Ok I need help. Question about 1974 z1 900 head

Ok when i got my bike the previous owner, my nimwitted uncle, decided to try and drill out a snapped exhaust stud. Now i dont know if he was on crack or what, but he managed to drill out so much material that there is nothing to tap into for a stud. Now my question is, can i use a head from a 1978 kz 1000? or should i stick with the z1/kz 900 head. The only reason im asking about the 78 kz 1000 head, is cause there is on on ebay that came from a running 12000 mile bike for super cheap. Or of anybody here has another head, or any advice its greatly apreciated. Thanks all

-Jim O

oldkaws4ever wrote:

Ok when i got my bike the previous owner, my nimwitted uncle, decided to try and drill out a snapped exhaust stud. Now i dont know if he was on crack or what, but he managed to drill out so much material that there is nothing to tap into for a stud. Now my question is, can i use a head from a 1978 kz 1000? or should i stick with the z1/kz 900 head. The only reason im asking about the 78 kz 1000 head, is cause there is on on ebay that came from a running 12000 mile bike for super cheap. Or of anybody here has another head, or any advice its greatly apreciated. Thanks all

-Jim O

If memory serves, the z1's used 6mm exhaust studs and the kz1000's used 8mm. What I'm getting at is if he drilled out the 6mm bolt, maybe you can tap an 8 mm hole. All you'd need to then would be to ream out the exhaust collar for the bolt to fit. Only your kzrider buddies would know its not stock!

just thinking out loud...
S

I've had success filling the hole with weld and then drilling and tapping. That is my buddy who is handy with a mig welder has.:laugh:

If you want it to look original use a 76 head. If you just want to get it running do like was mentioned above with the 1000 head & drill out the collars

so if i understand corectly, i can put the 1000 head on the z1, and all i have to do is drill out the colllars to make them fit the 8mm bolt. The head is a direct bolt on to the z1 jugs? Can i still use the stock 4 into 4 exhaust?

Kinda... A KZ1000 cylinder head COMES with M8 studs. You need to open up the holes in the exhaust collars... so far so good. The 77/78 heads are a direct bolt on deal. No further thinking required. The 79/80 heads are smog heads. You will need the smog head valve cover and gasket as they are different. You will need to plug the reed valve ports. Last, while you can use your 1974 cam chain idler, you can't use the smog head cam chain idler on an older head as it is shaped different and won't fit under the valve cover. And if you find a 79/80 head, and if it is from a MK II style engine, you can't use the cams from the MK II with your 74 crank... the number of teeth changed and the MK II cam chain has a couple extra links as a result. If the 74 head were mine and the hole were not too big, I would tap it for an M8 stud I think.

Couple of options...

On the bike repair..

You may be able to install a thread-cert.[NOT Helicoil]

Have the hole welded up by a good aluminum welder. Drill and tap it.

You really don't need to replace the head. If you do decide to go that route though, at least have the new head gone through before you put it on the engine. Valve Job, seals & guides if needed. Kind of foolish to swap out a head and not make sure it's 100%....

Larry C