Expansion chamber cones

[derail]

Hi Guys, I am wanting to attempt to make a couple of expansion chambers and are seeking the knowledge of others in the know. Does anyone know who might roll up cones out of sheet metal and what gauge sheet metal a two stroke race bike exhaust is usually made from. Because the bike is a bit odd, (replica RT63 Suzuki -dare I say a roadracer) I have to make a custom exhaust.
Thanks, Derail

[vandy010]

i made a pipe from an old 44 gallon drum once. it's about 0.7mm thick and did the trick ok.
i'd do it again and soon will.
as for rolling the cones, a sheet metal shop should be able to do it for you, or if your really stuck, 0.7mm can be formed by hand around a sturdy bit of water pipe/hand rail with a rubber mallet and beer but it takes time and you'll soon wish you went to a sheetie.

[DR]

0.80 panel steel or CR2SE or CA2SE (cold rolled) is the go.(says me of course ) Nice and clean, forms easily and you can near weld it with little filler wire if you get the the joints to meet nicely. Was near going to make a small hand roller for making exhaust cones but you can buy them relatively cheap. Just need to make sure the rollers can be adjusted eitherside and not both via a single adjuster. Tis simply a matter of stretching 1 side more than the other to form the cones though this may take a few passes and some trial and error depending on the metal and machine used.  Those RT63's are sweet little bikes Derail, love the little 2 smoke rotary valve multi's. 'specially when they have between 14 and 18 speed trannys to keep one's left foot busy I'm sure I have a mag somewhere with a decent write up on them and some nice pics but I'll need to search the archives as I can't remember the specific mag/book in which it was published

[pancho]

i made a pipe from an old 44 gallon drum once. it's about 0.7mm thick and did the trick ok.

ive seen some BIG exspansion chambers but that one must have been a sight! cheers wally.

[Nitram]

I have had cones rolled in the past by a bloke named Rick Roberts in Sydney.  I send him the specs and $$,  and he rolls me the cones and puts them in the post. He does an excellent job, both in terms of the quality of the rolling, and in terms of the accuracy of the size of the finished cones.  He is a real class act, and a true gentleman, as any one who has dealt with him in the past will testify.

I havn't had one done for 12 mths or so, but his phone number used to be 9247 2685.  But don't ring him in the evenings !  Daytime only.  Say hello to him from Martin.

Cheers

Nitram

[oldfart]

Contact GMC
Or
Take yourself down to local Library and find a sheet metal book and study it well 
A hand roller is the go 
First up practice on cardboard making lobster back bends and cones . When you've got it sorted then have a go with sheet metal

[Lozza]

No such thing as an odd two stroke, why just do what everyone else did before you and buy A Graham Bells book explains it in there pretty well.

[tony27]

Can be & has but you'll get no power unless they fire at same time, gets pressure pulses out of phase & hurts scavenging in a big way
Each cylinder really has to be treated as it's own unit

[Lozza]

Yes it's no problems Walter(there are some tricks though), main reason it's used is for space, most stock pipes on snowmobiles are 2 or 3 into 1.No need to have the fire at the same time as the design gets the one cylinders plugging pulse and the other gets the scavenging. A contact had to run a standard 2 into 1 on a World Championship Jet Ski class he made mod to the piston, "sent jetting to hell, but with that sorted lapped the entire field" Was pulled down several times and protested, they still have the cup.
Whats the application?

[Lozza]

Depends on what you want to happen 66HP per cylinder is quite reasonable, is it all off the bottom or more top end?

[Lozza]

What configuration is the engine, twingle or 180 deg? Heaps you could do to increase drive off corners, I'll give you ring during the week..............hijack over

[derail]

No worries, Hijack anytime- its all good interesting info, thanks to all for the idea's and contacts

[ss2fly]

Anyone got a contact for hand roller supplies or pics of any  that i can make?

Got to get this under way

[oldfart]

ebay ..... sheet metal roller     try and get one with a quick release 
                                          http://cgi.ebay.com.au/21-MANUAL-SHEET-METAL-ROLLER-ON-STAND_W0QQitemZ270390592143QQcmdZViewItemQQptZAU_BnI_Woodworking_Metalworking?hash=item3ef489028f&_trksid=p3286.c0.m14&_trkparms=66%3A2%7C65%3A1%7C39%3A1%7C240%3A1318%7C301%3A1%7C293%3A1%7C294%3A50

[DR]

this is the little blighter I was looking at, a bit more compact and a much better thing for the very limited work area I have. For $175 I figured it's not worth the effort to make one but it's the lack of space that's my main problem as I don't even have room for a bead blaster it sits on the floor and gets moved from here to there and anywhere inbetween..maybe I should simply fit some castors to save the back