How do I make this bike as quiet as possible?

[Wolfshoes]

It is possible to shroud the engine to some extent with indoor/outdoor carpeting held on with a velcro strap as a sound deadener.

As pictured, the carpet piece is laminated with a commercial remnant adhesive backed plastic and edged with shipping tape. The shroud was used all summer in north Illinois without heating being a issue when using Opti-2 two cycle lubricant which seems to allow the engine to run cooler. The brand label sticker sometimes found on the clutch cover seems to dampen harmonic resonance enough that it's worth having a material stuck to the outside of the cover for no other reason than sound deadening.

Regarding your question about licensing your motorbike. In general, they are not licensed as a motor driven cycle or moped in most states. Some states would like to make them have insurance but there does not appear to be any cooperation by insurance companies. Usually a motorized bicycle, as a consumer commodity under federal law, can be ridden up to 20 mph and a state or locality could allow a higher speed than that. In some IL state jurisdictions, the 20 mph is a boost after the engine takes over forward motion allowing a speed higher than 20 mph. As true with bicycles, under federal law you have the right to the lane of traffic. In Illinois, a motorized bicycle cannot be considered a motor vehicle if it cannot begin forward motion without pedal assist. Therefore proof of insurance or registration cannot be asked for. I understand it is not all that hard to get the federal legal ability to create VIN's as a builder if properly applied for. You would be expected to have built the frame. My opinion on the engine EPA engine problem is only computer controlled fuel injection will pass for street use as a motor vehicle. Grubee HT two cycle engines pass the EPA on motorized bicycles if the overall weight does not exceed 44 lbs; but after the engine purchase, there is no provision to check the finished bike at this time. Some states such as Indiana, Michigan, Vermont and New York are attempting to impose licensing and or insurance requirements and it is possible New Jersey is as well but I cannot comment on that.

 

[Steve Best]

Hey Darkfighter, smart thinking, good question. I'm working from this angle too.
I bought a few mufflers from my supplier and found this one the quietest:

http://www.motorizedbicycle.ca/exhaust-system/chrome-exhaust-muffler.html

I have followed Jag's advice and fastened 10"rubber hose to its exhaust outlet. I used steel mechanic's wire. It works.
The stock intake was very noisy too, solved with a better filter housing, which the engine needs anyway.
Jamming 1/2" long rubber hose bits in the cylinder fins got rid of a lot of "PING".
At this point, I have more noise coming from the gears. Make sure they are greased.
I haven't made noise dampers up for the gearcase yet. I'm thinking of a rubber coating on the inside.
Keeping rpm down and off the throttle near people helps, as does pulling clutch and pedaling.
Very little noise at idle or low rpm and load.

A tuned pipe would make more power but typically makes more noise.
Jag has a video that shows the value of having the stinger (outlet) come off the mid-point rather than the end.

I read an SAE paper about silencing 2 strokes several years ago. It concentrated on exhaust port shape (round is quieter than square or triangular, softer pulse wave) that I remember. The DT200 Yamaha is very quiet, using water cooling, a double wall tuned pipe and efficient muffler.

Darkfighter, sensible idea, smart guy.
If we want to keep our rights to ride we need to keep under the radar. Stealth makes sense.

Steve

 

[darkfighter]

Hmm, I liked the idea of a muffler with the catalytic converter built in, but want to buy from an American seller instead, since the CAD is almost back to normal.

By the way, does spark plug affect noise? I would imagine it to affect ignition which would affect it.

 

[Steve Best]

The same company has an American branch but they do not sell the non-cat chrome muffler to you guys. The black cat muffler is a close second. Cats don't go so well with 2 strokes, they soot and oil up. The American branch is https://www.motorizedbicycle.com/

Spark plug has no effect on noise at all.

Steve

 

[pghewins]

i managed to quieten mine quite a bit i bonded 6mm rubber to the outside of all 3 removable covers bought some exhaust wrap and wrapped the outside of stock exhaust cut top off empty butane can make sure its empty first lol and you arent smoking while you do this its the right bore to slide over the stock exhaust then drilled 12 or so 3 mm holes round the base easiest done if you fill with water and freeze it first packed with wire wool and slid over exhaust and held in place with jubilee clip has made quite a difference not such a tinny noise now and no noticeable loss of power swapping to a dellorto copy carb also made a big difference you can get the idle much steadier at lower rpm than with stock nt carb thanks to jaguar for his advice on how to set this carb up

 

[pghewins]

Hmm, I liked the idea of a muffler with the catalytic converter built in, but want to buy from an American seller instead, since the CAD is almost back to normal.

By the way, does spark plug affect noise? I would imagine it to affect ignition which would affect it.

a cat will be knackered on a 2 stroke in miles to much oil in exhaust gases and yes swapping to a good ngk or champion or bosch plug makes a hell of a difference to performance and the smooth running of engine from the spark plug provided in the chinese kits i use champion CJ7Y

 

[Purple Haze]

A lot of noise is not coming from the exhaust, but from the chain drive. Pull the left rear cover (the one with the clutch arm) and see if the chain is rubbing the front edge. (they usually do) This alone makes for a noisy ride. Dremel or trim for clearance. A good tensioner (spring loaded) will also reduce noise and lower maintenance. I've found the clutch very noisy on these engines, wish someone would come up with a better idea. Sickbikeparts has a kit that's like Dynomat to fit inside the covers, which helps dampen the clutch noise. The intake (carb) also makes quite a bit of noise. (hissing) Get a good air filter. If you have a muffler that comes apart, you can stuff fiberglass packing (available at motorcycle shops) into the case to mellow the sound. Don't go overboard with it, as it is restrictive.

 

[Guest-902282]

I know it may not be too loud, but it is getting pretty annoying having to turn the engine off within 50 feet of a pedestrian just to avoid weird suspicion. Perhaps if I pedal at the same time and turn it into an electrically assisted hybrid no one will understand to care enough about how it works.

I've got one myself and I'm having the same noise issues. And I to will turn the motor off to avoid to much unwanted attention.

 

[Boardtracker13]

If you want to make your bike quiet you need to look in to this bad ass shark muffler on Amazon I was amazed at how this free flow muffler sounds !

 

[Guest-456768]

Use earmuffs