GT550 oil questions

[Cragdog]

Hey guys,
I am trying to bring back to life an old 74 GT550, this is my first 2-stroke bike so I have some questions about oil, please excuse my severe lack of knowledge and thanks for chiming in with your comments.

1). Is the oil you put in the actual engine (when you do an oil change) the same oil you use in the oil tank that feeds the pump?

2). What types of oil should I use? I live in Southern CA and I have looked at a couple auto parts stores and the only 2-stoke oil I seem to find comes in tiny bottles and is meant for lawnmowers and weedwackers? Anyone know of a reliable place to purchase the correct oil around my area? I suppose I could order on-line, but I'd prefer to have a brick-n-mortar shop to pop into when I need new oil.

3). Is there any issue with running 91-octane fuel in these motors?

Thanks again for the help, sorry for the green-ness

[GT750Battleship]

Hi,in answer to your questions....
1. The oil in the oil tank should be a two stroke oil designed/made for two stroke motorcycles,brands such as Motul,Castrol,Silkolene anything two stroke motorcycle oil specific,mineral OR synthetic,personal choice.
2.The oil in the crankcase is 20w/50 motor oil,the same engine oil type that you would use in a car engine,this oil only lubricates the transmission & clutch in a two stroke,still important to change regularly !
3. fuel grade of 91 octane rating OR better is fine....keep away from Ethanol based fuels,not nice stuff..can cause all sorts of problems with two & four stroke older bikes !!!
4.I suggest you get yourself an owners/workshop manual & start reading up on how these bikes work..Haynes manuals & other manuals like Clymer come up for sale on Ebay all the time.
Good luck with the bike..if you get stuck with anything,post again...lots of help on here!

[Cragdog]

Thank you for the quick response!
I had a feeling the two were separate, just needed confirmation from a real 2-stroker! Hopefully once I get a few more parts (new points, fuel & oil lines, and finish wiring) I will start sharing pictures of my progress on this bike.
Thanks again for the help!

[tz375]

Oils are like a$$es. We all have one and they are all different.

The two oils are different, though you could probably use almost anything in a pinch. Your local bike store should have transmission oil and two stroke oil. My personal preference is Motul or Silkolene and I can get Silkolene on line from http://www.silkolenestore.com" onclick="window.open(this.href);return false;. I'm happy tp promote them because the owner used to sponsor one of my racers and their oils are top quality.

Avoid snowmobile and PWC oils. PWC oils are formulated to dissipate in the water and to work in cooler running motors. Snowmobile oils are typically formulated to run more freely at super low ambient temperatures that most of us don't ride at. There are exceptions of course but that will work as a starting point.

Two stroke oils are typically designed for injection (thinner) or pre-mix (thicker) so you want injector oil for street two strokes.

In the transmission, you can probably get away with any modern oils and we all have our favorites. Many oils have "friction modifiers" such as molybdenum which can cause clutch slip, so it's better to avoid those. My personal preference is Silkolene transmission oil but I'll happily use Honda 2 stroke transmission oils. And of course Trans oils use a different scale than regular motor oils, so a 75 or 80 is more like a 20W50 or so.

[pearljam724]

Everyone has to start somewhere cragdog. These aren't stupid questions. The difference between 2 strokes and modern 4 strokes is the 2 stroke separately lubricates important sections of the motor. The crank, transmission and cylinders. Where modern 4 strokes all of these components share the same oil from the crankcase. That's why its filled in only one section of the crankcase on a 4 stroke. Where 2 strokes need a separate oil to lubricate the cylinders and crank bearings. A higher octane that is low in ethanol would be best suited for these bikes. But, I run low octane with 10% ethanol and it doesn't create the smallest of problems. Not picking on you, your questions reminded me of an old thread I dug up the other day on another forum in reference to a 2 stroke beginner. The guy nervously asked, " My bike smokes, Is this normal ? "

[Cragdog]

Haha! They don't call 'em smokers for nothin!

Thanks for all the help everyone.

[Cragdog]

Alright so having never ridden this yet, I got one more for ya:

With a full gas tank and full oil tank, which will run out first? I assume it's the oil tank since it is much smaller capacity, but I'm not sure what ratios they are used in. And if I should expect the oil to run out before the gas does, approximately how much gas would I still have remaining when the oil runs out???

[ConnerVT]

You'll fill the gas tank quite a few times before you run out of oil in your tank.

[Cragdog]

Oh really? It must inject a very small amount of oil into the cylinders then, much less than I expected.
Thanks for the quick reply Connor!

[pearljam724]

Like Connor said, you'll fill up quite a few times. I rough gestimate would be around 1000 miles depending on how you ride. I still top mine off before every single ride. Oil for a two stoke is something you don't want to run low on.

[Cragdog]

Great info. Thank you both!

[k92006]

Hi guys,
Just bought a 75 GT 250 and 74 Gt 550.
The 250 was filled with injection oil but the 550 wasn't.
I'm new to the these Suzuki 2 strokes, only owned an RZ 500 many moons ago.
My question is: I filled the tank up and bled the line going from the oil tank to the oil pump just in case. I started the bike and eventually after a couple of minutes, can see oil trickling through the line going to the left side crank. The other lines seem empty. It's very difficult to see.. I then premixed the fuel present in the tank, as I didn't want to seize the engine. I took it for a 10 minute spin. I now think I see oil in one or two lines going to the cylinders but not 100%. Is this normal? Tks

[Cragdog]

Hi guys,
Just bought a 75 GT 250 and 74 Gt 550.
The 250 was filled with injection oil but the 550 wasn't.
I'm new to the these Suzuki 2 strokes, only owned an RZ 500 many moons ago.
My question is: I filled the tank up and bled the line going from the oil tank to the oil pump just in case. I started the bike and eventually after a couple of minutes, can see oil trickling through the line going to the left side crank. The other lines seem empty. It's very difficult to see.. I then premixed the fuel present in the tank, as I didn't want to seize the engine. I took it for a 10 minute spin. I now think I see oil in one or two lines going to the cylinders but not 100%. Is this normal? Tks

Are we talking about the 250 or 550 first off?
What I've done in the past is used like a turkey baster or syringe to prime the oil lines at the oil pump, usually the lines are transparent and your colored 2T oil is visible as you push it through the lines.

[k92006]

Thanks!
Sorry I'm talking about the 550.
Also, I'd like to change the gear oil but my Clymer manual doesn't shed too much light on how to change and what amount to refill with? I assume it's center nut beneath the center of the engine..

[Alan H]

That's right - but it's a bolt, and the 1500cc cast into the side casing is the amount of 20w50 motor oil to put in there.

To run oil through the pump faster, turn the oil pump lever to full and the oil will pump through quicker. The oil pipes should be full all the time though or otherwise no oil is getting to the bearings.
To give them a chance, take off the pipes that go on the crankcase near the bottom of the barrels and squirt oil (oil can or turkey baster) down the holes that go to the bearings. If you take the pump off, you can pump oil down the holes where the pump base goes and see it go down the pipes.
Don't take the pump off and run premix though as the oil doesn't get to the bearings and the engine will fail bigtime. If you want a copy of an early Suzuki service manual, PM me your email address and I'll send a copy FOC.