Excessive oil consumption - GS425E - Where to go from here?

[Guest]

Hi Everyone,

Over this past riding season, I experienced excessive oil consumption with my 1979 GS425E. At hotter temperatures, the bike could consume up to ¾ of a quart in about 200 miles. There are no external engine leaks and I have not noticed any smoke on start up. At this point, I am contemplating some top end work, but before I make any final decisions, I wanted to ask the collective group on their opinions on how you would proceed. Any feedback would be greatly appreciated.

Best regards,
Aaron

[Nessism]

Burning that much oil will be evidenced by a blue cloud following you everywhere you ride. Plugs would be fouling right and left also. At any rate, you best pull the top end and check everything out. Piston rings and valve stem seals will be needed at minimum.

[velvet jones]

Thank you, Ed. That is pretty much what I figured. Regarding sources for parts, are there any vendors you would recommend over others? Thank you again.

Aaron

[Chuck78]

Parts Outlaw or Babbit's Suzuki Parts House I have had good luck with. G&S Suzuki or Bike Bandit, no go... Especially G&S. Just use them as a price matching reference when dickering on price with other vendors. I think it may be Parts Outlaw that is no good for nickel and dime parts as they have a minimum part price of $2 and change, so if you order a bunch of o-rings or screws from them, they will cost a fortune, but if you phone them, you can get them to match the competitor's price on the small stuff, and they pretty much beat most places prices already on anything $3 and up.

[Chuck78]

Could be that you are only burning oil on heavy loads, getting some blow-by on the piston rings. Maybe at highway cruising or hard acceleration you aren't able to look back to see a faint blue-white smoke trail? My amateur approach would be to pull top end, gently remove rings from pistons, insert them into the bores, and measure ring end gap at various height positions in the bores. This will tell you if your rings are worn out or if your bores are worn out. If gap is different at different heights, then the bores are worn unevenly. They are pretty darn hard metal, so I'd suspect rings first.

Valve stem seals also are a likely suspect, but #2 behind rings to the best speculation from my experiences.

[velvet jones]

Thank you for the feedback, Chuck. Since I have limited time over the winter to work on this, an independent shop is currently diagnosing the issue and the extent of the repair needed. I will update the thread once I hear back.

Best regards,
Aaron