Mini maniacs

[Madmx]

There are 2 types of mini maniacs. The rider whose first bike was a a z50, Lil Indian, Rupp, trail 70..ect. The others are like myself. My 1st bike was a gs750l at 16. I missed all the mini fun as a kid.

The mini world is so vast. Big power and light chassis combined with short wheel base. Pull start to kickstart builds that are really built by owners. Definitely the biggest vortex of motorcycles I ever entered. I chased this with mopeds and scooters. But it is always parts!

I wander if it will ever end. Or will I finally hit triple digits on 10" wheels or smaller build. Minibikes are a nice mix of creativity, cash and skill.

A trail 70 with a 212cc 4 valve pulling wheelies at 50mph? Yup!! Some days I shake my head and other days dream of the 100mph pull start club...that 100mph has to happen in 1320

 

[Madmx]

My flashback ct70 clone 1st 10 Vin runs 17x32 and never topped out!! Light mod 125 easily cracks 70mph and is more relaxed than my tw200. Fun fun fun is the sound of thumpers. Briggs flatty to honda horizontal. This stuff never gets old! Jason's bike runs 77mph..Unfortunately 32 is as small as the rear sprocket can go on a ct70 wheel. The pull starts are one gear and can gear to anything that the clutch can handle.

 

[matty]

Never got in to the Mini bikes, Had a chopped down mobylete AV1 as a small child my dad made us to play on but that was it. Closest i got was the honda step through 50d 70s &90s both OHc and OHvs before them. I got them and felt they wee a useful tool they are not the best selling vehicle in the world for nothing after all.
Realy from pre teens it was Trials bikes BSA Bantam and BSA bantam villiers hybrids and Greaves Scotish and anglians with Ossa and montesa Bultacos in my teens until the TY Yamahas came out. yep all competition trials just missed the mini bike thing sort of entirely .
Got a decent GX160 laid about with a centrafugal clutch belt pulley on the crank ex wacker plate motor carb is typicaly rusty float bowl, now that in some coleman type self build for checking cattle on might be a good project any drawings or plans etc?

 

[Madmx]

Gx160 is a very desirable engine. Usually it is a gx160 head on a 212. The pulley clutch would probably work great to a jackshaft set up. Tires under 15 in can be geared direct from a chain clutch with an 11x72 ratio. The big wheel colemans run a jackshaft with overall gearing 10 to 1.

The easiest build we messed with took 2 hrs. It was a heavy duty bmx freestyle bike turned into a trike. We split the rear drop outs at the axle line. Then slid a go kart cradle in and welded. The go kart cradle is just 5/8 axle and a tube structure The tires are common front tires off of economy riding mowers. And the drive sprocket is mounted to the left wheel. We were going to build a 2nd version with a live axle. Even thought about twin engines and twin throttles for tight outside wheel drive turns.

The 1st trike has much abuse and has never failed. 3 different engines and two riders. I have watched the trike cart wheeling across the yard more than once.

I am not sure what parts are available outside the US but pullstart setups are about as crude as it gets. Most parts are industrial and agriculture in orgin

 

[matty]

Got a fair few motorbike frames and forks about in buildings could make up some sort of rigid fork and rear end frame to take the GX160, its a Good engine robbed it off a wacker plate we needed the wacker vibrator for a concrete vibrating table we made to make concrete posts with re bar cores. The GX160 ran but the carb kept blocking the steel float bowl was rusty as inside i took the carb off where it still lays today. A new carb only a few £ off fleabay and any hints on aftermarket generic performance carb for the GX160, motor itself is near perfect even clean oil and real honda version from 80s i am guessing, its been sat 25 years or so still turns over and only checked it for spark about 6 months back perfect.

 

[Madmx]

I think the gx160 has a cast aluminum flywheel. If not a pvl flywheel is now only $30. You can remove the governor parts and put a performance cam in while the side cover is off. The butterfly carbs are great for power. But the external linkage is not great for mud. There are adapters to run a vm, pkw or flatslide carb. Adapter is a few bucks. Then shim the valve springs or buy heavier springs. It gets more involved after these simple mods. Billet rods are available in different lengths to change piston to deck height or for high rpm use. Also milling the head, roller rockers, porting work and just any other old school engine performance mods are usually a phone call away.

 

[Madmx]

This build has more riding hours than dollars. The stepson rode it to work for a 3-4 months and he is good at trashing everything. I will end up fixing it up with new chain and sprockets. Put the hemi engine back in with different gearing. The 99cc still runs but the rear sprocket is done