Oil consumption, time for a rebuild?

[Admiral Beez]

Just finished a 1,200 km ride on my 1982 GS650G. I always ride with a litre of oil in the saddle bags, and on this trip the bike consumed a full litre of 10W40. My mates riding close behind said they only saw a slight puff of smoke when I was accelerating hard, otherwise the exhaust is clear. The spark plugs are not oily or black. There is a lot of rattle and clicking at idle. I’ve had the valve clearance adjusted and cam chain tension set. There are no oil leaks, so clearly the oil is being burned off. My mechanic did the compression test and said it’s good (I have to find his report) but also says the top end is tired. There’s only 42,000 km on the clock, 12k of that is me, but who knows how the past owner treated the bike.

What am I looking at? Head off, valve guides and valves renewed, cam chain and tensioner replaced, anything else?

[rphillips]

Seems a little excessive, but as long as you don't run it too low, it's more of an aggravation than anything. I'd probably try some good 20W50. I did that on an "80" GS1000 "G" by dealers advise & it used noticeable less than the 10W40.

[Admiral Beez]

Seems a little excessive, but as long as you don't run it too low, it's more of an aggravation than anything. I'd probably try some good 20W50. I did that on an "80" GS1000 "G" by dealers advise & it used noticeable less than the 10W40.

Good idea, I'll give that a go, thanks. The bike's like a two stroke, lol, always have some oil handy.

[Grimly]

Yes, try a different make or grade. It's quite possible the one you're using may be prone to high-temp evaporative loss, especially in an air-cooled lump.

[Cipher]

.83ml per click
4 to 5 drops of oil per cyl per km

A good red neck valve seal change is something to try
Had a friend did it on an old car and by golly it worked.
Saves a load of expensive basketry etc.

Needs air forced into cyl under pressure. Lotsa YouTube no doubt

Hell just do one cyl and see if the consumption roughly decreases by a quarter

Plugs no show any variation at all?

[Cipher]

Yes, try a different make or grade. It's quite possible the one you're using may be prone to high-temp evaporative loss, especially in an air-cooled lump.

Also a long trip at full op temp always seems to lower oil. Partial blowby thinning oil?
Id go up a grade as well. Even try a snake oil additive to swell tired valve seals

[alke46]

Given the fact that there is soooooo much talk on the subject of oils and the need to avoid oils that contain additives that are not conducive with our older machines and the wet clutches, just what brand are you willing to try in the 20w50 class?

[rphillips]

Ask 20 people, probably get 20 different answers & none will be wrong...Since the late 70's. I've always used Castrol GTX, & don't know why just always stuck with it, maybe because a Plymouth GTX was always my dream car.

[Rob S.]

Yes, Castrol GTX 20-50 was my brand in the '70's and '80's. If they still make it (the same), I'd still use it in my '70's and '80's motorcycles.

My '73 Kaw 903 Z1 used almost a quart every tankful. No big deal - had the centerstand and a nice clear sight glass.

[Cipher]

Yes, Castrol GTX 20-50 was my brand in the '70's and '80's. If they still make it (the same), I'd still use it in my '70's and '80's motorcycles.

My '73 Kaw 903 Z1 used almost a quart every tankful. No big deal - had the centerstand and a nice clear sight glass.

Self changing oil what a concept

[Admiral Beez]

Given the fact that there is soooooo much talk on the subject of oils and the need to avoid oils that contain additives that are not conducive with our older machines and the wet clutches, just what brand are you willing to try in the 20w50 class?

My old ‘69 Triumph 500 ran on Castrol 20w50 regular motorcycle oil for twelve years. Perhaps I’ll try that.

My local options are https://www.canadiantire.ca/en/autom...cycle-oil.html

What about adding this stuff? Will it make the clutch slip? https://www.canadiantire.ca/en/pdp/l...0260p.html#srp

[Rob S.]

Self changing oil what a concept

Yes. My oil never got old. Die young, stay pretty.

[Grimly]

My old ‘69 Triumph 500 ran on Castrol 20w50 regular motorcycle oil for twelve years. Perhaps I’ll try that.

My local options are https://www.canadiantire.ca/en/autom...cycle-oil.html

What about adding this stuff? Will it make the clutch slip? https://www.canadiantire.ca/en/pdp/l...0260p.html#srp

I suspect the Royal Purple Max Cycle 10w40 might be good for evaporation resistance, but without looking at the figures, I'm just barfing into the wind.
If it were me, I'd have a look on Bobistheoilguy.com and just try to get performance figures, doing a comparison between the current oil and say, the RP.
BITOG denizens are sometimes full of sh1t, but a lot of them have some idea what they're talking about, and if you're not actually burning or leaking oil, it might just be fixable by a change to something with High-Temp, High-Shear resistance.
Unless you actually have leaky seals, the Lucas anti-leak will do no good, as it's just a seal sweller. Even then, it's just to buy time if you're putting a junker into the auction.

[Admiral Beez]

I went for a 500 km ride last weekend and I have to say the oil consumption using heavier 15-50 synthetic was reduced. Here’s my plugs after the ride. The two inside plugs seems to run leaner, or cleaner. One of the outside plugs is sootier.

[Buffalo Bill]

Get a very good, or do a very good valve job and be sure to use new valve seals, and new valves if needed.
Not a cheap valve lap with drill…barf