Engine Silencer

A

AssembleThis

New Member
Dave here! Hi everyone! One of the biggest complaints I've noticed on various forums is how much noise these 2 stroke engines make especially when idling.
Well after a lot of thinking and designing I made a mod that removes about 50% or more of the internal engine noise. As you see in the picture my engine has 2 clutch covers. Because of the material and density of these covers they act like a drum. The silver cover, the first one. I took a marker and drew a line about 1/2" all the way around its circumference. I then used a drill and drilled holes all around it to make it easy to remove. Then I took an air grinder with a carbide tip and removed the entire center. Installed it on the engine and started modding the second cover. First I took an old tire and cut out a peace of tread the size of the cover. I used a steel belted radial so it was necessary to use a cut off wheel for the surgery. Careful doing this, those steel wires really hurt when they come flying. Wear safety glasses at least, a safety shield even better.
Then I took an old VCR case and cut a peace about 1/4" larger than the clutch cover. Auto tires are designed to withstand great heat but I wanted to be sure there was no way my clutch could be contaminated by the rubber or sealer. Now for the assembly. After you have cut the tire tread so it gos inside the second cover apply some sealant on the inside of the cover. I put a little in the center and a large bead about 1/2" all the way around the inside corner. Too much is a good thing here. You'll see why in a moment. I installed my tire baffle with the tread facing the inside of the cover. After the sealant is applied press the tire tread into it, then cover it with the thin steel plate. You now clamp it between two peaces of wood and let it sit over night, check to make sure the peaces are centered, when clamping you might have moved them out of alignment. Any excess sealant will ooze out. The next day remove it from the clamps and start the trimming. For this part "Pay Attention" you must grind or file the excess steel plate towards the clutch cover. If you don't you will separate or put bends or kinks in the plate which is bad. This is very thin plate and very easy to damage. If you damage this steel plate you will have to start over. I'm going to make another for my backup engine, when I do I'm making a video for my You Tube channel AssembleThis.
I've tested mine extensively and I can happily say I barely notice the engine noise anymore.
dance1
http://i.imgur.com/0dbjXzK.jpg
Well this my last post for the day, 5 is enough for me. I have many projects going on and dying for some food :). So stay tuned for the next AssembleThis post!
 
Many of the older hands here know how much noise can come through the clutch cover. There's been a few vendors that sell covers over the years too. I've seen just about everything from cardboard to old mousepads off computer desks used for home-made cover inserts.

Looks like you got it pretty well covered using tire tread :D
 
Or you could just stick a piece of Dynamat on the outside of the cover & then spray it with bedliner.

.
 
Hi FFV8. Tried the outside cover thing just didn't kill enough sound. Try both ways yourself and you let me know which is better.

Dave

.duh.
 
Could you some pictures of your method? How thick is the tire tread & steel plate?

AssembleThis said:
Dave here! Hi everyone! One of the biggest complaints I've noticed on various forums is how much noise these 2 stroke engines make especially when idling.
Well after a lot of thinking and designing I made a mod that removes about 50% or more of the internal engine noise. As you see in the picture my engine has 2 clutch covers. Because of the material and density of these covers they act like a drum. The silver cover, the first one. I took a marker and drew a line about 1/2" all the way around its circumference. I then used a drill and drilled holes all around it to make it easy to remove. Then I took an air grinder with a carbide tip and removed the entire center. Installed it on the engine and started modding the second cover. First I took an old tire and cut out a peace of tread the size of the cover. I used a steel belted radial so it was necessary to use a cut off wheel for the surgery. Careful doing this, those steel wires really hurt when they come flying. Wear safety glasses at least, a safety shield even better.
Then I took an old VCR case and cut a peace about 1/4" larger than the clutch cover. Auto tires are designed to withstand great heat but I wanted to be sure there was no way my clutch could be contaminated by the rubber or sealer. Now for the assembly. After you have cut the tire tread so it gos inside the second cover apply some sealant on the inside of the cover. I put a little in the center and a large bead about 1/2" all the way around the inside corner. Too much is a good thing here. You'll see why in a moment. I installed my tire baffle with the tread facing the inside of the cover. After the sealant is applied press the tire tread into it, then cover it with the thin steel plate. You now clamp it between two peaces of wood and let it sit over night, check to make sure the peaces are centered, when clamping you might have moved them out of alignment. Any excess sealant will ooze out. The next day remove it from the clamps and start the trimming. For this part "Pay Attention" you must grind or file the excess steel plate towards the clutch cover. If you don't you will separate or put bends or kinks in the plate which is bad. This is very thin plate and very easy to damage. If you damage this steel plate you will have to start over. I'm going to make another for my backup engine, when I do I'm making a video for my You Tube channel AssembleThis.
I've tested mine extensively and I can happily say I barely notice the engine noise anymore.
dance1
http://i.imgur.com/0dbjXzK.jpg
Well this my last post for the day, 5 is enough for me. I have many projects going on and dying for some food :). So stay tuned for the next AssembleThis post!
Click to expand...
 
Hi Russell! Since no 2 engines are exactly alike. Get a tread that will fill the clutch cover but not stick out after you stuff it in. The steel plate is very thin. Get an old electronics cover of anything, vcr, dvd, stereo. The purpose of it is shielding so no tread or sealant can contaminate your clutch. The sealant i used was auto RTV silicone black. The whole idea is to fill the second cover completely but not over fill it. It's ok if you put too much sealant in it, it will just ooze out when you clamp it together.
Hope this helps!

Dave

Stay tuned to the AssembleThis channel for more mods and upgrades!


.bld.
 
Last edited:
AssembleThis said:
Hi FFV8. Tried the outside cover thing just didn't kill enough sound. Try both ways yourself and you let me know which is better.

Dave

.duh.
Click to expand...

75% of the noise from that engine comes from the intake & exhaust. Some more is radiated from the cylinder & head. Best to go after the low hanging fruit first.

The noise generated under that cover is gear noise, and the pitch is high enough that damping it can be done successfully with a viscoeleastic damping material like Dynamat. The dead soft aluminum outer layer does a great job on noise above 4khz too. spraying it with bedliner protects the damping material, and gives it an even overall appearance.

Adding a second cover is a complete waste of time. You can bond that chunk of tire tread on the outside of a single cover & get the same effect. A mass of rubber sucks up a lot of sound energy - nothing wrong with 3/4" thick tire for that job. Just bond it on securely with something like Barge cement.

You need a very effective muffler to even hear the gear noise in most of those engines.

.
 
Hi FFV8! Thanks for your opinion. To each his own. Slapping something on the outside of the engine is one way of doing it I agree. But the cost to do it right is so low. Less than $8 for the entire mod and I never have to worry about it falling off or it looking like a hack job. In fact you have to look twice to even know it was modded. I believe every job no matter what it is should be done to the very best of your ability, if gluing a peace of tire tread to the outside of the case is to the best of your ability, that's ok. :) All I know is, it's so nice not to here that cover drumming away, especially at idling, it was very annoying.

.wee.
 
I like its clean appearance. looks factory, better than sticking something on the outside IMO. Creative approach to silencing a noisy cover. kudos.
kinda makes me wonder about pouring some urethane in a cover...
 
Last edited:
Rubberized undercoating (rattle can) from Wally World,sprayed on the inside of all covers works good too...also makes a great gasket.
 
Thanks turnofftheradio. I try to think outside the box lolol. I'm impressed myself with how well it works and it's so freaking cheap to do lolol. Once I finish all the mods I'm doing then I'll break it all down for a last paint coat. Might be a while though, like some time next year. So much designing so much fabricating. Doing the breadboard work for my control circuit and waiting for the rest of the parts so I can start assembly of the control box. I have some ideas on making an electric starter too. I cant wait to make the prototype for that. Also have to start winding generator coils and testing those. It sucks having to order everything online, takes so loooooong to get stuff. I love living in the country but that's one of the downsides. Anyways later, busy busy busy.

Dave

.bld.
 
You must log in or register to reply here.
Back
Top