Cracked head?

enekoizagirre · Sep 3, 2013

Hi,

after riding the bike along the summer (I've made almost 3500 km in three months), yesterday I got an oil leak coming somewhere in the front of the cylinder head and the right cylinder started smoking badly.
I've got an RH4 head, so my first suspicion is a crack in the head.
Any other ideas that could cause these symptoms?

Thanks

Rohan · Sep 3, 2013

A blown head gasket at the front there could cause this. Retorqued your head lately ?
A possible Commando foible is that the 2 little studs there can loosen off, or not be tight enough, or pull out - and cause oil coming down the pushrod tunnel to be sucked into the head.
Another possibility is a porous casting, not unknown either, but it would be odd if it happened suddenly like that.
You won't know until you have a look - and it may be very hard to spot even.
Sorry to be the bearer of bad news - ain't old bikes fun !
Cheers.

enekoizagirre · Sep 3, 2013

the first thing I've done is retorquing (is it like this as it is written?

) the head and there were no llose bolts, so that's why I'm suspecting the crack. I guess I'll have to wait till I take the head off an see what I got. Thanks

concours · Sep 3, 2013

enekoizagirre said:
the first thing I've done is retorquing (is it like this as it is written? ) the head and there were no llose bolts, so that's why I'm suspecting the crack. I guess I'll have to wait till I take the head off an see what I got. Thanks

We'll expect a full report with gory images.. (if there are any) :mrgreen:

Torontonian · Sep 3, 2013

Smoking crack is illegal. Probably a leaky head gasket . Try copper gasket with High temp copper silicone applied thinly to both sides ,ride,re-torque all nuts including exhaust ports.

trident sam · Sep 4, 2013

I had exactly the same symptoms a few years ago, turned out to be a loose inlet valve guide. Hope your's isn't
good luck.
sam

enekoizagirre · Sep 5, 2013

nailed it sam, mine is the exhaust one though...
I've never been so happy of having this kind of failure!

enekoizagirre · Sep 5, 2013

... so time for oversize guides...
should I just clean and install the +.002" ones or ream the hole before installing? (I think I know the answer, but weather is still cool here and I want to ride the bike asap!!)
Thanks

JRD · Sep 5, 2013

You need to ensure you have correct interference and that guide will fit perfectly : otherwise you'll have to redo it very soon . So unfortunately reaming is mandatory.
You can buy a bigger oversize guide and have it fit exactly whatever size you have reamed the head .

Cracked head?

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