TOPIC:

That's the pcv vent tube. I'll leave that alone.

Mine looks like that too. I may be able to get three on top and two on the bottom below the boots.
Steve

Irish-Kawi wrote:

650ed wrote: +1 The airboxes were not just slapped together without considering performance and noise. Here's some info that some may not have seen; a link to a Cycle World comprehensive pod test back in the day and an article quoting a Mikuni engineer who helped design airboxes. Both are related to stock street engines and airboxes vs. pods. Ed

kzrider.com/forum/3-carburetor/585949-po...-a-free-lunch#585949

Brilliant read and article Ed, and exactly what I was stumbling and bubbling through while trying to get across haha. Air is not looked at or seen as a gas in terms of engineering these bikes and how to tune and get performance out of them, it is treated as a liquid because in these conditions it behaves as a liquid. That means that there are man many many variables to consider as was touched on in that article. Unless someone has a fluid dynamics degree and engineering experience we just aren't going to outsmart these guys

Brett

Again, the engineer that designed this air box had to compromise. If the goal was only maximum air flow, the box would look much different. Since intake noise has to be kept to a minimum on a stock bike, restrictions are put in place to do so.

Our goal as "enthusiasts" is to reduce the restrictions at the cost of increased intake noise. The trick is figuring out how to reduce restriction and not disturb the engineered resonance tuning or air velocity.

I recommended placing the vents near the factory air filter to attempt to keep the intake resonance length close to stock. Cutting the pipe off of the cap is fine as long as the radius end of the cap is left in place. The pipe is simply there for noise reduction. The air filter creates air turbulence no matter what, so no worries about screwing that up. The air box boots are velocity stacks as I mentioned earlier. These will "smooth" air flow into the carb and maintain velocity. Don't mess with them.

JaFlo wrote:

Irish-Kawi wrote:

650ed wrote: +1 The airboxes were not just slapped together without considering performance and noise. Here's some info that some may not have seen; a link to a Cycle World comprehensive pod test back in the day and an article quoting a Mikuni engineer who helped design airboxes. Both are related to stock street engines and airboxes vs. pods. Ed

kzrider.com/forum/3-carburetor/585949-po...-a-free-lunch#585949

Brilliant read and article Ed, and exactly what I was stumbling and bubbling through while trying to get across haha. Air is not looked at or seen as a gas in terms of engineering these bikes and how to tune and get performance out of them, it is treated as a liquid because in these conditions it behaves as a liquid. That means that there are man many many variables to consider as was touched on in that article. Unless someone has a fluid dynamics degree and engineering experience we just aren't going to outsmart these guys

Brett

Again, the engineer that designed this air box had to compromise. If the goal was only maximum air flow, the box would look much different. Since intake noise has to be kept to a minimum on a stock bike, restrictions are put in place to do so.

Our goal as "enthusiasts" is to reduce the restrictions at the cost of increased intake noise. The trick is figuring out how to reduce restriction and not disturb the engineered resonance tuning or air velocity.

I recommended placing the vents near the factory air filter to attempt to keep the intake resonance length close to stock. Cutting the pipe off of the cap is fine as long as the radius end of the cap is left in place. The pipe is simply there for noise reduction. The air filter creates air turbulence no matter what, so no worries about screwing that up. The air box boots are velocity stacks as I mentioned earlier. These will "smooth" air flow into the carb and maintain velocity. Don't mess with them.

. can't say I necessarily agree with all of this, but that's the great part about so many people owning and working on and discussing these bikes is that we all have different opinions and if we can stay open minded we can learn a lot by listening and seeing things from different view points For the cap tube I would say it's an assumption that that is there for noise reduction but unless we hear from a Kawi engineer it's jut that an assumption. Yes noise restrictions compromise the performance aspect of designing an airbox but I don't believe that it's as dramatic a compromise as its being made out to be. Baffling is typically how sound reduction is dealt with. Meaning the main shape and design of the stock airbox would like lye look nearly identical if noise restrictions were removed from the equation and it would likely be the baffling that would be changed. Just my thoughts though and they are no more right or wrong than anyone else's

Brett

Irish-Kawi wrote: .......... For the cap tube I would say it's an assumption that that is there for noise reduction but unless we hear from a Kawi engineer it's jut that an assumption. Yes noise restrictions compromise the performance aspect of designing an airbox but I don't believe that it's as dramatic a compromise as its being made out to be. Baffling is typically how sound reduction is dealt with. Meaning the main shape and design of the stock airbox would like lye look nearly identical if noise restrictions were removed from the equation and it would likely be the baffling that would be changed. Just my thoughts though and they are no more right or wrong than anyone else's
Brett

I believe you are exactly right. Notice the stock airbox was used by the KZ650's that beat all the 750cc records at Daytona (see images below). I have no way of knowing if the stock filter, cap, etc. were used inside the box, but the carbs are definitely hooked up to the stock airbox. So if shape of the airbox or the airbox ducts were a problem those KZ650's would never have been able to exceed 130 mph for sustained periods using stock engines. Ed

Most racing classes have specific rules that regulate modifications. Stock air box may have been a requirement (I have no idea). It's pretty common in all types of racing to modify a stock part and bend the rules as much as possible.

Several years ago I did some dyno testing on an air box mod for a VW golf running in a "stock" class. Modifying the air box inlet netted 5hp at the top of the curve. Completely removing the air box and filter gained 10hp. Obviously the car had to have an air box, but a 5hp increase is very useful on a low power car.

JaFlo wrote:

Irish-Kawi wrote:

650ed wrote: +1 The airboxes were not just slapped together without considering performance and noise. Here's some info that some may not have seen; a link to a Cycle World comprehensive pod test back in the day and an article quoting a Mikuni engineer who helped design airboxes. Both are related to stock street engines and airboxes vs. pods. Ed

kzrider.com/forum/3-carburetor/585949-po...-a-free-lunch#585949

Brilliant read and article Ed, and exactly what I was stumbling and bubbling through while trying to get across haha. Air is not looked at or seen as a gas in terms of engineering these bikes and how to tune and get performance out of them, it is treated as a liquid because in these conditions it behaves as a liquid. That means that there are man many many variables to consider as was touched on in that article. Unless someone has a fluid dynamics degree and engineering experience we just aren't going to outsmart these guys

Brett

Again, the engineer that designed this air box had to compromise. If the goal was only maximum air flow, the box would look much different. Since intake noise has to be kept to a minimum on a stock bike, restrictions are put in place to do so.

Our goal as "enthusiasts" is to reduce the restrictions at the cost of increased intake noise. The trick is figuring out how to reduce restriction and not disturb the engineered resonance tuning or air velocity.

I recommended placing the vents near the factory air filter to attempt to keep the intake resonance length close to stock. Cutting the pipe off of the cap is fine as long as the radius end of the cap is left in place. The pipe is simply there for noise reduction. The air filter creates air turbulence no matter what, so no worries about screwing that up. The air box boots are velocity stacks as I mentioned earlier. These will "smooth" air flow into the carb and maintain velocity. Don't mess with them.

Another restriction is that the airbox is formed to fit around the down tubes that sit in front of the no. 1 & 4 carbs.
All motor vehicles are full of compromises. I'll let you folks swoon over the old days of beating up on the Honda
sohc 750. I'm more interested in applying more modern tech and engineering to improve upon some great machines.


.

The old Hondas were no problem except miller's 73 CB Hondadavidson. 1000cc's of power built by a guy that could squeeze every pony out of it and make it SCREAM. He walked on me more times than I care to mention.
My filters arrived today but I'm not home. When I get back I'll put them in and my 70 pilots too. Lean again. Adding them might just be the ticket.
Steve

Nebr_Rex wrote: Another restriction is that the airbox is formed to fit around the down tubes that sit in front of the no. 1 & 4 carbs.
All motor vehicles are full of compromises. I'll let you folks swoon over the old days of beating up on the Honda
sohc 750. I'm more interested in applying more modern tech and engineering to improve upon some great machines.
.

Down tubes in front of the no. 1 & 4 carbs? Seems like an odd configuration. My KZ650 has the cylinder head in front of all 4 carbs.

Honda sohc 750? I don't know about swooning, but you might find it interesting that the 750cc records that the KZ650's set were retained for 8 years after which the GSX-R finally set new 750cc records (but of course the KZ650 set the records using the smaller 652cc engine). I would suggest that between 1976 and 1984 there were plenty more 750 class bikes other than the Honda sohc 750. So what took the others so long to catch up to the KZ650? It wasn't a lack of money since Suzuki, Honda, Yamaha, etc. were pouring buckets of money into racing; and they certainly had riders willing to run on the track. Maybe they just didn't want to be embarrassed by not being able to beat the KZ650 records.

I understand your point about applying modern tech to increase performance, and if the engines have been modified with bigger valves, larger displacement, bigger carbs, etc. velocity stacks etc. might provide better top end performance. However, on a stock engine I am convinced that the stock airbox passes all the air the engine can use. Others may hold different opinions - that's ok too. Ed

For those who may have missed it .............

FWIW, I got my carbs dialed in yesterday and rode to work. Let's just say it I didn't take long. Glad I have the UK spec speedo so I could keep it reasonably under a ton. I don't know if I'm even going to worry about doing anything else to it.

I'd like to mention for those not familiar with my bike that I put 132.5 jets in when I was having issues after swapping on a ZR7 header. This seems to be the thing that was needed to make it all come together. I might see what happens if I lift the needles a notch.

Nebr_Rex wrote:

JaFlo wrote:

Irish-Kawi wrote:

650ed wrote: +1 The airboxes were not just slapped together without considering performance and noise. Here's some info that some may not have seen; a link to a Cycle World comprehensive pod test back in the day and an article quoting a Mikuni engineer who helped design airboxes. Both are related to stock street engines and airboxes vs. pods. Ed

kzrider.com/forum/3-carburetor/585949-po...-a-free-lunch#585949

Brilliant read and article Ed, and exactly what I was stumbling and bubbling through while trying to get across haha. Air is not looked at or seen as a gas in terms of engineering these bikes and how to tune and get performance out of them, it is treated as a liquid because in these conditions it behaves as a liquid. That means that there are man many many variables to consider as was touched on in that article. Unless someone has a fluid dynamics degree and engineering experience we just aren't going to outsmart these guys

Brett

Again, the engineer that designed this air box had to compromise. If the goal was only maximum air flow, the box would look much different. Since intake noise has to be kept to a minimum on a stock bike, restrictions are put in place to do so.

Our goal as "enthusiasts" is to reduce the restrictions at the cost of increased intake noise. The trick is figuring out how to reduce restriction and not disturb the engineered resonance tuning or air velocity.

I recommended placing the vents near the factory air filter to attempt to keep the intake resonance length close to stock. Cutting the pipe off of the cap is fine as long as the radius end of the cap is left in place. The pipe is simply there for noise reduction. The air filter creates air turbulence no matter what, so no worries about screwing that up. The air box boots are velocity stacks as I mentioned earlier. These will "smooth" air flow into the carb and maintain velocity. Don't mess with them.

Another restriction is that the airbox is formed to fit around the down tubes that sit in front of the no. 1 & 4 carbs.
All motor vehicles are full of compromises. I'll let you folks swoon over the old days of beating up on the Honda
sohc 750. I'm more interested in applying more modern tech and engineering to improve upon some great machines.


.

Not sure if it is just how I am reading it or taking it, but I can't figure out why you are trying to pick a fight.

As I said many many many times in this thread, we are each entitled to our own opinions and your opinion is no more right or wrong or factual than mis own, easy to just let it be I also don't recall anyone "living in the past" or talk of that in this thread but rather discussion on how modifications to the stock airbox may not be the benefit that many believe. In one of the examples a few posts back the author was talking about how changes to a VW airbox netted 5hp on the top end and further changes netted 10hp. I think that i a tremendous gain and hugely beneficial.... for power on the TOP END. What was not mentioned was what HP changes (loss or gain, but likely loss) was netted in the low and mid range due to those changes. As stated, any change is a compromise and f you gain HP in one place, chances are good that you lost HP in another to get that gain.

There was a gentleman named Tak Shiarmizu in Denver, CO that owned and ran Tak's Mile High Machine Shop... when I met him at 16 yrs old he was already 93 years old and had lived through the Japanese Internment Camps in California during WW2. He was one of the smartest machinists I have ever known and lived with him for 2 weeks while he taught me his trade and we machined, blueprinted and balanced my entire engine for my Camaro. But the very first time I met him he asked what I wanted my car to do... I started saying stuff like pull 1 G on the skid pad, do a 13 second quarter mile, get 25 mph etc etc. The more I spoke the bigger and bigger his eyes got until they bugged out and looked at me like I was a complete simpleton (and truth is he was right ) for wanting my cake and eating it too. Before he replied he went back into his shop on his hands and knees digging around before he pulled out a 1 foot length of 2x4 wood. He walked up and shook it in my face and said very heatedly... "If you want it to do a 13 second quarter mile, we will cut some of the 2x4 off of this end and put it on the other end, then it do 13 second quarter mile. If you want it to do 1 G on the skidpad, then we will cut some off the other end and put it on the opposite end. If you want it to do 25 MPG then we cut some from the middle and add it to the sides. But there aint no more F'ing 2X4, you can't add 2X4 to both ends and the middle, there is only so much 2X4 to go around and you will have to take it from some place to add it to another!!!!"

The whole point of him saying that is that there is always a trade off... in the VW example to get more top end ponies you cut off one end of the 2X4 and added it to the other end. The compromise was to take power from somewhere else in the curve to add it to another area, but this still holds true... THERE AINT MORE 2X4!!!!

Brett