Posted on September 27, 2009

       OK, it’s time to get back to the Turbochopper!!! I have really been able to make some serious progress on this project in a short amount of time. I am just about ready to put the bike on it’s wheels. However I must take care of a few items before I am ready to get her rolling. One of those items is the seat back/inducer shield.
       If you have ever heard a large turbocharger gas turbine run a full power you will know that there is a lot of energy being converted into heat, air pressure and kinetic energy. If anything should come out of balance while the engine is running look out!!! It really is something to be taken very seriously especially when in close proximity to a running engine.
       From the very beginning I have planned on positioning the GR-7 behind the jet bikes seat and not under it for this very reason. I definitely want to stay out of the rotational plane of the turbine in case of a catastrophic failure. However just being near the engine is a risky thing so I must try to minimize that risk within reason.
       To help reduce possible exposure to ballistic engine parts I fabricated a steel protective seat back that will hopefully protect my “assets” from any possible mishaps. The seat back will not guarantee complete safety but definitely help reduce the risk of injury on this already “dangerous” ride. I used some .090” x 1/2” square tubing to make up a frame and welded it directly to the front frame as seen below.

       I welded in a 1” x 1/8” steel bar to the rear of the frame as a future seat support before moving on to the next step of the build.

       Eventually the seat and seat back will be made of birch plywood base boards which will be pretty tough by themselves. However I wanted a steel plate on the seat back as a little insurance to protect my can from anything that can be shot out of the turbo’s intake. I made this plate out of 16 gauge cold rolled steel which isn’t bullet proof but is better than nothing.
       The shield plate was welded into place and finished off with the flap disc treatment.

       The next step was to install the battery tray that will hold the lawn tractor battery in the bottom front of the frame. I used angle iron to frame up this tray to fit the outer dimensions of the battery as seen below.

       The battery will eventually be held in with a Velcro strap as to allow it to be easily changed out with a charged one after use.

       The next item to take care of was to pre-mount the fuel cell. In this project I am using a Summit Racing 3 gallon “fuel cell” (not to be confused with a hydrogen fuel cell). A racing fuel cell is designed to contain volatile fuels in a rupture resistant tank or bladder. The fuel cells job is to contain the fuel even if distorted or partially crushed by a collision while racing. The last thing you would want to happen in a crash is to be sprayed with alcohol or top fuel (nitro methane) from your fuel tank and then have a fire break out :oP
       In my case I am not using a “volatile” fuel but dangerous just the same. If the bike were to be layed down at any decent speed it could cartwheel or collide with an immovable object. This collision could crush a standard fuel tank and produce a fine spray of diesel from the ruptured seams which could easily be ignited by the hot engine. I personally have seen this scenario several times with model airplane turbine crashes. All that is left is a burning pile of wreckage that was once a beautiful jet model.
       By no means do I plan on crashing my bike but I do want to be as safe as possible. The addition of the fuel cell to the bike is a decent safety measure.

       The summit fuel cell (Cat# SUM-290120) is made from seamless polyethylene plastic and features an aircraft style wide mouth locking filler cap. The cell also features aviation foam filling (see below) to prevent fuel slosh and aeration which can cause air to accumulate in the fuel system.

       I welded in a couple of 3/4” angle iron tank supports into the bike frame just under the seat. I then fabricated a couple of aluminum tank straps to secure the fuel cell into place.

       1/4-20 cap screws were used to secure the straps to the angle iron as seen below.

       The fuel cell was now in place and looking the part :0) I offset the tank to the front of the bike as to allow air flow into the engine’s oil cooler.

       I pretty excited at this point as I can now bolt the frame together to get a preliminary look at the bike.

       After a few minutes of assembly I could finally see what was forming into the GRV-2 Turbochopper :0)

       At this point I really am happy with the shape of the new frame and how it blends into the existing engine. I would like to think that this is a result of form following function ;o) Notice the Ducatti like framework. Must be the influence of my Italian heritage :0))))

       As you may have noticed in the pictures above the bike is on wooden blocks which hold it upright. I needed to build a kick stand system that can be kicked down into position and then retract when not in use. I got to work by cutting up various bits to make a “U” shaped kick stand which was eventually welded onto the front frame of the bike.
       The use of the U shape is to evenly support the bike and keep it level when starting up and shutting down the engine.

       The new kick stand was designed to “lock” vertically using the weight of the bike to hold it in place. A return spring was used to retract the kick stand back up under the bike frame during riding. Notice the kick down pegs (metal rods) welded to the legs of the “U” shape. These pegs make it easier to kick down the stand from either side of the bike.

       The new kick stand (when used with the parking brake) will assure the bike will not fall over during startup or when my 5 year old daughter jumps on it to play motorcycle in the garage :0)

       Another thing that I wanted to take care of while working on the front frame is the neck bulkhead. This plate will help “finish” off the appearance of the neck frame and hide the components that will later be mounted in the control panel area.

       I built the bulkhead plate out of .060” plate steel and welded it into the bike frame as seen below.

       The neck bulkhead was given the “flap disc” treatment and blended into the frame as seen below. Notice the rubber grommets placed into the cable holes of the bulkhead. They will protect the hydraulic line and throttle cable as they pass through the bulkhead later on.

       One last thing that I needed to tackle is that the bike has no foot pegs :0P I will surely need pegs if I am to stay on the bike at any speed.

       To fill this need I purchased a set of after market foot pegs on eBay that fit this build perfectly. After trying out different leg positions I settled on a good location for the peg supports which were welded onto the front frame.

       I used a set of 5/16-18 grade 8 bolts to secure the pegs to the bike as seen below.

       The pegs are designed to fold up for several reasons but one of the most important one is a safety issue. If one were to put his foot down while riding it could cause your leg to get thrown back and upward which would be bad in the case of a rigid peg :o( Fold up pegs will fold out of the way if you get caught under them with your leg, hopefully saving you from serious injury.

       Well I have got a lot done to the bike but I am still many hours from completion. However with a little luck I should be able to finish the bike in a few weeks and get her running!!! I can’t wait to see how fast the bike will go with the GR-7 as it’s power plant. Ultimately I will be happy if the bike will simply move under it’s own power, speed is just icing on the cake ;O)

       Please join me again as I continue the GRV-2 project on the next episode of the Turbochopper...

Don R. Giandomenico

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