Topic: cb750 low end power upgrade

[754]

 I am going to disagree with the larger valves and porting helping out the bottom end,,
 What I found works very well for lowend and midrange..(90% of the people on here never tried these).. Weber DCOEs with 30mm throats, that and dropping your gearing a bit..  I have never put a 750 rider on one with Webers that was not surprised by the mid-range response..

 still never forgot that guy on the stock bore 750 with Webers dusting that Z-1 badly off the light so many moons ago.. left an impression on me..(

[Spanner 1]

Yeah but this is 2012 ( believe it or not ) and trying to turn your 40 yr. old CB into something that will get off the line as quick as a modern sport bike is trying to regain your youth 
Leave your SOHC alone and get a more modern bike for when ya need to 'whack it ' 

[TwoTired]

But, it sure was quick around town and seldom lost at the stop light Grand Prix.

Don't you miss those days, TT? I sure do...

Yeah, I do.

[wedoo2]

If he does a gearing change down a tooth on the drive sprocket, what kind of RPM will he be running at say 65?  Is he going to always be looking for a higher gear that isn't there?  That is why I got rid of an 82 750; it just always felt like I needed to shift up.  Got old.

[Gordon]

If he does a gearing change down a tooth on the drive sprocket, what kind of RPM will he be running at say 65?  Is he going to always be looking for a higher gear that isn't there?  That is why I got rid of an 82 750; it just always felt like I needed to shift up.  Got old.

Yes, a gearing change for low-end torque will make the bike buzzy on the highway.  I did it on my 550 which spends little time at highway speeds, but wouldn't do it on my 750 which is the bike I take on longer rides. 

[andy750]

Dropping a tooth on the front sprocket from 18 to 17 dosent make the CB750 buzzy at highway speeds (at least not on my K2). I enjoy the faster stop light acceleration as well as good usable top end speed when passing cars on the highway.

17 is the way to go.

Andy

[Gordon]

Dropping a tooth on the front sprocket from 18 to 17 dosent make the CB750 buzzy at highway speeds (at least not on my K2). I enjoy the faster stop light acceleration as well as good usable top end speed when passing cars on the highway.

17 is the way to go.

Andy

I agree that 17 is the way to go.  I was thinking of the earlier 750's that already have a 17 tooth front sprocket.  I tried once going down to a 16 on my K1 and it was way too buzzy, but damn did it ever want to wheelie!   I guess it would help if we knew exactly what bike is in question here.   

[Tugboat]

So what RPM's are y'all turning at 65 with the 17-tooth front?

[754]

probably 400ish more.. not as much as I am turning with a 54 rear..

[TwoTired]

If he does a gearing change down a tooth on the drive sprocket, what kind of RPM will he be running at say 65?  Is he going to always be looking for a higher gear that isn't there?  That is why I got rid of an 82 750; it just always felt like I needed to shift up.  Got old.

Did the bike you got rid of also have a loud exhaust?
I got rid of one of my 550's that had 16T instead of 17T front...and a MAC exhaust system.  It was buzzy on the freeway.  And around town very noisy and fatiquing while trying to keep the engine in the power band for traffic avoidance.

Of course, I also had too many bikes.      But, that's the one that got picked for sale.

Cheers,

[Spanner 1]

17 front and 48 back ( stock ) on my K1 750 = 60mph @ 4,000 rpm just about exactly......

[the technological J]

subscribing... coming back when i can read a little better

[scottly]

If you really want to have fun, combine 16/48 gearing with 836 bore, Webers, and shave 130 pounds off the bike.