How can the rear cylinder head be cleanly removed from an X0/X1?

Camel, Sahara, Kanguro, Coguaro
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julianharty
Posts: 478
Joined: 15 May 2016 16:34
Location: High Wycombe
Location: High Wycombe Area (Bucks)

How can the rear cylinder head be cleanly removed from an X0/X1?

Post by julianharty »

I've spent a good hour trying unsuccessfully to remove the rear cylinder head from my newly rebuilt X0 (to helicoil a soft thread for one of the three cam cover cap bolts which wasn't practical to do in-situ).

The four studs that hold the cam followers and tappet block are doing an excellent job of stopping me from getting the head out even though I can rotate it 360 degrees in the area above the barrel studs in the frame. I even removed the front rear shock bolt to give me a bit more room. I'm getting the impression that the only way to remove the head is by undoing the front engine bolts and loosening the rear ones - or am I missing a trick?

For completeness:
  • I still have the airbox in situ
  • The rear downpipe (that goes to the exhaust) has been removed
  • The metal engine breather is out of the way
  • The rear carb is out of the way
  • The petrol tank is out of the way and the top monoshock bolt has been removed, the bike is on the centre-stand
  • I've tried removing the head to the left and to the right, by twisting it and by rotating it - it's been very close to coming out at times but keeps running out of room and one of the tappet block studs stops it from emerging
I've no wish to remove the cylinder barrel studs - that's likely to add to my workload and they've very happy where they are, ditto the barrel and piston are undisturbed.

Tomorrow I'll have a go at loosening the front engine bolts, etc. however if there's a way to remove the head without so much effort that'd be wonderful. Then I can repair the thread and get back to running in the bike (it's done a good 40 miles so far and is great fun).
norbert
Posts: 750
Joined: 15 May 2007 15:15
Location: Lübeck/Germany

Re: How can the rear cylinder head be cleanly removed from an X0/X1?

Post by norbert »

I´m not sure, if you can remove the rear head without any further action.
But often you can use a slightly longer screw if one of these three threads is weak o gone. At least it can help til you have to lift the head for other reasons. I´ve done this several times after measering the depth of the borings in the head to be sure that a longer srew will enter.
julianharty
Posts: 478
Joined: 15 May 2016 16:34
Location: High Wycombe
Location: High Wycombe Area (Bucks)

Re: How can the rear cylinder head be cleanly removed from an X0/X1?

Post by julianharty »

Thank you for your suggestion, however the thread was missing entirely in the hole so a longer bolt wouldn't grip either.

I ended up doing the repair with the head carefully moved about 3cm to the left which gave me enough room to enlarge the bolt hole with a 6.3mm drill and then tap and fit the helicoil style thread.

Before I started drilling or tapping the hole I prepared a clean room style working area with everything covered apart from the hole I was working on (I had dental work done on one of my back teeth with a similar approach and decided if it was good enough for professional dentists it'd be good enough for me.

I'm still not 100% happy with the repair as the repaired thread doesn't tighten as solidly as the other two tappet cover threads. However I now seem to have an oil tight tappet cover and as I'd also adjusted the tappet clearances the bike is even performing better :)
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