This project started because my son wanted to learn welding, painting and basic design.  Hopefully the time spent on this project will help him out in University where he plans to study Metallurgy at the University of Aachen in Germany.  The Hypersprint plans are from The Edge out of Australia.  The first problem we encountered is that when you buy the plan book there are no plans for the front end or the rear end.  It's noted on their web site that no suspension plans are included, they would like you to buy their off-the-shelf parts, somehow I overlooked this statement.  Soooooo, ours will look a little different to theirs.

After looking over the plans and researching on the web for other mini-buggies we noticed that none of the multitude of plans and sites have any reverse gear.  Since this thing will weigh around 700 lbs ( 315 kgs ) we thought that this was a serious oversight.  The idea of being stuck somewhere and having to get out and push it out of mess didn't sound like fun.  E-bay to the rescue, while searching through the ATV auction we bid and won a Forward/Reverse transmission from a Polaris 400 4x4, problem solved.

Next we looked for a motorcycle engine through The Want Ad Digest.  I would have preferred a Honda, somewhere around a 750 or 1000cc, but I wasn't looking to spend a fortune for it.  We found a Yamaha 1981 XS650 for $100.00.  Not what I wanted but it'll do.  With further web research for the bike I found that I can get a big bore kit for the engine to turn it into a 750 or an 840cc ( If the 650cc proves underpowered or when I check the compression this winter and it's bad I'll spend the $400.00 and increase the cc's ).  This bike model also has a history of broken sump filters and clutch slippage.  So the first thing will be to buy the modified filter from 650 Central and clutch plates and heavy-duty springs from HALCO in the U.K. ( I'll probably have them update the clutch basket from a 6 disk to a 7 disk because of the vehicle weight ) they also have a FAQ which answered my question of main jet size because of the pod air filters we'll use and the 12 inch mufflers and larger pipes ( Article on Minton Mods at 650 Central for increased horsepower by using larger exhaust pipes ).

As seen in the picture above, the frame is straight out of the plan book except for the very rear area which is the housing for the Forward / Reverse transmission and the rear axle assembly which will be discussed later.  Also the rear roll bar which has been curved outwards for space for the fuel tank from Northern Tool , the plans call for a fuel tank to be made and installed behind the driver seat and pumped to a secondary tank above the engine.  Seemed silly to me, so instead we'll install a 8 gallon fuel tank above the engine frame work.