just rember u cant reverse that that easy. and what about leak tests? how u gonna do those with the flage offf?
aftermarket exhaust leaks...
- Thread starter mjgnslngr
- Start date
un-bolt the flange... then put a plumbers pipe plug in it...why?
reverse it? i wouldnt Think of it! its an fmf, if it was a trinity or even a dynoport, no, id re invent the wheel for the exhaust before i welded it.
its a rubber expansion plug 4 bucks at an auto parts or hardware store. works slick!
shweeet man thanks!
its for the exhaust port on the head, when i have it apart tomorrow, ill get you a measurement. cool?
something like that. i have a few in the tool box but i cant remember which one i used. 1 1/8-1 1/4 sounds about right.
Hopefully I am not too late.
Most of the aftermarket pipes are made of thinner metal to be lighter. The FMF is.
If you weld it you may get stress cracks at the neck and curl of the pipe with time and vibration.
My KTMs use several different exhaust connections at the head. The "ball and socket" mount is my favourite. Ball connection, no gasket, springs hold together.
My KTM in my Blaster has a slip in flange like the aftermarket pipes, with "O" rings. Still leaks like a wooden boat.
With the vibration (we all know MX engines vibrate, right?
the header pipe dances around regardless of the springs and "O" rings.
I fill the darned thing with RTV too. Often.
I don't have an answer but am all ears listening for yours.
Luckily the Blaster pipe is fairly protected in the frame. On bikes, pipe damage is a big problem and if the connection is too rigid it can damage the cylinder.
Some picts of what we are looking at, sorry, none of an aftermarket Blaster pipe. Stock Blaster cylinder:
My KTM adaptor flange spigot without "O" rings on it, made by Glen at Heritage Machining:
Under constriction, you can see spigot and female flange on pipe. No "O" rings on yet.
Pipe in place, I cannot see any springs but they are used to hold it together.
You can see where a couple wedges have been welded in to correct bends for the frame and add length for tuning.
This type flange on the KTM is notorious for impact damage. One hit on the pipe and the female flange on the head cracks and smashes.
The usual answer is to press a steel sleeve around the outside of the aluminum cylinder flange. I have not done.
This might be useless information for most of you, but I am suffering from the leaky flange syndrome too, in spite of the slight differences.
Most of the aftermarket pipes are made of thinner metal to be lighter. The FMF is.
If you weld it you may get stress cracks at the neck and curl of the pipe with time and vibration.
My KTMs use several different exhaust connections at the head. The "ball and socket" mount is my favourite. Ball connection, no gasket, springs hold together.
My KTM in my Blaster has a slip in flange like the aftermarket pipes, with "O" rings. Still leaks like a wooden boat.
With the vibration (we all know MX engines vibrate, right?
the header pipe dances around regardless of the springs and "O" rings.I fill the darned thing with RTV too. Often.
I don't have an answer but am all ears listening for yours.
Luckily the Blaster pipe is fairly protected in the frame. On bikes, pipe damage is a big problem and if the connection is too rigid it can damage the cylinder.
Some picts of what we are looking at, sorry, none of an aftermarket Blaster pipe. Stock Blaster cylinder:
My KTM adaptor flange spigot without "O" rings on it, made by Glen at Heritage Machining:
Under constriction, you can see spigot and female flange on pipe. No "O" rings on yet.
Pipe in place, I cannot see any springs but they are used to hold it together.
You can see where a couple wedges have been welded in to correct bends for the frame and add length for tuning.
This type flange on the KTM is notorious for impact damage. One hit on the pipe and the female flange on the head cracks and smashes.
The usual answer is to press a steel sleeve around the outside of the aluminum cylinder flange. I have not done.
This might be useless information for most of you, but I am suffering from the leaky flange syndrome too, in spite of the slight differences.
Before you weld it, while it's tacked, try putting it on and off to make sure it will fit. I honestly don't think you will get a good seal to the motor with a welded flange.
I still don't think welding that is a good idea. My power pros had the same problem, I used a tailpipe expander, put the pipe on the flange and expanded. It helped a lot then a light RTV worked pretty good.
The toomey uses o-ring and looks to be a better design but the flange needed RTV to the motor, I leak tested the motor with the flange attached and it was sealed.
ok, i haven't done anything yet! i was going to start this afternoon after work.
Steve, you mentioned the vibration factor. i guess that's where i become confused. the motor itself is rigid mounted whereas the pipe system is not. most vehicles used rubber isolators or mounts for the engine, and the exhaust as well. this way everything has a chance to 'move' and 'flex'. in doing that, it prevents those 'stress' situations for all the components.
on your ktm, without a balance shaft, i can only assume it has a pretty good 'buzz' to it! i also see guys like, yz otis with his yz250 motor in a blaster who have also commented on the fact that without a balance shaft, his motor does tend to vibrate quite a bit. now with mine having a balance shaft and the motor mounted solid to the frame, i cant see the vibration being a factor. correct me if im wrong.
it just doesnt make any sense why the flange is separate on aftermarket pipes? it really is a piss poor design. the exhaust can 'flop' around but the engine is solid??? not good design work!
Slicker, i tried the pipe expander trick. it did help out quite a bit. but the pipe is still rubber mounted and it moves, causing it to 'wiggle' the rtv loose at least once a month. the pipe is currently mounted on the blaster. i was going to burn a couple of tacks on it as it sits, then take the pipe off and finish the weld. i have a tig welder and i see that the metal on the pipe is Very thin. i think if i set my heat low enough, ill get a good penetration without burning thru. (hehe, i said penetration!!!)
ive been toying with the idea of welding it for a while. i had a bill's pipe on my rm250 and it Never leaked like this! colins had a pro circuit on the yz and it Never leaked like this. really, REALLY bad design!
the fmf pipe on the blaster, i got from a friend who parted out his blaster. i dont really have any coin in it. if this Doesn't work and the pipe is a total loss, ill just save my pennies and go with a right bend. the plan is to have port work done this winter. nothing too extreme just a little more cleaning of the disaster that is the blaster flow design. in that case, id only benefit from a better flowing system.
Steve, you mentioned the vibration factor. i guess that's where i become confused. the motor itself is rigid mounted whereas the pipe system is not. most vehicles used rubber isolators or mounts for the engine, and the exhaust as well. this way everything has a chance to 'move' and 'flex'. in doing that, it prevents those 'stress' situations for all the components.
on your ktm, without a balance shaft, i can only assume it has a pretty good 'buzz' to it! i also see guys like, yz otis with his yz250 motor in a blaster who have also commented on the fact that without a balance shaft, his motor does tend to vibrate quite a bit. now with mine having a balance shaft and the motor mounted solid to the frame, i cant see the vibration being a factor. correct me if im wrong.
it just doesnt make any sense why the flange is separate on aftermarket pipes? it really is a piss poor design. the exhaust can 'flop' around but the engine is solid??? not good design work!
Slicker, i tried the pipe expander trick. it did help out quite a bit. but the pipe is still rubber mounted and it moves, causing it to 'wiggle' the rtv loose at least once a month. the pipe is currently mounted on the blaster. i was going to burn a couple of tacks on it as it sits, then take the pipe off and finish the weld. i have a tig welder and i see that the metal on the pipe is Very thin. i think if i set my heat low enough, ill get a good penetration without burning thru. (hehe, i said penetration!!!)
ive been toying with the idea of welding it for a while. i had a bill's pipe on my rm250 and it Never leaked like this! colins had a pro circuit on the yz and it Never leaked like this. really, REALLY bad design!
the fmf pipe on the blaster, i got from a friend who parted out his blaster. i dont really have any coin in it. if this Doesn't work and the pipe is a total loss, ill just save my pennies and go with a right bend. the plan is to have port work done this winter. nothing too extreme just a little more cleaning of the disaster that is the blaster flow design. in that case, id only benefit from a better flowing system.
so, i didnt get to it tonight. been fuggin with the pwk, im telling ya, its gonna end up on here for sale if i cant get it figured out, i mean it!!!
gonna try again after work tomorrow, if not, the weekend. one way or another, ill weld that sum biotch!!!
gonna try again after work tomorrow, if not, the weekend. one way or another, ill weld that sum biotch!!!
I have an apology to make.
I said that the DMC Alien pipe had a welded flange, I told lies.
I am sorry I was very wrong.
The truth is that the end of the pipe has a flange welded to it which has the same type of donut fitting as the stock pipe.
There is then a steel collar which is nipped up onto that donut shoulder by two bolts.
I again apologise if I have caused a problem with anyone trying to weld a flange on and then finding that it may not fit up.
The pic explains it better than me.
This is the DMC fitted to my sons bike, it has been on there for over 12 months and has never leaked!
Please excuse the dirt, but we breed work horses, not show ponies!
I said that the DMC Alien pipe had a welded flange, I told lies.
I am sorry I was very wrong.
The truth is that the end of the pipe has a flange welded to it which has the same type of donut fitting as the stock pipe.
There is then a steel collar which is nipped up onto that donut shoulder by two bolts.
I again apologise if I have caused a problem with anyone trying to weld a flange on and then finding that it may not fit up.
The pic explains it better than me.
This is the DMC fitted to my sons bike, it has been on there for over 12 months and has never leaked!
Please excuse the dirt, but we breed work horses, not show ponies!
