Building exhaust flnge from 7/8" Grd8 washer and piece of fork tubing

[mapbike]

Nothing fancy here and I haven't taken pix of it since some more cleaning up and the header pipe being brazed to flange tubing, but I just thought I would share some pix of how you can make a nice exhaust flange from a washer if you have the tools and want to take the time, I wanted the "Taffy Bike" to have a large unrestricted exhaust since the mods I have done to its engine will allow it to get so higher than normal revs, the header pipe has a 1" ID and is currently 18" long, I will likely reduce the length to 14-16" if I have room to go that much shorter and still be able to mount the expansion pipe where I want it.

These pix are all of things in the rough and honestly I didn't do a lot of cosmetic clean up since the header pipe from flange to chamber will be wrapped in exhaust wrap so none of it will be seen anyway, but is is cleaner then seen in these pix now and has been sprayed with hight heat flat black paint.

 

[bairdco]

y'know those bolt through frame adapters that come in the kits? the one where you're supposed to dri a hole in your frame to mount your engine?

drill the center hole bigger and boom, instant exhaust flange.

 

[mapbike]

y'know those bolt through frame adapters that come in the kits? the one where you're supposed to dri a hole in your frame to mount your engine?

drill the center hole bigger and boom, instant exhaust flange.

Thanks bairdco, I think I have one of those drill through the frame mounts, thats a great tip, Ill try to find it and try that mod out, little things like that are good to know for repurposing junk parts like those type mounts.

 

[bairdco]

they also work as intake flanges on motors with the larger intake.

 

[YesImLDS]

That's a pretty beefy pipe diameter you got there map! and a cool idea! I noticed when I got the exhaust manifold when I bought my SBP expansion chamber that it matched up to a door lock faceplate!

What kind of exhaust you gonna run on that beast a VW bug exhaust!? Probably would bolt right up to that exhaust piping!

 

[Trey]

Need it. Make it. Got it.

Lookin good Map!

Thanks for sharing that. I don't have a welder, but I bet it would only cost a couple of bucks to have that done at a shop.

 

[mapbike]

they also work as intake flanges on motors with the larger intake.

More good info, thank ya sir...... these little things sure can help people out sometimes and are always welcome to us hacks and tinkerers who just enjoy the process of taking what we have and making it work for what we need.

Thanks bairdco

 

[mapbike]

That's a pretty beefy pipe diameter you got there map! and a cool idea! I noticed when I got the exhaust manifold when I bought my SBP expansion chamber that it matched up to a door lock faceplate!

What kind of exhaust you gonna run on that beast a VW bug exhaust!? Probably would bolt right up to that exhaust piping!

The pix make it all look way bigger than it is, its only 1" ID, but it does look huge in those pix, I have a moped expansion pipe I got from treatland.tv a couple years ago that has been sitti g in a box, Im not sure the stinger pipe running through the silencer is as big as it needs to be, but Im gonna try it on the Yellow "Taffy" bike and see how it runs, I thi k the chamber will suit my needs or wants but I'm not so sure I won5 need to cut the silencer off and braze on a large ID stinger to get the flow where I want it.

I have one of the big fatty snake looking pipesI rigged up last year, and its an under performer do to the small 3/4" ID header pipe and maybe even because the exit is a bit restrictive also.

Ive found that one of the key things to higher rpm potential on my engines has been to get the exhaust right, an expansion pipe is not needed abut good if its done right, an expansion exhaust thats to restrictive on either end with have worse performance that a straight pipe or even a gutted out and modified stock type muffler/exhaust, Ive yet to have m6 fastest bike do its top speeds with an expansion pipe, all my top speeds have been done with very free flowing exhaust that I rigged up myself, problem is that they are very loud which makes no difference to me where I live, but for city people that kind of exhaust can draw negative attention to our bikes.

Im not shooting for a top speed personal record anymore so as long as I can get a couple of my bike to comfortably cruise at 40-43mph on the flat with a 32-36T on the rear Im happy, Ive done 50+mph on the one bike, done 48mph on another and Im good, I was inspired by bairdco way back when I got i to this hobby to build an engine that would get me to or over the 50mph mark, I did it and now Im happy at 40mph-ish for a top speed and a comfortable cruise speed of 35-40mph if I want it.

The right balance, the right jug, good clean ports, good compression, well tuned carb like even the little NT or NT Speed carb,the right gearing and a good free flowing exhaust will get what I want done with my bikes and thats what Im shooting for each time I put one together, having a good crankshaft balance is a huge part of all this, if someone has a horribly balanced crank all the other things dont mean much since the higher rpms will just help the engine grenade much quicker.

 

[mapbike]

Need it. Make it. Got it.

Lookin good Map!

Thanks for sharing that. I don't have a welder, but I bet it would only cost a couple of bucks to have that done at a shop.

Yep and for most of what I do, I dont use my welders, I use my torch and I use brazing rod or just a cleaned up cwire coat hanger to fuse many of these scrap pile projects together and just basic i expensive type shop tools formost of the work, I dont try to get to fancy with most of it, I just make up something that will work with what I have or can find at tractor supply or a local hardware store, I have a limited amount of time to spend on my bikes because of other responsibilities, but I do what I can as cheaply and quickly as possible to get what I want or need.

I like to do things that way on my bikes and then post it here hopi g to help someone else, yeah many fancy builds and parts get shown on here and its all great, but amny people have limited resources and live in an area where they have to do what they can with limited space and tools, so its good to show the simple ways to do somethings with simple parts and pieces also, I have a lathe and mill, welders and a pile of all sorts of tools but I like to keep itsimple and Im no professional machinist either, just a tinkerer so I use simple inexpensve methods as much as possible, I would rather make somthing than buy it if possible even if mine aint the pretty girl in the room when Im finished with it.....lol!

 

[Trey]

I've seen you do it man, and you've helped me out more than once.
Thanks...
Keep it up!

 

[xseler]

I've seen you do it man, and you've helped me out more than once.
Thanks...
Keep it up!

Amen to that, brother!!

I've done mechanical stuff for a long time, but another experienced set of eyes can help you see around a 'roadblock'.

 

[mapbike]

I love to learn new things, and so many people here have unknowingly increased my knowledge many many times on this forum, I try to keep it simple most of the time since I dont have the time to put into a long drawn out project as far as the parts and pieces are concerned and I try to make something I already have laying around work for what I need many times, doesn't always work out but when it does I always feel purdy good about it, to me that is part of the fun.

Anyone can order a part and bolt it on, but the fun of making the part myself when I can is what a tinkerer like myself enjoys.

, Map

 

[Davezilla]

Nice job on the header flange...this is an area that's the most overlooked and it doesn't matter how good the porting is if you cant get the hot expanded gasses out quickly... I remember you pointing that out in an old post last summer which motivated me to go ahead and cut up my ktm pipe and make it fit instead of saving it for a future build.. I already had a really nice exhaust flange that I took off my old pocketbike, I dremeled it out to match the size of the port which just happened to be the same size of these engine's exh ports, then I re routed the pocketbike pipe and fit it on the bike... it made a world of difference in the power department but fell short on the speed I was after.... the ktm pipe has a 1" stinger diameter so I cut it up and made it fit.... the end result was a much more aggressive sound as well as gaining about 7 or 8 mph...

On a side note, I'm also making a bigger flange for my new engine since the exhaust port is bigger than the outer diameter of the pocketbike flange I'm currently using, but also since the kx65 pipes have the slip fit at the header and double O rings to seal the connection I decided to go with 1 1/4" pipe directly off the flange and plan to use a piece of 1/2" aluminum plate to make an adapter from the exhaust port to the new flange, this is also just enough space to convert my oval port to round where the header flange will be. Ive been dreading the part where I was going to need to cut a hole thru a piece of 1/4" thick steel plate big enough to match up to the 1 1/4" header pipe, but you just found me just the solution I was looking for... a nice big steel washer since the big hole will already be taken care of and minimal or no die grinding will be necessary... just drill the 2 bolt holes, weld the header on, and done!!
Thanks for sharing this.... its gonna save me a lot of time doing it this way...

 

[mapbike]

Yep a flat washer can be used to make intake or exhaust flange, a long while back someone else on here did the same for an exhaust flange also if I remember right.

I've found the exhaust is a huge factor in whether a CG build will have good power overall or not no matter what else is done to it, one of my engines that would hit 48mph with a fairly straight through exhaust would only do 37mph when I put a more restrictive expansion pipe exhaust on it, the right exhaust on these little engines makes a good bit of difference especially when other mods have been done.

Some engines dont run that good no matter what you do, but even a good engine can be choked out plenty easy with a restrictive exhaust even if it has an expansion chamber.

Expansion chambers dont mean squat if it isnt at least close to being right and very free flowing in my experience on my bikes, fastest top speeds Ive ever done on my bikes were without expansion chamber exhausts, Ive yet to have the right one set up right, but Im hoping the next one I do will be better since Im using a different pipe and going to more pains to hopefully get it to perform like I want it to.

 

[2door]

Just to toss out another idea for repurposing stuff. Here's the exhaust flange on the Norton. I use the male and female parts of an 'explosion proof' electrical conduit fitting. The male section is welded to the flange that I made and the female part is welded to the pipe.
This allows removal of the exhaust system without disturbing the flange to cylinder gasket seal. The big nut tightens the two parts together and doesn't leak.

Explosion proof electrical fittings aren't something you'll find at Home Depot. You'll need a friend who is an electrician or buy them from a commercial electrical supply house. They're used when running electrical in an explosive atmosphere, like paint booths or flammable material storage areas.

Tom

 

[mapbike]

Just to toss out another idea for repurposing stuff. Here's the exhaust flange on the Norton. I use the male and female parts of an 'explosion proof' electrical conduit fitting. The male section is welded to the flange that I made and the female part is welded to the pipe.
This allows removal of the exhaust system without disturbing the flange to cylinder gasket seal. The big nut tightens the two parts together and doesn't leak.

Explosion proof electrical fittings aren't something you'll find at Home Depot. You'll need a friend who is an electrician or buy them from a commercial electrical supply house. They're used when running electrical in an explosive atmosphere, like paint booths or flammable material storage areas.

Tom

Looks good Tom and thats a good tip also, so many creative ways to do things with our bikes and thats what make it fun to me.

 

[Davezilla]

Looks Great and another excellent idea... Thanks Tom

Yeah I agree that expansion chambers don't mean squat when they're not set up at least somewhere close to how the engine is tuned... and that's why a lot of people with just a straight pipe can beat a bike with a cheap or poorly designed expansion chamber... They do work when tuned for the engine but when not tuned for the engine all they're gonna do is change the sound a little and work about as well as the stock pipe.
On the other hand, if one makes a straight pipe the right length and diameter they will also get a considerable power increase out of their engine and it's better to have a tuned straight pipe than a way out of tune expansion chamber. A straight p[ipe can be tuned either for good low end, mid range, or top end depending on the pipe length and it'll be a little less effective at rpms above or below where it's tuned, but still very usable at all rpm's.
This is where I found it much more beneficial to use dirt bike pipes in the 65 to 80cc size range since the pipe is already the right size for the engine, but it may still need some extra modification to perform well either by adding to the belly section or adding header length so it hits at the rpm's the engine was built for. The size and shape of the belly, baffle cones, stinger, and header all play into this and one can either make a nice wide powerband and give up a little on top or make a very narrow powerband but have some insane power when it hits. For daily riding it's definitely best to give up a little up top so the bike will perform well at just about any rpm.... A hard hitting pipe with a really narow powerband is only fun on the track... not so fun everywhere else...

 

[Springfieldscooter]

Great job map! Wish you would mass-produce a few and sell one to me!

 

[mapbike]

Great job map! Wish you would mass-produce a few and sell one to me!

Thanks for the comment Sscooter, well its a time consuming process to make this kinda part with simple tools and honestly I have little time to work on my bikes that I haven't even done another single thing to the bike this flange was for since making it, its painted and bolted to engine now but thats as far as Ive gotten.

At some point in the future I have thought about making some parts up like this for purchase so someone who may not have the tools to make it could get one, but for now the way I work and with all my other projects I just dont have the time.

Im surprised we dont have others already making some exhaust parts and pieces for these bikes other than what we've had available for a long time now.

The SBP exhaust is better than a unmodified stock pipe when plumbed right but still not all that good for a more modified engine.

I have some ideas I hope to work on when I have time that may give another option for someone who wants a good free flowing exhaust, but it will be a while before I have time to work on it.

Peace, Map