Operating temp and proper oil for air/oil cooled sportbike?

[CBR.worm]

I have a '92 Suzuki GSX-R750 with head work cams and a big bore (955cc) kit, aftermarket ignition, flatslides, etc.

The bike has over 100K miles on the motor as it sits, I used to race this bike, but now it is just a street bike.

On the track - airflow was never a problem, the oil in the pan would rarely get over 90C, now I get stuck in stop and go traffic every morning and the temperature climbs and climbs and climbs until I get moving again.

I have a couple of questions. First, the bike now smokes - surely due to worn rings, valve guide seals, etc - but it still runs well, and is not worth rebuilding.

What is an acceptable oil temperature in the pan before I should start worrying about it overheating? I have always thought that about 110C seems too hot - not becuase of any scientific data - it just seems like a big number - knowing that my water cooled bikes rarely ever reach the 100c mark. When it gets there I try to keep it in a high gear, or coast, or turn it off.

Second - what oil would be good for these operating conditions. The bike has a big oil cooler, and does still get revved to 12,500 or 13,000 rpm a few times a week. The factory recommends 10w40. From the factory this bike made about 80hp. now it is over 130.

I used Golden Spectro 10w40 for the first 30-40K miles, then started using the heavier Golden spectro - I think it was 20w50. At around 100K (5 years ago) I started using Mobil1 V-twin 20w50 synthetic.

I live in south florida - do you guys have any better recommendations for oil? Maybe something that smokes less as it burns?

 

[qadsan]

If your bike is smoking because the ring packs are carboned up, then you can use a product like Auto-Rx / Cycle-Rx to slowly and safely clean your engine and free up your ring packs. It won't fix anything that's broken or worn, but it will clean your engine and you may see your compression numbers increase as the rings free up 'if' that's an issue with your bike. The product also comes with a money back guarantee. I've only used it in auto applications so far and had good results, but I'm planning to try it on a few bikes later on. It takes a while for the product to work, but hard evidence will be in the oil filter, compression numbers, overall long term performance, etc. Taking before and after compression readings will clearly tell you if the product has helped restore some compression, which also means less blowby. Here's the link to the product. The inventor 'Frank Miller' is also a sponsor of this site.

http://www.auto-rx.com

I can't tell you what your normal oil temp should be on that particular bike, but you'll want a normal operating oil temperature in the crankcase that's hot enough to burn off water, fuel and other contaminants, which means it should be at least 212F. My dual sport bikes run normal oil temps anywhere from 220F to 260F depending on the bike and I can easily get the temps to 300F+ on some bikes while riding off road for during sustained high speeds.

 

[satterfi]

I'd run Redline.

10w40, 20w50 or a mix of the two that you liked.

Forget the Arx BS. There's no crediable evidence that crap does anything.

Don't worry about the nay sayers who claim Mo will make your clutch slip.

I know GSXR1000 and Eye-Abuser owners who use it. No problem.

 

[XS650]

The oil temp ranges on my 1157cc Bandit were about the same numbers qadsan sees, except my hottest temps were in stop and go traffic. They didn't seem to be a problem using HDEO 15W-40. I didn't bother with synthetic because I like to change oil every 3,000 miles when there is a wet clutch in the oil.

The Bandit engine is basically the old GSX-R engine.

 

[jsharp]

If you don't mind the expense, why not try the Mobil MX4T 10W-40. It's made for this kind of application. I think a 20W-50 is only going to give you even higher oil temperatues...

 

[rokky]

Florida temperatures. I'd be wanting to use the 20/50 or 15/40. Oils with a smaller viscosity range are normally less prone to viscosity shear. Synthetics not so much.
With your older engine, I would'nt bother using expensive synthetics, just a high quality diesel oil or 20/50. I used 20/50 dino oils in the summers only for years and years.
If you want to attain lower oil temperatures, try keeping the water temperatures lower. Using WaterWetter, EngineIce, and/or a Muzzy fan will help lots.

 

[wileyE]

Not sure what it converts to in C's, but my warmed up gs1100e (aircooled) runs around 220-260f on the gauge, it does hit 300-310f when it's hot out and its run hard or idled in stop and go. Most GS use roller bearing cranks so the don't build a lot of oil pressure, thick oil works well in them unless you after that .001 of a second at the strip. I've always used a mineral race oil in mine (it's pupose in life), 1st time I gave it mobile 1 it seeped out of every gasket on the thing! That was years ago, still have it and it probably has 20/50 or 15/40 in it, whatever was on the shelf.

 

[rokky]

Oops. Was'nt able to edit my post. Disregard my last two sentences.

 

[CBR.worm]

Ok, sounds like I am in the right ballpark. I have been riding the bike for years, but every year the traffic gets worse, and the bike gets hotter.

I have never seen the temp get over the low 110's even sitting in traffic - I will move my mental overheat alarm up a bit.

As for the oil, I guess I will stick with the heavy mobil 1 synthetic. I should start looking for a new motor, I don't think anything in this one is worth re-using with the miles that are on it. Maybe I can find a bandit 1200 motor to stick in there.