'HONDA - STOCK AIRBOX OR NOT'
- Thread starter Shooter
- Start date
I do some vintage racing, we always take off the stock airbox and either run single filters or open bellmouths or velocity stacks. It may seem difficult to change jets but it really only takes a few minutes. What you will be concerned with is the primary jet, this operates the carb up to approximatly 1/2 throttle then the main jet kicks in to full throttle. Now before some of you guys jump all over this with your objections let me say there are some other adjustments to make with air screws and needle jets. I am just trying to simplify this explanation. 350,550,750 Hondas are fairly simple. Usually just a jet change will fix it up to run on the street with a header What you have to do is match your carb settings with your engine mods. For instance, just a header and no engine mods might just be up 1 size on the main so there is no bogg going from half to full throttle. With porting and piston work you would need to make alot of adjustments. In this case I would recommend time on a dyno.
At this stage of the game I have done it enough I tend to go by the seat of my pants and can figure out what changes to make.
There are times when going 1 size down on a jet makes the bike run real crisp. Jets are cheap, any bike shop will carry them. They are easy to change, you will feel a difference.
I would think you would want to buy a book on carb adjustments, read it, read it again, find a donor carb that you can take apartand see the parts that the book is refering to while you are reading for the third time. Once you are familiar with the working parts and what their functions are you will be able to make your carbs run smooth.
I am now racing a 1970 Suzuki T250 which is a 2 stroke. Jetting is crucial on these to make them go. You have to moniter the weather, temp as well as barometer. Sometimes jet changes from morning till noon then another change at noon then another change in the afternoon. I am just learning but it is fun.
I used to race a CB350, and have been involved with a CB550 and CB750. The 750 had cams, pistons and head work, man it was fast. We had trouble with the jetting, we could get it close but not perfect always had a flat spot in different places in the rpm range. So off to the dyno it went. It was great after that.
Hope I didn't ramble to much, I am better at doing than I am at writing or explaining something. Any questions feel free to shoot me a line.
Greg
At this stage of the game I have done it enough I tend to go by the seat of my pants and can figure out what changes to make.
There are times when going 1 size down on a jet makes the bike run real crisp. Jets are cheap, any bike shop will carry them. They are easy to change, you will feel a difference.
I would think you would want to buy a book on carb adjustments, read it, read it again, find a donor carb that you can take apartand see the parts that the book is refering to while you are reading for the third time. Once you are familiar with the working parts and what their functions are you will be able to make your carbs run smooth.
I am now racing a 1970 Suzuki T250 which is a 2 stroke. Jetting is crucial on these to make them go. You have to moniter the weather, temp as well as barometer. Sometimes jet changes from morning till noon then another change at noon then another change in the afternoon. I am just learning but it is fun.
I used to race a CB350, and have been involved with a CB550 and CB750. The 750 had cams, pistons and head work, man it was fast. We had trouble with the jetting, we could get it close but not perfect always had a flat spot in different places in the rpm range. So off to the dyno it went. It was great after that.
Hope I didn't ramble to much, I am better at doing than I am at writing or explaining something. Any questions feel free to shoot me a line.
Greg
For street use I'd strongly recommend running the stock airbox. Certainly you can run pods, or heck just velocity stacks, but you'll have a lot of work ahead of you tuning and adjusting things.
What are your plans for the bike?
Another reason removing the airbox works in racing applications might be the corresponding removal of a bunch of the electronics and battery that sit around the airbox. Removing all these bits and the sidecovers would certainly improve airflow to the individual filters. Anecdotally people have suggested that cylinders 1 and 4 get different airflow than 2 and 3 when running pods.
Anyhow - it all depends on your application. If you're racing or building a performance oriented bike with different exhaust, ported heads, cams etc. etc. then pods are the way to go. For a stock bike I don't see the point. Good pods are expensive and require lots of tuning to make work well.
What are your plans for the bike?
Another reason removing the airbox works in racing applications might be the corresponding removal of a bunch of the electronics and battery that sit around the airbox. Removing all these bits and the sidecovers would certainly improve airflow to the individual filters. Anecdotally people have suggested that cylinders 1 and 4 get different airflow than 2 and 3 when running pods.
Anyhow - it all depends on your application. If you're racing or building a performance oriented bike with different exhaust, ported heads, cams etc. etc. then pods are the way to go. For a stock bike I don't see the point. Good pods are expensive and require lots of tuning to make work well.
Just a note to go with my last post.
The reason for removing the airbox is because they restrict the air flow to the carbs. Its got nothing to do with electrical parts around it. Even for vintage racing some fellows run the full wiring harness as well as a battery.
what your trying to do by removing the airbox is get more air down the throat of the carb. More air means more POWER as long as the carbs are adjusted to increase the flow of gas.
I am only familiar with bikes in the 1970's to early 80's as I beleive the bikes of the mid 80's to now have a very efficient sealed airbox. Removing side covers does nothing as i understand that the carbs actually suck in DEAD air.
I have owned lots of bikes and one of the first mods I do is remove the airbox and put on singles, I do this mostly for the looks of the bike. Looks are important. Next comes the header, mostly for the looks also for the sound. Again looks are very important, sound is equally as important. If a couple of horsepower is found its a bonus. These are street bikes I am talking about.
Step one, install desired part. Step 2, start and ride the bike. Step 3 make a mental note of the performance of the bike. Step 4, if there is a bog or flat spot or hic-up any other thing you might want to call it determine where on the throttle position it is happening, Idle, 1/4, 1/2, full throttle. Refer to the carb book that you have and it will tell you what function of the carb to address.
You may have something as little as a flat spot at 100-105 kph. No biggie just ride faster.
This is not the dark arts, I am not the brightest bulb in the package but with the book and some tinkering I get by.
Don't let anyone with little knowledge and narrow minded opinions influence your decision as to what you put on your bike.
Tin Tin I think this fellow ask for "tips" not opinions. It is his bike and you don't have to "see the point".
Thats the beauty of the older bikes we can do what we want to them to make them our own.
If you want to modify great, if you want to keep it stock more power to you. I won't judge or critisize what you do so please extend me the same courtesy.
Greg
The reason for removing the airbox is because they restrict the air flow to the carbs. Its got nothing to do with electrical parts around it. Even for vintage racing some fellows run the full wiring harness as well as a battery.
what your trying to do by removing the airbox is get more air down the throat of the carb. More air means more POWER as long as the carbs are adjusted to increase the flow of gas.
I am only familiar with bikes in the 1970's to early 80's as I beleive the bikes of the mid 80's to now have a very efficient sealed airbox. Removing side covers does nothing as i understand that the carbs actually suck in DEAD air.
I have owned lots of bikes and one of the first mods I do is remove the airbox and put on singles, I do this mostly for the looks of the bike. Looks are important. Next comes the header, mostly for the looks also for the sound. Again looks are very important, sound is equally as important. If a couple of horsepower is found its a bonus. These are street bikes I am talking about.
Step one, install desired part. Step 2, start and ride the bike. Step 3 make a mental note of the performance of the bike. Step 4, if there is a bog or flat spot or hic-up any other thing you might want to call it determine where on the throttle position it is happening, Idle, 1/4, 1/2, full throttle. Refer to the carb book that you have and it will tell you what function of the carb to address.
You may have something as little as a flat spot at 100-105 kph. No biggie just ride faster.
This is not the dark arts, I am not the brightest bulb in the package but with the book and some tinkering I get by.
Don't let anyone with little knowledge and narrow minded opinions influence your decision as to what you put on your bike.
Tin Tin I think this fellow ask for "tips" not opinions. It is his bike and you don't have to "see the point".
Thats the beauty of the older bikes we can do what we want to them to make them our own.
If you want to modify great, if you want to keep it stock more power to you. I won't judge or critisize what you do so please extend me the same courtesy.
Greg
Actually, the first two words of his first post are 'Discussion wanted', and we've certainly gotten that!
My 'opinion' on stock vs. pods for the SOHC4 Honda's is based on my personal experience with my CB750K, CB500K and CB550F, as well as based on many similar discussions over at www.SOHC4.net, the definitive forum for SOHC4 Honda's. I've tried aftermarket cheap pods, K&N pods and stock airboxes both the 500 and 550.
One strong point in favour of pods is removing/installing carbs. Makes it much easier than trying to sandwhich them between the airbox and intakes. If you're changing the header/exhaust to the point where jetting the carbs is necessary, then by all means, run pods too for both aesthetics and performance.
Not sure where I criticized you, T 250. If somewhere I did, I apologize. When I say I don't see the point of running pods on an otherwise stock street bike, I mean it from a technical standpoint. I'm not commenting on someone's personal choice of what sort of airfilter to run.
My 'opinion' on stock vs. pods for the SOHC4 Honda's is based on my personal experience with my CB750K, CB500K and CB550F, as well as based on many similar discussions over at www.SOHC4.net, the definitive forum for SOHC4 Honda's. I've tried aftermarket cheap pods, K&N pods and stock airboxes both the 500 and 550.
One strong point in favour of pods is removing/installing carbs. Makes it much easier than trying to sandwhich them between the airbox and intakes. If you're changing the header/exhaust to the point where jetting the carbs is necessary, then by all means, run pods too for both aesthetics and performance.
Not sure where I criticized you, T 250. If somewhere I did, I apologize. When I say I don't see the point of running pods on an otherwise stock street bike, I mean it from a technical standpoint. I'm not commenting on someone's personal choice of what sort of airfilter to run.
Ditch the stock airbox and run either REAL K&n filters (not those crap EMIGO ones) or V-Stacks..
I have had v-stacks on my CB750 for over two years now and have had NO issues what so ever..
I got K&n's on the CB450 and from the 15 min or so I rode it seemed fine..
I have had v-stacks on my CB750 for over two years now and have had NO issues what so ever..
I got K&n's on the CB450 and from the 15 min or so I rode it seemed fine..
Shooter
Been Around the Block
Thanx for discussion and info guys. I am definitely going to try not using the stock airbox because I have my heart set on that look. . If I can make it work ...great. If not - I will revert to stock.
Any links or pix to the real K&N filters used by ProTeal55?
Currently my bike is getting new seals and O rings etc in the Carb set. (leaks)
I will start the strip down next week.
Any links or pix to the real K&N filters used by ProTeal55?
Currently my bike is getting new seals and O rings etc in the Carb set. (leaks)
I will start the strip down next week.
Is it for a 750 or 550? For the 500/550, you need a specific filter - the cone shaped ones will not fit - the ones you want are shaped like canned tuna fish cans. Just a plain cylinder.
The taller ones won't fit between the carbs and frame rails on #1 and #4 cylinders.
The taller ones won't fit between the carbs and frame rails on #1 and #4 cylinders.
I also like "the look" of pods and for my riding style, I'm not worried about performance gains. I ride an XS650 with stock CV carbs. These carbs are notoriously a pain in the ass to begin with, but when they're on, they're good for regular old street riding. I was having some issues with mine which neccesitated me taking them off and on frequently. So one day, I just left the airbox off. With open carbs, it would backfire violently at the carb and was only rideable with the choke on. I experimented by hoseclamping some filter foam material from the stock filters right to the carb and that air restriction was enough to get it running good again. Now, I still have no intention of putting the airbox back on, I ordered some pods but they weren't restrictive enough and the carbs were popping again. So, I put back the foam material on the carbs and put the pods on over them. Now I have pods with no carb mods and it runs great. The only reason I have the sidecovers still is that I haven't moved the electrical gear yet but it's in the works. Hope this helps. I have very little knowledge of carb tuning and that can be very frustrating when you just wanna ride and something so silly is making your bike run like crap. Hopefully, through picking up info on boards like this from the more experienced guys, we can re-jet and tune, etc without worrying about the world coming to an end!!
Yep, the look is important to me - that and making it easy to work in and around the filters. I also like the stock side covers and figure with my luck at some point one will come flying off when I'm on the road. So, I want to keep them safe. Yes, that's a cop out, I know. But, I'm a cop out artist.
Nate, I had an xs650 a few years back. with foam filters it ran fine, but I didn't like the oily filters so I purchased some of the cheapo filters and it ran like shit. took me a while to figure out why, and it had nothing to do with added air flow. what was happening was that on the cheap filters the rubber gasket that connects them to the carb there is a flange or lip. that lip covers the edges of the intake side of the carb and deflects air away from the jets that are around the perimeter. once I figured it out I slid the filters out a bit and it ran much better. the nice thing about the valve cover type that proteal is using is that there is no internal lip to disturb the airflow.Nate said:
Fear My Twin
Chicks hate my bike.
71cb750 said:
Holy shit.
I just went out to my CB500t. Sure enough. That was my problem the entire time.
Honned out with a dremmel and all is well. I was using the tall K&N cone filters, built for bikes but with that internal rubber lip. Completely restricted air flow to the jets.
Thanks a ton!
