Motorcycle Repair: honda CB450 k1 no power, honda cb450, cam shaft

Question
hello Rich, thank for the previous advise.
i brought my honda to a mechanic, he checked the valve clearance and came
out that after few hours he couldnt set them up on the right clearance.  there
is too much space on the exhaust and not enough in the intake.
how can i fix it ? what other part could be damaged that replaced could help
this problem?
when i ride the bike which has a perfect idle but doesn't run over 5000 rpm
and 55 mph it goes on and off like hiccup of power and loss in any gear over
5000 rpm. its a depressing ride.

should i bring down the head of the intake valve to recreate the correct
clearance to obtain the right compression?
is been a while that im trying to figure this out, i also put a bigger main jet
thinking that could help.
is this engine too complicated? should i go to honda to have it inspected?
seems to me that between cam chain valve carbs points cam shaft all regulate
and timed is a lot of work and need to be perfect.
i cant think of what is it.
thanks again
Daniel  

Answer
Daniel, that was the second bike I ever owned and the first real super bike in my opinion. I'm afraid that a mechanic has to know a little about those engines to get them tuned right. Once you know what it needs to be right, they are pretty easy to tune up.  There's limited range of adjustment on the valves but I've never found one I couldn't get adjusted except after the first rebuild on my engine when I removed too much material off the valve seats.  The trick is to not over tighten the adjuster lock nuts because they will tend to rotate the rocker arm shafts and change the clearance.

The power problem could be either fuel or ignition but I'm guessing it's ignition.  You can confirm this by applying a little choke when it starts to act up.  If it gets better or worse when a little choke is applied it's fuel related but if it doesn't change, it's probably ignition.

Those engines are not that difficult to tune but they have enough quirks that make them a little difficult at times.  I'll be happy to help if I can.

Regards
Rich