carburetor jetting- long...

[Mark Wilson]

> >Check out the Areostich Tank Panniers. they really keep the wind off > your legs, including your knees. > > Any photos of these things installed? I'd like to see how they look > and how they mount onto the bike... What's involved in getting them > on and off? > > RM

There is a picture of my tank panniers about half way down this webpage - http://www.angelfire.com/mo/motormark/ Some people cross the straps over the tank, I like mine like this. All you have to do to get them on/off is hook/unhook 4 bungie cords. Get the big ones. MotorMark

[Thomas Baumen]

I was in WALMART the other day looking or the BUNSAVER self inflating seat cushion. They did not have any. But they did have a set of Tank Panniers for ATV,Snowmobile, and Motorcycle use in several colors and with features like a small tank bag between the two panniers. Cordura was the material and they looked rally cool. $29.95 ..........1/4th what Aerostich wants for theirs...... I am sure they are not as nifty neato as the Aeros but for $29.95 I bet they will work just fine. Tom Baumen

[RM]

--- Thomas Baumen wrote:

>But they did have a set of Tank Panniers for ATV,Snowmobile, and >Motorcycle use in several colors and with features like a small tank >bag between the two panniers. Cordura was the material and they looked >rally cool.

Tank panniers? At Wal-Mart? Where? The camping gear? Automotive? I'm amazed. Maybe it's a regional thing. Never seen tank panniers here in SoCal, along with no snow-shoes. I'm going to look tonight. RM __________________________________________________ Do You Yahoo!? NEW from Yahoo! GeoCities - quick and easy web site hosting, just $8.95/month. http://geocities.yahoo.com/ps/info1

[Donnie W. Jennings]

Hi! I have a Kawasaki Brand tank bag on my 02 KLR650 and would like to get a medium size pair of tank panniers that will work with the existing tank bag. Any suggestions? Thanks! Donnie

[LD]

Me too! I also have the Kawasaki tank bag and am looking for panniers that will work with it. I like the look of the Dual Star panniers and am wondering if anyone has any experiece with them... __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com

[D Critchley]

I bought some very nice pannier bags from Aerostitch. Because I have hwy pegs fitted, I had to make a choice between not using them or having an additional knee installed half way up my shin bone. It was a difficult choice, but now I have a problem finding socks to go over the extra knee. DC LD wrote:

> Me too! > I also have the Kawasaki tank bag and am looking for > pa > > . > >

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[Jud Jones]

--- In DSN_KLR650@yahoogroups.com, "Tom Bowman" wrote:

> > If anyone has a set of Aerostich Tank Panniers on their KLR and > could supply some photos, I'd be much obliged. Am considering a > set but would like to see how they mount, fit, and look. > > TIA, > Tom Bowman > Atlanta >

I posted a couple of photos that show the Aero panniers mounted on my bike and Craig Olson's. They are the last two pics in the Moto Mutts Mexico 2006 album. I suggest you cross the top straps; it helps the panniers sit better on the tank.

[Norm Keller]

Having modified the air box, re-jetting is underway. For anyone who is thinking of undertaking this project my A18 is stock as regards engine and exhaust. Elevation is usually between 50 feet and 2250 feet above sea level. The air box has had the flash arrestor screen removed and the inlet (rubber) snorkel removed. It has not had additional holes added. Maybe later. The first attempt to compensate was by shimming the needle up 0.024" which was expected to richen the mixture throughout the low and mid-range with less effect (if any) at the top end of the throttle range. There was a marked increase in power through the range of throttle and RPM as expected but a definite "flat spot" was experienced during the last 5% of the throttle opening. The flat spot was so pronounced that backing the throttle closed by about 5% produced a definite increase in acceleration. Not surprising! At that time I posted to ask if anyone had measured the slide travel and needle relationship to determine whether the needle leaves the metering orifice at wide open throttle. No measurements were forth-coming but several opinions were offered that the needle only contributes to low and mid-range (throttle position) metering and that the needle is completely out of the metering orifice at wide open throttle. No one has offered measurements to confirm that this is the case so I do not know whether this is theory or fact. Please note that I am not offering criticism of any kind but simply attempting to set out what I know. While it seems obvious that the needle plays no part in wide open throttle, it is often the case that the needle does not completely leave the metering orifice when the slide is wide open. It is well to consider CV carburetors such as SU and Stromberg in which metering adjustments are most often accomplished without change to the main jet, by changing the needle to affect even WOT jetting. I am not sure whether the KLR's Kehin follows this pattern. It seems to be commonly held that the Kehin's needle is completely out of the picture at wide open but not confirmed. Normal jetting practice is to select the main jet which provides best power at wide open throttle and then to select the needle which has the correct profile for the metering required at smaller throttle settings. Note the choice of the term "profile" rather than the more commonly used "taper". For street machines, it is often ideal to select for a rich mixture at wide open throttle with a more stochiometric ratio (closer to the 14.7:1 ideal air to gasoline) at smaller throttle settings for better economy. Selection of the main jet is relatively easy as compared to finding the correct needle profile. The reason for this is that the engine's air flow rate is not linear so one cannot simply select a needle with a standard taper. For tuning purposes, some suppliers offer a selection of needles with a wide variation of profiles in order to match requirements. Remember that an engine will be quite happy with a richer than ideal mixture so finding the ideal mixture = needle profile can be very challenging for a variable velocity carburetor. Motorcycle carburetors are of two main types: 1) Constant velocity such as the KLR's. 2) Variable velocity such as typical for smaller bikes such as TTR125 Yamahas and the like. Other carburetors types are also used but not commonly on bikes. Constant velocity carburetors generally use a diaphragm to control the venturi slide and can be identified by the presence of the diaphragm "pot" and that the slide and butterfly throttle are separate. Variable velocity carburetors (motorcycle) generally use a cable operated slide which both forms the venturi area and controls the air flow (throttle) into the intake. The cable operated slide carburetors are simpler to work out needle taper requirements because the needle will be 1/2 way up then the throttle is 1/2 way open, 1/4 @ 1/4, etc. For this reason it is simply a matter of determining whether the fuel/air mix is richer or leaner than desired at a given throttle opening and then selecting a jet which is either thicker (leaner) or thinner (richer) at that point. We used to sand paper the needle to get the right profile in many cases. When the constant velocity (CV) carburetor is involved as on the KLR things become more difficult. The problem here is that the slide is not directly connected to the throttle so the slide may be 1/4 open or 1/2 open, or 3/4 open when the throttle is (for example) 1/2 open. In this case you can see that selecting the idle needle profile is more challenging. If the engine can be operated on a dynamometer so that the bike does not need to be in motion, things are much simpler. If an exhaust gas analyser is available things are even simpler. Since I do not have access to a dyno, that could be fudged by measuring intake manifold vacuum at some throttle openings versus speeds as noted in top gear at a given RPM. The reason for RPM is that the KLR's speedo is on the front wheel. The idea is to mount the bike with rear tire off the ground, operate at the noted RPM and use the brake to load the engine until the throttle is opened to the point where the intake manifold vacuum matches that recorded. A quick measure of exhaust gas CO will indicate whether the mixture needs to be corrected richer or leaner. I may borrow a customer's portable exhaust gas analyzer and do this under way. Following measure a guess-timate of needle position and changing the needle will move the mix. The effect of the first needle change will pretty well indicate where the needle profile change needs to go. Since my bike has stock exhaust and is operated mostly at 50 feet, I had hoped that someone had done this work. A 162.5 main jet was installed for a ride to the cottage this weekend as the 148 (stock) with shimmed needle showed lean indications at WOT as noted. It should be noted that performance throughout the remainder of the range was vastly improved with better and smoother operation in the 2,000 RPM+ range. Performance with the 162.5 indicates a rich condition through the range but the engine revs better to 7,500 RPM. The last 10 miles to the cottage increases elevation from less than 100 feet to 2250 feet. As expected the indications of over-rich mixture became more evident as the climb continued. This is expected because the air is less dense at higher elevations so less mass of air will enter the engine at the same air volume. Since carburetors deliver fuel according to air volume, an increase in elevation will result in richer mix. When time allows a 155 will be the next try. I expect that the needle will need to be changed in order to provide the correct mixture because the air box changes will have no effect at small throttle openings but will be more pronounced as throttle opening increases. For this reason the 148 main jet and stock needle will likely be OK at lower throttle openings but a larger main jet or smaller needle diameter (same effect) will be needed at greater air flow rates (wider throttle openings). The reason for this change is that a decrease in intake air restriction will have little effect during periods of smaller air flow volume (smaller throttle opening). The effect of reduction in air intake restriction will be most pronounced as air flow volume reaches near maximum. This is the same effect as installing an air intake restrictor or exhaust restrictor onto a kid's motorcycle to reduce performance. The restrictor has no effect at part throttle but kills power increase at wider throttle opening. The reason for the increase in power throughout the RPM and throttle range due to a shimmed needle is that the air-fuel mix will be richer so power will increase. Remember that engines like a bit richer than ideal because extra fuel is available to ensure that all the air is burned (I know but it's easier to say this way and you know what I mean). If the mixture is too rich, the extra mass of unburned fuel acts to cool combustion temperature and power goes down. Many posts have indicated that modifications to the air box have required changes to jetting. It is usually observed that mileage has dropped by 5%, 10% or such. A reduction in air box restriction should have no effect on mileage under part throttle cruise conditions if the air fuel ratio remains as before. Hard to achieve! As noted earlier, an engine will operate satisfactorily when richer than ideal but less so, when leaner. When the ideal mixture ratio of 14.7 parts of air to one part of gasoline (by weight, not by volume) is modified toward the lean, it does not take much change before the effect is noticed by a drop in power. If the ideal mixture is modified toward the rich (more fuel compared to air) the change has to be much greater before a drop in power is noticed. IN fact, power will increase for part of the rate of change before dropping off to normal and then less. Someone posted to remind me that leaner mixtures can result in detonation which can be undetected. Detonation, as he noted can cause catastrophic engine damage, so beware running a too lean mixture. I always appreciate such cautions as anyone can fail to appreciate the obvious and it is only good fortune in the garb of a caring friend which often saves the situation! I can't remember who posted but thanks! We best notice more power and want to avoid a potentially dangerous, too lean condition. For these reasons, re-jetting most often concentrates on finding a jetting/needle combination which provides best performance rather than ideal economy. That said, I will likely look to achieve a similar combination but it should be recognized that this is not necessarily what everyone desires. If the carburetor is jetted to provide the same air-fuel mixture as stock, the result will be the same fuel mileage. There is nothing magic about this. If the so jetted engine is operated at wide open throttle, it will produce more power by burning more air-fuel mix of the same ratio as the stock engine. In this case the mileage will decrease but the bike will proceed at a higher speed. At normal part throttle, efficiency can be slightly better than before but not less. Several posts have indicated that main jet and needle profiles are what control air-fuel ratio above idle and below wide open throttle. As I have stated, the needle profile does affect wide open air-fuel ratio in many CV carburetors so, subject to more information, I will have to consider that this may also be the case with our Kehin. Another aspect of CV carburetor operation which seems to have been ignored is the contribution of the CV plunger spring. Many tuners ignore the spring except to consider that too light a spring will allow a lean bog to occur since the slide opens too quickly to allow gasoline flow to keep pace. Another factor to consider is that a lighter spring will allow the CV slide to be opened more by the same air flow rate. The slide is opened be vacuum operating against the slide spring. Vacuum in the diaphragm chamber is (quite) proportional to air flow through the venturi so the effect of greater air flow is to open the slide further. This is the "constant velocity" aspect of these carburetors' operation. Air flow speed through the venturi, above idle, is almost the same regardless of engine load/throttle opening. If it is considered that a given air flow rate will apply a vacuum to the slide diaphragm such that the slide will rise a certain amount, reducing the spring's strength will allow the slide to rise further. Since air flow volume has not increased, but the fuel delivery rate has increased because the needle is higher in the metering orifice, the air/fuel mixture will be richer. From this it can be seen that three factors can be utilized to affect air/fuel ratio. Main jet size (bigger = more fuel = richer), needle profile smaller = more fuel = richer) and slide spring (weaker = higher needle position = more fuel = richer). Don'tcha love it when things are shown to be even more complicated than before? (VBG) A confession is that I'm just too time and energy challenged to spend the time needed to get this right so will end up with a compromise as have others. Ultimately, one possibility would be to buy a new stock air box with screen and use stock jetting. Having felt the effect of removing screen and snorkel with shimmed needle, well that's not an option. (VBG) Time to shut this off for now and do something else. Since working on the bike at the cottage is not ideal, jetting will wait. Enjoy your turkey! Norm [Non-text portions of this message have been removed]