Bike gets pulled apart!

[bigblackfalco]

Finally,this morning when I started the bike and a huge cloud of white smoke came out the silencer,I decided enough was enough.
So I've ripped the left hand cylinder head off(as this side is down on compression) and found that both the exhaust valves are leaking.There is nothing major wrong with them.No bad burning or pitting.No excessive wear.They are still servicable.
I've taken them off to BLR engineers in Surbiton.
They are going to custom make some valve guides for me at £18.00 per guide.They will also reface the valves and seats.
Will let you know the outcome and anything else that gets done along the way.
Bailey.

[Jason M]

That's why I never leave mine on the side stand for more than 5 mins any more It would look like a James Bond smokescreen on startup otherwise.

As a novice question, how could you tell the valves were leaking? Wasn't there some significant 'chuffing' going on, or can you tell by the colour of the valves?

Sounds like the guides are cheap enough but again not really a job you can do yourself unless you have some liquid nitrogen or something handy.

Good Luck

Jason

[bigblackfalco]

The give away was:
Very,very hard to balance the TB's.Even when the guages were matched it still felt lumpy.And when you changed the revs the guages moved different rates.
The bike feels as though it is missing sparks/running rough.
Lefthand plug was always slighty fouled and the base was very sooty.
Pinking indicating excess oil/carbon build up in the combustion chamber.
The test with a compression tester revealed 10.2 bar on the righthand pot and only 8.5 on the lefthand.
Very high oil consumption due to worn guides.

The engineer rang me this morning saying that one of the inlet valves is bent!!!
As you know I bought this bike as a damaged repairable.I am pretty certain that these cylinder heads are from another S and have probably done far more than the 90K miles I've put on the bike.
To sum it up,I'd say the heads on later 4 valve boxers are pretty solid.
The valve guides are unfortunately made with very poor tolerances hence the high oil consumption everyone is aware of.
Bailey.

[bigblackfalco]

Just to let you know my bike is back in one piece and running like a dream!
It is running better than it ever has,so my assumption about the heads must be right.
Total price including hand made guides and all parts was £180.00.
If I'd taken it to a dealer £500.00 would've been more realistic.
Throttle response is nice and crisp and even.Compresion is up to 10.2 bar which is the same as the other side.
Bailey.

[Jason M]

That's great news Bailey, and cheap too. £500 would be a conservative estimate at Mr BMW's I reckon