200 degree exhaust temp ok?

[Guest]

I'm shaking down a recently rebuilt carb set, the set has been dipped and has new orings, I've also done a sync. I've noticed this set of carbs is running consistently about 195-205 degrees F as measured on each header about where it starts to bend with an IR gun. The other set I was running seemed to be more about 150-165 , but that set was usually running on the rich side.

You think 200 degree F is a bit too hot or nothing much to worry about? I might me just a hair short on float levels. I'm ok with how the plugs look and how the throttle respond. If this temp is reasonable, I'll call it good for now.

Temp is measured after the bikes been ridden for about 10 minutes.

78 GS750 VM Carbs

[posplayr]

That sound like carbs are well balanced although the absolute temp on 200 degF sounds low. Is that just idling in the garage?

[btbarb]

That sound like carbs are well balanced although the absolute temp on 200 degF sounds low. Is that just idling in the garage?

No, it's after about 10 miles of city start and stop driving, not putt putting around, usually winding first through third pretty good. This set did balance very easily and the overall smoothness after balancing was very noticeable compared to the other set.

[Crage]

Sounds low to me, I wouldnt worry.

[tom203]

Sounds low to me, I wouldnt worry.

Yeah, sounds low but I would worry. What temps do you get at base of cylinders? Test your IR gun on pot of boiling water.

[btbarb]

Yeah, sounds low but I would worry. What temps do you get at base of cylinders? Test your IR gun on pot of boiling water.

I'll get a reading on the base of the cylinders later today, in the past i get about 230-240 right next to the spark plug. The boil test checked out ok, showed 210-214 on water in a stainless steel pot.

[JTGS850GL]

Stock pipes? If so, aren't the stock pipes double walled? That would make it more difficult to read true temp and would tend to read low.

[tkent02]

Those guns depend a lot on surface texture to get a good reading. Chrome won't read the same as water or a cylinder head. Throw it away and ride.

[btbarb]

Stock pipes? If so, aren't the stock pipes double walled? That would make it more difficult to read true temp and would tend to read low.

Yes, stock pipes. I've read the threads here on IR guns, they are not a perfect tool for measuring temps. I normally get the reading from the same place on each pipe from the same distance in an attempt to reduce some of the variability.

Now that I think about it, I'll shoot some readings at several points around the pipe and see how much the temp varies.

[btbarb]

final data points for future reference

Readings around bottom of the head: 270-285

Readings around base of the cylinder: 230-240

Readings at various points around exhaust 3-6 inches from the port: 190-230

[tkent02]

I can't believe the pipes are cooler than the head. Just going by touch, you can touch a head or cylinders for a short time without getting burned, but an exhaust pipe, no way. Also if you spit test it the pipes are always much hotter. Must be the chrome thing making it read low.
But this is all useless information without something to compare it to. How do these numbers compare with a known perfect running motorcycle?

[btbarb]

.....But this is all useless information without something to compare it to. How do these numbers compare with a known perfect running motorcycle?

The Collective might know about a perfect running motorcycle, not me.

[Crage]

I can't believe the pipes are cooler than the head. Just going by touch, you can touch a head or cylinders for a short time without getting burned, but an exhaust pipe, no way. Also if you spit test it the pipes are always much hotter. Must be the chrome thing making it read low.
But this is all useless information without something to compare it to. How do these numbers compare with a known perfect running motorcycle?

I dont think its the chrome, those thermometer measure surface temperature. They dont work well really close up and as you pull the gun a way it shoots a cone and averages the surface temps. So the farther you pull it away from what you are trying to measure the more variables in a larger area it is trying to measure. It's going to be difficult to measure just a pipe with that tool.