How hot is too hot?

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Jmollari

Member
Jul 19, 2009
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Just looking for opinions on riding it hot weather. Just went for a ride and the temperature was 30 celcius (86 F) and really humid. I'm riding a 2004 KX250 and noticed a slight difference in power after riding for about 20mins so I made a habbit of just riding for 20mins then taking a break for fear of blowing up again this close to the end of the season. We don't get too many days that hot here in Canada but the past couple weeks have been pretty damn hot.

Im riding a dirt pit with lots of jump and whoops so i guess the riding is similar to track riding.
 
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Dan_1989cr125

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Apr 29, 2009
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Firstly i'd like to ask where you are riding! I'm from ontario and i'm looking for places to ride. I know what day you were talking about it was so hot i practicly had to use a spatula to peel my nuts off the seat. The difference could have been related to the extreme humidity we experienced that day. 2 strokes are not a fan of humidity. Were you keeping a good speed? Is your radiator topped up? You can buy temp strips from pro circuit that give you a relative idea of how hot your bike is. Too hot is when you start to see coolant boiling or shooting out of your overflow. Dont forget! where do you ride?
 
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Jmollari

Member
Jul 19, 2009
48
0
Haha I know what your talking about with the nuts, brutal. I don't know how they do it in the desert. Im in Sault Ste Marie, ONT. Looks like today is going to be another hot one but its pretty windy so it shouldnt be bad.

Pretty good riding here. Few decent pits and we have the Runway park track to practice on every wednesday.
 

whenfoxforks-ruled

Old MX Racer
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Oct 19, 2006
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Merrillville,Indiana
The temperature outside, how hot your engine gets, the loss of power? You are over due on a little maintenance. Running long on top ends can insure you will need to get the bore round again this winter. If you are going to continue this way, I would recommend a steel liner. I believe that they can stand abuse a lot better. And I am no fan of liners, loss of power from different heat dissipation and friction come to mind for the top of the list, not to mention the difficulty in matching the ports. Running long on plated bores pushes the softer material behind it, aluminum, and the bore is out of round. A steel liner will trash the piston before that happens to it. Too hot out to ride? Never heard of that one, drink plenty of fluids the day before. A dirt bike in any decent condition should do fine. I seen an 01 for sale cheap, never owned a 250 kx, yet. But from them kdx guys, oem hard parts are crazy priced! The price between routine maintenance and once a year catastrophic maintenance usually work out cheaper in the long run. It just requires a little effort.
 
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Jmollari

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Jul 19, 2009
48
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No I maintain my bike, just rebuilt it a month ago. I'm just not that familiar with bikes yet since i just got into them. I didn't think it mattered since you see all these people riding the desert but just wanted to double check. As for the loss of power.. I think I'm just being paranoid, the loss im talking about is VERY subtle.

But that idea on getting my bore round again may be something i have to do because when i did the rebuild the old piston had all kinds of play and skirt slap so it was probably not done for while before i did it. I ended up just putting a stock size piston back in. When i did the rebuild i looked into getting it sleeved but they do not have a sleeve for this bike yet, well that's what the machine shop told me.
 

Patman

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Consider this, I live in Texas and we see +100F for extended periods of time (+55 days this year so far!) and dirt bikes work just fine. Then think about Arizona where the temps I see are a cool spring day and it should be pretty obvious 86F is not an issue for a bike that is properly jetted and the cooling system is functioning properly.
 
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Dan_1989cr125

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Apr 29, 2009
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Guys, Put the heat aside for a momment as it is irrelevent on the day he is talking about we had record humidity. There was a slight fog in the air. My bike responded in the exact same way on that day. The air in arizona and texas is generally a dry heat. The replating is definetly something you want to look into. but the outside temperature wouldnt be revealing that. I'll call a friend at precision cycleworks and see if there is a sleeve available for your bike. the same reason your bike runs so crisp and snappy in the fall/winters dry air is the exact reason it runs slightly sloppy and weak in the summers humid hot air.
 
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Dan_1989cr125

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Apr 29, 2009
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There is a sleeve for your bike aswell if you would like i can speak to my friend at a shop where i get my work done. they are fantastic affordable and have a full machine shop and parts center. the part number for your sleeve from l.a sleeve is KA5538
 
A

adam728

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Aug 16, 2004
1,011
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While humidity does reduce power, it's not going to cause engine damage. I'm really not sure what you mean when you say "2 strokes are not a fan of humidity".

I've riden in all sorts of humidity in Michigan and Georgia. I've also riden in temps well over 100 F here in Arizona.

One problem with the "precieved power drop" could be the clutch. I had one slightly slipping in the past, the bike worked fine, but once good and hot it just seemed slightly down on power. After a few weeks noticable clutch slip started showing up. New clutch, and I no longer had that slower feeling when hot.
 
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Dan_1989cr125

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Apr 29, 2009
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I'm not saying it's going to cause any damage at all. They just don't run top notch when it's humid. The day he was out riding there was literally a dense mist in the air. We live near the great lakes and they cause some of the most humid conditions i have ever experienced.
 
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Jmollari

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Jul 19, 2009
48
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Went for another ride today and after about 25mins riding hard in the pit i had water spitting out my overflow. I also have straight water in the bike rite now, I dont know if antifreeze helps it run cooler or not. About the idea that the clutch could be slipping, well its very possible since everything seemed pretty worn on this bike when i got it and the clutch is about the only thing i havent changed yet.
So when you resleeve instead of chroming do you have to get the cylinder bored when u do your top end?

Hey dan , where are u in ontario?
 
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Dan_1989cr125

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Apr 29, 2009
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ahh thats definetly something you want to fix. Straight water corrodes your cooling system and doesn't provide adequate cooling for your bike. the boiling point of water is 100C which is easily reached. Adding 50/50 DISTILLED Water and aluminum safe antifreeze should eliminate this problem for you. If you have a canadian tire or motosport shop you can get the premixed anti freeze. I don't recommend riding your bike until you get that. If the bike still blows antifreeze after 25 mins of riding you should be looking into a head gasket change/head inspection for warp and make sure the gasket surface is in bonding specification. Take this post seriously!
 
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Dan_1989cr125

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Apr 29, 2009
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I forgot to mention that i am in Whitby, Ontario I do travel pretty far to ride but saulte ste marie is a hike! I'm from the USA but i am in the process of gaining status here so i'm fresh to the scene.
 
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Jmollari

Member
Jul 19, 2009
48
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Oh ok, yeah im not to sure about the riding down there. Welcome to Canada! Hope you enjoy the beer, don't treat it like that american stuff, you might get hurt :laugh:
 
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Dan_1989cr125

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Apr 29, 2009
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Haha i am enjoying the beer however that is a big rumor i experience here! We have a lot of potent beers in america. there are a few states that limit the potency but the city of boston (where i'm from) isn't one of them. our average beer is %6 some even get up to %15 a bottle of coors in the usa is the exact same as it is here. infact we have a larger beer selection in america. But this might be for a different thread. Send me an email or something we will stay in touch i'll let you know if i get up in the area! i have been wanting to venture up north and i might be soon.
 

Patman

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Dan_1989cr125 said:
The air in arizona and texas is generally a dry heat.
Click to expand...
:laugh: :laugh: REALLY? Could have foold me! I guess you never heard about the Brits paying their diplomats hazardous duty pay when stationed in Houston? See Texas is located on this little body of water called the Gulf of Mexico and.... well you get the picture.

Now as far as cooling, if the bike has has any water besides distilled water run in it there is a good chance it has created mineral desposites in the cooling passages which will reduce the ability of the cooling system to remove the heat. Adding antifreeze isn't going to make any huge difference in a properly maintained and functioning cooling system to do it's job. (Consider most closed circuit paved courses don't allow anything but water.) Down here where it really is both hot and humid all the water cooled bikes we have run do perfectly fine on 100% distilled water with a touch of Redline Water Wetter. The ones that have problems either have too high of a concentration of antifreeze or have had tap water put in the system. A perfect example was my KTM360 which was fine and dandy for years, after I sold it the new owner had it blowing coolant on a ride. Guess what was in it, a heavy mix of antifreeze and tap water.

BTW I always thought combustion was the same reguardless of if being every stroke or every other stroke. Silly me.
 
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Dan_1989cr125

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Apr 29, 2009
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Right Distilled water is best. The tap water is horrible for your cooling system. The heat generated on the bike really depends on the type of riding you are doing if you are keeping a good speed with plenty of airflow you bike with distilled water would be just fine but often times pit riding at low speeds with high revs can overheat things quickly. I think he should clean out his system and try anti freeze and see how things go. Like previously mentioned if it's still boiling he should test his radiator cap then his be looking into head gasket and head repairs. Also redline water wetter increases the boiling point of the water. :laugh: :laugh:
 
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Jmollari

Member
Jul 19, 2009
48
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Thats interesting... learn something new everyday. I've always run tap water/antifreeze mix in my sleds(snowmobiles for you hot weather area people) but never heard of using distilled water. Maybe distilled water isn't necessary when mixing with anti-freeze?
 
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Dan_1989cr125

Member
Apr 29, 2009
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distilled water is definetly necessary. Tap water contains minerals that create the deposits patman mentioned that can cause failures in your cooling system.
 
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Jmollari

Member
Jul 19, 2009
48
0
I dont get why im just hearing about this.. haha. So by distilled water you mean bottled water or what? Is this rule just for aluminum engines?
 

Patman

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Dan_1989cr125 said:
Also redline water wetter increases the boiling point of the water. :laugh: :laugh:
Click to expand...
I don't believe that was stated anyplace :think:

If you are interested as to why it works do a little searching both here on DRN and the web. Basically it allows the water to do a more efficient job not that it raises a boiling point.

Distilled water is available in bottles but not all bottled water is distilled. It's easy, read the lablel.
 

whenfoxforks-ruled

Old MX Racer
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Oct 19, 2006
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Merrillville,Indiana
Lets revue, the ambient temperature and high humidity has absolutely nothing to do with your over heating/barely perceptible power loss. Never use anything but distilled water in an aluminum engine, even them sled things in winter. Because your engine is loose, its over heating. You will soon be needing a quad to pull start it, or have a nice hill to bump start it. If it does not have a catastrophic failure soon$$$. Its a 2 stroke, you only get 3 dollar signs for fun.
 

Patman

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whenfoxforks-ruled said:
Lets revue, the ambient temperature and high humidity has absolutely nothing to do with your over heating/barely perceptible power loss.
Click to expand...
Maybe some of it has something to do with that "stronger" Canadian beer.

:rotfl: I crack myself up.
 

Patman

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Jmollari said:
Is this rule just for aluminum engines?
Click to expand...
Considering most radiators are now aluminum I'd say call it a universal application. Even when engines were iron and radiators were copper & brass distilled water was a good idea.
 
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