Exhaust temp

8 replies to this topic
  • Mark Morrison

Posted May 19, 2005 - 07:46 PM


Has any body done exhaust temp testing while on the dyno. We installed a YZ 450 in a US Super Kart we are getting temps in the 1500 degree range,this seems high to use. but this is our first 4 stroke

  • Rich_Rohrich

Posted May 19, 2005 - 08:06 PM


What do you have the exhaust valve open timing, and air fuel ratio set at at with the 1500 degree temps?

  • qadsan

Posted May 19, 2005 - 08:15 PM


I've seen temps on various bikes from 3" away ranging from ~1400F to ~1800F with ~4.5% to ~5% CO at WOT from what I recall, so 1500F isn't out of the norm from what I've seen.

  • Slowmotion426

Posted May 19, 2005 - 08:17 PM


...my son's 250F's header pipe glows cherry red when it's just idling...you can see it do this when it's dark... :)

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  • Mark Morrison

Posted May 19, 2005 - 08:20 PM


The vavle timming is stock. we are just now getting ready to test with a O2 sensor. our temp probe is about 6-7 inches from the exhuast gasket flange. The only thing that is diff. is the exhust system . The motor runs great for our combo. do to the diff. gearing that we run our jetting is alot different then stock. (200main 68 pilot needle 1 rich) water temp 130-150. weight with driver 550# top speed 117mph rpm 9200

  • adrian

Posted May 19, 2005 - 08:24 PM


A buddy of mine checked the temp on a 426 and he got a reading of 1200 deg

  • qadsan

Posted May 19, 2005 - 08:39 PM


...my son's 250F's header pipe glows cherry red when it's just idling...you can see it do this when it's dark... :)

That can be perfectly normal. Blacksmiths used to judge metal temperaturres by color as follows:

1,292F dull red
1,472F dull cherry red
1,652F cherry red
1,832F bright cherry red
2,012F orange red
2,192F orange yellow
2,372F yellow white
2,552F white

  • Code

Posted May 19, 2005 - 08:49 PM



  • Frostbite

Posted May 20, 2005 - 05:12 AM


I have exhaust gas temp gauges on my sled, 800cc 2 smoke. They say that when the exhaust is 1300F you're close to the melting point of the piston.
4 strokes should be able to run hotter temps since they fire 1/2 as much, giving the piston a chance to cool down.

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