Comparing Oil Seal 'Tube' for Cylinder studs "GSKT.CYLN.STUD *D"

[Bloggs]

I know this has been discussed before re the oil passage way up via the two studs leaking using the sealing tube/Gaskit/ORing (12909428003).

Having seen an amount of oil on the barrel fins before I started working on the bike I obtained a Gasket set for when I get the the engine. I found an Athena set as I understood these were better than some of the other options currently available. With the comments about the thickness of current head gaskets affecting the seal I ordered some Honda items to compare against the Athena version. Generally there are the same overall design and diameter. Trying to compare is not an exact science as the tapered edges and 'rubber' material of the tube prevent definative measurement.
Using a vernier caliper and measuring the point at which they slip through the jaws I measured  7.77 long for the Athena version and 7.9 for the honda version. So it does seem that the aftermarket version may well be undersized.
 
Just thought I would share what I had found.

[AshimotoK0]

I thought that was a --333--- part in the Parts Book ? Is the   ---428---- XL250 part a recommended upgrade?

https://www.cmsnl.com/products/gasket-cyln-stud-nas_12909333000/

My friend has just replaced the two Dowty type stud seals 90442-377-000 on his high mile 400/4, which were the  cause of oil leakage. He told me that the 350F used copper washers in that location, which don't have a tendency to leak.

https://www.davidsilverspares.co.uk/parts/by-part-number/partnumber_90442377000/

[magpie114]

Just gone down this road myself. Very difficult to accurately measure but I make the Honda version 7.9mm and Athena 7.82. Not sure whether this would make a difference and the Honda item (left) has a “cleaner” finish.



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