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It's a long way to 920 type(rary)

Discussion in 'Norton Commando Motorcycles (Classic)' started by yves norton seeley, Jan 14, 2018.

  1. jseng1


    Nov 26, 2009
    Has anyone else seen a gasket blow out the way Yves did? I think there must have been a thin spot for such a catastrophic failure.

    It would be better if Yves could find a way to avoid adding an external oil line.
  2. Klaus Monning

    Klaus Monning

    Nov 27, 2014
    yes, I'm exactly of the same opinion. So, if I was Yves I would try the following: A 1mm copper head- gasket between the cylinder head and the cylinder sealed with Hylomar NF and no gasket for the cylinder base, just Hylomar NF (again). And as Jim Schmitt stated, do not start the hassle with the central oil draing tube. This should only be left to the racing guys who have the ports opend up above 34 or 35mm.
    By the way it was in 1992, the pre- start at the Nürburgring when we were all waiting for the start. Suddenly something hit my right knee. Yes, you may guess it. It was part of the composite head gasket which I mounted. As it was just a free practice and the engine hadn't been propperly run in and I wanted to go slow and re- tighten the cylinder head bolts after practise.
    This was not necessary, because I had to change the whole gasket. From then on I'm a fan for copper- head gaskets.
    These copper gaskets have another advantage: There will always be a better heat distribution within the whole engine, because the conposite gasket will work as a kind of a heat shield (Isolator) and most of the heat will stay in the cylinder head.
    For my next racing experience I even left the cylinder base gasket out and just used a bit of Hylomar for sealing. Yes, it was oiltight. Even the compression ratio was a bit higher without any machine work.
    Now, coming to the point of machining a cylinder head gasket thinner. There are only 2 or 3 ways of machining:
    1.) Double Face Grinding in unclamped condition (in German we call this process Diskus- Schleifen): This process was invented in the USA (in 1905, I believe). With this process the cylinder head gasket would be inserted in a kind of a feeder disk which with the component rotates between two grinding wheels. The grinding wheels are used side ways. This means, they don't work with their circumferential surface but with their side face. Piston rings are ground with the very same process and here we need parallelisms of 0,002mm (yes, 2 microns). Let me add that I am a bit of a speciallist for this process and still doing some consulting work (I'm retired but need a bit of cash for financing my NORTON) for machine manufacturers but also their customers. The only thing is, that if you ask a company to do the job for you, they will probably ask you how many 1000 componets you are planning to machine, because setting the machine will take about 2 hours and the feeder disk is workpiece related and therefore specially designed and manufactured.
    2.) You can also try a single face grinding process. But here the component needs to be clamped, which in case of copper or aluminium is a bit tricky. The only way these materials can be clamped, is by vaccum.
    3.) Probably a lapping- or fine grinding process between two grinding wheels will also work. But with this process I'm not too experienced.
    Yves I wish you good luck. Before you try anything else try what I described above. I just costs you some work and a copper head gasket together with Hylomar.
    Best Regards
    Last edited: Jun 2, 2018
    chaztuna likes this.
  3. jseng1


    Nov 26, 2009
    That was some interesting info Klaus.

    Ron Wood told me that he milled copper gaskets thinner but didn't tell me how. You can save a lot of trouble by just using copper sheet of the thickness you need. Copper head Gaskets are available in .021"/.51mm - special order .025"/.66mm - .8mm and up to 3mm or so. This way your can adjust compression or adjust the squish band with unmilled heads or heads that have already been milled.

    I've tried the Hylomar but it didn't hold up under high temp as well as the pliobond.
  4. yves norton seeley

    yves norton seeley

    Feb 13, 2014
    OK Jim and Klaus I will do another try with a .025" / .66 mm copper HG and I will order the gasket from Jim to be sure that the tickness is equal everywhere
  5. yves norton seeley

    yves norton seeley

    Feb 13, 2014
    Hi There,
    To day I receive a Email from Elring HG factory, they ask me to take 3 head gasket at 254 Euros/piece w/o taxses, this must be over the 300$ each.
    I think it will be cheaper to ask the NASA to make a head gasket!
    The material they wish to use is FW 522, there is no gold in the gasket, you can find the data sheet on their website.
    So if I can find two other craizy guys like me I am ready to place an order
    I will ask Bruno to put a copy of the offer from Elring on this tread
    I am still wayting for the .025"/ .66mm cooper gasket from Jim Schmidt
    I am now riding with a .8mm cooper head gasket, only 500 kms, and no issues so far, but there is less power with the .8mm as with the .6mm, of course with a bore from 81mm the difference from .2mm makes a lot of volume. BTW I don't go over 6.000 rpm, the Police send me a letter to ask me if I am hill!
    I still keep my order at the other HG factory in Germany.
    Something else very curious: I use fluted bolts and studs from Jim schmidt, when I retorque the head I feel nothing on the bolts, still on the good tension, but on the 3 studs from the cylinder head, you know the 3 where you need the hands from Prof. Barnard to put the nuts on it, well on this 3 nuts I must retroque the nuts at least 50 degrees??
    Keep you posted
  6. Fast Eddie

    Fast Eddie VIP MEMBER

    Oct 4, 2013
    Yves, are the studs wasted as well?

    In my humble option Yves, that head gasket option is not a good one. You know as well as me that you should always have a spare on the shelf, so you need to spend a minimum of €600.

    And it’s still only an experiment. You still don’t know if it will raise other issues, you still need to modify your head via skimming and an external oil pipe etc.

    With Jim’s copper gasket, you know it will seal. You know it will give a fixed squish gap. You won’t need to modify your head.

    Worst case scenario is you might get some oil mist that you’ll have to wipe off once in a while.
  7. Jagbruno


    Jan 6, 2014
    Hello all, here is the price offer for the 'German job' for Yves' head gaskets. The word coming to mind is 'KOLOSSAL':

    Hello Yves,

    sorry that we took so long.

    Enclosed the calculation for the gasket


    Yves van Heers


    Sample gasket - Norton Commando





    Delivery time

    about 8 - 10 weeks after incomming order

    Terms of delivery


    Terms of payment

    advance payment

    Price settings

    All offered prices are net prices

    Validity of quotation

    3 months after date of this offer


    We can not give a warranty for the function of the gaskets, because we have no possibility to make some tests in the engine.

    We warrant that we will produce theses gaskets with all the measurements we have from the original drawing.

    Best regards

    Branimir Obradovic

    ElringKlinger AG

    Sales Manager Special Applications

    IAM Western Europe & Germany
  8. yves norton seeley

    yves norton seeley

    Feb 13, 2014
    Hi Nigel, I agree totaly with your opinion, for 600 Euro's Hitler was producing a whole "Konig Tiger" panzer
  9. mdt-son


    Jan 19, 2012

    One-offs are always expensive, especially if made by a large factory. I agree with the above that for trial testing, shelling out 600 Euro requires pretty deep pockets.
    Probably better to try other options first.

    BTW, cost of the combat ready Tiger I was 1,3 million Euro in today's money, development expenses not accounted for!

  10. o0norton0o

    o0norton0o VIP MEMBER

    Apr 27, 2015
    Why can't you mill down the barrels at either the head interface or it's base by a few thousanths, then use the thicker head gasket you already have to get the higher compression ratio you want ?? If at some time you want to go backwards and lower that compression ratio you can always use a custom base gasket to reduce the compression ratio again??
  11. yves norton seeley

    yves norton seeley

    Feb 13, 2014
    It same that Adolf toy's are more expensive as a Codo
  12. yves norton seeley

    yves norton seeley

    Feb 13, 2014
    Yes, but I will receive a gasket from Jim Schmidt that meet my compression ratio
  13. yves norton seeley

    yves norton seeley

    Feb 13, 2014
    Hi Nigel,
    Yes the studs are wasted as well, and following Jim S. advice I put inserts, Timeserts, if I remember well, in the head, and when I retorque the studs I don't have the feeling that the inserts are mouving inside the head
  14. SteveA


    Dec 20, 2011
    Depends what you mean by a few thousandths.....But...

    The reason for not milling the top of the barrels is that Yves has Maney alloy barrels with sleeves. Maney leaves the sleeves proud of the head face for extra bite on the gasket. Yves has also said earlier thah his sleeves moved under heat and he had to 'push' them back in. Probably not good for setting up in a mill.

    I have Yves' old 77mm barrels which I am looking at fitting at the end of the season, so I had looked at doing this as my cast iron barrels have 0.020" removed for compression, but as you see, no go. Milling the base gasket area 0.020" would work, but I would think that is a bigger milling job?

    So to run the same compression I already have I have to mill the head another 0.020". Since it is only milled 0.020" so far this is OK for my head. I could get another 0.010" ish by going to a JSM 0.021" copper gasket. I already have a JSM 0.030" (or 6mm as referenced) Copper gasket. As it is set now my piston/valve clearance is OK. Reduce heights any more and I may need to rework piston cut outs.
  15. o0norton0o

    o0norton0o VIP MEMBER

    Apr 27, 2015
    If Yves sleeves moved inside the casting, I would think he's going to have head gasket problems with any gasket. Even if the barrels can't move downward in their aluminum casting because of a rabbet of some kind in the barrel and casting's milling. I would think that one barrel moving upward still has to cause an imbalance in head gasket torque on the other barrel. If his barrel alignment isn't good enough to index a mill set up, then I think it's probably not so good for a gasket to seal either. Don't you think??

    BTW, thanks for that answer. I didn't realize the Maney barrels were made to be proud of the casting for better sealing. Pretty cool, except for the moving barrel part... which I'd probably call Maney to ask some questions about...
  16. yves norton seeley

    yves norton seeley

    Feb 13, 2014
    When the sleeves move in the casting, it was becouse I paint the barrels and put it in the oven at 200 degrees Celcius and I put the barrel with the bottom of the sleeves
    on the floor of the oven, so the casting go down along the sleeves, only a few mm, and no way to put him back by hand, I must use a hydrolic press to put him back in place and I discover no imbalance between the sleeves, no reason to look in this direction.
    To day I did 300 kms with the Seeley to a classic race in Holland, still with the 0.8mm cooper gasket, no issues so far...
  17. yves norton seeley

    yves norton seeley

    Feb 13, 2014
    Dag Ludwig,
    I put steel Beleville washers under the trough bolts...
    Groetjes Yves
  18. yves norton seeley

    yves norton seeley

    Feb 13, 2014
    You mean between the head and cylinder?
  19. rvich

    rvich VIP MEMBER

    Jul 25, 2009
    This is interesting. As I understand it, Ludwig is talking about filling the void left by the recessed bolt.

  20. yves norton seeley

    yves norton seeley

    Feb 13, 2014
    OK, I understand and will do it, thanks