Making a motorised bike legal

Angus taylor

New Member
Oct 10, 2017
1
0
1
22
I am very recently getting into the motorised bike hobby but i have recently been told that my 80cc motorised mountain bike is illegal in Western australia the rule is that any motor on a bike over 250w is illegal (80cc motors are about 1800w i think). I have recently been told that by making the gap between you spark plug shorter you can change the wattage and make you bike legal. IS THIS POSSIBLE? if it is can anyone tell me how i can do this and if theres any effects on the engine id appreciate it.
 

malatious

Member
Sep 23, 2014
61
15
8
Riverside, CA
Well 250W would be down around 11cc. There is no way adjusting your spark plug gap will get you down there. I have heard that Australia has very strict laws for motorized bicycles. I hope that doesn’t happen to us here in the States. To be legal it sounds like you need to go electric. Hope you can figure something out.
 

ZipTie

Active Member
Jan 8, 2016
750
48
28
Mpls Mn
I have several 250 watt front hub builds and I start from a dead stop with these torquey motors
,( i weigh over 200 lbs). Whereas my 80 cc gas Motors always needs me pedaling to go from a dead stop and avoid bogging and burning out my clutch. So a 250 watt geared hub seems to have more power at low range. So don't let low horsepower ratings scare you away from a legal ebike conversion kit. They are silent and range is about 28 miles on a charge
 
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ZipTie

Active Member
Jan 8, 2016
750
48
28
Mpls Mn
Here are two legal E-bike kits I built. They came out pretty clean I believe. I've built 4 so far and love them. I have about 800.00 into each one, I have these the way I want them. Although one can buy ready made legal ones now for about 600.00-700.00 and free ship on ebay and other sites. And yes, I like the non-grey area of legality when I ride these here in Minnesota.

Plus as an added bonus I do get to utilize all sidewalks and a ton of bike paths legally also. That is a bigger plus than one might think as far as safety and enjoyment of a motorized bike...just saying.

I Still enjoy my gas builds too.
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Legal e bike build 2.JPG
Legal e bike build 3.JPG
I Still enjoy my gas builds too.