1978 KZ1000 bogging down at high RPM?

Ok so my father bought a restored 78' KZ1000 and it's a beautiful bike and runs great. When the bike was purchased it ran good but needed a little TLC so I changed plugs, oil, coolant, filters, brakes. We ordered a full vance and hines exhaust and had it installed by a local shop which did a great install. The bike sounds great and runs great but now at high RPMs it seems to bogg down. The mechanic who installed the exhaust had some health issues come up but when he looked at it he literally spit on the intake manifold boot things and it started to show bubbles like a leak.
I ride newer sport bikes so im not that familiar with older bikes so I ordered new intake manifold boots and am planning on installing them in the next week or so.

Would or could this be the cause of it bogging down at high RPMs or am I looking in the wrong direction. Idles goods and runs like a charm at low RPMs.

Any advice would be greatly appreciated.

Fix the boots first then look at how it runs . Did you have the shop rejet the carbs for the new pipe ??

FireMedic wrote: I changed plugs, oil, coolant, filters, brakes.

Any advice would be greatly appreciated.

Coolant!!!! You sure it is a KZ1000??

Yes, well at least he said he did. lol
I am almost sure he did do it because when I went and checked it out he had the carbs out and he does run a quality shop. It just sucks because two weeks after work was done he had a heart attack and isn't doing much more work now.
For some reason the new orleans area lacks bike shops that work on older bikes.
I will try and install the boots and go from there just thought i'd ask around with people more familiar with these bikes. Thanks for the reply. I will try and keep ya posted on how it goes.

lol, sorry AIR cooled, just did the coolant on my hayabusa so must have had a brain fart.

AFA the upper RPM, you will need to go up 2-3 sizes on the mains, just for a start. Then plug chops are in order to fine tune the mains.
After the intake leaks are fixed, of course.

By any chance did you or the mechanic remove the air box and install individual filters or remove the air filter element from the air box? Ed

I am know where near a mechanic but if you wouldn't mind please explain what you mean by AFA main 2-3 and plug.

Sorry.
The main jets are in the carbs, and are the source of fuel when the throttle is wide open and you are in the upper RPM range. Larger main jets let in more fuel, which is required when you install a pipe.
Plug chops are a method of reading the color of the plugs when determining the optimum size for your main jets. White, main jets are too small, black too large, tan just right.
You'll want someone who knows what they are doing to do this, or study up on the web. Not sure what type of carbs your bike has so I can't point you to a tuning site.

Idle Mixture and Plug Chop link

Thanks for the help guys I'm definitely gonna do some more research and will probably look for someone who knows more about these classic bikes.
I will update what I find and all the replies are appreciated.