throttle body syncing by exhaust temp

[DavidATL]

I am interested in determining if we can evaluate throttle body sync by measuring the temp of each exhaust and I want to start a discussion among those with liquid sync tools AND some way to evaluate the exhaust temperature (ie, a non-contact IR temp gun). 

It's pretty easy to measure the exhaust temp and a consistent location should be easy to determine too. Just playing around, I've measured the front exhaust at 230F and the middle and end at 320F (K75R with lower fairing removed). I don't have any data on the throttle bodies sync state to add to that measurement.

Anybody up for taking and comparing data?

[Laitch]

Is there some way we can incorporate momentary air flow sensor inputs into this?

[The Mighty Gryphon]

It sounds like it could work, but I suspect that unless there was a probe inserted into the exhaust stream there would be little usable information coming from an exhaust header surface temperature reading. 

First off, I would think that the temperature changes would be very small over the range of idle mix settings I typically encounter when balancing the throttle bodies on my bikes.

Second, there is probably some thermal transfer lag as the heat travels through the walls of the headers.  This would require a lot of wait time while the tuner waits for the temperature to stabilize.

Last, I would expect the temperature readings on the headers to be easily disturbed by the slightest of air currents.  then there is the problem of finding the spot on the header where a usable temperature reading could be taken.

Personally, if I was to use header temperature as a tuning parameter, it would be at higher load/rpm regions of the operating range.

[K1300S]

It sounds like it could work, but I suspect that unless there was a probe inserted into the exhaust stream there would be little usable information coming from an exhaust header surface temperature reading. 

First off, I would think that the temperature changes would be very small over the range of idle mix settings I typically encounter when balancing the throttle bodies on my bikes.

Second, there is probably some thermal transfer lag as the heat travels through the walls of the headers.  This would require a lot of wait time while the tuner waits for the temperature to stabilize.

Last, I would expect the temperature readings on the headers to be easily disturbed by the slightest of air currents.  then there is the problem of finding the spot on the header where a usable temperature reading could be taken.

Personally, if I was to use header temperature as a tuning parameter, it would be at higher load/rpm regions of the operating range.

everything he said is spot on.   measuring the surface temp of a header tube is not useful for idle tuning.

exhaust gas temp (not header tube temp) is a useful measure for high RPM mixture tuning under load.  several race car friends of mine run EGT guages in the car for each cylinder.

[DavidATL]

I agree that expecting an absolute measure of the air/fuel ratio by reading header surface temperature is problematic. However, I do think that looking at the delta temperatures may speak to the *relative* AF of the cylinders. That is what I understand syncing to be all about. Might also detect a leaking intake coupling.

Unknowns for me include the effect on cooling of the various exhausts positions. In my case, two of the three locations are at end and one is sandwiched in the middle.  Does this have an effect?

I am hoping that someone on the forum who has recently synced their K75 via traditional methods will then take readings with an IR gun and compare cylinder to cylinder. I'd like to know what delta T's are observed in a known proper bike.