77 KZ1000 with 75 Z1 engine project

Hey guys, I have a 1977 KZ1000 with a 1975 Z1 engine in it.  It has a lot of problems and I have the motor out and overhauling it.  The head got new valve guides and 2 new exhaust valves, Bill Bune Enterprises did the work.  He also bored it out to a 1015 and I'm using IMD stock compression pistons.  It came with an unknown brand dual exhaust and I already got Delkevic 4 into 1 for it.  The carbs are Mikuni 26mm with the stock cams.

Question:
From what I've read the stock 26mm carbs are going to be restrictive on the top end for the 1015 bore.  The Mikuni 29mm smoothbores seam to the "Holly Grail" for this setup, but they are very expensive and hard to find.  I've been looking at the RS34 flat slides, but have read they can hurt the lower RPM range.  Would getting some different cams, such as the Web Cams #118, work well with the RS 34 carbs, or should I try to find the 29 mm smoothbores?  It's just gonna be ridden on the street, no drag racing, but I do have a lot of back farm roads that we open them up on!

Any advice would be appreciated, thank you.

I have a stock 77' KZ 1000 LTD with RS 34's and a Delkevik exhaust. I have the quieter baffle in and I haven't noticed any issues. It runs real strong even out of a slow corner. I also live out in the country and have a nice 12 mile test loop to play on.

26 mm carbs were standard on the 77 KZ1000.  They should be fine on your bored 900 engine.

VM26's will work fine with the stock compression 1015cc rebore and fitting some later Z1R/MK2 VM28's would bump the horsepower up another 5 to 8 ish HP which would be a much cheaper option than trying to source the 29 smoothies for very little comparative gain over the 28's.
The only major mechanical difference between the low to mid 80s hp of the earlier Z1000's and the later 90hp Z1R was the switch from VM26's to VM28's..
For the stock motor, if you still have the head off the bike i wouldn't bother with big cams ( for which you also need a compression increase over stock ) but go for head work first if anything and make the most of the gas flow potential and $ for $ value power gains.
Without porting the head any significant increased valve lift would be largely wasted and performance could actually suffer with your current stock comp IMD pistons.
Just porting the head alone would perk the bike up no end even with stock cams and no other changes.

 

Welcome to KZR, the most comfy air-cooled interwebs corner for all things Z-bike.

Good Ridin'
slmjim & Z1BEBE

Ditto thoughts on the re-use of your VM26 1200 series 1976-1977 carbs you already have. Depending on what you're going for of course. I've used them plenty of times on 1015/1045 10.25CR Wiseco rebore engines i've done over the years. Actually a better option without the complexity of the "pumper style 28's" would be a set off the 1978 Z1R, also 28mm. Smoothbore 29's are ok but often riddled with problems from previous owners. 

Thanks for the input, I was hoping you'd chime in on this.  This has been a project that was put aside for a while and I'm starting it back up.  There are a lot of options to consider on how to build this!