Went to the track and.....

I've looked into this a bit, and basically the answers I've gotten are basically that if you want to get a big bang, you've got to spend big bucks.

It seems like if you want to stay out of the bottom end, you can go for ported heads, short intakes, high comps and /or overbore, and a larger diameter full exhaust system.

If you want to crack the cases, there are all kinds of options.

Of course, if you're just looking to get the top end back, you could gear up a bit on the rear sprocket and then compensate on the bottom by letting it spin up faster with a light flywheel/clutch and light wheels.

I kinda like the last option first, because you're always going to be fighting an uphill battle trying to get an air-cooled two-valve to be even remotely competative with any modern Japanese I-4 sportbike. With lightening all those spinning things, you improve handling with performance. Once you're running it for all it's worth, then you can look at head work or maybe even a 4v bike.

Do you have the Sil-Motor 2-1 system? That's supposed to be a top end pipe, but I've heard that you really need ported heads and a hotter cam to take advantage of it.

Actually, I've heard that about the Arrow 2-1 also...

Don's right about the 750i.e. issue, it sounds like your bike is running out of breath before it's generating the RPMs to take advantage of your displacement advantage. The 41mm FCRs should be more than enough, so either the front side (airbox, etc) is too restricted, or the heads are at their limit for flow.

Hi-comps would probably be a good way (and not too expensive) to get some more power down lower in the band before you run out of air, as well as take the best advantage of what you have at the top.

Oh Yeah, I stuck the link in my first post that I had originally forgot... D'oh!

--Fillmore