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SuzukiSavage.com
/cgi-bin/YaBB.pl General Category >> Rubber Side Down! >> Overheating /cgi-bin/YaBB.pl?num=1211982988 Message started by Jimworx on 05/28/08 at 06:56:27 |
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Title: Overheating Post by Jimworx on 05/28/08 at 06:56:27 I was sitting in traffic and I realized how hot the bike gets. I was just wondering...how do I know if my bike is overheating? Does it feel different or does it just seize? |
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Title: Re: Overheating Post by KwakNut on 05/28/08 at 07:21:04 5675716B736E641C0 wrote:
Bad seizures are more likely when you're cruising under power and don't realise until it gets really hot - might notice a bit of power loss going up a hill then out of nowehere it can lock up. That's more likely to happen due to low oil or component failure than plain overheating. Mostly, overheating on an air cooled bike will happen when you're stuck in traffic and you can avoid catastrophe by stopping to let the bike cool when it starts running differently - might become uneven, lose idle or sound noisier. All signs to shut down or get onto a road where you can cruise fast enough for the wind to get to your engine. If that does happen, let it cool naturally or waft air onto it, application of liquid to speed the cooling (whether clear or yellow) is not good when the motor is roasting as it will cause uneven cooling which can distort/crack metal or disturb gasket seals. |
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Title: Re: Overheating Post by vtail on 05/28/08 at 12:29:24 At idle your engine develops very little power so creates relative little heat and even on high temp days does not get that hot. It might feel hot when standing still, cause heat rises. Also, synthetic oil can stand extreme temps much better. It's usually us that get overheated and cranky when sitting in high temps with riding gear and helmet.I've idled recep aircraft engines for long periods while waiting for take-off clearance. There is little air flowing over these cowled (enclosed) engines yet the temp rarely gets above 300-325 degree which is measured at the sparkplug hole. When accelerating at 100% the temps then quikly rise to 400-450 if properly managed. So i don't sweat it too much when idling. ;) Cause you can always install a cylinder head temp gauge (about $75) like ithe ones used on light-sport airplanes. |
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Title: Re: Overheating Post by bill67 on 05/28/08 at 12:37:18 I knew a guy years ago with a 400 kaw that left his bike idling at 40 degrees in the spring,went in the house and forgot about it after about and hour he went out and the pipes and mufflers where burnt so bad he had to the place the whole system. |
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Title: Re: Overheating Post by vtail on 05/28/08 at 12:44:27 4C47424218192E0 wrote:
If I'm gonna sit still in taffic for that long i shut're down. saves gas |
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Title: Re: Overheating Post by BurnPgh on 05/28/08 at 13:25:03 if im waitin that long i'll pull onto the shoulder and take a nap |
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Title: Re: Overheating Post by verslagen1 on 05/28/08 at 14:16:03 I had a cyl head temp gage a long time ago. After chugging up grapevine, it got as hot as I've ever seen it. Tried 2 ways to cool it down, shut her down and let it coast. And the other was to let it roll up some speed with the engine running high rpm's. Running cooled it faster. Yeah it has forced air cooling, but the heads aren't completely in that breeze. So what I want to know, was it cooling faster cause of the high rpms with the throttle at idle? And could pulling out the choke on a hot day help? |
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Title: Re: Overheating Post by Ed L. on 05/28/08 at 14:26:02 I get rough a rough idle with stalling when sitting in traffic on a hot day. It takes about 20 minutes for it to get bad enough so I either need to shut it down to cool off or ride it for two or three miles to get some air across the engine. I'm hopin that going up one size with the air idle jet will help. I've also noticed the same problem after riding on the superslab and then getting stuck in traffic as soon as I exit. Think that is because the engine doesn't cool off fast enough from the higher revs on I-95. It's an air cooled engine and needs air flowing around it to keep it's cool. |
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Title: Re: Overheating Post by bill67 on 05/28/08 at 14:27:51 In my Nissan manual it says if your pulling a trailer when you stop you should let it idle in neutral for a minute before turning off motor to let it cool down some. |
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Title: Re: Overheating Post by vtail on 05/28/08 at 15:09:34 445740415E5355575C03320 wrote:
Never ever pull the choke when hot. It'll overriches, could stall and washes down the cylinder which in turn can remove the oil from the rings which increases friction= more heat (Could damage cylinderwall). Idling for a minute lets it cool down evenly. Heat rises and the surrounding cooler air gets drawn onto the cylinder. :) Rolling of the throttle cools it nice cause you draw in lots of cool air and yes every other stroke we have combustion but not much of one ;) |
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Title: Re: Overheating Post by barry68v10 on 05/29/08 at 17:33:00 7C77727228291E0 wrote:
Bill, big difference here is you want the water pump in your Nissan to continue to pump coolant while the fan cools it. Air cooled engines don't work like that. If you have no air flow, you're better off shutting down with any air cooled bike assuming no forced air. |
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Title: Re: Overheating Post by Plano Rider on 09/18/08 at 16:13:09 My exhaust is smoking where it connects to the engine after only idiling for about 2-3 minutes in the drive way...is that normal? |
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Title: Re: Overheating Post by Digger on 11/27/08 at 19:59:02 72796B7776757B7B74796A7D76180 wrote:
Hi Plano, Check the area for an oil leak. Oil may be dripping on to the header and causing the smoke. IHTH! |
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Title: Re: Overheating Post by gazoo07 on 11/28/08 at 19:21:55 What many people dont realize is oil is a major factor in cooling an air cooled engine. It carries heat from internal parts of the engine to the cylinder walls where it can be dissipated into the air through the cooling fins. Mineral oil does a poor job of carrieing heat. synthetics are made in a lab and do a much better job of cooling the engine than mineral oils. I have been stuck on speedway blvd in Daytona Bike Week.(Anyone from Florida who has ever been to bike week knows how bad that can be) I have never had a problem even though people around me were pushing their bikes off the road because they had shut down from the heat. I have always used amsoil synthetics and have never had a problem. Gazoo www.lubedealer.com/1lube |
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Title: Re: Overheating Post by Charon on 12/01/08 at 07:27:56 I am afraid I must disagree. The heat is generated in the combustion chamber, not in the "internal parts of the engine." The only heat generated in the "internal parts of the engine" is that caused by friction in the moving parts, and that is a pretty low percentage of the total. The heat is generated in the combustion chamber by burning fuel and air. The engine converts about 25% of that heat to useable work and wastes the rest. About half of the waste heat leaves the engine in the form of hot exhaust gas. The other half of the waste heat leaves via the cooling system. The heat is directly imparted to the piston, cylinder head, and cylinder walls. The heat imparted to the head and cylinder is conducted through the metal to whatever is used as a coolant, either air or water. The heat imparted to the piston is usually conducted to the cylinder walls, somtimes via the rings. Some, but not all, four-stroke engines spray oil onto the bottom of the piston crown, and that oil is used to carry away excess heat. The side effect is that the oil scraper rings have more work to do getting the excess oil off the cylinder walls. Unless specifically designed to be oil-cooled (early Suzuki GSX-R), oil carries away only about 1 to 5% of the engine heat. The oil does cool engine bearings, as well as lubricating them. Lest anyone believe I am "picking nits," I submit for consideration the lowly two-stroke engine, widely used in such things as outboards, chain saws, and so on. Those engines do not have engine oil, except for the quite small amount that passes through them with the fuel. Therefore, they cannot depend on oil as a coolant. I will pass on the comment about synthetic versus mineral oils, as neither is very good as a coolant. The synthetic oils are reputed to withstand high temperatures better, but that doesn't make them better as coolants. |
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Title: Re: Overheating Post by gazoo07 on 12/01/08 at 09:28:16 OK Charon. You seem to agree that the heat is transfered from the combustion chamber to the cooling substance be it air or water through metal. So if we agree on that and on an air cooled engine the cooling fins are only on the sides of the cylinder. What happens to the heat that is transfered through the top and bottom of the engine through the piston to the conecting rod to the crankshaft? Through the valves to the camshaft? Do you think that you can put your bare hand on the side cover of your savage after it has been idleing in traffic or running down the highway for an hour? How did that heat get there? There is no combustion going on in the side cover(hopefully). If the oil does not help to cool the engine then why are so many bikes listed as air and oil cooled? As for the 2 stroke depending on its design it is cooled partially by the constant fresh supply of oil that is supplied by the injector pump or oil and fuel that is being supplied for combustion and lubrication. And yes they do tend to run somewhat hotter than the 4 stroke but this is mainly because they fire every time the piston is up. Gazoo www.lubedealer.com/1lube |
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Title: Re: Overheating Post by Charon on 12/01/08 at 19:43:25 Most air cooled engines do indeed have fins on the cylinder heads. Many but not all overhead valve air-cooled engines have cooling air passages between the valve stems and around the cam chain passages. I was unable to find a picture showing these passages, if they exist, on the Savage. However there are plenty of fins on the sides of the head. The intake valve is largely cooled by the incoming air-fuel charge. Some heat travels up its stem, but is mostly absorbed by the valve guides. The exhaust valve is cooled largely by heat conduction through the valve seat; partly by conduction to the valve guides. On the Savage the valve stems are contacted by rocker arms, not the cams, so are unlikely to transfer any heat to the cams. However the cams and rockers run in the head, and there is plenty of heat there to warm things up. Some oil circulates through the head for valve train lubrication, and this oil undoubtedly picks up some heat and carries it to the crankcase. Most of the heat leaves via the cooling air. We have already mentioned the cylinder. The area of the cylinder is greater than the area of the head, but the temperature is at its highest only at the top of the cylinder, dropping as expansion takes place during the power stroke. That is why the fins are usually larger at the top of the cylinder - because there is more heat to dissipate there. The piston crown is one of the hottest spots in the engine, exceeded by the exhaust valve face. Heat travels by conduction through the piston metal down to its skirts, and thence to the cylinder walls. Cooling pistons is one of the challenges for engine designers, and oil sprays are sometimes used. Some heat will travel from the piston to the wrist pin, thence to the rod. I doubt much heat makes it through the rod to the crank, because the air in the crankcase is relatively cool and the conduction path is relatively long. Most of the heat in the bottom end of the engine will come from friction in bearings and conduction through the metal from the cylinder to the crankcase. In motorcycles the transmission is also in the crankcase. Transmissions are not 100% efficient, so the 3% or so loss in the gear train will show up as heat. Briefly digressing to two-stroke engines. Cooling pistons in two-strokers is even more difficult than in four-strokes. There are twice as many "fires" at the same RPM, so only half the time available for cooling. There is no oil in the crankcase for cooling. The piston in a two-stroke is cooled partly by the relatively cool incoming air-fuel charge, but mostly by conduction to the cylinder walls just as in a four-stroke. Air-cooled two-strokes always have fins on their heads for cooling, since the only thing in the way is the spark plug. Let's give engine designers some credit for knowing how to design engines. Let's assume they make the cooling system most effective in the places where there is the most heat to dissipate. Look at the engine on your Savage. Are there any fins on the crankcase? If not, then perhaps the designers didn't think there was that much heat there to be dissipated. True, it runs hot enough you wouldn't want to touch it, but it isn't expected to dissipate a lot of heat. I point out that the hotter any part of the engine gets, the greater is the temperature difference between it and ambient air, and the more heat is dissipated. |
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Title: Re: Overheating Post by justin_o_guy2 on 12/03/08 at 12:58:54 Nice explanation. Mr. C nails it again. The belt squeaking is a waste of energy. |
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