butterfly valve

[Paulwhite]

hi all i need to make an adjustable butterfly valve for the air intake on the xvs bobber but not too sure the best way to go about it....

i can make the round plate no probs....its just how to connect it to the "axle?"(the bit that controls the movement) and how to make it so i can control how far it opens or closes ect,

the best idea iv come up with so far is to try and cut a bit of studding in half (legnthways) then wedge the plate in between, then stick a nut on each end to wedge it in the inlet pipe, but then comes the problem of controlling how far it opens... cause its replacing the original intake i need to move it at like 1mm increments to get the best out of the engine and find the "sweet spot" so to say..... but i dont think my idea will cut it. so any ideas are welcome

iv made a pic thingy to try and give a better idea.

[JimR]

hi all i need to make an adjustable butterfly valve for the air intake on the xvs bobber but not too sure the best way to go about it....

i can make the round plate no probs....its just how to connect it to the "axle?"(the bit that controls the movement) and how to make it so i can control how far it opens or closes ect,

the best idea iv come up with so far is to try and cut a bit of studding in half (legnthways) then wedge the plate in between, then stick a nut on each end to wedge it in the inlet pipe, but then comes the problem of controlling how far it opens... cause its replacing the original intake i need to move it at like 1mm increments to get the best out of the engine and find the "sweet spot" so to say..... but i dont think my idea will cut it. so any ideas are welcome

iv made a pic thingy to try and give a better idea.

Why do you need to make it in the first place ?

[Cynic]

Why don't you just go down the scrappers and get the throttle body from a small fuel injected car. Its ready made then you just need to work out the fixings. It will be ready to take a cable, fixings the lot.

[JimR]

Why don't you just go down the scrappers and get the throttle body from a small fuel injected car. Its ready made then you just need to work out the fixings. It will be ready to take a cable, fixings the lot.

Will a throttle body from a small injected car replace the orginal carbs ??? I have never done it ... does it work ? what electrics do you need ?

[Paulwhite]

well i need to make it cause the original air box for the engine wont fit in the frame so i need to come up with an alternative. (and you cant just put the filter straight onto the carb)the hole is an odd size about 46mm I/D , i cant get to any scrap yards as the ones i know of down my way have closed down , and iv looked on e-bay but there a little on the pricey side. (trying to do it as cheep as possible)

plus im wanting it to be like an idle screw on a carb so i can open it to a certain point then it can open more if the engine needs it.

[Paulwhite]

Will a throttle body from a small injected car replace the orginal carbs ??? I have never done it ... does it work ? what electrics do you need ?

no it cant replace a carb as you need something to do the air/fuel mix .....you could get fuel injection but its not worth the hastle to convert carb to fuel injection.

[JimR]

no it cant replace a carb as you need something to do the air/fuel mix .....you could get fuel injection but its not worth the hastle to convert carb to fuel injection.

I did n't mention that it was a retorical question some one else added that point I just replied. so as we are on the same page perhaps you could explain what the extra butterfly valve is required for ? I would guess the bike runs ok so you are trying to add some form of enhancement

[Paulwhite]

I did n't mention that it was a retorical question some one else added that point I just replied. so as we are on the same page perhaps you could explain what the extra butterfly valve is required for ? I would guess the bike runs ok so you are trying to add some form of enhancement

right il get u up to speed lol

im putting a cbr 125 (2004) engine into an xvs dragstar frame, the engine has a ported/polished head and free flow exhaust, it runs fine WITH the original air filter and box, but the airbox wont fit into the frame as its too big. so the problem i have is replacing the air box with something else that will work.(im assuming you know a bit about engines) i cant just stick a cone filter on the carb as its too free and just wont work, so the idea is to put that pipe on and "restrict" the airflow the same amount as the airbox, (as the engine needs to suck the air through the carb to get the right mix ect ect)

the best way i can think of is an adjustable butterfly valve to restrict the airflow allowing the engine to run the same as it did with the original airbox.

problem is im making it from scratch and wondered if anyone can come up with a better idea of how to go about making the valve

[barkwindjammer]

I think you'd be easier going down the 'make a suitable airbox' road, you mentioned that you are a dab hand with fibreglass, so I reckon you have the aptitude to fabricate an airbox that will fit the frame and do the job of getting the flow rate right, if you fit a butterfly then you will still have to filter the air before it enters the carb

if you can get hold of a CBR airbox then use the volume dimensions to calculate what you need

[drewpy]

right il get u up to speed lol

im putting a cbr 125 (2004) engine into an xvs dragstar frame, the engine has a ported/polished head and free flow exhaust, it runs fine WITH the original air filter and box, but the airbox wont fit into the frame as its too big. so the problem i have is replacing the air box with something else that will work.(im assuming you know a bit about engines) i cant just stick a cone filter on the carb as its too free and just wont work, so the idea is to put that pipe on and "restrict" the airflow the same amount as the airbox, (as the engine needs to suck the air through the carb to get the right mix ect ect)

the best way i can think of is an adjustable butterfly valve to restrict the airflow allowing the engine to run the same as it did with the original airbox.

problem is im making it from scratch and wondered if anyone can come up with a better idea of how to go about making the valve

the easiest way i can think of doing this is to get a straight cone filter preferably on an extension

something like this quick google i did

you could make a "vent" out of some alloy plate which you could turn to dial in the air flow that meets your engine needs

of course you could always go on a dyno and rejet, which is simpler!

[Airhead]

I dont know if your idea will work or not but now I understand your reasoning and its an interesting idea. However I think you are making it hard for yourself. So I assume the cone filter is within the box and you want to find the right restriction before the filter whilst having some kind of air box volume.

Why try to make a complicated butterfly valve for this?

Just drill a hole (not too big) aim to choke the bike at first, then gradually drill more or enlarge the hole untill you think its right, that would be a whole lot easier than this damper valve affair.

[barkwindjammer]

You could really make it fancypants by smashing up your Dads old Pentax

[Paulwhite]

cheers for the comments. here is what iv got so far

the problem is its too free, but putting that valve in the metal pipe in between the filter and hose will solve the problem......i hope.

ppl have said that you need at least 130% of the engines capacity of air, after the carb and b4 the filter for it to rev properly ....well there is more than that available here.

and the original airbox had a square k&n filter

[drewpy]

get a bit of thin ally and make a cone, you can resrict it that way!

[Paulwhite]

get a bit of thin ally and make a cone, you can resrict it that way!

im guessing the cone would go over the filter, and would have holes in it to allow the air through? if it is then it will be a pain in the backside to adjust for the engine.

i had a thought earlier, i could do the valve and spring load it so it would open with the force of the engine ...all id have to do is get the right tension spring then when the engine is at higher revs the valve will open more allowing more air flow.

[neversaydie]

cheers for the comments. here is what iv got so far

the problem is its too free, but putting that valve in the metal pipe in between the filter and hose will solve the problem......i hope.

ppl have said that you need at least 130% of the engines capacity of air, after the carb and b4 the filter for it to rev properly ....well there is more than that available here.

and the original airbox had a square k&n filter

Give us some idea of scale here. Whats the distance from the end of the red tube to the end of the (rubber?) clamp on the filter? Whats the ID and OD of the metal tube between the filter and the red tube? Can the length of that tube be increased? Whats the bore size of the red tube?

[Paulwhite]

Give us some idea of scale here. Whats the distance from the end of the red tube to the end of the (rubber?) clamp on the filter? Whats the ID and OD of the metal tube between the filter and the red tube? Can the length of that tube be increased? Whats the bore size of the red tube?

why would you need to know? all im askin is if someone knows a better way to make a butterfly valve, or has any idea of any other way of accuratly restricting air flow...... like barkwindjammer with the camera lens (mint idea by the way shame i dont have a camera to do it) or drewpy with the cover (the simplest ideas are normally the best) .

but anyway the inside diameter of the red silicone u-bend is 48mm, the aluminum pipe is about 44mm inside diameter and is 5 inch long (but is pushed right into the red silicone pipe), the tiles in the background are 5 inch each side. and it holds 525cc (1cc = 1 ml) of air. (not including the air filter) and it all comes off ebay .

[neversaydie]

why would you need to know? all im askin is if someone knows a better way to make a butterfly valve, or has any idea of any other way of accuratly restricting air flow...... like barkwindjammer with the camera lens (mint idea by the way shame i dont have a camera to do it) or drewpy with the cover (the simplest ideas are normally the best) .

but anyway the inside diameter of the red silicone u-bend is 48mm, the aluminum pipe is about 44mm inside diameter and is 5 inch long (but is pushed right into the red silicone pipe), the tiles in the background are 5 inch each side. and it holds 525cc (1cc = 1 ml) of air. (not including the air filter) and it all comes off ebay .

Why do I need to know? I dont need to, but you've asked if anyone knows a better way to make a valve, or can offer another suggestion to restrict airflow. I assumed that your request meant all users of the forum. On that basis, it better to know what physical size we're talking about in order to try and get a fit.

I offer 2 suggestions, 1st is log onto the RS Components web site and type in 282-5176 in the search box. I know its a ball valve, but does that make a difference?, physical dims look about right on the 40mm bore valve, cost is around £20. Failing that, the only other thing I can suggest is that you get hold of some plastic downpipe to experiment with as its cheaper and easier to work with, cut and fit/glue a disc in and as others have said, increase hole sizes in it until you achieve the reqd result. Once done, have it fabbed up in ali/stainless etc

Ray

[JimR]

right il get u up to speed lol

im putting a cbr 125 (2004) engine into an xvs dragstar frame, the engine has a ported/polished head and free flow exhaust, it runs fine WITH the original air filter and box, but the airbox wont fit into the frame as its too big. so the problem i have is replacing the air box with something else that will work.(im assuming you know a bit about engines) i cant just stick a cone filter on the carb as its too free and just wont work, so the idea is to put that pipe on and "restrict" the airflow the same amount as the airbox, (as the engine needs to suck the air through the carb to get the right mix ect ect)

the best way i can think of is an adjustable butterfly valve to restrict the airflow allowing the engine to run the same as it did with the original airbox.

problem is im making it from scratch and wondered if anyone can come up with a better idea of how to go about making the valve

Oh Ok,

I have read the rest of the replies and there are some points to take on board :-

You have adjusted to many things at once (or are trying too) to assume how the motor will react

What you are trying to build is a 'still air box' (very popular in the 70's on grass track/speedway bikes) look here

How we did that back then was to

Set the ignition timing (no need today with cdi) note:- the curve on your cdi box may be wrong & may need alteration or remapping

Fit one known datum ( Exhaust or air box, I suggest the exhaust and leave the airbox off)

check the bikes performance

adjust the carb to suit the current setup

when you feel happy with the performance (no flat spots/plug chops look good, no exhaust bluing etc ) run the bike again for a good while to make sure the engine does not heat seize ( through under jetting, needle adjustments & incorrect ignition timing)

If the engine does seize work out if it was an ignition failure (wrong timing) or a mixture problem & try again

Fit the airbox and note the changes to the engines performance ( with what you are trying to do I would guess the airbox volume should be very close to the Honda original) when you have every thing right just filter the airbox with a piece of ladies stocking/tights ... job done.

Perhaps you are trying to over complex the problem

[barkwindjammer]

Take note of what JimR has to say cos he knows what he's 'TOKNABOOT' , great suggestion tho from Neversaydie--a ball valve --that will give you infinate adjustment on flow-but like JimR says there are a lot more things to consider