83 1200TS - DPO issues

Dellortoman said:
So what was the cause? My Jota has leaked there ever since I've had it. Replaced the head gasket twice to try to fix it. The second time I had the head shaved to take out a bit of non-flatness. Bloody thing still weeps a bit of oil.
Click to expand...

Cam, check the liner protrusion.

Since becoming aware of this issue, as well as the differing head gaskets, the engines  that I have built have been completely oil-tight in this area.

piet
 
sfcpiet said:
Cam, check the liner protrusion.

Since becoming aware of this issue, as well as the differing head gaskets, the engines  that I have built have been completely oil-tight in this area.

piet
Click to expand...

Spot on Piet. Liner protrusion is a major area requiring scrutiny with rebuilds on all SF and triple based motors.
 
motoddrob said:
Not 1200s Q, in fact it's the opposite :D
Click to expand...

Don't mistake liner protrusion with the liner spigot Rob.  Just as important on the 1200 as on the others.  Can be dealt with differently though to get satifactory results.

piet
 
sfcpiet said:
Don't mistake liner protrusion with the liner spigot Rob.
Click to expand...

OK, I thought I was following, but you just lost me again. Does the liner have a spigot that's smaller than the liner OD?  It might be a dumb question, but it's been a while since I looked at a set of barrels, and I can't remember.
 
Can of worms Cam, I forget how many types of head gadgets there are but the bunch, big Euro Co, Athena just remembered made a change to the gasket spec and didnt tell anyone and it cause issues. There was a long thread a while back started when Greg P was having issues on a race motor and was looking for old stock head gaskets and it got discussed at length. It was well technical, above my pay grade. Have a search for that thread.
 
A few pictures of the gasket.

note how the enlarged holes cut into the copper rings . is this normal..?

I need to purchase a new base and head gasket for this engine.. How can I be sure I get the correct ones as being in tenerife I can't just pop back to the shop to exchange them will also need items 24 & 40

Richard


 

Attachments

  • P_20190523_094425.jpg
    P_20190523_094425.jpg
    25 KB · Views: 24
  • P_20190523_094435.jpg
    P_20190523_094435.jpg
    23.3 KB · Views: 17
  • P_20190523_094440.jpg
    P_20190523_094440.jpg
    29 KB · Views: 16
  • ficha tecnica.jpg
    ficha tecnica.jpg
    70.7 KB · Views: 17
  • 1000-44.jpg
    1000-44.jpg
    49.6 KB · Views: 15
Yes.

The usual sources will supply the correct gaskets.  Here in the UK Phil Todd (phil37 on this forum). Or OCT in Germany; Wolfgang Haerter in Canada since you also want  a tensioner blade and rivet (really??)
 
Dellortoman said:
OK, I thought I was following, but you just lost me again. Does the liner have a spigot that's smaller than the liner OD?  It might be a dumb question, but it's been a while since I looked at a set of barrels, and I can't remember.
Click to expand...

Cam,

The liner has a collar that locates in the top of the barrel casting.  On top of that, 750s and 1000s have a spigot that extends into the combustion chamber, 1200s don't.

It is the collar that needs to be 0.1-0.2mm below the gasket surface of the barrel casting to ensure that both the combustion chamber does not  draw oil and the gasket surface is externally oil-tight.  The gasket needs a slightly thicker fire ring in this case.

After thousands of heat-cycles, the barrel alloy tends to shrink, leaving the liners more-or-less proud of the gasket surface.  In this case, there is loads of pressure on the fire ring and the combustion chamber is OK, but the remainder of the gasket has not enough pressure to remain oil-tight, hence the weeps at the sides...

Protrusion can be re-established either by pulling the liners and machining the collar or milling the collar with the liner fitted.  I prefer pulling the liners, especially if a re-bore is on the cards.  Re-fitting used pistons and rings would entail a very slight hone to ensure no high spots result by the liner not being returned in the precise same position as before.  1200s can be corrected by skimming the barrel complete with liners and using a uniform-thickness gasket.

Quite simple actually. :D

piet
 
Thanks for that clear explanation Piet. The oil weep is minimal, so isn't motivation enough to pull the engine out and dismantle it at present. One day I'll get in there and have a closer look.
 
sfcpiet said:
Don't mistake liner protrusion with the liner spigot Rob.  Just as important on the 1200 as on the others.  Can be dealt with differently though to get satifactory results.

piet
Click to expand...

thanks for the explanation Piet. I was thinking spiggot.
Just goes to show I'm not an engineer!! :D
 
Very clear explanation Piet, thanks.

I have always wondered why some engines have that tell tale misting, now I know and I don't have to a ask Red another silly question regarding LAV engines  :(.
 
Rob said:
Yes.

The usual sources will supply the correct gaskets.  Here in the UK Phil Todd (phil37 on this forum). Or OCT in Germany; Wolfgang Haerter in Canada since you also want  a tensioner blade and rivet (really??)
Click to expand...

thanks but my concern is that as there are very few with the locating dowels does that need a special gasket ?
 
You must log in or register to reply here.
Back
Top