How hot is too hot?

[p1eric]

I've never owned an air-cooled bike before. Today it was 108 degrees in North Texas. Is there any extra care that should be taken in that kind of heat, other than keeping myself hydrated? For instance, should I turn it off while waiting at a red light? Should I not ride it at all? Is the oppressive heat extra bad during the break-in period?

 

[AZ7000']

Just ride it normally, it’s fine. 15-20 degrees ambient doesn’t really matter imo. I’m sure others have facts to share, I’ve never heard of an issue.

 

[DJ427]

NEW HONDA CT125 TRAIL HUNTER Engine Oil Cap Temperature Gauge Thermometer CT 125 | eBay

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I have this oil temperature guage on both of my 125's. These 125 motors run cooler than you think, I'm in N TX too. I also have a Honda Ruckus, its 50 cc water cooled with a straight exhaust, that little sucker screams, I can understand the need to water cool, lol

 

[SneakyDingo]

... well, one way to think of it is you're still in the manufacturer's warranty period so if you're going to find out, now's the time

 

[STUBBORN]

Hi, The old air cooled vs water cooled decision.
(Similar arguments exist for computers.)
Basically, an air cooled engine is simpler.
I like simpler (and really dark ale.)

I have this oil temperature guage on both of my 125's. These 125 motors run cooler than you think, I'm in N TX too. I also have a Honda Ruckus, its 50 cc water cooled with a straight exhaust, that little sucker screams, I can understand the need to water cool, lol

I like it. I bought the black face instrument dial on eBay. Long delivery wait though. I hope it doesn't break.

I have this oil temperature guage on both of my 125's. These 125 motors run cooler than you think, I'm in N TX too. I also have a Honda Ruckus, its 50 cc water cooled with a straight exhaust, that little sucker screams, I can understand the need to water cool, lol

Air cooled stuff works well as long as there is some air flow. See:

Air Cooled vs Liquid Cooled Motorcycle Engines - YouMotorcycle

Compare Air-Cooled vs Liquid-Cooled Motorcycle Engines. What's better? What's the difference? Come find out in this article + video!

youmotorcycle.com

 

[p1eric]

Thanks everyone for the replies. Sounds like overheating isn't a real concern unless I'm sitting in gridlock on an extremely hot day.

 

[AZ7000']

Thanks everyone for the replies. Sounds like overheating isn't a real concern unless I'm sitting in gridlock on an extremely hot day.

IMHO

 

[p1eric]

IMHO

Fair enough. Just based on the things said here and a few different articles/videos that's how I'm going to approach it.

 

[dmonkey]

The Austrlian post have ridden their NBC110's through higher temps, I wouldn't worry about it. If you had a modified engine that runs hotter than the original Honda design then a good indicator of a temperature issue would be detonation. Motorcycle safety courses will teach you to always be ready to roll at a stop light - in gear, hands on the bars, checking your mirror in case someone coming up behind doesn't see you or the red light. That said, I'll pull off to a far lane position and turn my bike off for longer stops when another vehicle is already stopped behind me, such as railroad crossings with a train passing, or one lane construction traffic with a light (common in the mountains). Nice to take a little break, save some fuel, and let the bike cool a bit for your own comfort.

A thing you do want to be careful of with temperatures on air cooled motors is submerging them in water, if you do a water crossing in cold water the quick temperature change to the motor can cause the barrel to shrink while piston is hot and expanded causing it to seize.

 

[Kev250R]

I've been riding an air-cooled TW200 for close to 20 years, both on the road and off-road, generally in hot weather and have yet to have a problem. I run a good-quality, semi-synthetic MC oil though and change it annually.

That said, here is a quick story (well I guess it depends on how fast you read it) about overheating an air-cooled MC. A couple of years ago a friend and I were on a ride on the fire break roads in our local Mountains (near Big Bear in So.Cal.) It was mid-summer and it was hot! We were riding a fairly challenging trail (Clark's Grade) which is largely exposed to the sun as you climb a steep, switch-backed hill. The trail was in poor-condition that day, we were going slow through deep ruts, loose shale and rocks I was mostly bouncing between first and second gears. I've not a fan of this portion of this particular trail so my plan was just to power-through the few miles of hell then take a nice break at the summit.

My friend who was riding with me was on a nearly-new water-cooled Yamaha WR250R and was a couple of bike lengths behind me. About halfway up the grade he starts blowing his horn which for us means to stop, so I did. My buddy rode-up next to me and said "My bike is overheating and yours is too stupid to know it's overheating!" Reffering to the fact that the TW is equipped with three warning lights (Hi Beam, Neutral, turn). My friends WR had many more warning lights, at least one of which was telling him that his water temperature was too high, so we stopped and let things cool-off for a bit, though I don't think my air-cooled bike was nearly as hot as his larger water-cooled one. We still laugh about that today.

All that said I shut the motor off when stopped at R/R crossings. At traffic signals I just let it idle. I actually notice my water-cooled bikes heat-up faster in traffic then my air-cooled ones do. I think oil quality is big factor in keeping air-cooled engines nice and cool.

 

[m in sc]

the ONLY time i was ever sort-of bit by an aircooled bike was my old 75 CB750F super sport. . I was w my GF at the time in 95, riding to go see Boston in charlotte and got stuck in traffic for a LONG time, like 2 hours. it was really hot and we werent moving. It got hot enough to basically shut down and i waited 30 minutes to cool the bike down to restart. Beyond that, was fine.

I'll be honest, if a liquid cooled bike is running hot, there's other issues, or you need to fit a small fan on the radiator. I had to do this on my rd i converted from air cooled to liquid cooled, and only for a possibility of severe traffic delays. as far as the trail, its a non issue IMHO

 

[SneakyDingo]

A thing you do want to be careful of with temperatures on air cooled motors is submerging them in water, if you do a water crossing in cold water the quick temperature change to the motor can cause the barrel to shrink while piston is hot and expanded causing it to seize.

TIL. Never heard of that before, makes sense though. Thanks for sharing that tidbit. So let's say I'm doing a water crossing where I'll be, uh, needing the snorkel air intake on the bike - is there anything as a rider that I should be doing if that's the case?

I've had a fan fitted liquid cooled bike that was approaching overheating, but I think it was pretty reasonable to expect it to overheat in that situation. I was on a 2004 Kawasaki ZZR250 (aka EX250, aka Ninja 250, but the touring variant available in Australia). I was rolling at speeds that would lug the engine in gear 2, so I needed to stay in gear 1. Traffic was preventing much airflow but also not moving fast enough to draw enough air through the radiator, even with the cooling fan spinning its little heart out. The bike's not supposed to be nor designed to run like that, so when it started to do that thing where it acts weird as it starts to overheat, I split lanes for about 3-4 minutes and the temperature dropped down again. It made sense - I was doing something that was outside the normal operation of the bike, it got hot, and the solution was to do the normal operation of the bike or pull over for a bit.

When this thread popped up I thought about my Kawasaki experience and if that would apply to the CT125. Maybe if the hill is long and steep enough with a heavy enough overall weight on the bike it might happen. This bike rides wonderfully in traffic and the gearing is low enough that you never need to rev it at slower speeds, so outside of a fat rider and a steep hill I would bet on Honda engineering winning the cooling game.

 

[dmonkey]

For water crossings I think you just want to power through and keep the engine running, and avoid extreme temperature differences (water below freezing, engine above regular operating temp from really lugging or revving it). If you stop mid-creek and kill the engine to take an pic for the 'gram or watch the water boil around the cyclinder head you're more likely to have a bad time.

 

[AZ7000']

I can show you a video of a crf450x that got dumped in a water crossing in Baja…. Got it out, push started it and ran the last 500 to Cabo. Could it have hydro locked? Yes, did it hydro lock? No.
Edit, it was in this video on go pro, not my phone…

Minute 13 for the water escaping the motor!

 

[dmonkey]

Oh yeah, I've pulled fully submerged bikes, quads, and snowmobiles out of water. It's not often that they hydrolock or that the cases crack from the cooling of water, but it does sometimes happen so best to try to avoid it when possible. At least the snorkel and high exhaust on the CT125 help reduce some of the risks there.

 

[SneakyDingo]

Thanks, I'm learning a lot from this.

 

[Kev250R]

I'll be honest, if a liquid cooled bike is running hot, there's other issues, or you need to fit a small fan on the radiator. I had to do this on my rd i converted from air cooled to liquid cooled, and only for a possibility of severe traffic delays. as far as the trail, its a non issue IMHO

I think it depends on the bike. My thought is that modern bikes run hotter then older (or older-design) air-cooled engines. I have two KTM's, a 200 Duke and a 990 Adventure. Both will run hot when sitting in traffic or a long light on a hot day. However both came from the factory with electric fans on their radiators and these work well to keep them from getting overheated (the water temperature gauges on both bikes never go over 3/4). These two are my first modern, liquid-cooled MC's, both are considered high-performance (yes, even the 200), both have fuel injection and both came from the factory with emissions equipment, which on my Duke includes a small Catalytic Converter (most of the emissions equipment has been removed from my 990 so I don't know if it ever had a Cat or not). I can tell you after the same ride in the city, under the same conditions the air-cooled engine on my TW200 seems a lot cooler then does the 200cc engine in my Duke. It's warm right now in So.Cal. so if I get a chance later this week maybe I'll try to see just how large a difference there is by taking some IR Temp readings after a 15 minute jaunt on both bikes.

 

[AZ7000']

I had a vw bus I drove to California, red apples are better then green. I hope it rains today, we could use the moisture. What oil do you use? My cousin knew a guy with a Harley. Man, does it burn when I pee!!!

Let’s suspend this thread until someone, anyone overheats a stock trail 125? Won’t happen…

 

[m in sc]

AGREED, NEWER BIKES DO RUN HOTTER, the lean ass fuel injection protocols are to blame for a lot of it.. and they are designed to take it for the most part. My old KTM390 was ridiculous, but survived just fine as well. was like what, 14:1 compression or something. But it physically ran hot.

as far as radiator fans, if they can't move enough air to continuously cool a radiator/motor down to an acceptable range, its undersized and should be dealt with, period. The old c10 concourses were notorious for this.. i know, i owned 2. the 1st thing i did with my KTM from above was fit an spal fan that cooled the motor down quicker because it moved a bunch more air.

want to run it a bit cooler? run an eife unit throw a bit more fuel in there and get the afr targets down to 13.5-13.8.

 

[p1eric]

Let’s suspend this thread until someone, anyone overheats a stock trail 125? Won’t happen…

Nah, let's keep it going. I appreciate the real experiences people have had. This is how we learn from each other.