GS850...how concerned should I be of overheating it in traffic?

It was a pretty nice 70-something-degree day today, but traffic sucked.

So...what about in a few months when it's 100 degrees out? How much idle time is "too much" when it's hot out? Five minutes? Eternity? No (legal) lane splitting here in GA.

Just wondering how much of a concern overheating really is. Anyone here cooked one idling/creeping in city traffic?

As long as you change oil every 3500 miles, the engines are strong. Make sure she doesn't leak too much...and don't rev her...


Ed

In Finley the temperature regularly reaches 40*C and for the first 20 years I've owned the Pig it was always thrashed in and around the redline to keep up with all the modern bikes.Now that I'm over 60 I will always give it a squirt but not often and not for long.The Pig has just clocked up 330,000ks.These motors are incredible.Just ride it like you stole it and KEEP UP THE MAINTENANCE.

I lost the temper in my rings when stuck in traffic and I let it idle. I was also stupid enough to just sit there with the bike idling. I deserved it for being a f.d.a. My 2 cents worth.

Yeah, it seems these have a great reputation for longevity/durability. Only have 22,000 miles on this one, so I'm hoping to get quite a few more out of it.

limeex2, how long did you sit idling and how hot was it out?

90 plus. traffic was backed up for well over a half hr. it would move just enough to creep forward about a car length every couple minutes or just enough not to shut it off. Like I mentioned,not the bikes fault, but my laziness/stupidity.

Yep, did exactly the same, on a 140Kmile engine when stuck in London traffic during a baking hot August afternoon. The bike got home ok, with no sign of trouble, except the usual fumes (it was needing a re-ringing by that point anyway), but the following morning it just wouldn't start. It would crank over like there was no compression - which there wasn't, to speak off. Stripped it and found the rings had all gone weak. Remarkably, for that amount of miles, a mic revealed there was no bore or piston wear, and all that was needed was another set of standard rings.
Since an accumulation of faults caused by the PO had reared their heads (knackered dogs on 2nd gear, trans to mid-drive oil seal, and some other things than needed a complete strip, I simply put in a spare engine that did for the next 100K, no problems.
I still have the new Std rings, the old good pistons, block, cams, crank etc, so I'll be using them on a good bottome end sometime soon to get the other GS850 together.

Thanks for the input, guys. Nice to hear that it also didn't (at least seem to) ruin anything other than the rings. I'll be careful of traffic on hot days and make sure the charging system is working well so I can cut if off and on confidently if I do get stuck.

Might also be a neat experiment to check the head temp under different conditions if I ever get one of those infrared thermometers...

Chaz said:

Thanks for the input, guys. Nice to hear that it also didn't (at least seem to) ruin anything other than the rings. I'll be careful of traffic on hot days and make sure the charging system is working well so I can cut if off and on confidently if I do get stuck.

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Meh, if it's tuned well it will start in a fraction of a second when it's hot, not much of a drain on the charging system no matter how often you do it.

An air cooled bike stuck in traffic is BAD. Sort of like leaving the bike sitting idle in the driveway for a long time. The header pipes turn blue (or red if running with the choke on). Rings losing temper make sense. Running synthetic oil may help a little, but nothing is going to save the rings.

Nessism said:

An air cooled bike stuck in traffic is BAD. Sort of like leaving the bike sitting idle in the driveway for a long time. The header pipes turn blue (or red if running with the choke on). Rings losing temper make sense. Running synthetic oil may help a little, but nothing is going to save the rings.

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Some designs can convection cool to an acceptable extent. A horizontal cylinder such as the Honda 90 or the current Honda Grom 125 can replace rising hot air with cool air from below. BMWs fare well. Even the GS twins do okay having generous finning and three sides exposed, but the center cylinders of a four are dependent upon forced flow as they're not only generating heat but being heated from both sides.

It doesn't take much airflow to cool these things; you just have to replace the air on the surface, and past a certain point - about 45 mph - increasing the airflow won't remove heat much faster. This makes a fan less air-cooled inline four an audacious design. It just needs to have a ten mph breeze. Doesn't take much but you need some.

A little breeze, or a little common sense goes a long way. If you are worried shut it off until it's time to move.

I know its a little different, but I have ridden lots of air cooled machines (atvs,go karts,mini bikes) and especially with the atvs (2 stroke and 4 stoke), we'd ride on 90 degree days barely moving (we ride in groups) and it never seemed to hurt them. Maybe being they are single cylinder that dissipate the heat more evenly or something?

TxGSrider said:

I know its a little different, but I have ridden lots of air cooled machines (atvs,go karts,mini bikes) and especially with the atvs (2 stroke and 4 stoke), we'd ride on 90 degree days barely moving (we ride in groups) and it never seemed to hurt them. Maybe being they are single cylinder that dissipate the heat more evenly or something?

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Exactly. Singles have inherently better airflow; a BMW twin is two singles from an airflow POV. The nikasil cylinder is another advantage that atv's are going to. Suzuki's SCEM is an example. Barely moving is a whole lot better than stopped. How hot it is doesn't matter so much because the air next to the metal gets hot fast even on a cool day. You can't get rid of the heat without getting rid of the air.

John Park said:

Exactly. Singles have inherently better airflow; a BMW twin is two singles from an airflow POV. The nikasil cylinder is another advantage that atv's are going to. Suzuki's SCEM is an example. Barely moving is a whole lot better than stopped. How hot it is doesn't matter so much because the air next to the metal gets hot fast even on a cool day. You can't get rid of the heat without getting rid of the air.

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Just curious how nikasil helps the rings... Does the whole cylinder stay cooler for some reason?

tkent02 said:

Just curious how nikasil helps the rings... Does the whole cylinder stay cooler for some reason?

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Liner less aluminum cylinders are the next step up from steel sleeved aluminum which is a step above cast steel. The heat sink effect goes directly to the cylinder surface - minus a few thou of silicon carbide and nickel. You also aren't trusting the conductivity between the liner and the finned casting, which is a bit variable. The outer fin temperature wouldn't necessarily be much cooler, but the gradient up to the cylinder wall would be less steep. IOW, the heat transfers a lot more efficiently.

The big problem with nikasil is that it can be susceptible to corrosion from sulfur in the fuel. That's pretty much gone in the US, but in Mexico you could smell the sulphur stink from the 82 octane regular.

I'm a bit wary of reasons for the rings getting hot enough to lose their spring. In my theory of things, the rings cool out the ring lands, which means the pistons would have to get pretty close to melting. There's more surface area that way than out the faces. But they're getting hot through contact with the cylinder wall, so it's maybe pretty much a factor of cylinder temperature.

I'm in favour of blipping the throttle every half minute of so just to throw some different oil at the cylinder walls and piston; not much extra heat and some fresh liquid. The plain bearing motors have a bit of an advantage in that they have a spray jet on the rod that shoots oil at the piston, but then have - except for the 2 valve twins - rather poor head finning.

I remember taking apart a tired Honda 305 and things looked pretty usable except that the rings were slack. A customer picked up the cylinder block from the bench and when he turned it over the liners fell on the floor. I think the liners expanded so much they stretched the block. Metallurgy got better after about 1970 but there's still a limit.

The BMW 4.0 V8 motors had Nikasil cylinders at the exact time sulfur reached its peak. It was a very expensive problem. Porsche used the same alloy, no problems, maybe Porsche owners didn't buy regular at the KwickyMart. http://www.bimmerforums.com/forum/showthread.php?1957814-M60-Nikasil-recall.

Then again, remember the Chevy Vega with hypereutectic silicon infused cylinders? Very rare to get 40k out of one. Sulfur was removed from US fuel around 2000 so if they survived they are still good

bobgroger said:

The BMW 4.0 V8 motors had Nikasil cylinders at the exact time sulfur reached its peak. It was a very expensive problem. Porsche used the same alloy, no problems, maybe Porsche owners didn't buy regular at the KwickyMart. http://www.bimmerforums.com/forum/showthread.php?1957814-M60-Nikasil-recall.

Then again, remember the Chevy Vega with hypereutectic silicon infused cylinders? Very rare to get 40k out of one. Sulfur was removed from US fuel around 2000 so if they survived they are still good

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The Porsche was air cooled and didn't have the same acid buildup in the oil due to higher oil temps, or so I've read. Moto Guzzi has used it for ages, and the Porsche cylinders were supposedly made in their facility. Jaguar had so much trouble they went back to liners. Most dirt bike motors are small oil capacity [ read marginal] and rarely have any condensation buildup to worry about. Doesn't seem to be a problem and the ring/cylinder longevity appears to be excellent.

Interesting thread. I hadn't heard of sulfur being a problem with the nikasil cylinders before (admittedly hadn't looked into it).