i was wondering if anyone here has seen or done a shroud around the engine ie"dirt bike engine cover" to quiet some of the engine mechanical sounds? in one post someone said the seen one on a post here but that was posted over two years ago.
engine silencing shroud?
- Thread starter robert0508
- Start date
Air cooled 2 strokes rely on circulating air to cool the engine.
Being able to channel the air around the engine on a high speed 2T race bike is one thing, but shrouding the engine on a low speed vehicle which spends a considerable amount of time stopping and starting isn't a good idea.
TiM
Being able to channel the air around the engine on a high speed 2T race bike is one thing, but shrouding the engine on a low speed vehicle which spends a considerable amount of time stopping and starting isn't a good idea.
TiM
i'm not saying to cover the engine entirely with air holes to breath, im just saying to use some materiel to help divert the noise coming from the engine away from the sides and push it out the back, not really hurting airflow just like a odd umbrella thing coming off the top tube.
I tried the elastomer engine case damping material in my HT and it damped out a lot of the tinnyness from the bottom end of the engine. It's those self adhesive decals cut to the shape of the side covers made from the rescue tape soft rubber material.
Another thing that works a lot to make a bike engine quieter is a plastic airbox plenum for the intake. Almost half of the noise comes from the intake, and a airbox damps out the sharpness and quiets it down a lot. I found a plastic Folgers can with a velocity stack inlet from a cutoff handlebar grip, with a UNI filter inside works great and didn't hurt the performance at all.
Another thing that works a lot to make a bike engine quieter is a plastic airbox plenum for the intake. Almost half of the noise comes from the intake, and a airbox damps out the sharpness and quiets it down a lot. I found a plastic Folgers can with a velocity stack inlet from a cutoff handlebar grip, with a UNI filter inside works great and didn't hurt the performance at all.
i've done that, also will be putting plasti-dip on the covers to silence that but other noise i cant kill was thinking i could divert it to the back of the bike so there would be less echo when biking near houses
the exhaust is all the way to the back its as silent as i can get, the noise is coming from the engines moving parts, and the vibrations that cant be killed with a proper mounting or rubber pads. i already know about the intake and exhaust mods and how to quiet them. i am asking about a "shroud" "cowling" "cover" "shield" for the engine. forget the intake or exhaust noise, im looking for ideas or a pic of someone who made a DIY thing to divert the noise from the ACTUAL engine to the back of the bike were there will be less buildings and people.
You could make a plastic fairing that goes around the sides of the bike and still ducts cooling air to the engine. I'd avoid a fabricated aluminum one because it will resonate and make it louder. Soft mounting stuff doesn't tend to work too well, its better to have everything good and tight to avoid fastener failures and loosening up, which will cause more vibration and noise.
Diverting sound, or acustic control is a very difficult thing to do. Your idea of attaching a shroud or fairing to "move the noise to the rear" isn't really feasable. Sound can be diverted, softened, changed in tone or frequency and controlled to a degree but it doesn't react like a fluid. It doesn't flow like water or air.
Shrouding the engine with a sound deadening material might quiet some of the offending noise but keeping sufficient air flowing over the cooling fins of the cylinder and cylinder head are crucial factors that you shouldn't restrict.
I'd take some of the advice offered above. You might be surprised at the results.
Tom
Shrouding the engine with a sound deadening material might quiet some of the offending noise but keeping sufficient air flowing over the cooling fins of the cylinder and cylinder head are crucial factors that you shouldn't restrict.
I'd take some of the advice offered above. You might be surprised at the results.
Tom
Your mention of sound deadening material reminds me that maybe you could line a plastic or composite fairing with some Dynamat, they make a bunch of different types, some thin and light enough to be used on a bike. Maybe contact cementing some neoprene foam onto the inside of a fairing might do the same purpose, and its cheap at places like OSH.
sound can act kinda like water, putting your hand to direct the sound from your phone/tablet speaker to hear better is like putting a shroud around your bike to help direct the sound another way, may not be 100% effective but will help with the loudest parts and will also help with the riders hearing if the engine itself is loud. and thats all i was looking for , a covering for the engine that in turn stoped the engines mechanical noise from coming to my ears and al from echoing off of houses when i come home.
Rereading this thread I have a feeling that there is more than meets the eye. You say you have the exhaust routed to the rear but you didn't say what you're using as a muffler.
You also said that the "mechanical noise" from the engine is louder than the exhaust or intake sounds. If that truely is the case you have something wrong internally. The engine itself shouldn't be that noisy.
Could the sound you're hearing and objecting to be described as gear noise? A whine or grinding sound? The reason I ask is that I had an engine that was extremely noisy, gear sound, and it was traced to a primary gear (small gear on right side of engine) that was drilled off center and also angled. When it rotated it meshed with the larger gear, secondary, and wobbled. It was crazy loud and very annoying. I replaced that gear with a good one and dramatically reduced the engine noise.
You can check for this condition by removing the spark plug, disengaging the clutch and spinning the engine with a drill and screwdriver bit on the slotted screw holding the primary gear to the crankshaft. Watch that gear as it spins. If it wobbles that means it is not engaging the teeth on the secondary gear properly and will produce noise.
Tom
You also said that the "mechanical noise" from the engine is louder than the exhaust or intake sounds. If that truely is the case you have something wrong internally. The engine itself shouldn't be that noisy.
Could the sound you're hearing and objecting to be described as gear noise? A whine or grinding sound? The reason I ask is that I had an engine that was extremely noisy, gear sound, and it was traced to a primary gear (small gear on right side of engine) that was drilled off center and also angled. When it rotated it meshed with the larger gear, secondary, and wobbled. It was crazy loud and very annoying. I replaced that gear with a good one and dramatically reduced the engine noise.
You can check for this condition by removing the spark plug, disengaging the clutch and spinning the engine with a drill and screwdriver bit on the slotted screw holding the primary gear to the crankshaft. Watch that gear as it spins. If it wobbles that means it is not engaging the teeth on the secondary gear properly and will produce noise.
Tom
It could also be running too lean and pinging, when a two stroke preignites or (hopefully not) detonates, they get really raspy and sound like a ball peen hammer on aluminum.
