RE; 4 Valve heads.

All; In a stolen thread, "fessed" that I'd like to make more HP w/out going huge block. I've a mild GS1100 (1164 wisco 10.5-1)w/ mild MTC cams and a flowed head. running 36mm GSXR slingshots I get @ 133 Hp 110 torque. a nice tractible ride. still it looks like, well a GS1100E. I would like to make similar power from my 77 KZ1000 A1. but don't want to A.go sleeves.B.bore cases,C.machine cases or head to fit studs. While Im not a restorer, I wish to retain the looks of a period KZ. thus J-head is out. Thoughts? G

Here you go

Oh Boy, I will take a guess.
If a stock KZ is around 80 hp and you 130 hp? That is appx. a 62.5% increase in power. My guess would be:

1075cc pistons @ 10.25:1
Flowed cylinder head w/650 valve train
290* duration / .438" lift cams
welded crank
33mm Carbs.

My Z1-R was dinod back in 79 at about 130. what it had was Yoshimura "Bonaville" cams(about .360 lift and 130 duration), 1103 RC 10.5:1 kit. Amels 34mm SBs no welded crank, flowed and ported head with Manly oversize SS valves, Yoshimura exhaust.

Otto

Otto
So my guess wasn't to far off base. Might get alittle more then 130hp. Those are husky little cams. He said no big block or J head.

pretty hard to hide a fogger system on a KZ Jay lol. hard to beat the jump in hp tho... got a nice hidden system on my 12

I think you will need a good head/cam package and a big bore to get the 130 hp NA. might want to look into an oil cooler...

Not sure you'll get to 130hp without some machine work.

I'll tell you about a nice package that will give you a great increase although I've never had it on a dyno. This is a very streetable setup and will last a long time. This setup will run the quarter mile in the mid 9 second range in a stock KZ frame with wider swingarm and a slick.

900 crank (WELDED- Necessary)
1200 or 1260 Stock block kit (Jay can install the sleeves into the stock 1015 block and provide a great set of 1200/1260 10.5 to 1 pistons and he can bore the cases)and it looks stock!. APE K410 cams with shim on-top buckets. I know these cams seem too small for a 1200 or 1260cc kit but for some reason they work fantastic. The cam are drop in and with the shim on top bucket the maintenance is easy....
Use your 1977 head and just have the ports cleaned up and go up one size on the intake valves.
Use 33 smoothbore internally bored out to 34mm (again, they look stock).

I know this more machine work than you want to do but this setup, or something similar, is the way to go for a good strong street engine.

I've built this same package twice in the last few year and had a great time with the bike on the street and at the track. Best of all it looks just like it did when it came from the factory.

A word of advice, even though you didn't ask.
Don't do anything if you're not going to weld the crank.I know there are those out there that have built big engines and never bothered with the crank, I don't know how they get away with it. I've completely destroyed two stock engines,running street tires, by spinning the crank while shifting between first and second gear under full throttle...take it for what's it's worth.

Good luck,
Buzz

I agree . that would be a nice motor.Basicaly the motor i am putting together right now,just more cam, and carb.i have vm33's and rs34's.
I depends on how much u want to spend. u can save a bit by going 1075cc ,and stock valves. no sleeves required.I would definatly weld the crank for piece of mind.

My Z1-R was punched to 1103 10.5:1 with no problems ever. I have never welded a crank and have never had a problem. Go to about .360-.384 lift cams, these will not require any head cutting and will drop right in. Do some port polishing. I would also recommend a oil cooler if you punch the motor to any size. Go to an electronic ignition and a good set of hot coils. Change to a more modern set of carbs, if you only go to a set of 34mmCVs which you could get on eBay for less than a hundred bucks. The only thing that is left is a good header. Makes almost no difference which one you pick. This should give any stock GS1100 a run for its money+++.