DIY motorbike question

shazza541, Jun 30, 8:14am
My daughter has one of those little electric ride on minijeeps, anyway i figured it needs more power so I have a 31cc ryobi weedeater motor here which i'm gonna strap on the back of it instead. I have the axle and drive sorted, the problem is the engine itself is quite loud (especially when you're a 2year old girl and its revving out right behind your ears). Would fitting an exhaust of some sort to it divert the noise or quiten it down, and if so what sort

m16d, Jun 30, 8:20am
Maybe your 2 year old little girl is quite happy with the electric motor.

desmodave, Jun 30, 8:21am
When youve done the lgunna stuff and its dunna stuff come back with some pic's.ear muffscheapest option. Do ya think a 2 year old is gunna handle the jandle

shazza541, Jun 30, 8:25am
no its slow and doesn't handle going on grass

skin1235, Jun 30, 9:07am
definitely modify the exhaust, you may have to butcher the existing one to get a steel base to weld more pipe to
mufflers are essentially an expansion chamber, remember if you want it quiet you need to keep the outlet smaller than the inlet but also have sufficient between the two to dissipated the energy as heat rather than noise ( thats essentially all a muffler does), properly done you'd hardly hear it 10 ft away, certainly not intrusive sitting in front of it

skin1235, Jun 30, 9:11am
the more interuprion you can cause to the exhaust charge the better too, the 15mm weedeater exhaust into a 180mm piece of 32mm with washers internal with 15mm for the 1st 2 washers, 12mm for the next 2 and 10mm for the last 2, will have it running so quiet you'll be wanting to pull the cord again

think silencer on a rifle

red97, Jun 30, 9:29am
sounds like a great idea but it brings up a number of safety issues which you have obviously thought about because you are trying to address one of them here, the noise, exhausts are very hot, petrol is very flammable, exhaust gasses are unpleasant to breath, in my humble opinion given the age of the intended driver i would be more inclined to go with aheavier duty electric motor, something like a 400 watt contiki motor would suit if geared correctly, would be easier to govern with a simpleESC to suit the skill level of the driver and could release more power asskill levels increased. i feel this option would be cheaper then making an exhaust quiet enough to have running a foot away from a young ear and i have a hunch that if yougot it quiet enough it would be that restricted itwould have lost most of its power and would just be gutless hot and flammable

clark20, Jun 30, 9:34am
I had a 6V bike for my girls,I used a power drill battery for it (9.6V), one day I put 2 in series (19V) and it would spin the wheels , lots of fun

kazbanz, Jun 30, 10:15pm
Shazza-Have a look at the miniquads for sale on here.The really small ones are powered by chainsaw motors.There may be an exhaust/chamber off the shelf for them. Also the tiny two wheelers--also powered by chain saw engines.
I seem to recall a crowd called "newmans" sold that stuff.
Incidently stuff you might not have thought of.
1) brakes -I bet there aren't any
2) wheels-the little plastic wheels on those lectric jeeps are known to wear out/collapse anyways--let alone add a bit of HP.
3)heat--is it made of plastic that burns up!
Not for a second trying to discourage you --just saying look at it carefully is all
Now if you took a mini quad and fitted the body and sterring wheelfrom the jeep onto it I reckon you might be onto a winner

NZTools, Jun 30, 10:36pm
The crappy plastic gears in the final drives of those things wont handle any increase in power.