Oil on fins

FastFred · Dec 29, 2009

Hi
Been to se a very smart MK3 today for sale. Has oil on third fin up on the head. I know this is a difficult question but any advice appreciated. Would you buy it? Worst case is a cracked head but I would have thought unlikley. Heard that porous heads can be repairied. HELP!

possm · Dec 29, 2009

Is this looking from the front ie to where there push rod tubes are as i have had 2 850 heads that have cracked in this area- where the two front studs are

L.A.B. · Dec 29, 2009

FastFred said:
Has oil on third fin up on the head.

It's not unheard of for one or both of the 5/16" stud drillings in the barrels to have broken through into the pushrod tunnels.
Oil then wicks up the stud/s where it escapes and runs out at the third fin. The remedy is to remove the head and the studs and coat the threads with gasket sealant.

possm · Dec 29, 2009

I have actually found cracks in the area L.A.B. discribes where the manfacturing mill would have made its final cut and no sealer would have fixed the 2 that i had, new head or major repair job.
Al

maylar · Dec 29, 2009

I certainly don't doubt your experience Al, but it's far more common for oil at that spot to be from wicking up the studs than from a cracked head. Let's not scare the guy away.

JimC · Dec 29, 2009

Getting rid of crankcase pressure will help stem those pesky leaks from the 5/16" studs, too.

FastFred · Dec 30, 2009

Thanks guys. Decided to back out of the sale. A new head is £950. Yes the chance is low and it was probably the studs leaking but other factors put me off. It had a 920 kit (which I always have lusted for) but it was clear he had tried to fix the leak and not cured it. He had had the head skimmed at a local engineers. I asked how much they took off and he didn't know. Nice bike but had no history so I will look for another. Cheers.

daveparry · Dec 30, 2009

I think you've made a wise decision there Fred!
regards,
Dave

1973 Interstate 850
1984 Suzuki XN85 turbo
1999 R1100RT
1994 R80RT

lynxnsu · Dec 30, 2009

Hallo Fast fred I have a spare 920 head bare with 0.8mm skimmed of and no broken fins
If you get stuck let me know we can work out a swap or so

Oil on fins

FastFred

possm

L.A.B.

Moderator

possm

maylar

JimC

FastFred

daveparry

lynxnsu

Similar threads