montjuic exhast gaskets

S

sjeffers

New member
Location
northern ireland
there is a minor oil /vapour leak from one cylinder onto one of the montjuic exhaust down pipes. Its been like this for years and after the engine heats up normally disappears. However recently its got worse. It seems to be coming from one of the exhaust manifolds. I have tried exhaust sealant but dosnt seem to work.

I am hoping its just a matter of new copper exhaust gaskets?
Does anyone know the dimensions and where I can get a set of new copper gaskets?

thanks
 
Not meaning to stir up trouble, but surely there should not be oil/vapor in the exhaust? If there was wouldn’t that indicate a worn valve guide or even bad rings?
A head gasket failure would seem more likely, especially if there is no oil smoke in the exhaust from that cylinder. Is the inside of that pipe wet with oil mist?
 
Alzero said:
Not meaning to stir up trouble, but surely there should not be oil/vapor in the exhaust?
Click to expand...
Quite a few people on the forum have had this problem on motors that do not use any appreciable oil and do not blow smoke. It seems that the pressure leak at the gasket takes with it some of the unburnt fuel mixture that gets pulsed back into the engine.
 
Make sure that's where the oil is coming from. It is the least likely source.
Likely culprit is head gasket or cam cover.

Many thanks to Craig aka Ventodue on this forum:
Exhaust gaskets are the same on all big Breganze machines.
OEM size (source: parts book): 38.2mm (ID) x 43.7mm (OD) x 2mm.
1. Imperial (aircraft) alternative
AN900-24 = MS35769-39
1½” x 1¾” x 3/32” = 38.1mm x 44.4mm x 3.4mm.
These work.
2. Honda alternatives
Part number: 18291-MM5-860
(37.4mm x 44.8mm x 4.1mm)
Part number: 18291-MN4-920
(35mm x 43mm x 4mm)
Honda CB250 (Super)Dream; CB 450S, VT 600C; XL 600V '87-'99; NTV 650 Rev. '88-97; XRV 650; CBR 900 RR '92-99 etc etc

Paul
 
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