Well, its been a while since I have updated the site and things have been hectic around here. I have mostly been programming the computer control unit lately. That doesn't make for very interesting pictures though, so I didn't bother doing a page on that. ("Oh, here's another shot of me programming the computer!".... you get the point.) It finally cooled down a bit outside, so I thought it a good time to fabricate some engine mounts and see how well all of our careful measuring paid off.

Engine mounted in the frame with the new mounts

The engine mounts were fabricated from 1/8th inch plate steel and were hand contoured to fit around the compressor opening of the ST-50 turbocharger. The front mount bolts to a plate located where the down tube used to be. The plate is made of 1/4th inch bar. 3/8th bolts are used to attach the assemblies together.

The frame had to be cut to accept the larger engine

The down tube was cut off to make room for the jet engine, as were other parts of the bike frame. The parts had to be removed to allow clearance for the tight fitting engine.

Air will enter the engine between the front forks

The air inlet to the compressor will flow right between the front forks. A custom filter will be made to keep road debris from being kicked up into the engine by the front tire. I may fabricate an inlet duct to optimize air flow, after I mount the oil cooler to the frame. The oil cooler should arrive tomorrow, so I will get on it as soon as I can.

The engine cradle mounts had to be removed to make room for the engine

The combustor plumbing just barely misses the frame. I had to remove the lower engine cradle brackets from the lower frame. They were located just right of the lower right bolt on the turbine housing as seen in the picture above.

The fit into the frame is very tight

You can get an appreciation of how tightly the engine fits into the frame by looking at the photo above. The modifications to the frame were minor, but enough metal had to be removed to make me cringe a bit. As other YSR enthusiasts probably know, these frames are hard to come by, and one of the only parts not still available by order from Yamaha. Cutting one up almost seemed sacrilegious, but never fear friends. The bike is still very much structurally sound, and reinforcements will be added along the way.

The new engine cradle will bolt on to the left of the combustor

The jet fits into the old engine space well. You can see the lower engine cradle mount just to the left of the combustor. I had to remove the one on the other side to make room for the jet. The one on this side will be kept and used for the new engine cradle.

The rear shock will have to be relocated to make room for the jet exhaust

The jet exhaust will be routed up through the frame, but the current rear shock location is in the way. The rear shock mount will be cut out and relocated closer to the rear tire to make clearance for the jet pipe. Testing showed that the new location should work fine and proved enough clearance.

The engine is the exact width of the frame

The engine almost perfectly matches the width of the frame. The front lower fairing will have to be slightly modified to allow clearance for the duct work from the compressor to the combustion chamber. You can see the duct here in the upper left side of the photo, right in front of the turbine inlet. The fairings should cover most of the engine and will make showing the bike more fun. I can see the conversations now. "What kind of engine you got in there?" and my reply "It's a jet engine!"... to be followed by "Awww, you're just full of it!"

The oil cooler will mount above the air inlet

I think that the oil cooler will be mounted right above the inlet to the compressor. Man this thing is crammed into the frame!

Close tolerances on the fuel inlet to the combustor

The fuel inlet and spark plug are close proximity to the tire. There should be more than enough clearance though, and right angle plumbing adapters will keep things nice and tidy.

Plenty of space to put an electric starter

If you look, you can get an idea of how I think I might run the inlet duct to the turbo. It would curve up, and then back forward ending up right behind the forks. I would make it flare out slightly for better intake performance. I am still working on the electric starter option, so I might have to do a bit more work there than can be expected. There is definitely enough room to mount the motor I have in mind for the starter though.

Tight duct work is needed for ground clearance

That tight curve in the duct work from the turbo to the combustor makes more sense in the photo above. It was needed to get the air there, while keeping ground clearance. A 3 inch clearance was the standard we decided on for the entire bike, and it seems to be just about right.

I did not paint this, but I did clean the rear faring already

With the tank and rear fairing on, the bike starts to look a bit more complete. It is of importance to note that yes, the rims will get a new powdercoat before the bike is finished. Why do people paint these things with black barbecue paint before racing them? Just look at the tank!

Looks almost exactly like the mock up picture

Note how closely this resembles the mock up picture on the main page of the site. By taking careful measurements and doing a little 3D modeling, we got the fit to be just about where we wanted it.

Scatter shields will go underneath the tank, just in case

Scatter shields will be welded underneath the tank in case the turbine flies apart at high speed. Not something you want to happen, but just in case it does I would rather them be there than not. If the fuel was to hit the hot turbine casing, FLAMES GALORE!!!!! So keeping shrapnel from puncturing the tank is high priority in the event of an accident.

A YSR with a jet engine, hmmm..... interesting

The front view again with the tank on. It will be different to look at one of these bikes with compressor blades on the front instead of cooling fins on the engine head.

Not much room for accessories

As you can see, there won't be much room for the pumps on the bike. There is a little secret though, and it's hiding under the fuel tank.

Plenty of room under the tank

The tank has a 2 1/2 gallon capacity, and the underneath is hollow to allow the original engines airbox to fit up and under. The space is more than adequate to fit the oil pump, and maybe the fuel pump too. I just don't want to get anything directly over the turbine housing, as it would have the heat rising up and would probably not be good for whatever components were mounted there.

Yellow strap is for temporarily holding the rear of engine up

The space is clearly visible in the above photo, as is the mounting tab for the front engine mount. The yellow strap is holding up the rear of the engine by the turbine housing. The rear mount actually bolts to the jet pipe and is clamped to the turbine housing. Without the jet pipe on the bike, it won't attach, so I had to support the weight somehow.

Space for afterburner to fit under the fairing

The rear of the bike give a clear view of the space I have to work with for routing the jet pipe up to the afterburner. It will be close to the rear tire, but should have enough clearance so that there won't be any problems. The exhaust will be heat shielded, so the tire should remain unaffected.

That it for now, or at least until the new parts get here. I will get as much done as I can when they arrive and will try to update again soon. Sorry to everyone for the delays in updating. Hopefully the cool weather will hold out so that I can work comfortably to get more done.

'Till next time, thanks for checking out the build and feel free to drop us a line with any questions. Sponsors are always welcome if you have a product you feel could be helpful in the build.

Russ W. Moore
Bad Brothers Racing

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