Overheating at stoplights


14 replies to this topic
  • Navy509

Posted April 24, 2008 - 02:04 AM

#1

I got a plated YZ426 last fall and had it die on me while waiting for a long stoplight last week. Usually when stopped at a long light I can feel the heat coming off my bike, I try to rev it just a little bit to keep things flowing, then the other day we had the nicest weather so far this year (only about 65) which is nothing compared to what the summer will bring 100+ daily. :thumbsup: So the bike died and I just kicked it over no problem, was this due to overheating and if so, anything I can do to help with the situation in the future? Bike runs great, no problems what so ever, just the heating at long stoplights.

  • Birdy426

Posted April 24, 2008 - 05:12 AM

#2

Doubt it was due to overheating. Was here steam and coolant coming out the overflow? If not, you weren't boiling over.

  • rooster wrooster

Posted April 24, 2008 - 06:38 AM

#3

Don't rev it at stop lights, your just adding more heat. You need air flowing over your radiator to dissipate heat.

  • 642MX

Posted April 24, 2008 - 09:12 AM

#4

Don't rev it at stop lights, your just adding more heat. You need air flowing over your radiator to dissipate heat.


I agree with it needing air to cool the radiators, but revving it won't hurt anything, actually it speeds up the water pump and helps move the coolant faster.

The best thing to do to a dual sported YZ is to use the WR coolant catch can or fab one up yourself. That way you won't be spraying coolant over the road and you won't lose any from the system.

  • x2468

Posted April 24, 2008 - 09:56 AM

#5

ya, it's not a 2-stroke. no need to rev it when it's sitting. idling creates enough heat! contrary to belief, the slower you go the hotter your motor gets.

  • x2468

Posted April 24, 2008 - 09:58 AM

#6

I agree with it needing air to cool the radiators, but revving it won't hurt anything, actually it speeds up the water pump and helps move the coolant faster.

The best thing to do to a dual sported YZ is to use the WR coolant catch can or fab one up yourself. That way you won't be spraying coolant over the road and you won't lose any from the system.


yeah but it also adds heat, and the radiator fluid circulating in, faster or not, won't be very cool if your not moving.

  • 642MX

Posted April 24, 2008 - 10:44 AM

#7

yeah but it also adds heat, and the radiator fluid circulating in, faster or not, won't be very cool if your not moving.


I'd be willing to bet that they make more heat idling. The pilot circuit is real lean and fuel is a cooling agent. I can let my 444 idle in the garage and it glows the header, if I hold the throttle open (about 1/4 open), it won't glow the header nearly as bad.

Give it a try. Start your bike and let it idle until the header glows. Then rev the motor and watch the red color disappear.

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  • grayracer513

Posted April 24, 2008 - 01:42 PM

#8

There's a couple of things going on. One in the case of the header is that when you buzz the engine, the air that pumps through as it coasts back to an idle is COLD due to the pessure drop under the slide.

The other thing is that the cooling system, built not to cavitate at 11000 RPM, doesn't move much water at idle.

  • BRYANS01

Posted April 24, 2008 - 02:03 PM

#9

what about those prodesign inline coolers i would think 2 of those might help disapate some heat i mean anything is better than nothing.

  • grayracer513

Posted April 24, 2008 - 03:02 PM

#10

... anything is better than nothing.

Maybe, but on a cost/benefit basis, such gizmos do very, very little.

  • Navy509

Posted April 24, 2008 - 05:51 PM

#11

Yes, I know about the fabulous glowing header. When I just flick the gas a bit, (small revs) the red header goes back the normal titanium color, I was also thinking the coolant if flowing more while revving, Yes/NO? I am aware that the radiators need air flow to cool properly, but guess what… there is no air flow at a stop light.

High flow pump? Inline coolers? On a normal basis I avoid stop lights as much as I can, but cant all the time. So what would the effects be of starting a YZ426 and let it idle for 10 minutes, same thing going on here.

  • grayracer513

Posted April 24, 2008 - 08:04 PM

#12

Y I am aware that the radiators need air flow to cool properly, but guess what… there is no air flow at a stop light.

You have an electrical system, why not run a small pair of fans?

  • Navy509

Posted April 24, 2008 - 08:46 PM

#13

Fans on a dirt bike? I've never seen that, but sounds like a very good idea.

  • mutt2jeff

Posted April 24, 2008 - 09:33 PM

#14

Pick up a 120 mm computer fan, strap it to your radiator and wire that up to a switch. At a light, just flip that switch. Wire it in using a spare computer molex connector, and you can take it off in seconds.

  • YZ125 DR650

Posted April 28, 2008 - 01:00 AM

#15

Pick up a 120 mm computer fan, strap it to your radiator and wire that up to a switch. At a light, just flip that switch. Wire it in using a spare computer molex connector, and you can take it off in seconds.


great idea... ive tossed the idea of a fan around but with lack of watts from my e-system decided it was out of the question. Most computer fans however @ 12Vdc pull less than 1 amp.

anyone add an oil cooler? do you think it would help any?

chris





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