Tip: How to reduce engine noise.

[Large Filipino]

All I know is that my speedometer don't lie. 18 mph is the cruising speed I like cause that's the speed where I feel my engine is not working too hard. Before I switched to Maxima which made my engine quieter my comfort speed was closer to 16 mph.
Today my average speed was at a comfortable 20 mph. Before this modification,20 mph would vibrate the heck out of my pedals and my buttocks and slowing down to 18 improved it a lot. Today 20 felt like 18.
Maybe my engine is just breaking in even though I've already taken it over 300 miles.
It's unlikely though that my engine broke in right at the same time I put these tire pieces in.
You don't notice the sound difference right away,but you sure notice the reduced vibrations and the higher speed.

 

[joelvanderhoof]

I just tried this. I put rubber between the fins. It made quite a difference. It was immediately noticeable on my bike
Now with my 36T sprocket I can cruise right along at a nice speed and the engine is quiet and not overworked.

Thanks guys. Great suggestion!

 

[japat100]

i did have a sound meter and looked everywhere for it with no luck ,,it gave the db and also the frequency . from 20 to 20000 hertz.. . i am thinking that the rubber changes the high frequency into a lower frequency ,,it may be just as loud but not as hard on the ears since it in the lower range
,i here some members saying the motor runs smother and don't seem to work as hard ,,i guess anything under the sun is possible .but its hard to believe that such small pieces of rubber would have such a big effect ,,, i always thought if a person could set this motor in real good rubber mount 1 inch thick you would get rid of vibration and would run very quiet ,,but when you have it metal to metal it will take allot more then small pieces of rubber between fins to make any a mount of deference , one thing that i tried is to set the muffler in asbestos so its not metal to metal ,,that seem to helped a bit ,but again it may have change the frequency and just as loud ,, but if your ears enjoy the lows instead of the highs frequency then thats great

20 to 20000 if you have good hearing is about what us humans can here at sea level ,,as we get older the higher end of frequency we start to lose ,,,,this is good if you have a nagging wife with a high pitch voice ,,

an older man i knew worked at a saw mill and he was hearing impaired as a child ,, happily marriage for 30 years with 3 kids ,, when for a operation to restore his hearing and it was a success ..6 months later he and his wife separated ,,yes he packed up and left

maybe he should have put small pieces of rubber in his ears
japat

 

[mikesbike]

It sounds like many of you don't have to many miles on your motors. Mine is over 3000 now. Over those miles I've isolated just about every vibration and rattle I could find. I assure you I've been through the butt and hand numbing stages where bike parts break and fall off. I found that the biggest vibration issue came from the chain drive. I use the inline skate wheel idea from this forum. Two of them. One for tention and the other on the top chain as a guide. (no tention!) For noise reduction the cluch is loud when not engaged. I now put a small length of heat shrink tubing over one of the three pins that hold the clutch plate. The tubing just fills the small gap and illiminates the clattering noise. Its a huge improvement. Try it! Gear whine is pretty loud on my bike. I use WAY more grease than a "peanut sized dab" My clutch pads have never fouled because of it. Marine bearing grease works great on these bikes. (its light blue) The marine grease is kind of waxy and sticks to the gears well. It helps that issue. I'd like to figure out how to quite the carburator. How do you do that? If the rubber in the fins trick works for you do it! I say try anything. I can't hurt unless you do something that can't be undone.

 

[gone_fishin]

yeah...this one can't hurt anything...i suppose if you use the wrong material you're gonna be scrubbing baked/melted gunk off the fins.

it does work, i've had 5 different 70's on my bike, all have performed and sounded almost exactly alike...this really does work as intended, takes the tiny vibes of the fins outta the noise-equation. does it boost performance? i don't see how it could, but it prolly does improve your perception of performance. i can hear the engine now instead of the peripheral sounds, it sure does make me think it's running better...and that's a good thing, too, in it's own way

 

[OldPete]

yeah...this one can't hurt anything...i suppose if you use the wrong material you're gonna be scrubbing baked/melted gunk off the fins.

In the event of a melt down. The gel like heavy duty paint remover works well for cleaning bare aluminum fins of air cooled engines. Before a long road trip if one wishes to have an easy engine clean-up after the trip is over...spraying the engine fin area with Pam work a charm. Did this on my air cooled '83 BMW for years.

 

[gone_fishin]

cool! does using "butter flavor" make for a more pleasant riding experience i wonder?

sorry, couldn't resist.

 

[sideshowsideswipe]

hope I have some rubber at home I can use, my garage consists of a big flat tupperware hidden under the bed with all my tools in it.

 

[alesterfeind]

Genius!

I love this forum! I got home last night and found some old automotive rubber fuel line that's about 3/4 inch. I cut it in 1/2 inch lengths and then cut the small piece in half through the diameter. So the rubber pieces I have are shaped in a crescent shape: (

I tucked them between every fin on the engine that I could, on the sides and the head. What a difference! All this time I thought my engine was knocking or had problems internally, but now it putts along like a little motorcycle engine without all the pinging and ringing noise. Thanks guys!

 

[mickey]

I tried cut fuel tubing between my fins and it does have a mellowing effect, much less ring-ding and slightly less overall noise. I only placed a single row down both sides and between the largest fins on the head.

Coincidently, while test driving I started to lose power. When I checked the motor, broken head bolt. Right at 500 miles on this Kings "80cc". I've been looking for longer engine mounting studs and my local auto stores don't carry any 6mm studs longer than 1 inch. Now I have to find one 115mm long which means snooping the industrial supply where they don't much care for small retail sales. Does anyone know of an online source for replacement cylinder studs?