Exhaust temp

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

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

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.

...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... :)

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

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

...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

Ouch!

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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