Suggestions For Quieter 2-stroke

Hi,
I have 1980 390 OR.
Im wondering if anyone has suggestions towards making the bike more quiter ?
or
Any Aftermarket silencers that you have used which made a difference in dB and silenced it ?

For my stock exhaust;
I already done the repacking
I do have a spark arrestor

For Aftermarket parts;
I did found couple of options but i wasn't sure if they would work or not. or i wasn't sure if its worth to spend the money, without knowing if they gonna cut the dB and silence it.

Here is couple of options i found

HVA Factory Silencer
Speed & Sport Silencer


Thank you.

yes !
air chamber exhaust +
rubber head cylinder +
silencer original WR
(bazooka)

Thank you for letting me know !!
looking forward to it.

Thank you !!
But i didnt understtand what you mean with "Air Chamber Exhaust" ?


I was looking for a rubber that will fit to head cylinders. Lets see if i can manage to find something...or i will just cut something myself.

For the exhaust wrap; do you wrap around all exhaust system, or just the portion of it ?

Unfortunately exhaust wrap will destroy the pipe and could change the tuning.

Intake noise is a big factor... not sure how easy it would be to muffle effectively.

Than you for letting me know.

Can you explain this please? I thought using exhaust wrap would be a good way to protect my riding gear from the hot header on my 500 Exc.

Look up "header wrap bad" on Google. It traps moisture and heat and exhaust metal deteriorates as a result. I've seen it first hand. No (car) header manufacturer that I know of will warranty a set of headers that have been wrapped.

As far as tuning, two stroke exhaust is like a "supercharger" that pulls exhaust out and fresh mixture out and where reflected wave then stuffs fresh mixture back in just before port closes... the speed of those critical pressure waves in the pipe is temperature dependent... raise the temp is like changing the dimensions of the pipe.

to keep the bike quiet just don't start it

The bike can make noise in different areas, one, the most obvious, is out of the silencer, there, longer and/or bigger silencers do normally tame the dB's down.
On bigger two strokes another source of noise is the expansion chamber itself, it vibrates a lot and is already doing a lot of noise from it. Make sure that the expansion chamber is mounted correct, with the rubber mounts in good condition.The pipe wrap mentioned before will lower the noise with the mentioned side effects.
Another origin of noise can be the intake, if that is your case you could glue some foam in the inside walls of your airbox, this will get you fewer volume and will affect the tuning but it will also bring the noise down, my Beta 2019 enduro bike comes with the side panels of the air filter box covered with a thick 2cm foam, I guess to pass EU inspections.
Noise can also come from the engine/chasis if the engine bolts are loose, check them also.

Cheers.

thank you!!

Probably one on the expert here will know for sure but I'm pretty sure the WR models had to meet noise requirements for Enduros and started coming with double-walled pipes with insulation in between the walls around 1977 or maybe earlier? The double wall cuts way down on noise.

I'm not sure if they used that tech on the OR? OR was kind of a cross between the WR and CR. If not, you might be able to pick up a WR pipe/silencer from a similar year?

himm, interesting. Im gonna look in to this, and will do some research. im not sure if OR is same....

rubber hose gas possible

rubber cylinder !
(picture Bultaco)

I know the 87 wr I had used exactly what was mentioned above with the insulation in between. It helps a ton with the noise. Not sure how you would go about making one though. Sacrifice another stock pipe?

are you referring to " double-walled pipes with insulation in between the walls " ?

Yep. The “second wall” was just a piece that matched the pipe exactly.

The pipe in the pic has two clamps up near the top. Those clamps are holding a second wall as well as some type of insulation.

Got it, thank you.

Hello everyone, i thought i should give an update on this topic.
I end up getting Anti Vibration strips + straps from vintagehusky (John)
After i gave a try, it did make a big difference actually. Specially those straps on top.



But, saddly straps were Old stock and they didnt last long due to age, and they snapped after a ride....Im only using the rubber strips, and they do make a difference too.
but not as good as those straps....