heads and mileage / guides replacement now

[hanskloss]

Another question to ones in the know - what's considered as high mileage on a Zed engine, particuralry head? I've taken a head off Z900A4 engine with 23 thou miles and there is some play at the valves/valve guides (wobble test - haven't measured yet), not much but I thought there won't be any at this mileage as this engines are known to be bulletproof. What's your experience?

[kev edwards]

Much depends on regular maintenance, and how the engine has been run if it has had a sedate life with regular servicing it should hit 50,000 plus, if thrashed around much much less.

[nanno]

My Z1000J has (officially*) done around 70.000kms and except for the stock pistons being as dead as they can, the head was in remarkable good shape until I overreved it and two valves touched the pistons.

Crank and gearbox are still untouched.

Cheers,
Greg

* I suspect due to a crash and new clocks being fitted, it had done approx. 20.000 to 30.000km more.

[hanskloss]

Thanks for the info, had a second look and it's not bad at all, the manual mentions about 0,2mm play at the guide, I'll have the head cleaned and will let bike shop to measure the guides diameter to be sure.
Just out of interest, how much does the guide replacement cost in UK?

[hanskloss]

Got the head back from bike shop and the exhaust guides need replacement measured 7.15~7.16mm (service limit by manual is 7.08mm), intakes are better at 7.04~7.05mm but I'll be doing them all. As it's the first time they'll be pressed out, am I right to think new set of standard size APE guides should be fine? Or do I buy oversized ones?

[zed1015]

Std size guides will be fine, just be sure to heat the head enough for them to drift out easily without dragging alloy along with them.
oh! and be sure to thoroughly remove any carbon build up off the exhaust guides as that won't do the guide bores any good either.

[hanskloss]

Thanks zed1015, had the carbon off as much as possible (ultrasonic + scrubbing). Got the guides removed by a machine shop today, old guides outside diameter measured cold is 12.00~12.01mm, head insides (measured hot) were 12,03~12.04 on intakes and 12,05~12.06 on the exhaust side, guides to head was tight fit. Only place I found guide diameters was kibblewhite site ( http://valvetrain.kpmivalvetrain.com/vi ... motorcycle ) where standard size is 12.07mm, guy doing the job suggested getting oversize at 12.12mm for exhausts but I've ordered std APE guides allready and we'll see how it goes, I'll post measurements later