TOPIC:

turboguzzi wrote: should fit, gasket is the same as gpz/kz, hy vo chain, etc.

That's cool. I'll do some research to see if there are any hidden catches like cam profiles and such. There's a good deal on a complete head with cams and cover on eBay. I'll check around locally as well.

If I get my 1000 running OK I may not worry about it.

get the cam cover too, its specific to the zr7 head

turboguzzi wrote: get the cam cover too, its specific to the zr7 head

Thanks for the heads up. My parts budget is kinda light right now. I need to sell more take off parts. (Hint, hint).

I did find an oil pump out of the UK. Now I can't decide whether I should use the KZ pressure relief or ZR. Seems to me the pressure would be needed since I'm not modifying anything else. I'm suspecting the reason the ZR pressure is lower is because the oil passages are probably bigger to allow more flow.

Turboguzzi:

Zr7 head is supposed to have bigge intake and exhaust valves than a kz750, Could you confirm this?
At least parts are specific for ZR7.
Intake valve: 12004-1140
Exhaust valve: 12005-0023

Bigger valves and still no higher HP...

undiablo wrote: Turboguzzi:

Zr7 head is supposed to have bigge intake and exhaust valves than a kz750, Could you confirm this?
At least parts are specific for ZR7.
Intake valve: 12004-1140
Exhaust valve: 12005-0023

Bigger valves and still no higher HP...

Good catch. Most likely for fuel economy. But put in some hotter cams and high compression pistons....

This would concern me about clearance. Would there be an interference issue with standard KZ/GPz pistons?

May be you need to enlarge valve pockets on pistons dome.

undiablo wrote: May be you need to enlarge valve pockets on pistons dome.

That would be a bit unnerving. I'd hate to take too much and weaken them .

i checked a few years ago when i was building my racer, valve sizes are the same. lifts are nearly the same too and from the factory, there's good clearance anyway. so cant see the need to enlarge valve pockets, wouldn't worry.
zr7 is essentially the same engine as a kz750 in terms of ports, etc. so that also why it's not stronger. The gpz had higher power via hotter cams, compression and carbs, not valve size. i installed it only because it was a super fresh motor, not for more power....
even if you needed to enlarge, say for a 35mm instead fo a 34mm , it's only 0.5 mm per side, done this in many race motors, never had a piston failure and not that hard to do even if you need to.

BTW, increased valve size will not automatically increase hp, you'd have to open the seat throats to take advantage, otherwise the so called "curtain area" of the valve a t full lift remains the same.

turboguzzi wrote: i checked a few years ago when i was building my racer, valve sizes are the same. lifts are nearly the same too and from the factory, there's good clearance anyway. so cant see the need to enlarge valve pockets, wouldn't worry.
zr7 is essentially the same engine as a kz750 in terms of ports, etc. so that also why it's not stronger. The gpz had higher power via hotter cams, compression and carbs, not valve size. i installed it only because it was a super fresh motor, not for more power....
even if you needed to enlarge, say for a 35mm instead fo a 34mm , it's only 0.5 mm per side, done this in many race motors, never had a piston failure and not that hard to do even if you need to.

BTW, increased valve size will not automatically increase hp, you'd have to open the seat throats to take advantage, otherwise the so called "curtain area" of the valve a t full lift remains the same.

So, I'm guessing I could swap my cams over and besides maybe some port polishing I'd have a GPz head..... You're not helping my parts budget any.

I've been looking at pics of ZR heads compared to KZ heads. I can't see any difference between the post '79 cover bolt pattern. Is the reason you are saying the ZR cover is specific due to the emissions air valves? If that's reason we've had those here since they came out with the MKII in '79 and they should be interchangeable. I've deleted that on my engine already (take the tubing and valves off and put vacuum plugs on the carb, air box and valve cover ports) and would love to have a non-US spec cover but they aren't easy to get over here.

bolt pattern the same save for the four bolts at the cam ends, both zr7 head and cover are noticably wider in the area where the half moons sit for better sealing, look at my first pic in the thread and youll see what i mean. kz cover is 39cm wide, zr7 41cm!

cams are the same though

besides that, yes, I blocked off the emission valves with plates

turboguzzi wrote: bolt pattern the same save for the four bolts at the cam ends, both zr7 head and cover are noticably wider in the area where the half moons sit for better sealing, look at my first pic in the thread and youll see what i mean. kz cover is 39cm wide, zr7 41cm!

cams are the same though

besides that, yes, I blocked off the emission valves with plates

I see. The only area of the head I wasn't looking at. Thanks Guzzi

undiablo wrote: May be you need to enlarge valve pockets on pistons dome.

37 & 30 valves?

these are definitely NOT kz750/GPZ/zr7 valve sizes......

cant believe that they are zephyr's either