[DoomX]

I have a Katana 750 wich is air/oil cooled. I was wondering if my engine can overheat in certain condition?
Last weekend i was stuck in traffic for 20 minutes in the L-H lafontaine Tunnel in montreal. It was so hot in there, with a minimum of ventilation and all these cars running on the idle... I felt like i was about to fade out. and my bike was felling the same way. it was like being sit on a oven

Then when i release the clutch my bike choke out and don't want to start. Just like if my battery was almost dead... my starter was turning just a litle bit.. like a lack of power. I park on the side, wait 5 minutes, and then restart my engine. everything went back to normal!

does the heat can cause that? I don't want to be stuck in this tunnel... ever! :x

 

[DrBob]

Yes, these were symptoms of overheating, or more specifically vapor lock, which was more caused by the sitting than the hot air in the tunnel. The bike is completely air cooled, as the oil cooler works by passing air around the hot oil. But if you are sitting still, there is no air passing through the oil cooler, so it does not do you a bit of good. And because you are at idle, the fuel is not flowing in the lines very fast, and the fuel in the lines closest to the motor will eventually get so hot that it stops being a liquid and the carbs are getting just fumes and it will stall. You were probably just getting to this point when you rolled on the throttle, and the bubble of gas in the line mixed with the increased air flow causing the bike to lean out and stall. The only solution is to let the bike cool so the fuel turns back into a liquid and the bike will run again. Any battery weakness will be exagerated by the heat, so the slow cranking could be the first sign of an aging battery.
If you get stuck in the tunnel again, shut the bike off before it gets too hot, and push it forward as traffic creeps along, and re-start only as needed to move with traffic. As long as the bike is running you are generating more heat, but without the air moving you don't get any cooling at all.

 

[DoomX]

this make sense thanks. I notice a bit of smoke raising above my head when that happens... maybe it was comming out of my carbs?
Don't you think that it would make a more reliable bike if it had a fan install on the oil cooler? Or maybe it's possible to find an aftermarket fan that fits there?

 

[DrBob]

I don't think it would do any good, as the oil cooler alone is not going to cool the bike enough to prevent overheating or vapor lock, as their just isn't enough surface area to disipate all the heat. But it certainly helps the bottom end, as there are no cooling fins on the engine case

 

[vinson16]

it doesnt make sense to me why they make oil cooled engine when it cools the bottom end when the heat is comeing from the top? :?

 

[DoomX]

My next bike will be liquid cooled for sure...

 

[87gsxrnut]

Don't you think that it would make a more reliable bike if it had a fan install on the oil cooler? Or maybe it's possible to find an aftermarket fan that fits there?

No. Some of the Katanas have a fan on the side of the motor under the fairing however. This motor was designed for the racetrack, not the street. It's origins go back to 1984. They are known to run a bit hot, but that is the norm. If you think your's runs hot, you should have seen my old 13.5:1 750 race motor.

it doesnt make sense to me why they make oil cooled engine when it cools the bottom end when the heat is comeing from the top?

Huh? That statement makes no sense. Do some research on engine cooling.

- Nut

 

[Uncle Bob]

Next time take the bridge, scenery is better ! LOL

 

[DrBob]

Cooling the oil makes it last longer and protect better, and the cooler oil helps cool the bearings which are a high-wear item. An oil cooler might lower the engine tempurature by 15-20 degrees if everything else is working OK, but on its own it will not prevent overheating.

 

[87gsxrnut]

You could buy an HEL cooler, or a new one fromt he stealer. Fact is, I am racing an old GSX-R 1100 w/the FACTORY cooler on it, and it runs just fine. I own six old GSX-Rs, and have NEVER run anything but the stock cooler in all kinds of weather, and it has always worked fine.

Unless you seriously radically modify your motor, the stock cooler is usually enough to dissipate the heat. Granted, you have to have air running through it to cool it down, but those I know that have tried to install fans have had very limited success with them.

The answer in the 80's racebikes was to use an additional cooler installed in the upper subframe behind the number plate. A vent was cut below the number plate to allow airflow. That was on a 750 motor pumped up to the absolute insane limit of about 135 RWHP. These were motors designed for sprint racing, and were running on the absolute edge of blowing up all the time.

If you get stopped in that tunnel, then kill the motor and push it along. ANY bike sitting in those conditions will run hotter than normal.

Soooo . . . I think you will survive OK dude. Do your oil changes regularly, and take good care of her.

- Nut

 

[bikeprillia]

Alternatively you can run on low vapor pressure gas such as using Xylene or TOluene additives. However starting cold in the morning might be a problem.

 

[Easy Rider]

Welcome to the forum.

You are approaching a record, no doubt, by replying to a 13 year old thread.

 

[Aussie Steve]

Yes Ken, its time to give out the late reply award....