head reconditioning

[vanzen]

My understanding was that the part of the stem that went through the guide was rougher than others, resulting in excessive wear and/or sticking ...

If I recall, early on, Black Diamond rec'd clearance specifications which were inappropriate ...
Rather than "roughness", I would suspect thermal expansion coefficients ...

[SteveD]

Any word on the Swiss made "Intervalve" valves? Motobins sell and recommend them.

[ME 109]

The only fault I could find with intervalve, through exhaustive testing, is that they don't like being put in the wrong hole.
Well, not for too long anyway.

[Roy Gavin]

http://www.moorespeed.co.uk/bmw-tuning

Ritchie does a one piece valve and matching guides for a bit less than stock, and they seem to stand up OK on his110 hp racing hack

[SteveD]

I have a pair of inlet valves to replace.

One of mine has some mushrooming on the stem, and will need to be cut out.

I'm planning on getting the local lads to do that.

If I take the heads off and deliver them, it'll reduce cost. Is the total job too difficult for a novice headspert? I think I removed the heads and barrels once, maybe twice, way back in the 1980's! Having written that, I can't imagine it being too difficult, unless there are some specific tricks to it. Any guidance might help and would be welcomed.

[Garnet]

I'm sure Jeff can do it in his sleep, or least has done it whilst sleeping.

[mattcfish]

My understanding was that the part of the stem that went through the guide was rougher than others, resulting in excessive wear and/or sticking ...

If I recall, early on, Black Diamond rec'd clearance specifications which were inappropriate ...
Rather than "roughness", I would suspect thermal expansion coefficients ...

I was under the impression that reaming out BMW guides was common practice. My old BMW valves were too loose in my new Amco 45 guides. The new valves from Intervalve were too tight. A local shop ordered a special tool to do the job and got me a perfect fit. No oil burning for the last 6 years of heavy riding. If you buy German valves with German Guides do they actually fit without adjustment?

[ME 109]

The boys at BM Cycles should know their stuff.
I'd plonk the heads on their bench and leave it to them.

Things to get right on re-assembly...... take the barrels off and replace the o rings, maybe with the over-sized o ring.
Get the sealant for the barrel base right, not too much.......not too little either.
Take the gudgeon pins out, leaving the pistons in the barrels.
Maybe get new gudgeon pin clips.
Make sure the valves are in the right holes
Make sure oil comes out of each top stud before putting the valve covers on.

Got a torque wrench?

[SteveD]

...
Got a torque wrench?

Yep.

Thanks Jeff.

[KenHawk]

I had my Big Port heads rebuilt through Dave Gardner in San Francisco and he sent them out to Kibblewhite Performance Machining for a complete rebuild, including their Black Diamond valves. Dave claims that he has had hundreds of pairs of heads rebuilt using those parts, without one failure. Well, the heads were beautifully done and have been on the bike for 6K miles and so far they're perfect but time and miles will tell.

I have heard that the early problems with these valves centered around the metallurgy of the valves and guides and the required guide clearances based upon expansion rates. I guess they have to match and the clearances are substantially different than whats required when using the stock parts.

I'll be putting miles on the Hot Rod this summer, so we'll see how my engine holds up.