Final stage of the XBR build

[JOOLZ]

I finally managed to get hold of one of those small superchargers, the Aisin AMR500, off of a 650cc Japanese micro car, this will be my winter project.
I will have to make up a side plate with an oil seal for the crankshaft, the engine pulley and a mounting plate and covers and also work out what carb I will use and how to modify the jetting for use with the supercharger.
I have the original XBR cdi with 20' advance so that should be fine, but I will have to machine the piston crown to lower the compression.
This winter should be busy, Im hoping for a few more fine days for riding between then and now though

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[Oldtimer]

Make sure the oil feed is a good one.

[tommy]

hi joolz busy winter  ahead eh, you could probably use extra base gaskets to lower the compression tommy

[JOOLZ]

Hi Tommy I thought about base gaskets, but it would be very thick to get it from 10.75:1 down to 8:1
The supercharger has its own on board oil supply just needs topping up every now and then

[Propellor]

Looking forward to seeing this one.

Tommy, regarding adding base gaskets, how would this affect camchain tension and valve timing?

Joolz, are you planning on putting the blower upstream or downstream of the carb? What carb are you going for?

[iansoady]

You could probably get someone to laser cut a thick base shim using the gasket as a pattern. Just adding gaskets will only make a minimal difference.

By my calculations* a 1mm shim would increase the c/c volume by around 6.6cc. A c/r of 10.75:1 on 498 cc indicates a c/c volume of around 50cc. To get 8:1 you need a c/c volume of 70 cc-ish so a shim of 2 mm +.

*which of course could be wildly off..........

[JOOLZ]

The capacity of the engine is 601cc I think it will need a 4mm spacer to reduce compression, the carb will be fitted before the supercharger so that mixture is going through it, more efficient that way, but the plenum will have to be fitted with a spring loaded blast plate to relieve any backfire.
I will have to slot the sprocket further as the cam timing will be way out
Carb options are stick with the Amal I have now and modify it to cope they have the parts available so easy to do but the carb would be a bit undersized
Switch over to an SU 1 3/4inch they have been used many times with superchargers, a mikuni carb off a Harley could get a 44 or even a 48, or a real oddball idea is a 50mm Lectron but that would be very tricky with the jetting, and I cant think of anyone else who has tried the Lectron with a supercharger

[JOOLZ]

I rebuilt and painted the supercharger to match the bike   The XBR comes off the road at the end of the month then the serious work gets going

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[Moto63]

Best of luck joolz with the "new" project I will defo be reading this thread with a keen interest. Like I say good luck. Cheers Michael 

[timbo]

Yep, me too 

[Propellor]

Best of luck joolz with the "new" project I will defo be reading this thread with a keen interest. Like I say good luck. Cheers Michael

+1

[JOOLZ]

I have made  start on the project now, found a space to put the supercharger, but its an extremely tight fit, nothing lines up properly so lots of headaches on driving the thing, I think my brain will explode with all the variables involved, but I am getting there slowly

[Moto63]

Keep at it joolz, I,m sure you,ll get there in the end. Plus the end result should be brilliant. Please keep us posted on any developments. Cheers. Michael

[Propellor]

You thinking of putting an outrigger bearing at the crankshaft end? To help take the over hung load of the belt? I assume you're using a belt?

You keeping the starter motor?  Where's the blower going? Or you keeping it a secret till it's finished?   

[JOOLZ]

The supercharger has to sit on top of the oil tank, I got rid of he starter motor a few years ago so that is not an issue. I wont be having an outrigger bearing on the end of the crank, I am trying to see if I can fit a pulley to the back of the alternator rotor, that means removing the flywheel from the back of it to give me clearance, if I cant I may remove the crank end alternator altogether and fit a small alternator behind the cylinder.
I cant get a straight run from the crankshaft to the supercharger as the frame is in the way so I might have to make a second pulley to move the  the drive further inboard through 2 shorter belts.
Its all very easy and straight forward in my head, its just the implementation thats the problem, and it has to be done with what I can make at home and what is easily and cheaply obtained off the shelf and adapted

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