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Header Temp Range for Tuning Carbs???
Posted: Thu Feb 05, 2009 8:51 am
by NHFZR600
Hey guys its that time of year again... and i cant remember what the temp range on the headers is to tune the carbs using an infrared temp gauge... whos got the info? Thanks!
Re: Header Temp Range for Tuning Carbs???
Posted: Thu Feb 05, 2009 9:05 am
by slayermd
There is no real temp range. The goal is to get the temps as close as possible through out the pipes.
Re: Header Temp Range for Tuning Carbs???
Posted: Thu Feb 05, 2009 9:46 am
by yamaha_george
slayermd wrote:There is no real temp range. The goal is to get the temps as close as possible through out the pipes.
+5 on that , there is an optimum temp INTERNALLY but there is a whole slew of variable that must be factored in to calculate that which requires Knowledge & Instruments WAY passed what we are likely to muster as owner / tuners.
Having said that if you have "tapped" headers you can rig Oxygen sensors and match between those and the infra-red gun.
Re: Header Temp Range for Tuning Carbs???
Posted: Thu Feb 05, 2009 9:47 am
by NHFZR600
yea i realize the temps are all supposed to be close together but what is too high (Lean) and what is to low (Rich)???
Re: Header Temp Range for Tuning Carbs???
Posted: Thu Feb 05, 2009 9:57 am
by yamaha_george
NHFZR600 wrote:yea i realize the temps are all supposed to be close together but what is too high (Lean) and what is to low (Rich)???
Oxy sensors will tel you that but leaner is usually higher than rich. As to temp if you are measuring in 30+ heat and 90% humidity it will be a whole side hotter than measuring in +1 and low humidity hence the lack of hard & fast temps.
You will have to read & carb adjust till within 10 degrees (inner pots are gonna be hotter than outers and then read your plugs & / or use a oxy sensor in the tail pipe or better still individual tap offs OXy sensors in each head pipe.
Re: Header Temp Range for Tuning Carbs???
Posted: Thu Feb 05, 2009 2:05 pm
by ragedigital
I think I was around 550 at 2k RPM or something... make sure you do it in a garage where the wind doesn't affect the temps. Keep the door open though - don't need another CO statistic.
Re: Header Temp Range for Tuning Carbs???
Posted: Thu Feb 05, 2009 3:10 pm
by NHFZR600
THNX Rage!!!
Re: Header Temp Range for Tuning Carbs???
Posted: Thu Feb 05, 2009 4:23 pm
by reelrazor
Let me add that no load temps really won't tell you much.
If you tune for mix at xRPM no load it is going to be waaay lean when loaded.
And temps will vary a bunch depneding on how far down the pipe you are. Teh bets you can do is spot the IR beam on a given spot that is as similar as the others (usually the outside of the downward bend).
With sled motors, the rule for EGT /pickups/probes is 100mm from the exhaust port..that's checking actual exhaust gas temps.
And there will be a break point where lean actually falls into cooler temps(lean misfire).
I am pretty convinced that an AFR guage (even if temp. install to tune) and road testing is the way to go.