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Old 06-28-2008, 11:27 PM   #1
Alan b
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Default Honda Magna VF 750

CHOO-AY DOO-AY!! (This is Thai for PLEASE HELP ME!).
I live on Koh Samui, a small island in the Gulf of Thailand. I have a Thai friend who 'discovered', and fell in love with an older version Magna VF 750. It was in a sorry state, and he has spent months putting it back together... no manual! He finally got it sorted (sort-of), but it is running incredibly hot, and is a pig to start (particularly after it has been 'warmed-up'), normally draining the battery after only a few seconds. I'm sure we will sort this out eventually, BUT, having limited knowledge of the bike, he has filled the engine with WATER as a coolant! I am convinced that the bike needs COOLANT, not water, but havn't a clue WHAT TYPE of coolant. Does anyone know what type? ... and is there an alternative coolant that can be used ... for example, a car-type coolant? It is a certainty that we will not be able to get the recommended 'Honda' coolant here on the island... we need an alternative! Also... can he continue to ride the bike using water as a coolant? PLEASE HELP!

I can be mailed directly at 'hello.in.there@hotmail.com'

Thanks people... ride safe... alan b
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Old 06-29-2008, 12:31 AM   #2
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"Car Coolant" (Ethylene Glycol) in a 50-percent mix will work acceptably. Be aware that the Honda V-4 engines have a tendency to run a bit hot "normally" (due to their configuration), ESPECIALLY if the carburetors aren't well-sorted.

Also, be certain the thermostat is working properly, and the radiator cap is holding at the proper pressure - if it's letting coolant go to the overflow-tank "early", the engine will overheat rapidly.
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Old 06-29-2008, 04:49 AM   #3
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The bike just runs hot. That's one of myriad reasons I sold mine. I had to rig a switch to run the fan constantly in stop and go traffic. The radiator is too small.
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Old 06-29-2008, 11:54 AM   #4
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Flush the system, check the thermostat, do all the usual stuff you'd do on a car. The systems are essentially identical.

Water alone cools cooler than "coolant" (the 50/50 mix of anti-freeze most of us use). Race mechanics fill the system with distilled water and then put in a pint or so of an additive package. These include a surface tension reducer, anticorrosive, and water pump bearing lube. "Purple Ice," fer'instance, in the rad. Moddersmart - I Mod Smart Do You? - Liquid Cooling :: Additives & Adhesives :: Additives :: Performance Coolants :: Royal Purple Ice Radiator Super Coolant Additive - 4oz Bottle Anti-freeze is good for not freezing, it's not that great for heat exchange. It does have chemicals to keep the tap water it's usually mixed with from corroding your radiator away. I'm going to switch to distilled watermixed with a conditioner on my bike for another good reason: antifreeze is slicker than any ice if your radiator hose pops and green stuff dumps all over your rear tire. You might as well pour oil on your tires. Go ahead, ask me how I know...
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Old 06-29-2008, 12:15 PM   #5
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Quote:
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Water alone cools cooler than "coolant"
Nope. Sorry Ken - you're partially mistaken there - While it's TRUE that water at atmospheric-pressure is a better heat-exchange fluid than 50/50 Glycol mix - once you enclose it in an engine cooling-system, you've got a whole different animal.

I don't have time to type the whole sci-fi BS thing, but adding a 50/50 Ethylene-Glycol mix will raise the boiling-point of your coolant to around 230deg F. Add a 13psi cap to that system, and you're around 265deg F before it all turns to vapour. All with only a few fractions of a percent in "loss" of the heat-transfer rate, VS water alone.

Without either, you're at the mercy of a maximum of 212deg F at sea-level before you're dancing-around your bike as it billows steam out of it alongside the freeway.....................
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Old 06-29-2008, 01:11 PM   #6
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And after he does all that it'll still run hot!
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Old 06-29-2008, 04:10 PM   #7
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I don't have time to type the whole sci-fi BS thing.....................
What, you're on your way to give the Sunday lecture to the Post-Doctoral Engineering students? Siddown, yak a spell. Your stories don't start for another hour.

No doubt pressurization raises the boiling/vaporization point, but it does that for water or an alcohol/water mix. The issue is which liquid absorbs and releases heat better. My sources tell me water beats alcohol every time. Unless, of course, you're talking about drinkin' alcohol; that will release heat better than water under any circumstance.

I say we have a debate here. Snarli, Zawa, and LR get to declare the winner after 1 post, 1 rebuttal post, and 1 follow-up post each. Winner gets the other guy's bike. Bicycle. A picture of the bike.
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Old 06-29-2008, 05:09 PM   #8
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Quote:
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What, you're on your way to give the Sunday lecture to the Post-Doctoral Engineering students? Siddown, yak a spell. Your stories don't start for another hour.

No doubt pressurization raises the boiling/vaporization point, but it does that for water or an alcohol/water mix. The issue is which liquid absorbs and releases heat better. My sources tell me water beats alcohol every time. Unless, of course, you're talking about drinkin' alcohol; that will release heat better than water under any circumstance.

I say we have a debate here. Snarli, Zawa, and LR get to declare the winner after 1 post, 1 rebuttal post, and 1 follow-up post each. Winner gets the other guy's bike. Bicycle. A picture of the bike.
Oh, you win of course Ken. After all, we are all whiteys.
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Old 06-29-2008, 05:39 PM   #9
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Oh, you win of course Ken. After all, we are all whiteys.
WHAT!! General Zod, Military Director of the Kryptonian Space Center, creator of an army of robotic Mini-Zods, the acknowledged Super Criminal of the Planet Krypton, a Whitey? I think not, Sir, I think not.
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Old 06-29-2008, 10:10 PM   #10
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Quote:
Originally Posted by Kenneth_Moore View Post
What, you're on your way to give the Sunday lecture to the Post-Doctoral Engineering students? Siddown, yak a spell. Your stories don't start for another hour.

No doubt pressurization raises the boiling/vaporization point, but it does that for water or an alcohol/water mix. The issue is which liquid absorbs and releases heat better. My sources tell me water beats alcohol every time. Unless, of course, you're talking about drinkin' alcohol; that will release heat better than water under any circumstance.

I say we have a debate here. Snarli, Zawa, and LR get to declare the winner after 1 post, 1 rebuttal post, and 1 follow-up post each. Winner gets the other guy's bike. Bicycle. A picture of the bike.
I'll not deny that water is a better heat-exchange medium than a 50/50 glycol mix - so long as you're not going to heat it above its boiling point and "put a lid on it" (and still want it to remain a thermal fluid, rather than steam). Where it breaks down (and one of the reasons you should run a coolant mix year-round) is spot-boiling due to the Leidenfrost effect. As I'm not a Boing(sic) Engineer, I couldn't remember the term (but DID remember the effect), and had to take a few minutes to look it up. Here's a little article by Jearl Walker that explains it: http://www.wiley.com/college/phy/hal...rost_essay.pdf

Essentially (in an engine), you get a hotspot that forms a boundary-layer of steam around it, which causes it to get HOTTER (as steam-vapour isn't all that good of a heat-exchange medium), causing the steam-pocket to expand further and form a cavity that allows no flow of coolant through it - and all your cooling-water belches out of the overflow-bottle into the street, your engine overheats, and possibly melts-down.

"But" sez Ken "All them racers run just water and a bottle of wettin' agent....." Yes, they do. They also run ginormous radiators compared to your average streetbike/car. Part of that size is due to the fact that if you make more HP - you gotta do something to bleed-off the heat from all those extra ponies. The other part of it is to over-compensate for spot-boiling, and actually cool-down their heat-exchange medium (water) further than necessary (as compared to what your average street-engine needs) - to stave-off Leidenfrost Effect.

The wetting agent decreases the surface-tension of the water (but doesn't increase the boiling-point appreciably) and sometimes also decreases vapour-pressure (so some claim), and pressurizing the system can raise the boiling-point to around 243deg F. But you can have hotspots in nooks and crannies of a cylinder-head in excess of 275deg F. A veritible breeding-ground for spot-boiling.

As with Detonation - once the spot-boiling has started, it's damned-hard to get it to stop. So the radiator is oversized, even accounting for the excess heat from extra HP. And sometimes racers still have problems.

Yes, you lose a bit of heat-exchange rate with a glycol-mix. But the numbers are miniscule - you gain over 20deg F using a 50% mix, and the reason racetracks don't like it is because of the bloody MESS it makes when you overheat an engine, or crash and bust the radiator all-over the track. If water were the "perfect" medium - why would a racer run a coolant mix at all, even before tracks started banning it? For that matter, WHY run "water wetter" if water alone is so damn good in a radiator? Why not run 100% glycol if THAT stuff is so good?

Because mixing certain fluids enhances properties they possess individually that are desirable. "Synergy", at work in the Real World.
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