Valve seal

[Al]

If the pistons and bore are 300 miles old then you could expect those figures to rise significantly as the rings bite in a bit more. If its the same comp ratio / pressure on all cylinders then you may well have a valve stem seal adrift assuming everything else is well.

AL

[Wrigers]

Thanks AL. Its always better to get a second opinion. .

[8 Valve Mark]

did you have the carbs open when doing the compression test? they should be.. it seems like a dodgy valve seal to me. i believe i have an unused viton set if you need them, but I'd advise changing all 8 if unsure of the originals' provenance (i can speak french? viola! ) of the ones fitted in the rebuild. maybe fit two to the offending cylinder to eliminate the smoke problem, then fit the rest.. mark

[Wrigers]

Just a quicky chaps, taken the cams out this afternoon and observed this amount of oil on buckets n01, whilst buckets n04 are nearly dry. Being as though n01 pot was the problematic one, is this a clue as to what's been going on, or is just because it had been on the sidestand.

[zed1015]

The oil is there just because it's been on the side stand.
HOWEVER! If you keep the bike on the mainstand it will allow the oil held around the cam buckets to drain away and limit the amount of oil that can seep down the guides which will then reduce the amount of smoke you get on start up...

[PAULJAC47]

A lot depends on how a rebuilt engine is run in,always used cheapo oil and used the bike on the road varying load and revs within limits,seen more than one bike with glazed bores due to being run in incorrectly.

[Mr Bump]

Just recently I’ve had a freshly rebuilt head do something similar. It came back to me with guide seals , valves and springs fitted. Put it on the bike, did about 8 miles. Stopped to adjust the tickover and it was pluming out smoke. On strip down I could see that oil was dripping off of three inlet guides, at least one exhaust guide was wet too, lots of oil in the bores.

Valves and seals out - oil was sitting on the tops of the guides under the guide seals in all eight positions.

Compared the seals with a set of vesrah ones I had sitting about. The seals fitted are viton, slightly grey and quite soft. The inner round ridge that engages with the groove in the guide is smaller, the outside diameter is bigger and I think the diameter of the seal lip(contacts the valve stem) is bigger too.

My diagnosis is that the valve stem seals used don’t fit properly, I’m just finishing putting it all back together using the cheapo vesrah seals as I’ve never had any problems with them before.

Should hopefully get her fired up tomorrow and find out if I’ve fixed it. If I have then there are viton seals about that don’t actually fit properly. Z1000a head.

I’ll let you know. Hopefully I’m right....

Olly

[Wrigers]

Thanks for that.

[Mr Bump]

Yep, fixed. Just done about 30 miles without a puff of smoke. Let’s hope it lasts.

Looks like there are viton seals in circulation that are too big. Good luck with your bike.

Olly

[Wrigers]

Cheers for that Olly, glad it turned out ok. Ill keep you posted on the re build,,,