Be sure that really the lower gasket is the cause and not the cam chain tensioner or the blind plug on the other side of the cylinder. Perhaps you can also seal the leak with dirko or some similar sealing agent. If you are working on the engine, clean the oil pump intake filter and drill the banjo bolt, which holds the 2 oil lines to the heads, to 2mm.

Hallo Roel, it enhances the oil flow to the camshafts in the cylinder heads. Fitting the larger oil pump from the XV1100 is also a good idea.

Quote from hornschorsch on 19.02.25 at 11:30:34:


Geht das nicht zu Lasten der Ölmenge für die Hauptlager? Bei Yamaha in Japan gibt es keine so schlechten Konstrukteure.

So… no actual answer to my original question🤔 Anyone?

Good afternoon lasse mynttinen,
well, it would be a good idea to implement here some Picture of your problem. It would help to check up how deep your problem goes.

Basically, with an engine with 95000 km on the counter, it could be a good idea to change the Cam-Chains,
especially if you don't want to work much on your motor in the near future. Some things have already been mentioned.
First of all: What does the compression test look like? between 9.5 and 11 bar? The difference between the two cylinders should not be greater than 1 bar.

In summary:
a) Compression test before disassembling the motor
b) Renew timing chains
c) Install the oil pump of the XV1100 (Virago)
d) Clutch still OK? possibly renew it
e) When the cylinders have been removed, eventually hone them through slightly.
f) messure the Cylinder inner diameter and the outer diameter of the Pistons whether the pairing of both matches together.
  The Maintenance Manual gives you more information about it.
g) Check the Carburettors for proper conditions, are the different jets there where they belong to? Does the Diaphragmas are still in good Conditions?
h) If you have your motor in parts on your bench, clean all surfaces where gaskets, joints, etc. will come in contact with.
i) if you want to reinstall the cylinders DO NOT forget the O-Ring which come over the Cylinder Skirt. It is important to keep the Engine inner by-pass-gas inside the engine. Otherwise the gas will pass throu the Cylinder foot gasket by the time.
g) in General: Take your time, be carefull. In the end, it pays off.

Sources:
XV750 5G5 Maintenance Manual :         https://www.tr1.de/pages/technics_manual.php?key=XV750se&lng=eng
XV1000 5A8, 19T Maintenance Manual:  https://www.tr1.de/pages/technics_manual.php?key=XV1000&lng=eng

Spare Part List:  https://www.tr1.de/technics/microfiche/Parts_XV1000%2782-19T-EU_(en).pdf  for 5A8 in French avaiable, also.
Spare Parts Supply:
www.kedo.de
https://www.motorcyclespareparts.eu/de
or the well known Internet shop(s)

Be aware that some parts a limited available, because of the age of the Bike. Somtimes it is a challange.

Or alternatively, observe the whole thing carefully and take your time to get all the necessary components and gasket set. So that you have everything together when you start with the engine repair. Maybe in autumn or winter.

To work on the engine, it self, you have two options:
a) You remove the engine in one piece and put it on your workbench or
b) You remove the upper main frame and the entire front end.
It's just six screws and the usual stuff.

I have done that work last May on my Bike. After I had collected all aspected neccessary Items, I start with the work.
To give you an impression, here a collage of several Pictures and a very good self made tool.

Best Regards
Anja