Geared properly you'll be OK...top end will drop as you gear it deeper. Why not try a 79 HF? They're cheap too
The 79cc Pred engines are cheap and powerful (this bike rocked) but the transfer case isn't, this 79cc Prediator with a Q-matic was like $375 and that's just the engine and Xfer case.
The 49cc kit with everything (gas tank, base mount, back sprocket, throttle, etc) is less than that delivered.
I really like that 29" Macargi frame for fitting big engines in and I will be testing it's limits next week as I have one of these 86cc 4-stroke, 4-speed kick start motorcycle racing engines on it's way to try to cram in it.
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Specifications:
Single cylinder, 4-stroke, 2 valves
Bore x Stroke: 47mmx49.5mm
Measurements: 17" x 10 1/4" x 8 1/4"
Displacement: 86cc
Compression Ratio: 9.47:1
Carburettor: racing carburetor
Ignition: CDI, 12 volt, permanent magnetic stator
Maximum Power: 6 hp@ 7,500 rpm
Maximum Torque: 4.25@ 5,500 rpm
Gears: 4-speed, semi-auto, 4 DOWN.
Idle: 1,500 RPM
Final Drive: 14 tooth #420 front sprocket included (we have other sprockets on sale too!!)
Lubrication: 0.8 liters, 10W/30 4-stroke motorcycle oil, pressure and splash
Fuel: Unleaded
Package Contains:
Buyer will receive 88CC Motor, 22MM Carburetor, Intake manifold, intake gaskets, Shifter, Kick Starter, Wiring Harness, CDI, Spark Plug and Ignition Coil.
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$289.95 delivered and already ordered
I already have everything new in the shop to build it out, most of it free because of all the jackshaft and other custom stuff I do and left over parts get saved, so it won't cost me a cent more than the $289.95 for a 4-stroke 4-speed shifter
other than the bike cost which is another matter...
I spent all morning surfing the net looking for an ideal bike with good brakes I could mount this engine in with a rag joint left sprocket and came up dry.
That's OK, I can upgrade that 29" $230 Fatal Love with a new front shock and disc brake wheel, throw a C brake on the back to aid the coaster brake, and a seat post shock just for giggles and grins for about the same so I should end up with a kick ass quick and fast comfortable new personal 4-stroke 4-speed shifter ride for under $500.
That would get you around ghandi but don't expect to buy or even build one anywhere near that cost, when I sell it the price will be around $1,400 and worth every penny.