OzVMX Forum
Clubroom => Tech Talk => Topic started by: Ji Gantor on May 20, 2010, 11:12:22 am
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This topic is for dummies so all experts by experience or trade and/or including Google Sages would best spend their time on a more advanced level repair.
That said fellow Dummies lets get to it.
The attached image is of a typical Japanese two stroke silencer.
This model was welded up shut so no real way to service it.
By now the packing would be toast, via by oil, carbon or just blown out.
I could spend $150.00 and get a DG silencer but why not try and fix the old one.
First cut the end off and drill a few holes so we can attach a new end cap later.
Always wear gloves and a respirator when dealing with any/all fibres.
Ji
(http://i726.photobucket.com/albums/ww268/Jigantor1963/Pipe1a.jpg)
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With a pair of long nose pliers and a stiff length of wire remove all the packing and place into a plastic bag.
To stop fibres from blowing around wet the packing before removal.
Ji
(http://i726.photobucket.com/albums/ww268/Jigantor1963/Pipe4a-1.jpg)
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When the packing has been removed and all the fibers have been sealed into a plastic bag spray degreaser into the silencer to clean.
Use a metal scraper and removal all carbon build up.
The fine holes in the beginning of this silencer were clogged by carbon, packing and oil.
I used a 8mm rod with a E circlip on the end to free the blocked holes.
Ji
(http://i726.photobucket.com/albums/ww268/Jigantor1963/Pipe5a-1.jpg)
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Measure the inside, out side and length of end pipe so we can start manufacturing a new aluminium end cap.
Ji
(http://i726.photobucket.com/albums/ww268/Jigantor1963/Pipe6a-1.jpg)
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Interesting... Keep going ;)
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Hey ji, what about cutting both ends of the silencer so you can slide the whole outer off to get at the core? I'm just thinking that if you're going to the hassle of rejigging it to make it repackable, you might as well go the whole hog and make it easy to clean out.
Adding a stepped section to the stinger end for the muffler body to slide over would give you sdome to pop rivet to and seal things up.
Flux Capacitor, you need to change that avatar, it's freaking me out ;D
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Hi Mainline,
Yes I could do that but it may not be in the spirit of VMX after all I would have to check back through every MX magazine of 1981 to find some reference to that happening. Also the fixing lug is on the steel tube section so that would have to be welded onto the new aluminium skin, thus that would be a lot more work than just making an end cap. I don't think this is nationals legal unless I can find a magazine clipping which by the way I am not looking for. This topic is just to show what I have done, what readers do or think is up to them, I am not trying to get anyone to do anything, or saying this is the only way to service a silencer.
If I do take this bike to another national which I doubt I have another stock silencer.
Is it not funny to think that I can not aluminium skin this silencer myself but I can buy an aluminium DG silencer that is totally legal.
If I can find another damaged silencer I will reskin it in aluminium as I purchased the materials today just in case.
Ji
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alrighty then ;)
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Commercial welsh plugs make ideal end caps
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Hi Lozza,
Have you found what horsepower or torque gain there is if the silencer works as designed.
Ji
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Is it not funny to think that I can not aluminium skin this silencer myself but I can buy an aluminium DG silencer that is totally legal.
I'll take the bait. What's to stop you reskinning in aluminium or to have both ends removable?
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I thought you said that people can not just go making their own parts for their bikes unless it was done in the day.
Besides what are you doing here this is VMX for Dummies is that not what you wrote.
I thought you would have better things to do than slum it here.
Ji
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Still maintaining the rage Robert, that's good mate it shows you've got some spirit. Now down to business, where in the rulebook does it say that you can't make a muffler with alloy outer or removable ends? I'm not being argumentive, I'd just like you to enlarge on a statement that could send a wrong message to guys who build their own muffler. I admire your attempts to teach us the way to do it but you shouldn't rule out others suggestions because you've deemed it to be ilegal.
Give us something to work with here Robert.
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Mark I am going to keep making my own parts for my bikes out of any material I can get my hands on despite what you say about the spirit of VMX.
The spirit is different to every person.
If it is not against the rules than it is legal in my book.
Where does it say in the rule book I can not make a brake pedal out of titanium.
But what is the point Mark, after all, to you any one that visits my topics is just a Dummy!
Why don't you go back to preaching about the spirit of vmx and what bikes you would like to have or Ebay finds that seems to be more your style than trying to help other members restore their bikes.
Ji
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OK, no problem Robert. I do however look forward to catching up with you at CD7 where we can discuss the spirit of VMX over a refreshing cup of tea and an iced vo-vo. ;D
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I also look forward to seeing you Mark.
Ji
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OUch......
all i can say is in VMX so long as they follow the same line exhausts are free, including a 2010 can ( its all about DB's). But alas other general bike or major parts may not be, as per the rule book
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the muffler on my PE is made from a grease gun and a TV table ;D
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Hey Paul how many channels does it pick up.
Ji
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I thought mufflers are not defined as a 'major component' so you can modify them or make new ones as long as it it looks reasonable? Or maybe even looks dont even matter and you can run a carbon fibre one if you really wanted to, much like the same rule that allows ANY handle bars. Am i right?
edit -Ok i missed Freakys post so it look like he has answered it for me. I dont know how your making the cap Ji but i know a guy who has been spinning up muffler caps out of steel on his lathe for PE mufflers because everyone used to either hack the dome end cap off or open up the small hole bigger.
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Hi LWC82PE,
Yes you and Freakshow are correct.
I would not use carbon fibre as that is a bit to modern for even me.
My reference here is it may not be in the spirit of VMX that does not make it illegal just immoral.
Ji
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Hi LWC82PE,
To your edited comments.
I have two manufacturing methods to make the end cap.
One is turning it up in a lathe and the other involves TIG welding.
I will only show one method here.
If I can find another damaged silencer soon I will show how to reskin it in aluminium.
Ji
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I would not use carbon fibre either.
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Hey Paul how many channels does it pick up.
Ji
just the one, and it's got a bit of static ;D
seriously though, the tv table had perforated trays on it, I chopped one up and rolled it into a baffle. Works a treat.
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I'm intriged how do you make a dome cap with using the TIG method?
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I see no issues with CF mufflers. I'd have them on all my bikes if I could ;) a titanium brake lever eh..hmmmm sounds nice. Sorry, back to the topic :P
(http://public.bay.livefilestore.com/y1pljW3nfIYADGTA3m8yMPac6gx1Ho8Hr4KHn1C7Jm9AkGC0jMIuzX54U0o51snOhCkNT1IRXq4YznzwteNQLQFgA/TS125%20Duster%20Doc.JPG)
this bike would have to run with evo's at any title event but not because of the muffler ::)
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discussing the spirit of VMX with Firko, sounds like you 2 are on a date ;D
Keep up the work Ji, as i cant even weld ( well so ive been told) who gives a rats arse anymore as no-one really knows the rules. Just join me at the back of the pack mate and no-one will even blink at ya with your flash silicener thats 100gm lighter.
Cheers Trev
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I will be very happy to be there with you Trevor.
Ji
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Hi Doc,
There is nothing saying you can not use carbon fibre, go for it.
Titanium or stainless steel skin to me is perfect as these two materials were used on bikes back in the 60s.
Nice bike to.
Ji
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Hi Ji
Really enjoy your posts like this. I am an absolute dummy, really interested in this thread as my Yz125E silencer is badly in need of re-packing and looking forward to the rest of the info to finish off this job.
Mind you If I could buy a DG one that looked right I would probably take that option being a lazy dummy as well. (dont like the universal look that seems the only option for my model from my investigations so far)
Cheers
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Hi Slawesy,
It is raining today so I can not finish.
Will get to it over the weekend.
I hope what I show will help.
If you are in Queensland and need some help let me know.
Ji
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Hi Lozza,
Have you found what horsepower or torque gain there is if the silencer works as designed.
Ji
A general rule is short = more bottom end longer more top end. Short is 250mm long is 290mm Making sure you don't loose HP and pass noise test is the trick
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Thanks Lozza,
When dynoing is there any marked diff on power with or without a silencer?
Ji
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There are no restrictions on materials or shape for a muffler, some just look better suited than others.
If your going to “skin” the muffler with aluminium then their wouldn’t be any reason to cut up the original as you would end up replacing everything anyway.
Good originals can be sought after by the guys doing the original resto’s.
I have repaired a few by grinding down the 2 seams of the muffler to take it apart. You can then remove dents, fit a new core, repack and put back together again. You can make them look like new again but I wouldn’t like to do this more than once as the seam gets too small to be able to reweld too many times.
Ji’s way of fitting an end cap will make them easily repackable.
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Thanks Lozza,
When dynoing is there any marked diff on power with or without a silencer?
Ji
Not something I have spent time doing. A contact who spends lots of time on this stuff found a combination of hole size and spacing that kills dB and actually made more power. I have no reason to doubt his findings.
Again in general a well designed silencer will only enhance output
I see no issues with CF mufflers. I'd have them on all my bikes if I could ;)
So I'll have to make some more then? ;D Is that the third bike it's been on Doc?
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Loz noooo, the mufflers I'm using (as pictured) are Rod Tingate RGV250 items I scored from an ex race bike. They cut noise quite considerably and weigh nothing. Yours was much smaller in diameter ;)
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Commercial welsh plugs make ideal end caps
I've used welsh plugs but they're usually a bit thick. I found industrial trolley wheel hubcaps lighter and equally suitable.
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Can someone tell me how you make a dome cap using a Tig welder?
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Hi Odd1,
The end cap will not be domed.
It will take on the apperance like a walsh plug if you like.
Using standard pipes and plate all welded together.
Ji
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Basicly you are making it in segments?
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Yes
One large outer pipe
One smaller inner pipe and
A flat plate disc all welded together.
Ji
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Ok Thank you
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I will finish this topic this weekend if it stops raining.
Photos and how I did it will accompany.
Certainly not as good as Oldfarts front number plate holder, but I am getting better.
Oldfart I will strive to raise the bar to your level, it may take a few years.
Ji
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Mmmmmm Iced Vo-Vo's ;D
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Hi E74 is this a good time to ask about those Z spokes
Ji
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Ji , My moto is make it easy and simple. ;D Firko you grumpy old man can I join in on a cuppa too ;D ;D
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If anyone did want to make the end cap domed, just get yourself a small piece of sheetmetal and some kind of sturdy bag you can fill with sand. I used an old welding glove (the actual real-deal item is called a shotbag) Get yourself a mallet with a rounded end, hold the piece of sheetmetal on the bag/glove and give it a few thumps. You'll obviously see some dents appearing.
The sandbag idea is to try and keep the dent you're making fairly uniform, as the sand won't displace very much as you hit it.
Once you've dished the sheetmetal a bit, move onto a nice smooth bit of concrete and again using a mallet with a rounded end start working the dent into a smoother more uniform shape. When you've got it concave enough hold the muffler tubing over it, scribe the circle onto the sheetmetal dome and snip away. Then all you've got to do is drill a hole in the middle and weld a flange onto the back of it, so it'll slip inside the muffler, or whatever method you have in mind of putting the whole thing together.
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C'mon man, show us how the end cap turned out.....
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Sorry mate I thought everyone was more interested in CD7 now.
If I have time this week I will post end result.
Personelly I would like to see Mainline show how to make a dome end with a sand bag.
I know this is how it was done in the past and some still know how to get it right today.
That would be very interesting.
Ji
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Well I took a quick trip down to Action Aluminium and picked up some materials.
This aluminium can be turned and welded.
It is T6 so it is tempered so it will lose some of its strength when welded but thats okay seeing how it is not holding anything up.
Ji
Good Luck and Tight Nuts
(http://i726.photobucket.com/albums/ww268/Jigantor1963/Pipe1a-1.jpg)
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Wire brush and file the existing ported tube until smooth and round.
The small tube is going to fit over the existing ported pipe inside the silencer.
Sand, lathe or grind the inside diameter until it fits over the end.
Sand, lathe or grind bevels as required.
Don't block any of the porting holes in the existing tube.
Test fit looks great.
Tight nuts
Ji
(http://i726.photobucket.com/albums/ww268/Jigantor1963/Pipe2a-1.jpg)
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If you can find an outer tube that just slides in then cut to length.
Mine was not quite a perfect fit so I lathed mine down so it was.
Remember to not make the fit to snug or it won't come apart next time we want to pack the thing.
Bevel edges as required.
Make sure the outer tube extends past the end just so you have something to grab on to later when servicing.
Looks good so far.
Tight nuts
Ji
(http://i726.photobucket.com/albums/ww268/Jigantor1963/Pipe3a.jpg)
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Time for a test fit.
It should slide in with just a little resistance, not a machine fit and not sloppy.
We will silicone and bolt this in later so there is no need for a machine fit.
The silicone is to prevent exhaust gas leakage.
Don't make this end cap to heavey as it may over stress the fixing point on the frame. This could lead to cracking as the fixing brackets are usually welded to 1mm thick steel.
Test fit looks fantastic.
Tight nuts
Ji
(http://i726.photobucket.com/albums/ww268/Jigantor1963/Pipe4a.jpg)
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To make the tube seperator we can use two hole saws on a flat plate or we can lathe what we need.
Either way will get the job done. Some blokes may be able to cut this out of a flate plate with a scroll saw.
If this is racing bike no need for a polished finish.
Keep the sealing area as tight as you can and bevel edges as required.
Time for a test fit.
Looks perfect.
Tight nuts
Ji
(http://i726.photobucket.com/albums/ww268/Jigantor1963/Pipe5a.jpg)
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This end cap has the seperator plate at the same location that the original silencer ended thus keeping the designers requirements.
Tight nuts
Ji
(http://i726.photobucket.com/albums/ww268/Jigantor1963/Pipe6a.jpg)
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I did not cover any of the original porting holes in the existing pipe.
This pipe must have been designed for bottom end power as it is exactly 250mm long (thanks Lozza)
All the parts are now ready to be TIG welded up.
Tight nuts
Ji
(http://i726.photobucket.com/albums/ww268/Jigantor1963/Pipe7a.jpg)
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Talking about beating sheet into shape, I recently needed to extend a fibreglass rear guard down through the swinging arm. I grabbed an old 'keep out' sign about 300x150 made from aluminium and proceeded to hand form it using my version of the leather sandbag. I placed the sign on the lawn and then started to belt it into rough shape with a hammer. However not much progress was being made till I gave up with the hammer and started using the back of the axe! Apparently the old swb signs were made from a very high grade hardened alloy material. However i carried on regardless and after making a large groove in the lawn achieved a section in the shape required for the task at hand, which when finished off with a hammer and dolly was quite acceptable. This piece was then fibreglassed on to the end of the other bit and was immediately discarded 'cause i found a better one! The main lessons gained 1]Make sure the material is MALLEABLE 2] Check if there is a better part somewhere first 3]Keep in the back of my mind that if I need a strong piiece of alloy sheet check out the old swb signs! 4]Fix the groove in the lawn. cheers wally.
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Most sheet ali sold in Australia has been usualy tempered to T6 condition for hand beating etc etc you need to get O condition or annealed which is very soft/ductile/malleable. Just try to buy some though fine if you want a ton of it :o
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Hi Wally,
I have panel beated a lot of aluminium but not made something from scratch.
I have seen the sand bag technique before it works great.
The first hammer blow looks scarry but after one hundred it starts looking great.
Using a planisher afterwards certainly smooths out the surface.
Tight nuts
Ji
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Obviously you have had both pieces of pipe and the disk in a lathe so why didn't you just machine the end cap up in one piece out of a piece of solid? it would look shitloads better. ;)
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Good tip to soften aluminium is to use oxy
1. use more acetylen in flame to paint the aluminium black
2. use more oxygen in flame to burn black colour away, carefully
3. you have soft aluminium.
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Welcome Oppet,
That is a great addition to this thread.
Tight nuts
Ji
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There are many different alloys of aluminium designed with different characteristics like the ability to be turned, welded or non corrosive.
Different elements are added to the alloy to increase strength as well.
The other thing that increases strength in some aluminium alloys is heat tempering.
If you have ever purchased ali you may have noticed that it has a series like 6061 and at the end there may be T6.
The 6061 tells what elements are in the alloy while the T6 describes the temper.
To reduce the strength of a T6 ali alloy all you have to do is anneal it with heat.
This will make it much more easier to work with a hammer.
Tight nuts
Ji
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Hey oppet going back in history again [as us old farts tend to] I had a A\Healey 100 which had lots of aluminium sheet in the bodywork. I needed to repair a crack around the radiator air inlet and one of my mechanic mates said its easy[usually means they have never tried themself] to weld sheet aluminium you just cover it with sooty flame with the oxygen turned off and then start welding with a neutral flame. If the sooty part gets to far from the tip look out! SO after blowing several holes I gave up and bought some eutectic filler rod.cheers wally.
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TIG welded.
Inside welding very difficult to get the torch in there.
Tight nuts
Ji
(http://i726.photobucket.com/albums/ww268/Jigantor1963/Pipe9a.jpg)
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External TIG welding is much easier.
Tight nuts
Ji
(http://i726.photobucket.com/albums/ww268/Jigantor1963/Pipe8a.jpg)
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Test fit.
Looks and works great.
Tight nuts
Ji
(http://i726.photobucket.com/albums/ww268/Jigantor1963/Pipe10a.jpg)
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Geez your ali welding has come on leaps and bounds there Ji, especialy the inside weld. I would be very happy with that appearence.
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Me to.
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You guys are too kind.
I just keep practising.
Tube welding is the hardest, you have to keep stopping so you can turn the job around.
Tight nuts
Ji
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I was not going to polish this end cap but it looks so good I think I will.
I still have to pack the silencer and tap threads into the new ali end cap but all the hard work is now done.
Tight nuts
Ji
(http://i726.photobucket.com/albums/ww268/Jigantor1963/Pipe11a.jpg)
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Test fit.
Looks and works great.
Tight nuts
Ji
(http://i726.photobucket.com/albums/ww268/Jigantor1963/Pipe10a.jpg)
When are you going into production?(http://i323.photobucket.com/albums/nn458/mx250syd/icons/emot-clint.gif)
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Hi Graeme,
No mate I am happy doing my own work.
That way it is still fun.
I would like to know what GMC thinks, may be he can start making them for sale.
Tight nuts
Ji
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You guys are too kind.
I just keep practising.
Tube welding is the hardest, you have to keep stopping so you can turn the job around.
Tight nuts
Ji
I'll show you a little trick one day ;)
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Nice job.
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I only finished before CD7 for you Oldmxracer.
I am happy you like it.
Tight nuts
Ji
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Hey Lozza I am always interested in tricks of the trade mate.
I look forward to your master class.
Tight nuts
Ji
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Thanks Ji. I will be trying to duplicate that I'm sure!
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Go for it mate.
If you are in Brisbane let me know so I can give you a hand.
Tight nuts
Ji
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I'm a USA guy, but thank you for the offer!
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Just trying to help with a brother VMXer.
It would be cheaper for you to buy a nos one off ebay wouldn't it.
Tight nuts
Ji
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Why didn't I just lathe this whole thing up in one piece.
First let me say that you may be able to purchase tubes that don't need any turning but still require welding together.
Mine did not need very much turning and I could have done it without using my lathe if I was prepared to spend more time.
Second take a look at your bikes, not everything on them is turned or milled. The original manufacturer cast a lot of items than welded tabs on.
Why ?
Because to turn or mill every part would take so much more time and cost a lot more money.
The tubes I purchased only needed a light skim, which took about 2 hours in total. Welding took about 30 minutes.
The materials cost me $11.00 and I have enough left over to make another 6 or so.
If I had purchased a aluminium bar 6061 T6 75mm diameter by 1 meter long that would have cost me $75.00. The time to lathe it down to size and then shape it with test fits would have taken 4 or 5 hours on my little lathe. If you have an industrial lathe it may be able to be turned in 3 hours.
So like the bike manufacturers I decided to spend my money and time on other things and make the job simple and that after all is why I called this "Silencer Repair for Dummies"
Tight nuts
Ji
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Yes Ji, your welding skills seem to be coming along nicely.
6061 is a structural grade alloy, as their is no strength needed for a muffler end cap then you can just as easily use maching grade Aluminium Alloy.
If you hunt around some of the Aluminium suppliers you can sometimes find short offcuts of materials that will come in handy for little jobs
While it's a nice job I actually think it looks a bit out of place on that muffler, it actually looks too good for the muffler. I think it would benefit if the whole thing was painted black.
I often get asked about doing budget repairs on mufflers, while they can be rebuilt it's the time factor of fiddling with them that is the killer. Materials are minimal but several hours and the costs build up as you can see. I have repaired a few mufflers like yours but I have taken them apart at the seams to take the dents out & fit new cores & packing. I usually do this because guys want the original look and the end cost is much the same as making one from scratch.
The packing in old mufflers often becomes fossilesed and useless and the perf cores are often broken or in poor shape.
The down side of this repair is that if the core is damaged then you would probably need to cut the other end off as well as the cores are usually welded in at both ends making replacing them difficult. With a good torch though you can usually see the core damage before you start to chop.
In short, it's a good budget fix for the home handy man that has time up his sleeve.
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Hi and thanks GMC,
The machining grade aluminium is hard to weld so I read in the suppliers catalogue.
Have you found this to be true?
I stick to 6061 because the shop always has it in stock and it is pretty cheap.
I will think about painting it black or may be black anodising.
Oldskool told me its pretty easy to do at home.
Tight nuts
Ji
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Yes machining grade is a bugger to weld and you wouldn't want to put any trust into the strength of the weld to support anything.
6061 is hard to find in varying sizes, 6060 is more common in different sizes, will weld okay and is fine for many parts including muffler end caps.
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I have tried welding machine grade steel before (that is turning in a lathe steel) (all so known as Free Cutting Steel)and it is a pain.
They add lead to the steel so it turns nice but when welding the heat boils the lead out into the bead.
I have found you have to weld grind, weld grind about 3 or 4 times before the lead is all gone from the welding zone.
Tight nuts
Ji
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Ji,
How do you clean the old packing out with that set up?
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cut,pack,weld :'(