From Aus 66cc Speedster


New Member
Local time
10:05 AM
May 7, 2014
Sydney, Australia.
Hey Y'all

The names Michael.

Got into motorised bicycles due to the loss of my drivers licence as I need a form of transport to get me around.

I've got a bit of a back ground with cars, currently studying Mech Engineering.

Anyway, it's been a good 6 months now that I've owned a motorised bicycle. In that time I've had engine mounts go, studs thread and snap, keyways **** themselves, wheels buckled, expansion chambers cracking numerous times after strengthening etc.

Initially I bought the bike buckled with the engine, then got a decent Mongoose Mountain bike and transferred all the stuff over.

It has a disc brake rear wheel running no brake, as I used the disc brake as a mounting adapter plate for the standard 44t sprocket. I have a disc brake front end, just have to put the caliper on and switch over the rim.

I plan on getting a spring tensioned sprocket chain tensioner, trying to keep the bike as efficient as possible. I have noticed since the upgrade of the rear hub assembly, the bike is simply ****ing awesome. The sprocket spins true and center, making the efficiency of the overall drive system greater.

I have also pulled apart the engine, done some minor filing of mating surfaces and sanding of intakes and exhausts (Nothing in regards of changing the cylinder ports though), minor speed carb mods (drill jet out .8mm) with no air filter and bigger fuel lines with in line car fuel filter, removed all baffles and mufflers from standard exhaust (will need to make up reinforcement bracket and finish off rest of heat wrap). I have a RR CDI but the coil **** itself, so I'm awaiting a new one.

So after all this you ask yourself where am I currently at?

Going to get the front end sorted, rip apart the engine for a full rebuild with bearings, transfer ports done and new gaskets, bit of polishing also, titanium wrist pin etc. I don't want to port this engine as it is my first bike and it already hammers. The most I would like to do is balance it after I do some piston mods to match the piston to the exhaust and intake.

At the moment I have confirmed this bike hitting 60km/h (37.5mph). I know the bike has another 5km/h in it, just haven't had a chance to use a phone with a GPS besides my mates today.

My plans are to get this as efficient and reliable with the speed carby. Once this is done and I'm happy with the outcome I will move onto a new project (another mountain bike that will be twice as light with twice the power, with slicks built for speed.. maybe with a reed valve and proper carb).

I solidly believe I can get this engine hitting speeds of over 70km/h with the Speed carby.

I will post up pictures and get a thread started over the next couple of days.

Anyway, glad to be apart of a place where everyone's common interest is the bicycle, and an internal combustion engine.