Engine does not want to redline

[waffawaffa]

Hey everyone, I just bought a 1979 CB750f and just joined this forum. I hate to be one of those people that you just meet and they start talking about their grievances, but here I go.

 I love the bike except for one small issue. After 8k on the tach the bike hesitates to reach the redline. The bike just feels like it is starting to really take off, but it's held back from its full potential. The bike will reach redline slowly and roughly at 3/4 throttle, but goes no where at full. Everything on the bike is stock except the exhaust (I don't know what bike they came from).

I tried running it at half choke and nothing was noticeably different. Another run at full choke, and the bike ran exactly the same as without any choke at all, which I find interesting on its own.

The previous owner had recently tore down the carbs to clean them and add new gaskets. They are pretty well balanced and have a steady flow of fuel coming in.

I would really appreciate it if you engine guru's could help me out or point me in the right direction.

- James

[TOOLS1]

Welcome to the forum. I am not really up on the CV carbs. However it sounds like the vacuum operated slides are not going all the way up.
TOOLS  

[shinyribs]

I am along way from being a carb guru.But if it runs the same choked,i would tend to believe there is an airflow restriction some where.Tools' idea sounds about right.Hope you get it figured out...i can learn something that way

[waffawaffa]

My engine is using up a quart of oil every 200 miles. No leaking anywhere to be found, no smoke out of the exhaust. Can an engine burn oil without any smoke from the pipes? I'll be checking the plugs once the gas tank becomes lighter to further diagnose the problem.

[samir_nayanajaad]

A quart every 200 miles!!!  These bikes aren't magic it's going somewhere need to find out where.  And if these carbs are vacuum operated like tools is saying look for a vacuum leak or maybe a vacuum hose not hooked up or incorrectly hooked up. (manuals can be downloaded from this site)

Also check your air filter for clogging, if the bike sat outside for any length of time damn chipmunks squirrls and the like will cram pack every nook and cranny with leaves and nuts you name it. And for some reason they love air filters, at least in my experience.