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Discussion in 'Thumpers' started by vrago, Jan 12, 2005.
I wanted to add something to this thread since we're talking about turbulence and vanes and stuff. I was searching on ebay and came across a "bosley fuel system" modified carb. Hmm I really should keep better track of my bookmarks.. but anyways, I did a little digging and found the dude's patents and it was all very interesting. I'll try to dig it up later as the ebay auction is gone.
The internal carb modifications were way over my head. I mean, it had triggers and weird stuff like that. But he also had a machined piece added onto the motor end of the carb which was easier to understand, and more relevant to this thread. His observation was that backpressure comes mainly along the outer surface of the bore, and so with his motor-side spigot he added a specially perforated extension which left a small gap (1 or 2 mm) between the connecting boot and spigot. It was designed to recycled the backpressure to help with atomization and flow.
I sent you my $49.95 but the post office returned it as undeliverable...
This is probably old news but hear goes, on an FCR with it's pump it will squirt for about 3 seconds stock so most people end up doing the BK mod to reduce the squirt time to about 1 1/2 seconds this helps the bottom end to be crisper that may be why you say the FCR likes to be rolled on instead of wacked open. With the pump time set right the FCR is very a very snappy carb.
Oops, apologies, it is "boswell fuel system". Here's a picture (off ebay) of the motor side spigot which I described in my last message. Very interesting and I might have to try to make something like it in the future. If you look up Mr. Boswell's patents he describes how it works, as well as the other performance improvements he makes to carbs, but like I said those parts are complicated.
Who is the bigger sucker- the guy spending 100 bucks for a powernow, or the guy spending 68k for a bike powered by an ex500?
I have thought about pieceing something like that together myself- pilfering the engine out of the wife's ex.
68 grand... Can't hardly get that through my head... Jesus christ, they should be using brand new 450 twins direct from aprilia for that price. Or from an sv650- which would at least make some power. My 625 makes equal power to an ex. 68k- 5k = 63k for accessories.