Trials Australia Forums

Neo

Howard might have something to say about the flywire but I think it would work. The main issues with playing with the exhaust before or at the muffler is upsetting the back pressure wave. What this does is push unburnt fuel back into the cylinder ready for the next firing. Too much flywire and the burnt gasses will not get out of the engine quick enough and not enough fuel mix will get in. The opposite happens when you take the muffler off completely, too much unburnt fuel escapes.

I would try a few different densities of rolled mesh (don't use nylon flywire) of differing lengths until a balance between sound and performance is found. If it works, remember that the flywire will glog up with soot etc. and will need replacing or washing out (just like an air filter). The other advice would be when you get bike away from home make sure the daugther gives it a good hard ride for the first 10 min to clear out the engine pipe and ports.

Masking sound!!!!

Get an old hearing aid and pretend you are deaf.....then turn the TV up to full volume and fit a very loud external bell on your phone. That way if anyone complains you can claim discrimination against the hearing impaired!!!!! Sure winner!!!!

Anyone want to live next to me?????

Hi Neo,

I didn't realise that it was that bad already. So please ignore my less than helpful remarks. I would try and avoid court at all costs - there are never winners. I'm sure there are cheaper, more devious ways to gain satisfaction. Seems others have lots of ideas, but pony skins?????

It seems the best solution is the quiet bike. I once saw a "bush muffler" used on a way-too-noisy offroad rotary-engined buggy. It was a sheet of light alloy rolled into a tube around the original muffler (hotdog) to extend the length. It was held in place with a hose clamp and a self-tapping screw into the original muffler. It had a chicken wire inner tube that fitted over the orginal outlet and extended out of the new "muffler". The other end of the alloy sleeve was crimped down to the size of the chicken wire inner (looked rough, but it was built quickly). The space between the alloy tube and the chicken wire was filled with fine steel wool (because that was all that could be found) It worked well enough to pass the buggy through scrutineering, but I think the steel wool burned out half way through the race.

Whatever you do, be aware of what Parla Gully said about the back pressure wave. If it is increased to much it can toast pistons, which is why I like the longer muffler option.

Good luck

Rob W

Neo

Wouldn't worry too much about burning up pistons.....if she is riding that hard nothing will shut it up enough. The flywire is an ok option for low rev practice in low gears but I would not be using it at any other time. As far as steel wool goes.... well......at least a two stroke is unlikely to burn it but that stuff does catch fire and not a good idea in hot weather. I repack my mufflers with yellow insulation bats. You might find if you remove the baffle and repack the muffler with new fibreglass and maybe even get some woven fibreglass mat to wrap around the baffle tube you may make it much quieter. A removeable retrictor like a large nut placed halfway along the baffle tube might also do the trick. Just tie some wire to it so it can be pulled out without destroying the baffle.

Neo,
I`m not familiar with the muffler on the Gas Gas 80`s, or how quiet they are new. I am assuming the bike is second hand, and done a fair bit of work, as most kids live on them.
My recommendation is to repack the rear muffler. My sons have CR 85 & 125 motocross bikes, I have to repack the mufflers every three to four months. The layer around the perforated tube becomes soaked with oil, I just replace this with one single wrap of fibreglass mat ,and put back the rest of the factory packing.Clean the tube aswell, all those little holes let the sound waves into the packing. Cheap, quick option. If it`s quiet enough, great. If not, your going to need a bigger muffler.
If you need to go the bigger muffler, there are plenty of aftermarket ones available.
Cheers,
ShercoH

Neo,
I`m not familiar with the muffler on the Gas Gas 80`s, or how quiet they are new. I am assuming the bike is second hand, and done a fair bit of work, as most kids live on them.
My recommendation is to repack the rear muffler. My sons have CR 85 & 125 motocross bikes, I have to repack the mufflers every three to four months. The layer around the perforated tube becomes soaked with oil, I just replace this with one single wrap of fibreglass mat ,and put back the rest of the factory packing.Clean the tube aswell, all those little holes let the sound waves into the packing. Cheap, quick option. If it`s quiet enough, great. If not, your going to need a bigger muffler.
If you need to go the bigger muffler, there are plenty of aftermarket ones available.
Cheers,
ShercoH

Hi everyone.

Howard, the Rookie muffler is the common 2000 Sherco / Montessa 315 style, but just a bit smaller. I bought some muffler cloth yesterday so I’ll get repacking soon. The guy in the shop said I should pack it loose as this makes it quieter?? – any opinions on this?

BJ – do you find yellow batts any quieter than normal muffler cloth?

Also, from all the stuff I’ve read so far, it sound like a "muffler on the end of a muffler" would not do any harm. I like the idea of having something I can quickly bolt on and off. I found a universal one at this site:
http://vro0m2.server101.com/bk/uni_muffler.htm
But I’ve no idea how I’m going to fix it to the bike yet. – anyone have any opinions on me taking this option too?

Rob, If this fails I’ll have crack at the Bush Muffler ideal with coth or yellow batts.

One way or the other I’ll post a picture of the final result.

Best of - pop, pop, pop - balance!

Neo
PS. – Howard, this has also raised the question, is it possible to repack the muffler on my 02 – 290? – Looks all welded up to me.

Neo,
I think the fibreglass cloth is the way to go. Another muffler on the end will help,though if GGG keeps falling off that side it`s too big.
The only way to redo the Sherco muffler is to cut it open and re-weld. Have had some success with degreasers or acetone. Make sure it`s dried out before starting. Would recommend a new muffler, as the improvement in smoothness is amazing.
Cheers,
ShercoH

Neo

Yellow batts quieter dunno???? But bloody cheap when you find one on the side of the road!!!!!

You could make a tip for the Muffler that points the exhaust outlet down to the ground rather than it pointing straight out.