You can't have low rpm at high speed without good low-end torque...
The pipe may be fighting you on this...
...or,... you're just geared to high...

A 30hp bike is working pretty hard at 75mph... it will never do that at low rpm...
You may want a bigger bike,.. or a slower road...

I had no problem stock at 75 on the interstate.... yeah she vibrated a little, but she complied with my demand....
Rode it from north florida to north Carolina... about 70% interstate....
I can't figure why guys change, what really does not need to be changed...if you want bigger.... faster....
Go out and buy one that is.....

Lots of guys do....

I don't blame folks for wanting more...but to try and make a 650 into a 800 just is not going to happen.

And that's my four cents...  

IDK hoot about the BCB pipe,, I dunno what the stock pulley ratio is.
I Do know that I gutted the header inner pipe and had the outside welded back together, tight, neat, clean job,, dude liked my work and did it for free.. I put his tools up exactly where he had them..
Stage One cam, jetted, Supertrap, 14 disks, some kinda tuning on the air box,, made the volume bigger between carb and filter. It would push past 80 any day, and busted 100 one perfect day.. temperature and humidity matter on these things.

Serowbot is right.....the changes you have made to the gearing have dropped the engine rpm down to a place where it is no longer making enough torque or horsepower to get the job done.

I looked at the 5 speed gearing chart, and a dyno sheet I got offline. For a 65 mph speed the stock engine in that chart was making about 24 hp at 4,400 rpm.  With your gearing the engine has dropped down to about 3,750 rpm at 65 mph.....where it is making about 21 hp.  The gearing change has dropped your available horsepower about 12%.  

You most certainly can get the engine to pull this gearing well - but you do have to make some changes to the engine.  The Wiseco piston in 95 or 96mm will make a big difference as the compression is increased significantly....and the Woessner piston in 97mm helps a bit more.  The Stage 1 or Stage 3 cam will help as well....the Stage 2 may be too much as the power is shifted into the higher rpm - and your gearing will not let your engine get up into those rpm's in higher gears.  Opening up the the "donut" in the exhaust port will help get some additional flow - but rumors are that you should not take it out completely.

I have a 95mm Wiseco, Stage 1 cam, Mikuni round slide, lightly ported head, and I run a 18" rear wheel with 25/65 Kawasaki pulleys.  My bike can pull high gear well, and it runs out of juice in high gear around 85mph.  If I want to go faster (seldom) I need to shift into 4th so that I can allow the engine to gain additional rpm to make more HP so we can battle with the increasing wind resistance.  My bike is a Cafe' conversion and has a bit less weight and wind resistance as I am tucked in more than an upright rider is.

corey v84 wrote on 01/29/15 at 23:38:49:


Bone stock, or with some 'mods' like a gutted muff? my bike, as it came form the factory, would hit 90 on a flat road without a lot of headwind any day, no problem, with saddlebags on it, 85 going uphill or with a strong headwind, and I hit 80 very easily yesterday on the interstate with a spitfire sheild and bags, and there was throttle left over
this is with a bone stock engine and the carb untwiddled, and a slight whistle timed with engine exhaust pulses that I think means a small exhaust leak

$1000 doesn't sound so bad, compared to buying another bike
My XS1100 spins about 4k at 70 IIRC, but that bothers me more than the S40 at 70, because I find the frequency of the vibration annoying, where the S40s engine, at the 4400+RPM it needs to run that speed, doesn't bother me, I like it's sound / vibrational frequency better than that of the big I4

corey v84 wrote on 01/30/15 at 11:45:29:


Nope.....the Wiseco is built for the DR650, and it just happens that it can be made to work in our bike by boring it out from 94mm to 95, 96 or 97mm.