performance cam question for a kz900

so im thinking of getting cams for my stock 1976 kz900 my question is what is the best setup and lift measurement i should go for my stock motor, all i really have is pod filters and accel coils, future mod will be dyna ignition and obviously the cams, .420, .465, etc...... thats what is confusing me. never realy messed with cams before, so big help is needed.

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info fast....

cams around .400 lift are shim on top.

Higher than that you would want to consider shim under or 650 bucket setup...

I think the stock lift is .345

1983 GPZ stock cams are a good cam upgrade at .365 lift and would be my rec for a bike in stock trim.

u can use shim on top with .410"(no higher) cams as long as u use APE's VS900K springs.
when u start increasing cam size, u start moving the power/torque curve up in rpm's. u need higher compresion pistonscto regain some of that lost bottom end torque.

Do you want drop in cams or are you going to have the head apart?

The tappet bores need to be clearanced for the lobes if it's bigger than a drop in and the valve cover should have the + marks ground flush also.

You may need expensive aftermarket buckets and retainers. Springs you need regardless but there are good springs and not so good springs...depending on the lift you need.

Cam Motion makes a .420 lift grind Z4 that will run shim on top.

But the most important question is how do you realistically intend to ride the motorcycle? Be honest with that one because it's the single most important factor to picking the right cams. Get it right and it will be a joy. Get it wrong and you'll have a fussy bitch on your hands.

There are 2 basic ways to approach an engine build. The right way and the wrong way...

Come back with some realistic answers and a realistic budget....get some good answers that will allow you to select the right components. It's the combo that makes it happen. The cams are only a portion of the combo.

Read this KZ FAQ

Larry C

Ahh I've learned quite some info now I was planning on just droppin cams plus oil cooler cus I know for a fact its gonna run hotter, but now I see there's more to it then to just droppin cams just because, my bike has around 17xxx miles so I don't know if the pistons are in tip top shape for a cam upgrade, so my best bet is to keep savin and throw in a big bore kit while I'm at it too, the way I drive honestly is pretty much fast all the time but sence its stock I think it needs a little more umpph I'm pretty much a noob wen it comes to tuning an engine so that's y I ask as much as I can before doin an upgrade

Have u seen that setup before? If so wat size motor on the gpz and wat difference would it make on my 76 900, can those cams just be dropped in no hassel or do I need to fiddle w :huh: ith anything else to fit them?

The biggest noticeable performance gain you can bolt on the bike is a good rack of carburetors to start with. Bolting in drop in cams will give it some punch also but to make them really work well you need good carbs anyway.

The GPz11 cams require sprocket work that you're probably not going to be able to do yourself.

Follow the link for Cam Degreeing, should answer most of your questions of the process...

cam-degreeing-for-zombies

What Larry said in an earlier post is very key. How will you use the bike?

I ran 0.410" cams in a Z1 with 10.5:1 pistons, 29mm smoothbores and with the head ports cleaned up. Great performance - but not a bike that was happy cruising around town. If you plan on drag racing and riding on the street, 0.410" is a good compromise - you lose a little low-end, but gain once over 5,000 rpm.. It can retain shim over bucket - so valve clearance is far easier.

Matching components is very key - for a cam to be effective you need head work, pistons and carbs to match.

Stage 1 drop-in cams (0.360" or 0.365" lift) provide a noticeable boost to performance, but really don't hurt performance at lower RPM. Stock carbs can feed these, whereas anything higher lift really needs carbs and head work.

LarryC wrote: Read this KZ FAQ

Larry C

Larry, I just have to say that your write up is phenomenal! Thank you for taking the time to explain how everything works together - I'll be pointing lots of people to that site in the future.

Just thought Id mention that if you use the GPZ cams in your 900 you lose the tach drive & need an electronic tach. I have the 260/260 395 lift cams in my 900/1105 and it is a pain in traffic or slow going. It does run strong but has the head, 10.25-1 pistons & carbs to back it up too