Well I think we might be talking apples to oranges here, your 7.3 motor is water cooled,big difference! our air cooled motors are cooled by air passing the outside and by the oil moving through the motor . the combustion temp of gasoline runs between 3000 and 5000 degrees , the higher the compression ratio ,the more efficient the fuel burns and the hotter the combustion temp. Using a blower with 5% boost jams about 34% more fuel into the cylinder than normal ,this in itself raises the combustion ratio and therefore the temp of the head sees.By lowering the combustion ratio to begin with you might keep combustion temps at a level that the motor can handle ,while still retaining most of the additional power.Cars didn't see turbos until unleaded gas and combustion ratios were dropped to around 7.5:1 , our bikes start at 8.5 : 1 and I would GUESS that with the boost would run at least 11:1, lowering the ratio to 7.5 :1 would lower this to around 10;1 and we already know that with a larger piston and stage 3 cam we can run about 10.5;1  this may be enough to drop combustion temp to a level that could be sustained at steady highway speeds .The easiest way I can think of to do this is use a thicker base gasket on the cylinder ,making the compression chamber slightly larger,if you have enough cam chain stretch to have used a Vercy tensioner 's second hole, you might just need to move it back to the first hole.  An oil cooler on our bike seems a waste of time to me as we have low oil pressure to begin with and splitting the flow ,or sending it through additional piping and a cooler would drop it even more, and our electrical system might not be up to driving a fan for it to make it useful at idle.I admire SavageBob for his efforts, but I don't envy  his problems.I wish him good luck and hope that we all can learn from his project.

track racer wrote on 12/25/17 at 11:11:09:


Ok well in summary I'm running a little AISIN AMR300 supercharger off a 660cc Subaru Vivio/Pleo. If you do the mini-battery mod located down on the swing arm, there's plenty of room for it. I made up a wee shelf for the mini battery just using the left overs of the OEM battery tray.

The hardest part is the drive shaft. I took off the stator cover and had a shop machine out the little access port to accept a 50mm sealed bearing. Which I pressed into it. Then I sketched up some plans for a custom shaft which replaces the stator bolt and mounts through the bearing.

Then I made up the supercharge mount out of an old Ford alternator bracket I found. The next hardest part was offsetting the SC and getting it to line up perfectly. The first time I started it simply flung the belt across the room. It has to line up perfectly. I made up a top bracket to secure the SC to the frame. And a tensioner pulley mount etc. I made up the SC cover from an old SOHC cam belt cover I found.

I have no idea what actual boost I am running as it seems impossible to tell on a single cylinder. But I'm using a 95mm drive pulley off the crank and the factory AMR pulley on the SC. I'm guessing it might be around 10psi as it doesn't accurate the relief-valve which is set at 15psi.

Carb is a CV-40 from a Harley with aftermarket goodies on it including a twin-shot accelerator pump. I'm currently running a 42 Pilot, a 172 Main jet, and the needle is on the second notch. I have an aftermarket adjustment screw turned about 4 turns out.

I have a relief valve like this one: https://www.ebay.ie/itm/SHORROCK-C75-C142-supercharger-relief-valve-NEW-/2722...
located on the OEM supercharger manifold, right before the hose connects to the head. There was a obvious place for it to go.

I also have a custom 1.5" header and drag pipe with the exhaust ported out.

savagebob wrote on 12/27/17 at 19:48:01:

Many thanks Savagebob. That will work.

track racer wrote on 12/29/17 at 08:35:18:


Just the Boyesen Twin Shot pump, the EZ-Just mix screw, an aftermarket spring, and a trumpet.

That 34 Crocker speedway...Ooooo, so nice!

It is begun. Supercharged 650 in a 1934 Crocker speedway tribute. Good stuff!

Will do. Just trolling to check interest. Not enough done right now to justify a build thread that moves along smartly. We will get a bit ahead then catch up in build threads. Thanks

hotdog