Step 7: "Puke tank", seat, and engine mounting.
Our next step is to make what is known in the racing world as the "Puke tank". No- it isn't for seasickness, but rather for the engine. Since the engine will be running at sometimes 50% faster than it was originally designed for, the crank case will sometimes spit oil from the crank case breather. Since you don't want that stuff all over the track or you for that matter, you make sometimes called a puke tank. Mine is made out of ABS plastic pipe, brass hose fittings, and PVC for the breather on the right side (in white). This is mounted to the back of the mower under the seat, connected with a hose to the engine valve cover.
Next, I decided to machine slots into the engine mounting pan. I made keyhole shaped slots that enable the engine to be slid forwards and back so that the chain can be fitted and tensioned properly. This is the longest chain on the build, thus a spring-loaded tensioner was fabricated in addition. Since the chain here is hanging horizontally, you want to have constant, gentle pressure applies to keep it from falling off. The tensioner is simple, using a channeled nylon idle pulley typically used on mower decks. Like the skateboard wheel, nylon holds up just fin on chain. The pulley is mounted to a arm that is bolted to the underside of the simulated mower deck via a nylock nut and bolt. A spring is attached to it as well as a bolt welded to the underside of the engine pan. As you can see, the chain fits nicely from the centrifugal clutch to the RAGB.
Now the seat. This step is actually kind of important. You'll find that staying on these mowers on a bumpy dirt track with sharp corners is difficult.The inertia will threaten to throw you off. But at the same time, if you do fly off, you want to clear the "scene of the accident" and not get run over by your own mower. So it needs to be low. The solution is to have a low seat with low sides that keeps your rear attached to the seat. It'll actually give you more control. One last word- it helps to have padding. A steel seat with no padding can be... painful. My Wife covered mine with upholstery from an old chair.
Next, I decided to machine slots into the engine mounting pan. I made keyhole shaped slots that enable the engine to be slid forwards and back so that the chain can be fitted and tensioned properly. This is the longest chain on the build, thus a spring-loaded tensioner was fabricated in addition. Since the chain here is hanging horizontally, you want to have constant, gentle pressure applies to keep it from falling off. The tensioner is simple, using a channeled nylon idle pulley typically used on mower decks. Like the skateboard wheel, nylon holds up just fin on chain. The pulley is mounted to a arm that is bolted to the underside of the simulated mower deck via a nylock nut and bolt. A spring is attached to it as well as a bolt welded to the underside of the engine pan. As you can see, the chain fits nicely from the centrifugal clutch to the RAGB.
Now the seat. This step is actually kind of important. You'll find that staying on these mowers on a bumpy dirt track with sharp corners is difficult.The inertia will threaten to throw you off. But at the same time, if you do fly off, you want to clear the "scene of the accident" and not get run over by your own mower. So it needs to be low. The solution is to have a low seat with low sides that keeps your rear attached to the seat. It'll actually give you more control. One last word- it helps to have padding. A steel seat with no padding can be... painful. My Wife covered mine with upholstery from an old chair.
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Liquid cooled engines aren't actually allowed in sanctioned mower races for various reasons. But something else to think about is that this is a sort of rough sport and we bang into each other a lot. The last thing you want is to smash a radiator out there.