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Base gaskets M900...

Discussion in 'Technical Help' started by Dukedesmo, Dec 8, 2012.

  1. So, looking at fitting the cylinders/heads to the Monster engine and have a question regarding the base gaskets.

    I have 2 different types of gasket as shown in the pic below;

    [​IMG]

    Arranged in pairs above/below. The middle pair are what were fitted, the left pair are a new (almost identical) set and the right pair are another new set in which both gaskets are the same as each other rather than being a different front/rear as were the originals.

    I'm not 100% sure how the original pair fitted (forgotten which was on the front and rear cylinders) but assume it was as per these pics;

    [​IMG]

    [​IMG]

    This leaves the rear oil feed hole not within the gasket? but if the gaskets are swapped then the front cyl oil feed hole is blocked;

    [​IMG]

    So the other type fit 'better' IMO (are the same as 916/ST2 etc gaskets);

    [​IMG]

    [​IMG]

    But either way how does the front cylinder oil feed hole seal? on the rear there is an 'O' ring to fit in the recess but I can't see where one would fit on the front?
     
  2. I think you should use the silver ones. :upyeah:

    I think the front pot oil feed seals by an o-ring in a recess of the base of the barrel itself? I run a little threebond around both sides of the gasket just to be safe...
     
  3. Must be a bloody small 'O' ring?...
     
  4. May be getting confuzified between the recessi in the barrel & those in the head/barrel meet? My bad. :)
     
  5. Between the head/barrel is a hollow dowel/nozzle with an 'O' ring around it to seal between the head/barrel, although I have plugged this hole (I'm using the MBP end caps with external lubrication) so will just fit a solid dowel.

    I don't remember seeing any 'O' ring in the front cylinder base when I took it apart and I can't see one in the parts manual - just thinking that it's a leak waiting to happen... :rolleyes:
     
  6. Block it off then! Drill & tap, loctited grubscrew - job done! :upyeah:
     
  7. But I still need oil to flow to the cylinder, just not to the head.
     
  8. (doh) :biggrin:

    No o-ring on my parts list either? Bizarre... mines oil-tight with a smear of threebond either side of the gasket tho?

    Did you check the bottom of the right barrel? The vert pot wont have one anyway?
     
  9. Threebond will have to do then, just seems odd that there's no 'O' ring on the front, yet the rear cylinder has an 'O' ring? The feed hole to the rear is even there on the 916 models and not used but prone to leaking (tapped & plugged on mine).

    Still, I suppose it's no more strange than not having a head gasket...

    Now just got to establish if the base gaskets are the right thickness for squish with the JE pistons? - the originals are 0.3mm, the 'new' type 0.4mm and I have some (from 916) that are the same as the new type but 1mm.

    But got to get the bastid oil ring on the JE piston first though, it's a 3-piece ring (2 flat, 1 'crinkly') but when assembled is slightly thicker than the groove - guess it needs some 'application' to get it in...
     
    #9 Dukedesmo, Dec 8, 2012
    Last edited: Dec 8, 2012
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