Z1OwnersClub GB

Re torqued the head on the Mkii the other day and one of the 10mm end bolts did not take up. The other one is fine, best repair for the stripped bolt in situ ? Or does the head need to come off again ??

given it screws into the barrels I'd be tempted to take the head off

you will have to remove the head because there is a locating dowel on the outside 6mm bolts

been there,head off unfortunately

From memory the thread goes all the way through. Although not ideal, I'm sure you can fit a longer bolt & then spin a nut on to the protruding end. It'll hopefully get you by until you need to have the head off.

Ah well, was fun while it lasted. Head off in the coming weeks it is then. Dont think I could settle for a nut on the outer Ginger. Pity the head is off again after only a few hundred kays, since a full rebuild there'd be no need for anything else done at the same time ? Thoughts on head gasket too since there has been a weep of oil hence the retorquing exercise in the first place ?

Use it until the head gasket starts leaking if it ever does I have known engines running with stripped threads on the outer 6mm bolts for years

i would heli coil both outside 6mm threads to be sure the other one don't strip when you put it back together

It is possible to Helicoil those outer 6mm threads in situ without removing the head but it's a 50/50 chance of success as long as the locating dowels don't rotate whilst drilling and tapping.
I've done it a few times and have been lucky enough so far not to have any spin.
The dowels are not hardened so do drill out easily and there's enough meat on them to take the 1/4" Helicoil tapping drill and tap.
You drill down from the head and through the dowel which self aligns the drill in to the stripped thread of the barrel then tap the Helicoil thread .
It is the torque of the tapping which may rotate the dowel and put a stop to the operation.
If successful you then need to fit a 1.5d Helicoil which should be wound in until it is one thread away from emerging out of the barrel which ensures it is clear of the dowel and then fit the 6mm bolt. Job Done..
If the dowel spins you have lost nothing and will still need to pull the head, if it doesn't you have saved a shit load of cash and time off the road.

A little fortunate for now, did a bit of measuring and got a bolt some 5mm longer that I put in and managed to torque up to spec. Long enough to go into some old thread but not protrude out of the bottom so will suffice for now. This one is an allen head so will look for a similar hex head to replace that longer one and will hopefully be good until the head really needs to come off.
Speaking of spec, I was talking to my engineering mate and mentioned my problem, he asked what i torqued it to and I just said to spec which of memory without looking again was 95 - 113 inch/ pound . He said Kawasaki were notorious for maxing out their 6mm bolts on the outer head and cam caps and in the 30 odd years he has been rebuilding them he only torques up to 85inch /pound. So have taken that on board and will run with it from here on in.

my book says 104.

nicomkii wrote:A little fortunate for now, did a bit of measuring and got a bolt some 5mm longer that I put in and managed to torque up to spec. Long enough to go into some old thread but not protrude out of the bottom so will suffice for now. This one is an allen head so will look for a similar hex head to replace that longer one and will hopefully be good until the head really needs to come off.
Speaking of spec, I was talking to my engineering mate and mentioned my problem, he asked what i torqued it to and I just said to spec which of memory without looking again was 95 - 113 inch/ pound . He said Kawasaki were notorious for maxing out their 6mm bolts on the outer head and cam caps and in the 30 odd years he has been rebuilding them he only torques up to 85inch /pound. So have taken that on board and will run with it from here on in.

6mm x 1 Pitch = Torque to 7 lbs / ft max in an old plain alloy thread. Same with Cam Caps bolts .....any more than that & your on THIN ICE....best just snug em up with a 'little touch' of Blue Loctite on the last 3 of the bolt threads.