killer or your fuelling will go up the shit. Also your neigbors won't hate you as much! A Catalyser in and of itself isn't vital but since it keeps the nasties out of the air AND is beneficial to the running of the bike, why not?

A Fat Duc seems to make no difference once the 068 map is in and not having it in line means you don't get the annoying 'Service' icon coming on intermittently.

Drilling the airbox gives slight benefits, especially at the top end where you would expect it to but it increases noise for the pilot, (Although the induction honk is, if ear plugs are worn, pleasant rather than tiring and deafening.) but doing so is not something I would describe as a 'Must Do'. The nice thing is the factory airbox lids are dirt cheap. Buy one and experiment. if you don't like it? Slap the full lid and snorkel back on.

The main bike used for these experiments was mine but i have also seen other bikes one stock, one with an Ago pipe with cat in but no dB killer and one with a truly horrid Staintune on it with a dB killer. The Ago equipped bike with the killer out behaved very, very similarly to my Termi equipped bike with the killer out and the stock lid on the airbox. The Staintune with the killer in made the Griso sound like an asthmatic, farting tortoise and its performance was roughly similar..The owner took mine for a flog and said that the Staintune would be on fleabay the next day and the stocker back on until he decided what else to buy!

Just my experience, not gospel on tablets of stone but I hope itbwill help other owneres in their decision making.