Topic: Running your bike in the HEAT, question..

[754]

I am asking becuse it happened to us..

2 750,s we were riding through the desert in daytime.

One of us ran at about 55mph for up to 60 or more miles at a time(between stops), I ran at about 65mph the whole time.

By the time the other guy showed up, I was already rested!!

Which is easier on the motor, say that both bikes were identical, temp was over 100F

[Jerry Rxman Griffin aka MuthaF'er]

Only depends on how many beers you had before he showed up and whether or not you drank his beer too.

[ev0lution7]

is this one of those trick math word problems because i HATED those in school i wanted to shoot the idiot who put those on tests

[andy750]

You were riding too slow for the air cooledness to take effect  ...I always ride through deserts (Mojave, Baja Central desert, etc) at 70mph+. If you slow down it gets too hot 

cheers
Andy

[Johnie]

Desert...heck, it is 11 degrees here this morning.  I see where Andy is coming from to ride at 70 MPH.  But when you think of it, if the air temperature in the desert is 100 degrees going through the cooling fins, I do not know if it will make much difference on the engine temp if you are going 60 or 65 MPH.  Sure the air is going through the fins 5 MPH faster, but that air cooling in the fins is still 100 degrees.  You know...pie R squared.

[MCRider]

"Pardon me, but pie r round". Jethro

[ct_racer]

I beg to differ...



But seriously, wouldn't going 70 take more work and thus create more heat?  And with air not taking heat with it nearly as well as say... water...  wouldn't going faster still make your engine run warmer.  I got a saturn with a coolant system hanging on by a thread and I know if I shift at 5k vs. 3k it gets hella warmer...

[andy750]

I wasnt really being serious about going faster is better as its "cooler". I was merely teasing 754 on his slow speed  .

But from my experience there is no problem running your 750 in 100F heat for extended periods (all day for a couple of days). I rode down Baja from San Diego to La Paz and it was hot every day - I really melted when I stopped. Bike (CB750 K4) was fine though. And myself and 10 other SOHC riders rode across the Mojave desert in August (2004) it was 110F+...we were all melting....only one bike (1978 CB750) blew a headgasket - but that was going to happen whatever the heat. At the end of that day our bikes were fine and we were cooling off in the pool in Barstow, CA.....

cheers
Andy

[moham]

In the hot desert, rest during the day and move at night. Like an animal. With a motorcycle.

[MCRider]

I wasnt really being serious about going faster is better as its "cooler". I was merely teasing 754 on his slow speed  .

But from my experience there is no problem running your 750 in 100F heat for extended periods (all day for a couple of days). I rode down Baja from San Diego to La Paz and it was hot every day - I really melted when I stopped. Bike (CB750 K4) was fine though. And myself and 10 other SOHC riders rode across the Mojave desert in August (2004) it was 110F+...we were all melting....only one bike (1978 CB750) blew a headgasket - but that was going to happen whatever the heat. At the end of that day our bikes were fine and we were cooling off in the pool in Barstow, CA.....

cheers
Andy

There may be a little truth to higher speed cooler running. I think (with no objective data) that if you run at your bikes sweet spot, where it makes the most miles per gallon, is where it will make the least heat. The by products of combustion being power, heat (in many places) and exhaust gases (unburned fuel) which also carries some of #2 heat.

My Phaedrus 1, which was an 888cc, with ported head, Kerker header, stock cam and 17/48 sprockets, got the most mileage at 70-75mph (45mpg+) and thats where I would run for the least heat.

Again, the only way to prove this would be with gauges.

[goon 1492]

I wasnt really being serious about going faster is better as its "cooler". I was merely teasing 754 on his slow speed  .

But from my experience there is no problem running your 750 in 100F heat for extended periods (all day for a couple of days). I rode down Baja from San Diego to La Paz and it was hot every day - I really melted when I stopped. Bike (CB750 K4) was fine though. And myself and 10 other SOHC riders rode across the Mojave desert in August (2004) it was 110F+...we were all melting....only one bike (1978 CB750) blew a headgasket - but that was going to happen whatever the heat. At the end of that day our bikes were fine and we were cooling off in the pool in Barstow, CA.....

cheers
Andy

There may be a little truth to higher speed cooler running. I think (with no objective data) that if you run at your bikes sweet spot, where it makes the most miles per gallon, is where it will make the least heat. The by products of combustion being power, heat (in many places) and exhaust gases (unburned fuel) which also carries some of #2 heat.

My Phaedrus 1, which was an 888cc, with ported head, Kerker header, stock cam and 17/48 sprockets, got the most mileage at 70-75mph (45mpg+) and thats where I would run for the least heat.

Again, the only way to prove this would be with gauges.

+1 on that, I'm sure it can be closely compared to automobiles, and how the gearing is setup for the sweet spot to be at typical highway speeds.  Yours sounds like you bumped up the sweet spot to a higher speed than typical highway speed

[MCRider]

SNIP
+1 on that, I'm sure it can be closely compared to automobiles, and how the gearing is setup for the sweet spot to be at typical highway speeds.  Yours sounds like you bumped up the sweet spot to a higher speed than typical highway speed

On my bike, I wasn't going for better gas mileage, at higher speed, but it was a pleasant side effect. I think the ported head was biggest contributor.

We just bought an economy car, Nissan Versa and the EPA sticker said 34 mpg highway, but in parenthesis below it it said "many drivers will get between 30 and 40mpg".
I think that is because the EPA uses 55 mph which is below the sweet spot. Maybe?

[manjisann]

We just bought an economy car, Nissan Versa and the EPA sticker said 34 mpg highway, but in parenthesis below it it said "many drivers will get between 30 and 40mpg".
I think that is because the EPA uses 55 mph which is below the sweet spot. Maybe?

I think it's just cause they don't want to get sued when someone only gets 33 mpg 

Brandon

[MCRider]

We just bought an economy car, Nissan Versa and the EPA sticker said 34 mpg highway, but in parenthesis below it it said "many drivers will get between 30 and 40mpg".
I think that is because the EPA uses 55 mph which is below the sweet spot. Maybe?

I think it's just cause they don't want to get sued when someone only gets 33 mpg 

Brandon

Yup, could be.

[ofreen]

Which is easier on the motor, say that both bikes were identical, temp was over 100F

I doubt there is any practical difference, assuming the slower bike is geared correctly and not being lugged down.  Stock engines?  I agree with Andy.  55 to 65 mph with ambient air temps over 100 degrees will not faze a healthy stock 750.  They are pretty understressed.  Mine has a lot of miles and gets run at those temps extensively every summer and it just shrugs it off.

[goon 1492]

Man that pie is making me hungry........
I am going to make on tonight...... Blueberry

I agree too on the cooling, the temp is 100f and that is still cooler than the engines temp. So as long as their is air passing thru then the temp of the engine will maintain constant. It just won't cool off as fast because of the warmer ambient temp. I don't think I explained that right

[jeanhank]

This summer I travelled up US 95 in Nevada from Vegas to just north of Scotty's Junction... it was about 110ºF and I averaged about 80mph... Before that I was through New Mexico, Arizona, Utah, travelling about the same speeds...

For my body I found it cooler to be completely covered head to toe while moving, including a fleece hood around my neck and my sleeves tucked into my gloves.

Let's just say the bike leaks not a little bit of oil now.  It was WORTH IT

[mlinder]

My old BMW 318 got the best gas mileage at 83mph. Was obviously its sweetspot in 5th.

These old hondas, and other old quality aircooled bikes, were designed to handle 100 degree weather at speed all day every day. Look how cold-blooded these old aircooled bikes are. It's partly due to being designed to handle these kinds of situations. Most will tell you it takes a good 10 to 15 minutes of riding for the 750 to reach proper operating tempurature. So much of the heat is being whicked away from the cooling fins.

[goon 1492]

My old BMW 318 got the best gas mileage at 83mph. Was obviously its sweetspot in 5th.

These old hondas, and other old quality aircooled bikes, were designed to handle 100 degree weather at speed all day every day. Look how cold-blooded these old aircooled bikes are. It's partly due to being designed to handle these kinds of situations. Most will tell you it takes a good 10 to 15 minutes of riding for the 750 to reach proper operating tempurature. So much of the heat is being whicked away from the cooling fins.

Ain't that the truth, my ol' chevy 3/4 ton truck barks at me until its warm.

[toycollector10]

Think of a two-stroke engine. Twice as many bangs per mile than a four-stroke. they call them petrol cooled. The charge entering the combustion chamber does a good job of cooling. My guess it that it would have to be very, very hot for the ambient outside air temperature to have a major effect. Think lean running doing more damage and also mis-timing.

[mrbreeze]

I used to always run a vac gauge in my 60's-70's carbed cars.The idea is to keep the needle as high as you can.When you drown the needle is when you are loading the engine which is creating more heat and burning more fuel.When you peg the needle,you are getting the best milage and aren't making as much heat.If your tune is on and you match your road speed to your engine speed.....you aren't hurting your engine.In other words......lugging is bad!!!! I would say rolling at 55 is OK compared to 65 unless you are lugging it.On the other hand.......over revving can also be bad.If you have loose clearances,dirty oil, etc.............you can build a bunch of heat real quick and destroy bearings.

[754]

I think at 55 it was close to lugging it... it had a 19T front sprocket..also an oil cooler..

[ieism]

What the **** are talking about. I'm trying to think of a way to keep my balls from freezing off on my morning commute, and you guys worry about overheating a Honda? Sadistic, that's what it is!

(Just joking)

Wouldn't it depend on were the engine is running coolest too ( i.e. If it runs lean or rich somewhere up the revrange)?

[754]

Yeah that would make a difference..
But I was asking more about same bike at same temp at 2 diff speeds.

Not being correct on you jetting could make a big difference.

[mlinder]

I doubt 5 mph makes any real difference at those speeds. The horsepower required to go 65 is like 12 or less. Hardly pushing any SOHC bike, regardless of model.