I'm building one

[Drew]

Does it currently have a carb rubber?

I'm guessing if it has already seen race attention it probably doesn't have standard reeds and inlet port...

Ports are opened up, and it has reeds and a carb rubber, that are bigger than what I'd expect to see on a 70's 100cc 2 stroke.

[husaberg]

Ports are opened up, and it has reeds and a carb rubber, that are bigger than what I'd expect to see on a 70's 100cc 2 stroke.

Probably not std then The DT100 was quite small my guess would be a rd250 set up.

http://4.bp.blogspot.com/_Zpvp6nQo0H...dimensions.JPG

[koba]

Ports are opened up, and it has reeds and a carb rubber, that are bigger than what I'd expect to see on a 70's 100cc 2 stroke.

I have that 32 but it probably won't fit whatever carb rubber is on your motor. + it's likely to be a bit too big to start with.

[Drew]

I have that 32 but it probably won't fit whatever carb rubber is on your motor. + it's likely to be a bit too big to start with.

Bryce has one he reckons, so I should be doing test track laps this weekend.

Does anyone know if a two stroke can be made less obnoxiously loud without hindering the performance? I fuckin hate the sound of singles, two or four stroke. Might be getting into the wrong class on that basis, but needs must an' all that.

[F5 Dave]

yeah an effective muffler just needs some volume, some thought & some support. if left unsupported for ages it will vibrate crack. perforated tube & some direction changes are good things.

I made a 2ndry muffler when a track was getting hard on noise that I could bolt on. It was another section with a reversal & some more perf tube slightly larger di than primary. Didn't make any diff on the dyno. Sadly it couldn't be supported so I made another with just a reversal end cap for the rest of the time so it doesn't break all the time. And when I say 'I'. I mean I gave it to Damon.

20mm tube should be about right for your 100. Don't want to start too big as that is giving noise away to start with. Too small isn't good for piston crown temp though. Within 30-40cm you can fit a reversal & heaps of perf tube. A reversal can just be 2 bend bits of pipe welded to each other so they miss, ie outside walls a couple of cm. use ally tube, steel 'rings'. Some like that silent wool packing, but I find Daytona mat is better.

[Drew]

Cheers for that Dave. If they standard cans off the MVX weren't so bloody heavy I'd split the pipe in two off the expansion chamber and run two of 'em.

[F5 Dave]

You still want to have a stinger effect from a hole equal to about 20mm & 200 long. maybe could make the same with two real small pipes, but not sure of the formula.

Depending where the pipe ends up the cleanest way to mount the muffler may end up being under the tail piece or under the bike. Mike's MB has the stinger do a 180 & the muffler mounted under the engine with a 180 facing the outlet back again. Not much issue as it's only gas bleed at this point of the pipe. Sketchy has done the same thing.

In fact there is more potential benefit from making the diffuser cone closed and taking the stinger off the pipe at the widest point. The amplitude is lower so it is quieter & again it doesn't seem to care where the bleed of the gas is taken off. I first saw this idea in a dirt bike magazine over 20 years ago, erm closer to 30. The Kawi 100 I had use of for a while used this system. Makes the muffler crashproof & you have heaps of room there from the looks.

Two pipes off the centre with thin mufflers would be real quiet, again not sure what dia, whether plain area calculation would be enough to get you close, couldn't say.

I don't understand your mounts from the grainy pics.

[koba]

Cheers for that Dave. If they standard cans off the MVX weren't so bloody heavy I'd split the pipe in two off the expansion chamber and run two of 'em.

I cut an RGV one down so it didn't weigh so much.

My bike is quiet as using the method Dave describes above. When the muffler fell off it was still one of the quieter bikes on the track.

[husaberg]

A quick note on mufflers

Taking note of what Wob had said when repacing my sons KTM muffler for the nationals last weekend.
I repacked he muffler as tight as i could.

It was packed as tight as possible (Basically wound on) it may indeed have been more powerful as Wob had said it would be.
But I had to repack it looser as i was getting quite a few comments on the line from the officials that i should consider it time to repack the muffler as it was rather loud.
Once I repacked looser that night it was indeed quieter but was possibly slower?

[quallman1234]

I have a standard TF125 muffler, you can have if your stuck for one. It will be restricted as hell, but very quiet.

[CHOPPA]

A quick note on mufflers

Taking note of what Wob had said when repacing my sons KTM muffler for the nationals last weekend.
I repacked he muffler as tight as i could.

It was packed as tight as possible (Basically wound on) it may indeed have been more powerful as Wob had said it would be.
But I had to repack it looser as i was getting quite a few comments on the line from the officials that i should consider it time to repack the muffler as it was rather loud.
Once I repacked looser that night it was indeed quieter but was possibly slower?

Yeah he packed my mufflers back in the MX days, fuck the bikes were loud! They were the fastest bikes on the track though

[Brian d marge]

Yeah he packed my mufflers back in the MX days, fuck the bikes were loud! They were the fastest bikes on the track though

arg me hearties , tis be a reason for that ....personally ( cause I'm a crap rider ) I would go for quiet and the loose packed ....

its early ,,,I need coffee , why do people have meeting so frigen early, I don't do early !

Stephen

[husaberg]

I have posted this elsewhere But as everyone is lazy
As a tip for others the best easy source of thin wall like 1.2mm or something.
Its irrigation tube mainly used one market gardens now not real farms ask around if your have rural mates but cheap as by the meter at Mico's comes in 75 and 100mm

I used to just buy the fibreglass packing wool string not cloth at the car muffler shop
$10-15 will do all the mufflers you are likely to ever use in a lifetime of racing. About 1 kg

As Drew is on an limited budget go to dump rip open oven and find high temp fibreglass matting hiding inside

If you want to get real trick for a 4 stroke the rotary guys use stainless steel turnings from a machine shop. They last forever even with a pp20b.
For the baffle I just used to spend a few minutes with the drill and a bit of exhaust tubing. Make up a couple of ends one circle with a hole on it the inside. The other a flat bit of sheet about 25mm wide and 250mm to 330mm long weld at right angles. Bend around the circular disk end as you go. Secure with rivets hold it on with springs to the stinger. Away you go.

Either that or get a couple of Speights cans, some Pinkbats and a cold chisel. Drink beer first before assembling muffler..

[Drew]

It's built! I didn't have time today to chuck a throttle cable on and start it, but that is all that needs done. Some testing to make sure it runs good and I'll be at the next meeting to race.


Stay out my way, I figure anything as slow as these bikes is a full contact sport!

[Kendog]

It's built! I didn't have time today to chuck a throttle cable on and start it, but that is all that needs done. Some testing to make sure it runs good and I'll be at the next meeting to race.


Stay out my way, I figure anything as slow as these bikes is a full contact sport!

Awesome work.
Next race is this Sunday, see you then?