GT550 oil questions

Everything you want to know about oil but were "afraid to ask"!

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k92006
Still in the Driveway
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Country: Canada
Suzuki 2-Strokes: GT250,GT550,RZ500,FJR1300,Katana750,YZFR1

Re: GT550 oil questions

Post by k92006 »

Awesome thanks!:)
titanx04
On the street
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Country: Australia
Suzuki 2-Strokes: 76 GT550

Re: GT550 oil questions

Post by titanx04 »

Ok I know this is an old post but just working on 76 GT 550 again so need to confirm a couple of things as my manual is not clear even though it’s a Suzuki manual.
The oil fillet near oil pump- does motor oil go in there or gearbox fluid.
Does the 1500cc stamped mean 1.5 l?
And lastly to drain the oil is the plug facing straight down or the one angled to rear?

Lastly what air filters are being used, mine are falling apart ( standard air box)

Any one live on central coast nsw.
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Alan H
Moto GP
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Suzuki 2-Strokes: 4 x GT550s - J, M, A, B.
Location: The Republic of South Yorkshire

Re: GT550 oil questions

Post by Alan H »

titanx04 wrote: Mon Aug 16, 2021 10:06 pm Ok I know this is an old post but just working on 76 GT 550 again so need to confirm a couple of things as my manual is not clear even though it’s a Suzuki manual.
The oil fillet near oil pump- does motor oil go in there or gearbox fluid.
if you mean the rubber with the raised section to hold, yes. 20w50 MINERAL oil. Not anything synthetic, or the clutch will slip. Some folks use gearbox oil, but Suzuki did not specify that.
Does the 1500cc stamped mean 1.5 l?
Yes.
And lastly to drain the oil is the plug facing straight down or the one angled to rear?
Yes, the vertical one. The angled one is the selector dêtente and a spring and plunger will fall out if you remove it.
Lastly what air filters are being used, mine are falling apart ( standard air box)
Standard ones. There are plenty about.
Any one live on central coast nsw.
Dunno that one!!
Think of how stupid the average person is, then realise that half of them are more stupid than that.
titanx04
On the street
Posts: 17
Joined: Wed Feb 25, 2015 1:12 am
Country: Australia
Suzuki 2-Strokes: 76 GT550

Re: GT550 oil questions

Post by titanx04 »

Thanks Allan, well I did take the angled one out and yes there was a spring and a bulletin shaped piece . Hopefully in okay. Pointy bit up. Didn’t realise and my funnel overflowed
It did have 75/95 semi in it. Or 75/90.

Have had a bit of oil running out of exhausts so that’s something else to look into.
Crank seals have been done.
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Alan H
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Joined: Thu Feb 16, 2012 11:50 am
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Suzuki 2-Strokes: 4 x GT550s - J, M, A, B.
Location: The Republic of South Yorkshire

Re: GT550 oil questions

Post by Alan H »

Oily exhausts usually means it needs a good long run, not just garage runs.
Think of how stupid the average person is, then realise that half of them are more stupid than that.
titanx04
On the street
Posts: 17
Joined: Wed Feb 25, 2015 1:12 am
Country: Australia
Suzuki 2-Strokes: 76 GT550

Re: GT550 oil questions

Post by titanx04 »

Yeah that’s my problem, unlicensed unregistered 😂

The air filters are they 40mm, sets on ebay.
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tz375
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Re: GT550 oil questions

Post by tz375 »

Alan is correct that a good hard run should burn off excess oil in the crankcase and exhausts, but it may be there from a weeping check valve in the oil supply lines. It's quite common on our old bikes for oil to seep down past one or more check valves.

We all have preferences for oil and again Alan is correct that Suzuki specified regular old engine oil, but oils have changed a lot since the seventies. Do not use any oil that says Friction Modified or terms like that. They will cause clutch slip. My preference is to use gear oil for a 2 stroke transmission and Honda sells that in an easy to use liter container. If you want to use engine oil, that is probably OK and many riders still use it in their 2 stroke transmissions with no ill effects. But transmission oil is supposed to have higher shear strength and should help the old transmission last a little longer.

To be honest though, we typically don't do enough miles on our old bikes to make much of a difference.
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