Kelum

This might be helpful... Superbike Air Intake System The topic of modifying the air intake system has been discussed as extensively as what fuel octane to use and the what's the best oil. Here's the basic issue so you can decide whether to throw out the stock air filters. Your engine is prevented from making more horsepower mainly because of the difficulty of getting enough air. You can easily add more fuel if you can get more air through the engine. Superchargers and turbochargers are the common way of doing this in automobiles. Four valves per cylinder are often used in modern motorcycles. The governing flow restriction is the throttle body diameter, the size of the intake and exhaust valves, and camshaft lift and duration so if any upstream flow area is smaller, it'll just see a higher air velocity as air passes through it. If you introduce a flow obstruction such as an air filter into the upstream flow you'll get a reduction in air pressure at the throttle body and flow into the engine will be reduced. A dirty air filter will be the biggest flow obstruction. There has been much discussion about opening up the front air intake openings in the fairing and to remove the decorative grill in order to reduce flow restriction. I've done it, and it's probably a good idea to open up this space, but the fact is that air velocity will simply increase to supply enough air if you leave it alone. Similarly, there have been a lot of questions regarding removal of the rubber blocks in the air runners of later year bikes. Again, these blocks incorporate a nice smooth venturi that simply accelerate the flow through them on the way to the airbox but are designed to restrict airflow very little. They really don't hurt anything if you leave them in. Their purpose is to reflect sound waves so as to reduce induction noise to achieve overall legal limits. Before we get to the question of air filters, we first need to consider the air intake system design. One reason for using an airbox and intake runners is to direct cool air to the engine. This design approach also results in a small pressurization of intake air that increases with bike speed. It also reduces the volume of the intake flow noise. But there's also a performance benefit because the airbox is a Helmholtz resonator. That is, a resonance effect occurs when you connect an enclosed volume of a suitable size and shape to an engine’s intake stacks causing the air inside to resonate at a frequency that results in pressure peaks coincident with the cylinders’ intake stroke frequency (at a particular RPM.) This can theoretically increase power by 10–15% within a particular RPM range by boosting airflow into the engine. Airboxes need to be well-sealed and stiff in construction to maintain these resonance characteristics. A simple way to illustrate this is to blow across the mouth of an empty bottle. The sound you hear is the natural frequency of a Hemholtz resonator. If you change the shape and free air volume of the airbox, you change its resonance frequencies, and the engine RPM at which it responds to enhance filling the engine with air. For example, a larger Corse airbox is tuned for optimum filling at a higher RPM where race bikes normally operate, but where street bikes usually do not. If you fill the example empty bottle with filter foam (mostly air) and blow across it, you'll get no resonant frequency sound at all. An airbox also functions as a plenum, a space where the air velocity is reduced so as to eliminate turbulent airflow prior to being smoothed and accelerated down the velocity stacks. In fact, if you just place your finger anywhere near the edge of the top of the velocity stack you'll see dyno power dropping off due to the disturbed air flow pattern. The air in the plenum is also considered "free air." That is, it’s already passed through the air runners and filters so it can be supplied to the engine without any flow restriction. If you use the auto industry's standard calculation of air required for "nil" vacuum restriction within the air intake system, you should have at least 130% of engine capacity in available air volume between the throttle butterflies and the air filter element. All of this tells us why Ducati places the superbike air filters in the air runners. This location avoids lowering the frequency of the airbox (by not filling up a large portion of the airbox volume with a bulky foam filter) and prevents disturbing the airflow near the velocity stacks as well as improving throttle response by maintaining a large free air volume between the filter location and the velocity stacks. This is also why Ducati didn't use over-the-velocity stack bellmouth style filter. This location doesn't meet that 1,300 cc. plenum volume needed to avoid degrading throttle response (which a dyno doesn't measure BTW.) Dyno tests say you get somewhat less peak horsepower with these filter types but on a stock bike they don't seem to make a lot of difference. Another point to consider is that unless you have customized a FIM chip on a dyno in an attempt to match the flow and resonance characteristics of an over-the-bellmouth filter you'll have to use a chip that was developed using the stock filters. (I've read more recently that JHP in the UK sells chips that are dyno tuned using under-tank filters. http://www.jhpducati.com) The computerized engine management system uses a fixed fuel injection metering scheme controlled by the EPROM chip that was developed in combination with the stock intake/exhaust configuration. Unless you install a programmable FIM chip and sort out any changes on a dyno with a knowledgeable operator/programmer you won’t get optimum (low-end?, midrange?, high-end?, power?, throttle response?) performance. Ducati engines are the result of countless hours of development work on a dyno. They are designed as a unit with airflow and exhaust flow optimized together for each engine configuration. When you change things like intake and exhaust configurations it’s a hit-and-miss proposition. Many times you make improvements in one RPM range and performance at other speeds decreases. Without dyno before-and-after checks, multiple changes can produce confusing results. Also, seat-of-the-pants tuning can be misleading. If a change, say, reduces mid-range performance at the expense of high end power the engine feels peakier and this feels like an improvement. But is it? Strange dips in dyno horsepower and torque curves can and do occur at speeds where you spend most of your time riding. Regarding the large foam in-airbox filters, the people at Sigma Performance (www.sigmaperformance.com) distributors of arguably the best aftermarket chips for superbikes recommended using the stock filters. They state that all FIM chips are made and initially tuned with the stock filters, and they highly recommend staying with the stock units. This is because they say they have found that a new CLEAN stock air filter gives 2–5% better performance than any of the aftermarket filters and they have only seen reductions in performance when using over-the-bellmouth filters. As a type, they change the air box resonance and require about a 3% leaner mixture to get back some of the power. They say that these filters have flow characteristics that aren't well matched to the fixed metering of the stock fuel injection system. So it seems that the main advantage of an over-the-bellmouth filter location in the airbox is that it allows only clean air into the motor. The fuel tank-to-airbox seal is notoriously poor on superbikes, and will often allow dirt into the airbox bypassing the stock filters. So, if you see bits of sand and grit and dead bug parts in the bottom of the airbox one solution is to replace the stock tank-to-airbox seal with thicker stick-on foam tape, or use the updated seal from the 1999 and-up bikes. Also, access to the stock filters requires some effort so if you don’t clean them regularly an aftermarket filter may be a better choice for you. Further, over-the-bellmouth designs, however, will reduce the chance of engine damage in case of a crash. IF you crash, AND the gas tank becomes dislodged from the air box breaking the seal, AND debris gets into the air box these designs can prevent engine ingestion and further damage caused by the crash. Your insurance company will thank you. So even though the stock filter location is better, that's not to say that the stock filter is best - they do have significant drawbacks themselves. They use single density foam that has a uniform pore size and they are run dry (i.e. without applying a dirt retention oil.) So, it flows air well, but isn't a very efficient filter and a lot of smaller dirt particles pass through to the engine. This accounts for most of the dirt coating the inside of your airbox. So, the stock filters won't stop any dirt particle smaller than the foam cell size unless they are run with dirt retention oil. The stock system is actually a two-stage filter if you consider the debris/insect-filtering effect of the air duct inlet screens. As a type, foam air filters are a reasonable balance between good airflow, dust holding capacity, and filtration efficiency for small particles. The way that better foam air filters work is simple. Open cell polyurethane foam is wetted with specially developed sticky oil. The sticky oil is suspended in the path of the dirty air on the strands of the web-like cell structure of the foam. This makes it difficult for small dirt particles to pass through the depth of the filter without sticking to the strands. Larger particles are trapped if they are bigger than the distance between the cell strands themselves. As the outer wetted strands become loaded with dirt particles and no longer sticky, the wetted strands downstream continue trapping dirt, until the entire foam thickness is utilized. Also, as dirt particles build up on the strands the space between strands decreases, further increasing the filter efficiency by trapping the smaller dirt particles that initially could pass between the strands in a clean filter. This approach prevents the surface loading and air restriction that single-stage paper filter elements experience and consequently extends the service life of the air filter element. Finally, when the filter is sufficiently dirty to stop trapping small particles and clogging reduces airflow, it can conveniently be washed, re-oiled, and re-used. When oiling a foam air filter, use as little as possible, but do get adequate coverage. Some manufacturers use foam as part of a multi-stage filter design. Stage 1 might be a screen or a coarse foam layer that stops larger debris from clogging up the stage 2 filter layer. Stage 2 would be a medium or fine pore foam to collect smaller particle that the stage 1 layer missed. Stage 3 could be a finer foam or cotton gauze layer that catches particles down to micron sizes. One or more of the Stages can be oiled to increase filter efficiency, and the whole thing, if made sturdy enough, can be cleaned, re-oiled and reused. The only filter (other than the OEM) that won't reduce airbox volume is made by Sportsbike (Australia). It mounts at the air tube entrance to the air box. It uses two pre-oiled, clean and reuse, single density foam filters. Its main drawback is that has a smaller cross-sectional area (about 7 sq. in. vs. stock 32 sq. in.) and less dirt holding capacity than any other design (except for the tiny MadDuc "things" that mount on the velocity stacks.) I think that it's important to be skeptical of the marketing hype by aftermarket filter manufacturers and their failure to provide ANY comparative dyno results that demonstrate that their product provides some performance advantage, or at least no loss in performance. Modern high performance motorcycle engines are the result of countless hours of development work on a dyno by the manufacturer. They are designed as a unit with airflow and exhaust flow optimized together for each engine configuration. Purposely (say to save costs) using an unnecessarily restrictive air filter in their design will decrease performance relative to their competitors and their marketing advantage. So, where are the dyno charts from the manufacturers of the aftermarket air filters? If they really improve performance over stock filters across the RPM range then it’s really a marketing advantage to release their design development dyno charts. Without evidence to the contrary, think it’s safe to conclude that it is not to their advantage to release any dyno charts or comparisons with other vendors. The aftermarket air filter market for motorcycles seems to be built on hype by the manufacturers and by the profits to their sellers. They compete on hearsay and testimonies from “happy” customers or recommendations from their own vendors— not on proof of superior performance.

Venturi pumps work that way Paul....your guess is correct I think..

Damn that's been a sarcasm, I didnt notice...poor English, thanks Buddha they were not too harsh!

I found.. There is DEFINITELY harm in having too much engine oil. The most common problem is -- believe it or not -- lack of lubrication caused by low oil pressure. What happens is the crankshaft "whips" the oil in the oil pan into a foam. The foamed oil is then pushed through the lubrication system. The air bubbles causes a drop in oil pressure and less oil is delivered to moving parts. This results in increased wear, lower fuel economy, higher temperatures and generally just a Whole Lot Of Bad Things. The action of the crankshaft whipping up the oil also robs the engine of some power; it takes effort to push the crankshaft through all that extra oil. Drain the oil to the proper level. .......................................... You'll also blow out your engine seals. Gaskets that keep oil from getting into the wrong places. Replacement means engine removal. ............................................. it can also cause stuttering, bounced checks, male pattern baldness, halitosis, some rare untreatable malignancies and severe birth defects. don't risk it, drain a couple quarts out! ........................................................................... Have none of you heard of hydrolock? How about the piston attempting to submerge itself in oil, and the rod bending/breaking? Oil doesn't compress. It is the foundation for hydraulics. ...................................................

Yeah that's cool...I was very much worried due to lack of a main stand..however...how strong the silencer area to hold the bikes weight...I think its not advisable..so u need to place the lifter where the cradle is...the bike is longer so the rear end wouldnt raise that easily..however..this is a great idea to have a try.. Thanks for all the replies...thanx Gas up-Lets Go and Growl for the solutions..May you never get a bike trouble! Oh..guys I just wanna say..right after I rode the bike and stopped..the rear hub became extremely heavy..which meant extreme friction...we removed break shoes too and they were kinda worn...one bearing too required replacement.. Yes the Cush rubbers were broken only..they perfectly fitted the hub.. And my mechanic said too much oil in the engine causes issues only in the two-stroke engines, 4 strokes wont have issues..is that true guys..he's been working with bikes for ages..even from long before I was born..

Hi guys..I opened the covers, wheel was not moving, one bearing requires replacing, all the dampers were broken from the top small piece of rubber that connects one pair..they were not worn out though..bearing's worn out seemed very small...so what is the problem here..thanks for replies..

These guys seem to be cool.. enjoy!

Really..he he...Paul what will you feel as u ride the bike when these dampers are worn out? will you experience what I am...?

Thanks Paul, am really worried of this strange friction issue...I should get it checked...this has become a big issue only because the bike has no main stand...otherwise checking is not a prob..mechanics are reluctant to have look, they scratch head when it comes to remove the rear tyres..

Hi guys, Rear sprocket of the bike had some slight forward-backward rotation which I didnt pay much attention, but now the movement distance has increased lets say twice the earlier distance..I asked from a mechanic and he said its the rubber dampers..but we didnt disassemble it to see.. I checked on the net to find dampers but couldnt find any vendor. Am referring to what the image below depicts; Uploaded with ImageShack.us As I ride I feel some creeky noise from the rear axle..its not very loud...break working fine, as I move the bike neutral engine off the wheel causes a slight vibration on the frame which is prominent if you hold on the sissy arm.. They are available for other bikes as a 4/3 set but I dont know what is the size and dimensions..can someonehelp me with the dimensions so I can match them up with what is available in the market? The wheel not shaking at all..its perfect...sorry am hoping I gave u the idea..I may not be using proper words u use for stuff like this... Thank you guys...!

Yeah Ray, thanks, those manuals have bunch of details..I went through the fork disassembly which had two different entities. I wish to buy a complete gasket set too...plus the steering head may be.. Need to change oil and may be oil filter.. Thank u very much!

Hi guys, I think I wasnt given correct answer to my oil seal vs dust seal clarification request. I found these from ebay and before ordering I just wanna know if oil seals and dust seals are two different entities and since am going to refill forks would I need to keep both in hand? Can you tell me if these are oil seals or dust seals? How can I find oil seals? http://cgi.ebay.com/ebaymotors/Yamaha-XV125-XV-125-Virago-1997-2000-Fork-Seals-_W0QQcmdZViewItemQQhashZitem53dfb7ff3aQQitemZ360235663162QQptZMotorcyclesQ5fPartsQ5fAccessories link says they are oil seals..

Oh about Havoline Super 4T engine oil... It is 4 stroke motorcycle engine oil SAE 20W-40 for Air and liquid cooled Japanese high performance motor cycles... This is the standard being used here.

OK Paul, Ray just mailed me two manuals..will go through them..thank you guys!

Yeah guys..I should do all those as quickly as I can..thanx a lot...hey I know where the oil level window is Anyway thanx for the useful tips, I just saved them for reference in a word file.

Hi Guys, I got bike checked for the front forks the other day and the mechanic said I will have to replace the CUP SET...that is what they call it in bikes may be the term is wrong..is it the bearing set I dont know..they just use wrong English terms mostly so my not know the technical term. Like I said earlier here there's a Taka Taka hit on the handle when you are on the bumps of the road..perfect on leveled roads. I made the bike upright and held the wheel hard to see if it moves front-backward from steering head...yes there's a very small movement. Mechanic tightened the bolts in steering head but said soon I will have to replace this CUP Set..at this point I wish to get the oil of the front forks changed..for this I think I need both dust seals and oil seals..am I right? Should I keep them ready..dust seals are what you see black outside right..they needs to be replaced..on one fork I see some oil mark which suggests me that I should change oil seals too? I just want to know, how often do you have to clean or change following? Engine oil filter - I think u can clean this with kerosine maybe and reuse it. Air filter - normally garage people get the sponges and squeeze them in petrol..is that the accepted way? Engine oil - what is the indicator that tells me I should change oil, heavy, sticky blackish oil? I filled the reservoir with 40 havoline oil right after I bought the bike..is there an upper limit in oil filling, what if someone overfills the engine with oil? I think more oil gives better lubrication? Does oil filter wear out normally..replacing or cleaning, which is the economical? Oh Paul, Neversaydie and Chris...bike is doing good..I am looking at ebay to buy some parts - oil and dust seals for front forks, oil filter may be and complete gasket set..

Paul...I think I will need a more latest bike..normally I dont like old ones...I will consider this seriously...

Well Paul..tires are in line now..I need to keep dust and oil seals ready for the front forks..am going to buy them from ebay... Tires are inline now..we removed the swing arm and placed it on a leveled floor..surprisingly enough both arms were at same level..however, the very end of left swing arm was kinda twisted somewhat..but tire was not affected..we corrected it.. Paul, I will be able to sell this at a similar or higher price..but for importing a bike lot of handling and freight charges plus taxes will e involved right..then the price will get closer to the amount I specified..or even higher..different countries have different import/export regulations/taxes etc.. But let me consider importing one someday...lets see if its possible..hope you will be around till then...

Hi guys...the socket had similar dimensions on both arms...there were no cracks and the bushes were working fine..there was no misalignment in rear tyre..what the hell was causing shocks to bend.. will soon have to put new dust seals and oil seals for front shockets.. B)

I get ur points..they are reasonable..but I spent all my saved bucks to buy this and lets see, let me try shock guy and see what he has to say.. Bike having some issues...nothing so far in the engine....except as you ride it say 30 kms...sometimes say I ride at 40kmph...engine suddenly pauses as if I hit breaks and in nearly 2 seconds start to run normally...I dont know what it is but problems other than the engine can be slowly taken into consideration..at the beginning I thought to myself I would bring this bike into superb condition..I bought this for 120,000 rupees which equals to around 1000USD...for that amount I think its cheap.. Cruiser bikes are not very popular here but already many have asked if I would sell it. At least I would be able to bring this bike to a good condition and if problems rise I would sell it. I love to import a bike Paul but it would be huge money..also I prefer 125cc as they are fuel efficient, also you cannot import above 350cc bikes to Sri Lanka..police bikes here are 400cc so u cannot exceed their capacity..means they should be able to catch any civilian bike..I love latest bikes I see on Yamaha.com...but am not that good with money...I think Viragos are pricey in UK? I will check front forks too with that guy..oiling would fix it hopefully, no oil coming out...will I get some hole to fill some oil once I unscrew top bolts of front forks? I think this faulty swing arm causing front wheel to wear out more at left?

Hi Ray thanks for the concern and reply...well here there are good roads in the most cases..you should be mindful when riding to avoid them..you can have a look at sri lankan road images here; http://www.google.lk/images?hl=en&q=sri%20lankan%20roads&um=1&ie=UTF-8&source=og&sa=N&tab=wi&biw=1272&bih=600 As for the bike issues, yes you are right about the safety and all..but in addition to these shock problems all the other areas are in good condition..engine was checked with a mechanic and and all the electric items are working fine so far..am going to have a look at air filter and oil filter plus sprokets once I buy the tool set..with me she will be fine.. I should address swing bar and front sockets and hopefully that will fix the issues..so I should wait till those get done..if the problems going to persist I would consider selling it... This guy I spoke about deals with all the shock absorber and axle cases in japanese vehicles..he's got tools...so let me try..I still do understand your point Ray..but I love the bike too much to lose it..I want a comfy ride and this has made me feel like am on a cradle...

I found a guy who I think will give me a solution...must take bike there soon..

Hey Paul that left spacer we talking about is on the rear sproket career right..I think I have it...well if the spacer is missing I think the axle should become narrow...I mean gap should be shorter..but there's no issue, at the back view, shocks are perfectly vertical.

I experience some TAKA TAKA sound when bike riding on uneven surfaces in front sockets..I checked steering head and its fine, I think I need to oil the sockets..for that you need to remove those oil seals and you need to keep new ones ready I guess? Am I right? When I looked for oil seals on ebay...I saw DUST SEALS for front shocks and OIL SEALS for fron shocks XV 125..both these names stand for the same or are they two different items... Please check the link below...I dont understand these prices, they seem to be very low and similar irrespective of the item's function and size... http://motors-parts.shop.ebay.co.uk/Motorcycle-Parts-Accessories-/14780/i.html?_trkparms=65%253A2%257C66%253A2%257C39%253A1&rt=nc&_nkw=yamaha%20virago&_dmpt=UK_Motorcycle_Parts&_sop=2&_trksid=p3286.c0.m14.l1513&_pgn=9 I think I should buy this... http://cgi.ebay.co.uk/FORK-SEALS-YAMAHA-XV-125-XV125-VIRAGO-1998-2001-/290394463876?pt=UK_Motorcycle_Parts&hash=item439cdbde84 My friend in US will buy them and post me..at her cost Please help me Paul..

Plus I want to buy some Allen key set and necessary wrenches for the bike? Will I have to show the bike to the shop when buying them? Or what are the sizes u use Paul? Sorry if am questioning too much..