Phil A

Mate, I did this to my Centauro in 2001....., so I guess that gives you some new verified durability data. These photos were taken recently while I was setting up a Centauro in England to tour Europe for 3 months two up with gear....... There is some more load/ durability data for you. As soon as I rode the new bike it felt like it was solid in the rear drive compared to the one at home. Hence these photos, for the V10 site, because as I toured Europe setting up Injection systems for friends and aquaintances, I couldnt believe that not one had this (to me) basic modification done. Dont force me to take sides...... I am mostly, well this thread anyway, here for the entertainment value.

Well, before the testing begins for squishibility, practicability, power transmission ability and durability I would like to register my design. :D

Yep heres one....... The rubbers are contained and cannot escape to be squished flat.

The warping may be a sign that things have been warm at some time. I would recommend the mod Ernst has mentioned.

This place must be the best value for no money entertainment on the net. Why would ya go to a circus when you can come here for freee he he he :lol:

I'm with you Guzzimoto, Go on a ferry trip and take steering damper with you..... When you get to the centre of the channel, go to the rear of the ferry and throw it as far as you can..... If your Guzzi needs a steering damper then its not set up properly. Phil A.

It never ceases to amaze me that people actually believe that they are buying a perfectly sorted and functional motorcyle when they buy a Guzzi! From Italians.... ha ha ha!! What you do get is a collection of parts designed and fitted by an emotional luigi who leaves piece of his soul with every part. With these parts you can build a very special motorcycle if you so desire. Nothing more nothing less.

Luhbo, I didnt say that the dragstrip was real world. You said that carbs wernt as good as injection and I used this to illustrate that in some circumstances the were in fact better. To answer your question, in some areas they have too much timing and in others they dont have enough. For example, when the cylinder is reasonably volumetricly efficient, they will use more timing to reduce emissions, but at idle the leaner they run it the better it complies, so to do this they need to retard the ignition. This is more or less opposite to what the engine likes. A happy engine lasts longer runs smoother, makes more power and uses less fuel. Design flaws in the inlet manifold for example (flat spot as you blokes call it) can be improved by changing timing and fuel figures. You can combine this with airbox design to improve efficiency to a point where it is negligable. It is usually still there to some degree, but it is masked enough for the average rider not notice it. One thing you need to be aware of as you experiment is that generally speaking, more timing moves the peak combustion pressures to earlier in the cycle, with a comparable transfer of heat, and less timing does the reverse. Another generalisation is that more fuel = less heat, less fuel=more heat. More timing =more heat and less timing =less heat. and making heat at the right time is what this game is all about.

Arnt the epa the people who wanted us to believe that pumping cold air into an exhaust manifold would give us clean air out the tail pipe? My experience is that for any given max hp figure, flat slide mikunis will give you a faster 60 foot time on the drag strip than injection. Guess I spend more time doin it, than ROFLMAO. There are tooo many things to learn to do that. By the way, I prefer injection overall. Half reasonable engines make around 4hp /cubic inch. This vintage crap we play with doesnt even make 2. This doesnt mean its not fun, you just need to keep a perspective on where things are at. If we tune a bike with std exhaust, injection, etc, etc, get it to do faster and quicker figures than the factory, and use less fuel, then just maybe we have got a rough idea of what is going on inside that engine. If you then add something like Cliffs simple, efficient, (compared to the factory one) and cheap computer you have got some real learning aids. Wasnt there a Dr John who showed the factory how to do it a while back? Pretty sad isnt it when 10 years later there is still nothing coming out of the factory with similar performance. The critics said that the Daytona was 10 years behind the times. Where does that leave the factory now??

This is just a general reply to get you thinking. With this system, ie 2d, (ie two reference points on a pre-written map) you will never get even close to ideal ignition timings. A very rough generalisation will tell you that there are two main issues that conspire to keep you in the dark. One is that you need a 3d system to give you a load reading to give you anything like a reasonable figure for timing settings for any given set of circumstances. The other thing is that compression ratios are a dynamic situation, ie changing with load, speed, air temp, atmospheric pressure etc, etc. and as far as i have seen there is no system which even looks at dynamic compression figures. Fuel injection systems at the moment are about where carbies were in the early 1900s so do yourselves a favour, buy one of Cliffs computers, so at least you have a learning tool to have some fun with, and ride, ride, ride. Regards, Phil A.

Skeeve, You will find that you will need two bottles. One with a longer thinner neck and one with a shorter steeper neck. Start with the flatter one and get the outside part of the bell done first. Then use the more tapered one to "throat" the bell. Yes I know this sounds arse about, but you will see why as you do it. "all is not always as it seems" Another tip is to heat the plastic in the exact place you want things to happen. You wont get much if any heat transfer through the plastic. Heat the plastic until it goes "Shiney" that is its critical temperature. Dont try and do too much re- heating on top of each other. Simply heat it up.... do some molding then quench it with water. Then repeat the process. If you keep adding too much heat on top of each process, you will get the whole thing out of shape. Yes, the hole sizes are just a comprimise on noise and filter life. If you want maximum power, throw away the airbox and the pods and put bell mouths on the injecter bodies. Phil.

I know am a constant source of amusement to you Pete, but ya cant argue with the horses i can find that are tied up inside these things just waitin to be let loose All of the comments made on this last page sound fairly valid to me however due to time constraints I wont try and answer each one. One thing I will say, is that that I believe that once the bike is moving, the temperature difference between the front of the airbox and the top of the box is minimal. I will just try and give you a simplified version of the logic that went into each modification. Thinking time was over aperiod of months and months. No I dont sleep. The bellmouths I think, speak for themselves. There is heaps of data published on this topic. The principles I use have been used forever. It is the application to which it is applied that usually requires the thinking. In this case it was the fact that 30mm snorkels wont supply 50mm throttle bodies! That is a no brainer. Because the air box adds resistace then you would need at least 2 x 60mm supplies. Is it really that hard? The bell mouths can only be made so big. We still have a deficit to make up. Ok ok we now get to the holes. As previously mentioned, we have a wayward harmonic screamin around inside the air box. As the supply holes to the box (30mm) are smaller than demand (50mm throttle bodies) then there must be a low pressue situation in the box. The lowest pressure is going to be in that back corner of the box. Try and imagine that you are diving head first into the engine (via the airbox). What is the shortest route to the cylinder? It aint via the furtherest corner of the airbox I can tell ya. Sooo......... if we put a couple of holes in the corners of the box lid, we might just let out a bit of that errant harmonic, and if we are lucky the low pressure condition in the rear of the box might let some extra air in. Double bonus. Now....... the shape of the individual holes and the formation of the holes is exactly the same explanation, but it is the hardest to explain and understand. As the air begins to fall into the begining of the teardrop it forms a slight low pressure around its extremeties. IT being the "bit" of air that is falling into the hole. This in turn "sucks" more air into that low pressure area, which creates a bigger low pressure area which sucks more air etc etc. You need to try and visualise this in 3D. It makes a little tunnel of air or a tube of air heading into the hole. The first hole effectively creates a low pressure area around the extremeties of this tunnel of air (which it has stolen from the air travelling between the box and the tank) forcing the remaining surrounding air to move towards the centre and down towards the lid. As it moves toward the centre and down, we put two more holes in its path to further entice it down into the box as described above. Effectively the first hole has created a low pressure area moving down and in, behind it. Does this make sense? Dont forget that all this is taking place in a shape that is dictated buy the airbox lid and the fuel tank, therefore this is aided by the fact that we have a "relatively" captive supply of air needing to go somewhere. The teardrop shape definitely improves the flow for two reasons. One is utilising the vacume or negative supercharger effect, and the other is that it keeps the air from tumbling over itself at the edges as it does through say, a square hole in a flat plate. Hope this helps.

John, Yes I did remap at the lower rpm settings, especialy under half throttle. This is where I found some of the greatest gains. This also applied to the 1100 sport I did. The rideability issue was my main motivation for all of this with the V10. My bike will now willingly walk away from 1500rpm in top gear. This is not something I make a habbit of, but it will. I have remapped every piont of the original map. Greg, you will be surprised how much difference the teardrop holes will make all the way through. You will get as much or more gain than the original 3 holes gave, and will probably fill in the deficiency? you found over the cut away lid setup. This improvement came as a vision at 2 am one morning, (why I keep a notepad and biro near the bed!) It took some time to test and get a design I was happy with. It took me a while to understand why it works, but there was a logical explanation once I worked it out. Probably wont bore the masses with it.. Im guessing you can work it out if you look at it long enough. Phil.

John, 1. (a) as you bellmouth the snorkel you actually considerably improve the throat of the snorkel. The snorkel is not quite as bad as it seems as the id is fairly large due to the original reservoir shape in there.We just utilise it better. (b)the snorkel protrudes down into the faster moving air flow than at the top of the air cleaner lid itself. Does this make sense? Therefore "scooping" air up into the cleaner lid area. ( c ) A hole simply drilled into, say, the front of the airbox will not flow anywhere near as much as a hole fed by a bell mouth. 2. Strangely enough, the top end performance of a standard bike, given the limitations of aircleaner snorkels/mufflers, airbox design, exhaust etc is actually half reasonable. I believe this to be so, because it is these figures that are advertised to sell or market the bike. eg 85hp at 7500rpm etc. When we improve things it is more difficult to get big gains, top end, due to the original effort spent in actually getting the top end right in the first place. In answer to your question. yes, the factory settings are already nicely lean to maximise performance, so further airflow yields very little gain if you retain the original fuel settings. 3. In this area we achieve greater gains than you would believe possible. In fact we get a 4% (approx) gain from idle. I found this hard to believe at first, however I guess that the same decrease in resistance that gives us the top end must also give us better flow from the bottom up. In fact I have improved torque at 2800rpm by approx 25%! which is way more than we get in the top end. Therefore this mod to a std bike without correcting the fuel delivery, will give you worse stalling/surging/hicuping than original. Greg, the initial mods were round holes as described however as I supply this design with my maps I figured it is all around the world by now. You will be surprised how much difference it makes. Please excuse my ignorance, What is the BMC? Ciao,

Maybe this will explain things a little clearer. These mods will make your engine run lean so I dont recommend them them to anyone who does not have the provision to add more fuel to compensate. ie My16m or similar. Pierre, exhaust rear mufflers are 2'' straight through. Centre muffler is stock. For the mods described no modifications were done to the bell mouths or the ram tubes attached to the throttle bodies. YEP, pods on stock runners with airbox removed and these airbox mods give similar hp figures. YEP, this was a "noise and filtration driven approach " Regards, Phil A.

Dlaing, my appologies for mis interpreting your post. Absolutely not. I think there is always room for improvement. Dr Johns contribution I spoke about was the centre muffler behind the gearbox on the V10. This is often ridiculed and I feel, misunderstood. He also spent some time getting extra power from the "original " airbox ie, pre production. One can imagine that the snorkels are the doings of political horsesh*t.

Ryland 3210, yes now I read this again, it was a poor explanation wasnt it. I guess my main aim is to get people thinking, as often it is simply a matter of applying the laws of physics to solve problems. I never give the complete answer as I believe those who can "make it work" will do the homework a reap the rewards. Its a bit like the old saying... If have to explain, you wouldnt understand. If my statements provoke questions I am only too pleased to discuss them to inspire further thoughts or improvements. There is so much we dont know and I find constructive discussion will always yield results. DLaing, dismisses my simple modifications to the airbox, however if he took the time to reproduce it, some glaringly obvious improvements will follow to give even better flow. Most people dismiss Dr Johns center expansion box however I have found that on a road bike where ridability is important, it works very well in conjunction with getting the rest of the system sorted. I find that an internal combustion engine sometmes works "in spite of how it is made" not because of how it is made. For example, A V10 or V11 is so poorly set up that it will stall. It will not run! How poorly does an engine need to be set up that it wont even maintain combustion??? To me this is totaly incomprehensible. Havent we been building engines for nearly 150 years? And we cant even get em to idle!!! Come on.... its not that hard. The most efficient engines are still from during the war years. Lets quit the political horseshit and build engines that are worth using. The fastest quickest , engines in the world today are still based on 1950s designs. What sort of crap is our political system forcing down our throats? End of rant back to your questions. "Inversion"..... look up organ pipe theory. "Destruction of lost energy" This is reference to the energy which is lost at the "bell mouth" Once it is lost to the "air box" as such, it becomes problematic or extremely complicated to deal with. In the case of our road bike it is easier to write it off or get rid of it to avoid its undesireable or more difficult to deal with, effects. "The effect".... this was a bit broad wasnt it! This reference begins at the back of the inlet valve, which is the source of this harmonic energy we are discussing here. As the valve slams shut it initialises an harmonic. This is the primary harmonic effect we try and utilise and find problematic at times. On this part of the effect we can verey loosely apply normal organ pipe theory. This is the energy that "inverts" "Some" of this energy is lost, see above, and this creats another effect. In this case an unwantd effect. Some manufacturers use what they call a still air box to influence this effect. This is a long story however if you need further reading, look up Helmholtz resonator. Another effect that I have never seen mentioned is the secondary harmonic that is set up between the throttle butterfly and the bell mouth. With this effect you can prove that adding to the ram tube length is not the same as adding to the inlet manifold length, however the ram tube is the way that most people seem to go. Remember I mentioned inlet momentum? Think of this in relation to the above statement. As the butterfly is opened and shut, the weight of air behind the butterfly takes on one characteristic and the air in front of the butterfly takes on another. This is why slides in some carbies achieve better results than the butterflies in our system. Pods and air cleaners can all be made work better by throwing the f*ckin things away, however for those of us who want maximum longevity from our engines, the well set up airbox is as good as anything. A good way to understand inlets is to fit one that is too big and then change everything else untill you get it to work. Then you will begin to understand how it works. I am up to 2x 46mm carbs on the race bike previously mentioned and you could send a 10 year old to the shops on it. Thankyou for taking the time to put some thought into my post. Hope this helps. Phil.

The harmonics nature is to invert at the open end of a tube. It is only the energy that is lost that is disipated in the filter/air box. Hence my air box design, which I have published here in the past. The art is to maximise the destruction of the lost energy so not as to add to the effect again appon reflection, minimise the noise, and maximise the air flow at the same time. The damping effect of the filter is minimal. After optimising the design of the airbox I have the same power as with pods. I would rather have the air filtering ability and quieter intake than the maintenance and noise of pods.

Even with the short inlet, The harmonic will simply complete several cycles up and down the tract between engine cycles. Eventually you reach a point where the gas flow is going into to the engine and the harmonic is going outwards away from the engine.. This stops or slows the charge causing the" flat" spot.

As it would take volumes to reply to the posters on this thread, I would like to offer some things to consider in conjunction with what has been written. This way each poster can consider/apply the thoughts to their own understaning of what is happening without me creating arguments based on subjectivity. Firstly, you must appreciate that there are two completely seperate things happening in the inlet /exhaust tracts at any one time. One is gas flow and one is harmonic wave activity. Each has nothing to do with each other but needs to exist in the company of the other. Some of you have a handle on harmonics to some degree but no-one seems prepared to change it. Harmonics travel faster thru a denser medium. Consider this in conjunction with the exhaust back pressure discussions. More back pressure = more torque down low. That is, untill the resistance is a greater loss than the gain made by increasing the density via back pressure. Consider this. these bikes have a "flat spot" at 2000, 4000 and 6000, and (8000(4 valvers) The 4000rpm one you are all aware of and can feel seat of the pants. They make really "easy" power at 3000, 5000,and 7000 rpm. You can test this by fully loading a 4 valver with pillion and gear and head up the steepest hill you can find in say second gear. It will come on as hard at 7000 as they do in stock form at 5000. This is an example of the harmonic at work. You can prove this to yourself by lenthening the inlet tract say 100 mm. It will instantly change the good power rpms and the bad power rpms to different settings. The same harmonic that is discussed at length in the exhaust system is available in the inlet tract. How many of you continuously modify the inlet tract as you do the exhaust to find that elusive torque gain? Dont confuse inlet speed with pressure. The higher the speed the lower the pressure. However inlet momentum, which is, weight X speed is absolutely critical. BUT I hear you say, I filled in the dips in the inlet tract with resin and the flat spot improved. Yes, but I put it to you that this was due to the fact that you increased the speed of the charge therefore increasing the momentum of the charge. This is also evidenced by the fact that on that same engine you will have lost a little top end power. This is because the smaller tract cross sectional area limits the flow at the top end. Also if you increase the speed you decrease the density, moving the effect of the harmonic to a different spot. The charge density is a dynamic thing it varies on every stroke depending on temperature, density, atmospheric pressure etc Bigger is always better. If it wasnt you would be riding a smaller bike. If you make something bigger and the bike goes slower then something else is too small. The bigger you can make the inlet tract while maintaining the momentum the more torque you will make. A good example of this is my 500cc single which does 130mph on the salt (add 10% for bitumen) at 5600rpm. It has two 46mm mikunis on it. (See it on the DLRA web site) Hope this gets the wheels turnin. Phil A. "All is not always as it seems"

Followed a link Nog posted below to the ural site. If you are bored ther is a laugh a minute in here. For example, regarding the sump issues. Before you pick up a spanner-look under the engine at the sump, if it is a pressed steel one- only a couple of inches deep- that is your'e first problem. These engines are air/oil cooled and require a vast amount of WARM not Boiling oil, especially for the left hand piston- which is why it has it's own oil feed in the cylinder. Take the sump plate off and slit round it with a hacksaw blade held in a rag and weld in a strip of steel four inches 100mm deep. This will give you a reserve of about a gallon of oil. If you have a cast alloy sump, buy a steel one and do likewise. The welding of the sump will distort it and you will have to use silicone gasket goo to make a good seal. Use builders merchants silicone sealer- it's the same stuff as in the bike shops. By the way, fit sump and engine sepperately, you won't get them in the frame together.This modification will do the most for reliability especially if your Ural / Dnepr likes to drink and so will you after all this And on carby balancing, Now, if you don't know the method for Ural / Dnepr carb balancing I had better tell you as it is crucial to smooth running and reliability, more Urals have popped because of this than anything else. It is a much more accurate method than any other. Warm the bike up, 10 miles at least, put it on the main stand and run the engine in top gear, lock the throttle with a clamp so that the speeedo reads 45-50mph and short out one cylinder with a screwdriver or remove the plug cap, if the engine dies then open the carb on the cylinder that wasn't shorted out using the throttle cable adjuster. Then repeat this procedure on the other cylinder. You are aiming for the bike running evenly and at the same speed which ever cylinder is shorted out. This method relies on the spark plugs being in good order -don't mess around, buy new ones (........Charles) Now adjust the slow running tick over screws to finish the the job, this method is more accurate that stethoscopes, vaccum gauges or bits of rubber pipe so don't go wasting your money. The later Karburettorskis are pretty good, but if you had earlier ones like me, get Mikunis or Amals and make up adaptor plates to get them to fit. Viva la moto guzzi. Phil.

Met a bloke at a rally on a Ural and sidecar once. It was the third and last day and he had just arrived. He was resoldering the nipple back on to the front brake cable, which by the way was inside the drum and had wrecked heaps of brake bits before he could stop. He had some really nifty tools with him. He said he usually set off for a rally the weekend before to make sure he got there! I said, they cant be that bad can they? He said, I set off around OZ once, (about 20000km) and took a spare motor gearbox and diff in the sidcar. I ran out of parts before he got to Sydney (2000km) He said he got to meet heaps of people along the way because he spent most of his time camped on the side of the road doing repairs! Never forgot that bloke. I found this site somewhere, might be of interest. http://www.RussianIron.com All the best on your adventures!! Phil A. "All is not always as it seems"

Thanks Graham, that pretty much sums it up. Its good to see your photos, I still havnt taken any of mine so I wiil just take this oportunity to add some comments for the benifit of those like Greg. The front hole in the lid needs to be about an inch further forward to get the best effect. What seems to happen is that as the air starts to dip towards the centre hole it starts to pull the layers of air outside the diameter of the inside hole, towards the low pressure area created by this air dissappearing down the inside hole. In other words the air gets pushed inwards and then down towards the rear two holes. (some would say sucked.) If you dont have the front hole far enough forward then the rear air for the rear holes is not pushed in at the maximum effort. ie a lot of it over shoots the rear holes which are then in a partial vacuum (relatively speaking, and you run the risk of decreasing the flow into the rear holes.) Sounds a bit complicated doesnt it but if you spend enough time working with smoke then it all becomes easy, ha ha. Graham, Your bell mouths are not big enough yet. I wondered why yours didnt hit on the tank! You need the id at about 50mm the od should hit on the tank so that you just need to file a 20mm flat on the lip of the bellmouth where it touches the tank. You get better flow by turning the bellmouth further outward and fileing the small flat than leaving the bellmouth smaller. Dont ask me how I know this! Greg, my experience with lid vs no lid vs big sqare holes etc is that once you get up to a reasonable flow then you just seem to get dirtier elements quicker with out a large increase in hp. Guess its the law of diminishing returns set up. Eg if you drill 3 holes and get 1hp, the why dont you get 10 hp by drilling 30 holes? The design of the box and lid (and other factors) determine the optimum area. Make sense? There is another reason as well and that ie that you are "letting out" a destructive harmonic that is active within the airbox. This one I will leave alone for fear of starting a riot! Your comments on the respective results for the respective mods ie (thought that would be more and thought that would be less), just tells us that it was the lid that was the main problem. make sense? For those that were interested, YES I did all this work on the 2 valve as well and believe me, give or take, at different rev ranges all this info is valid. Do you think the inlet air knows weather it is going into a 4 valve or a 2 valve? yeah.... right.... Nogbad, If you cant feel the difference in 9ft/lb of torque, thats a nearly 20% increase at 2800rpm. then mate, i think this game is definetly not for you... I have been studying inlet tract behaviour for over 25 years so I am sure you understand I have to leave something for YOU to work out! My most developed inlet tract is on this 500cc single http://www.dlra.org.au/profiles/140.htm which runs 2 x 44mm Mikunis (you try and even get em to work) and 5lbs of boost Yes, created by the inlet manifold there is no supercharger on this engine. It has run at over 130mph. It will be the first single to run 150 on the salt. Thanks, love the constructive discussion, Phil A. "all is not always as it seems"

Greg, can see there is a few here interested in this so I dug out some data gathered while developing the V10 inlets. Dont shoot me please the box is the same as the V11 The facts as I have them are these: All of these steps are independent of each other. If your remove the origional mufflers(snorkels) off the inlet and bell mouth the inlets to approx 35mm id you get approx 2hp between 4500 and8000rpm. If you remove the filter but leave the lid in place, you get approx 1.7hp. If you drill 3 one inch holes in the top rear of the air box lid (one in each corner an one 2'' forward in the center) and retain the air cleaner element you get approx 1.5 hp. If you remove the lid and leave the filter in place you get approx 3.5hp from 4300-5500rpm it increases steadily to approx 7hp at 6300 then tapers of to approx2 at 8000 or so. Once you totally remove the air box but retain the std bell mouths on the injector bodies the gains above 6300 do not taper off as above with the gain being approx 5hp at 8000 or so. Probably the most noticeable gain with this last set up is 4 or 5hp in the middle of the dip at 4000- 4800rpm. If you increase the bell-mouth id to approx 50mm and retain the holes in the rear you get 4.5hp all up. Once I had remapped the MY16M to match I have exactly the same power with the airbox (with origional filter) as with no airbox what so ever! A total gain of approx 7hp while running the stock filter. Probably the best gain was 9ft/lb at 2700rpm! with a 5ft/lb gain at 4300rpm. Hope this is of interest. Phil A. V10 sport. "All is not always as it seems"

Nigel, I think you definitely have a problem. The info I have read states that luigi had to move it all sideways 1.4cm sideways when they wanted to mount the 4 1/2 inch rim to use the 160 tyre. Looks like your frame is 1mm out of whack! Ha Ha. Love it. Regards, Phil A