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Breva 1200 cylinders on an 1100 sport ?

Discussion in 'Spine' started by paul ginis, Jan 4, 2015.

  1. paul ginis

    paul ginis Just got it firing!

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    Hello,
    Can I fit Breva 1200 cylinders (95mm bore) on my 1100 Sport i.e. (92mm bore) or is the distance between the studs different?
    Thanks for your advice
    Paul
     
  2. Android

    Android Cruisin' Guzzisti GT Famiglia

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    Hi Paul
    I'll get my digital caliper on my sport barrels tonight and send you some dimensions.
    AndyP
     
  3. paul ginis

    paul ginis Just got it firing!

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    Hi Andy,
    I measured 60mm center-to-center between all barrel studs, the piston wrist pin diameter is the same at 22mm……an easy conversion ?
    Thx,
    Paul
     
  4. Android

    Android Cruisin' Guzzisti GT Famiglia

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    the studs are indeed 60mm between centres on a 120mm PCD (pitch circle diameter)
    wrist pin is 22mm dia x 58mm long, cylinder bore is 95mm dia.
    barrel dia that locates in crankcase is 102.5mm , guessing here because my 200mm calipers cannot quite measure the dia as their throat is only 50mm
    length of dia that is located in crank case 52.5mm
    Length of barrel out side of crankcase 78.8mm

    Looks like it could work
     
    Last edited: Jan 5, 2015
  5. paul ginis

    paul ginis Just got it firing!

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    Wow Andy, great stuff, how accurate can you be?
    That looks like an easy job, boring out the crankcase and double-checking the piston-to-head and piston-to-valve clearance, but that's std practice!
    Thx a lot, Andy, I'll keep you posted!
    Paul
     
  6. Android

    Android Cruisin' Guzzisti GT Famiglia

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    Being an engineer (toolmaker) can help sometimes.
    I could give you better dimensions but I guess you are just looking to see if its viable......so what's 4 thou between friends.
    you'll be getting the barrels yourself and machine to suit.
     
  7. ghezzi

    ghezzi High Miler GT Contributor

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    easiest way of checking deck height of pistons, mount an old and new piston together on the same wrist pin.

    If you're having the crank case machined, then get the whole lot balanced while its apart.
    Most Guzzi's I've owned were smoothest at 140kph, last one I rebuilt I had the crank balanced for whatever RPM coincided at 115kph, as I like to cruise between 110-120kph.

    Also lightening the fly wheel first by just drilling a pattern of holes, reducing weight by 25% made a huge difference. Twas a sweet 850 Le Mans that one ................................
     
    Last edited: Jan 6, 2015
  8. paul ginis

    paul ginis Just got it firing!

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    Hi Andy and Wayne,
    My 1100 Sport barrels are longer at 79,5mm but I wanted to tighten up the squish clearance anyway, just looking at the combustion chambers you can see the squish band is not working at all. I'll order the 1200 Sport pistons and barrels and check all the clearances.
    Any idea how tight I can go on the squish clearance ? Cylinderhead modification is next on the list…..
    Thx lads!
    Paul
     
  9. ghezzi

    ghezzi High Miler GT Contributor

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    closing it to 1mm is the norm for a street machine, still safe.
    Going down to .8mm is still within boundaries, but you need to be careful. Rod stretch/ expansion etc.

    Changing barrel heights, don't forget pushrod lengths.

    Also somebody here advertised Carillo rods yesterday, worth a look.
     
  10. guzzigray

    guzzigray Cruisin' Guzzisti GT Contributor

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    Hi. Just something to think about : 1200 pistons have a higher piston pin location on account of that engine's longer stroke and rod length so with a Sport 1100 rod the piston will be lower in the cylinder. (offhand I think the rod is 144mm for the 1200 and the Sport is 140mm). You may need to trim the cylinder base to account for this.
     
    Last edited: Jan 8, 2015
  11. paul ginis

    paul ginis Just got it firing!

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    That's some very relevant information ! Trimming the cylinder base is no problem, plenty of meat there, but with the 140mm rod the rod angularity will be different from the 144mm rod…...
     
  12. guzzigray

    guzzigray Cruisin' Guzzisti GT Contributor

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    I doubt it would make much difference though trimming the cylinder will bring the spigot lower into the crankcase. That will be worth checking regarding rod angularity and crank weight throw.

    Cometic gaskets here in the States can produce copper head gaskets in varying thicknesses. Stock Guzzi 95mm gaskets compress to thicker than 1mm. Let me know if you need help sourcing (I just built a 95mm bore race engine).

    102mm spigot diameter leaves very little meat for gasket sealing. I think Guzzi addressed this by using locating 'dowels' on the cylinders and heads to avoid any 'movement'. Also I think 1200 oil return holes are bigger. Not trying to state any of this is fact. Just random thoughts………..
     
  13. ghezzi

    ghezzi High Miler GT Contributor

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    easiest way of checking deck height of pistons, mount an old and new piston together on the same wrist pin. (said that earlier)

    If you are building a bit of a hot rod engine, and piston deck height is altered, do some very careful research with regard to conrod lengths. Altering the rod/stroke ratio changes the rate of deceleration/acceleration of the piston as it passes top dead centre. This intern can effect induction pulses and port air speed. With higher reving engines you may gain HP, but with lower rpms you may loose the torque you would have gained from the bigger bore. It's all theory .......................................
     
  14. guzzigray

    guzzigray Cruisin' Guzzisti GT Contributor

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    Just to add more info……

    I just received a set of 1200 pistons and cylinders I bought on ebay. The oil return holes are bigger and moved outboard so to use them on a V11 block would require machining of the case to match (dowel holes would have to be machined into the block too. Not sure deleting the dowels would be a good idea ). The V11 head return holes would be mostly blocked too.

    The 1200 piston has a tapered squish area so a V11 head squish area would need to be machined to set squish clearance.

    I think after all the messing around finding a used 1200 engine to drop in may be a better way to go :)

    Interestingly the piston dome has similar dimensions to a mid valve piston. The piston dome measures 29cc according to my rough calculations. The longer stroke and bigger bore allow this smaller dome while achieving the 9.8:! stated compression.

    After looking at some calculators I'm thinking a 95mm x 80mm, mid valve head with 11.5:1 compression could be very interesting. Especially as the combustion chamber would need to be enlarged to keep the comp ratio at reasonable levels thus allowing room for bigger valves….
     
  15. paul ginis

    paul ginis Just got it firing!

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    Thanks for the information !
    The oil return holes on my 1100 sport are 7mm dia with 72mm c-to-c distance, there are no locating dowels…..
     
  16. guzzigray

    guzzigray Cruisin' Guzzisti GT Contributor

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    I'll post some pictures to help explain it tomorrow.
     
  17. guzzigray

    guzzigray Cruisin' Guzzisti GT Contributor

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    Well, my camera if on the blink. Won't upload pix to my laptop. To be continued………..
     
  18. GuzziMoto

    GuzziMoto GT Reference GT Contributor

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    If you are talking about dropping a newer CARC 1200 motor in a V11 you will have to figure out a work-around for the alternator. The CARC motors have the alternator up high in the crook of the V and I would think it would interfere with the spine frame.
     
  19. guzzigray

    guzzigray Cruisin' Guzzisti GT Contributor

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    Good point…. I know a vintage Ducati alternator can be made to fit the crank of the newer models but that's a racing mod. It only put out 200 watts I believe. (a V11 timing cover can then be used).
     
  20. guzzigray

    guzzigray Cruisin' Guzzisti GT Contributor

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    Though it looks like Radical Guzzi has a solution to putting an 8V in a Tonti…….http://www.radicalguzzi.com/teileliste-parts-for-v7-12-bike/
     

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