Head matters.

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Location
bedford Uk
When one gets one's head looked at by a head doctor is it possible to get and old 180 head up to the much coveted corse spec or does one have to buy an rgs head?
 
If the existing head is ok, I wouldn't 'uck about with it, just be grateful? Personally I gave up with head recon work, and bought an unused RGS one...better quality metal etc. Had Keith cut some 3 angle valve seats even on that though, and new billet cam blocks.I think every Lav triple owner I know has had head issues...waiting for that 3d copying technology to rescue us I think!
 
The head on POP is a 76 180 head but now has Corsa porting and valve sizes.
 
Hi Grant, can we take it that the head works as it should, with no issues? Can you say who did the work...presume changing the valve seats apart from anything else? No cracks? There' still time :-*
 
The all alloy head had cracks from plug holes to valve seats.
Everything dug out, welded up, ported, new seats, guides, smaller plug holes offset further away from seats.
Van Dijk did the work. I guess he knows what he is doing.
Everything ok so far but poco kilometros se?or.
 
Wow, very skilful work, sounds like you splashed  some cash there..worth it of course. Met him at Spa...bootiful bikes and nice guy. Not being an engineer, I wonder how welding stands up to combustion temperatures...guess must take a lot more heat the alloy than is generated in use. My son is doing an MEng so I should ask him...but he has wangled study term in Adelaide!I digress....
Give us a bell when you are in the vicinity...time for a CLEM funded lunch I reckon? Your bootiful Stradas are on the mantle piece btw.
 
would love a lunch time meet with you dieseldav.

I should point out that any head that has alloy welding is unlikely to get retempered, not always a sad thing but it must be desirable to have it done thus, and Gjis van dyke ,although a very well set up motorcycle mechanic and engineer with lots of modern machine tools, I don't think he does all the head work himself, with a lot of it farmed out to subcontractors, again not a bad thing and of course he will be taking responsibility for the quality, I am sure this is the case with almost all the Laverda dealers, in that external work is required, there is also no reason why those dealers should not take credit for the excellent work that is being done, the trouble is there is a lot of very poor quality head work still taking place.

I fell out with a cylinder head shop (substitute "a" for The and insert capital "c" and "h") many years ago they worked on a worn out 180 head and created two cracked cast iron skulls (which they denied) then the stainless valves seized in the guides, and ran up and down with them enlarging the borings for those guides, then they repaired that and left the head badly warped, (caused a blown head gasket and leaking cam cover) and also with very soft alloy material,(causing cam blocks studs to pull out at less than 10 ft/lbs) result, converted head to a door stop and never went there again (knowingly)

CLEM
 
The welding and porting was done by a guy Gijs said worked on racing Porsche engines.
Gijs is meticulous in his work and in his choice of subcontractors.
Whether it was re-tempered or not neither Clem or I can say, but Gijs has done a few of these and I trust him.
 
  I used to have the heads at "Motodd" done by a world championship winning artist. - then did my own - this allowed for a lot of experimenting from a sound base. Almost any good tuner will get you more flow - but you then need to burn that extra charge - so - it's not just the head that needs attention - piston and liner position and shape, exhaust system, cams & timing, carb size and many other variables dictate the success or otherwise of a "Head job". - Not a massive fan of the Corsa head myself. - Regards - Phil
 
Exactly Clem, it's the basic guide and seat work that seems to be the cause of major problems time and time again. Wrong or incompatible metals, wrong clearances, bad methodology in fitting seats, leading to them falling out...we have all seen the horror stories. So good to know of sources that can do that stuff properly as sooner or later most engines will need it.
 
Dellortoman said:
A cylindrical liner usually gives the best results :D
Click to expand...

Probably badly worded Cam - I mean that the bore of liner means that the inlet valve, especially when it is enlarged, is too close on the 75mm bore - the 80mm (or larger) is much better - or a chamfer is needed if retaining 1000ccish. - Regards - phil
 
I was just reading in "Old Bike Australasia" about Joseph Ehrlich who designed the EMZ split single 2-stroke during WW2. The cooling fins on the barrel were arranged with large fins interspersed with small fins. I quote from the article:

"This, Ehrlich's explained, was to provide what he referred to as "differential cooling" to allow the liner to slightly deform or corrugate when it reached operating temperature, and thus retain oil around the pistons."

So maybe cylindrical isn't necessarily best after all.
 
Dellortoman said:
I was just reading in "Old Bike Australasia" about Joseph Ehrlich who designed the EMZ split single 2-stroke during WW2. The cooling fins on the barrel were arranged with large fins interspersed with small fins. I quote from the article:

"This, Ehrlich's explained, was to provide what he referred to as "differential cooling" to allow the liner to slightly deform or corrugate when it reached operating temperature, and thus retain oil around the pistons."

So maybe cylindrical isn't necessarily best after all.
Click to expand...

Or... being as split singles and differential cooling never really caught on cylindrical is best.


    Keith
 
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