pyro probe placement in a 85 250R?

[dansvan]

Anyone use a pyrometer in thier 250R pipe to tune and keep track of lean conditions? If so how close to the piston did you place it?

[Somekindofjerk]

If you want to keep track of Rich/Lean mixtures you need a wideband O2 sensor mounted 2 inchs form the exhaust port. A pyrometer will show you temperature and a little bit of an indication to rich/lean mixture but is more just a temperature gauge. For the pyrometer mount it about the same, 2 inchs or so

[Tri-ZNate]

To give the most accurate measurement of combustion temps you need to place the probe as close as possible, but be reasonable. 2" sounds good, its not like having a turbo and placing it after that, which makes you read 200-300* cooler than what you actually are

[Billy Golightly]

I've often wondered about using an o2 sensor but have been told by numerous people that they wont last in a 2 stroke environment. The pyro is a decent substitute.

[250rfan]

Anyone use a pyrometer in thier 250R pipe to tune and keep track of lean conditions? If so how close to the piston did you place it?



Why don't you just do a plug chop :wondering

[Bryan Raffa]

2-6" from the exhaust port no further or you wont get a correct reading

[TeamGeek6]

Should be in the casting just past the exhaust port, but Id think twice about that for fear of breaking the cylinder. $$$$ Isnt there a steel insert between pipe and port? That would be the place. If so, might weld a tube inside to route the sensor closer to the port.

Yes, O2S wont survive long due to the oil, but itll work for a while. 4 strokes dont burn oil. ITs a gamble for $60-100, but the only way to cheaply measure AFR. Other than that it takes a heated sensor on a machine for at least $400-ish.

A company named Kistler makes a temperature sensing spark plug that pro racing teams use (like Indy cars), I dont know the prices.
The plug has a sensor built in the end of the plug.

www.kistler.com ?

[dansvan]

Plug chop = Wide open throttle only. Ever seen a midrange burn down? It happens.

I would be worried about two things with an O2 sensor. They are physically larger than a small pyro probe. This would disrupt exhaust outlet and the pressure waves inside the pipe. Especially that close to the inlet side of the pipe where it is very small to begin with. Secondly with an O2, I don't think you would get accurate readings due to the fresh air charge coming out of the cylinder and then being forced back in. I guess a third issue is the oil washing over your very expensive wide band sensor.

I've used pyros to tune countless snowmachines and have a pretty good idea of where to put the probe. But I was just checking to see if anyone had set a standard.

Another thought. You do a plug chop. Looks good. Runs super well. It's 75 degrees out, and kinda muggy. Buddies call you up in the fall and want you to go ride. It's 40 degrees, clear and crisp. You were on the edge before at 70 degrees. You go blasting down the field now and you could very well be over the edge. Having a pyro to glance at may save you a piston and a rebuild.

[250rfan]

Plug chop = Wide open throttle only. Ever seen a midrange burn down? It happens.

I would be worried about two things with an O2 sensor. They are physically larger than a small pyro probe. This would disrupt exhaust outlet and the pressure waves inside the pipe. Especially that close to the inlet side of the pipe where it is very small to begin with. Secondly with an O2, I don't think you would get accurate readings due to the fresh air charge coming out of the cylinder and then being forced back in. I guess a third issue is the oil washing over your very expensive wide band sensor.

I've used pyros to tune countless snowmachines and have a pretty good idea of where to put the probe. But I was just checking to see if anyone had set a standard.

Another thought. You do a plug chop. Looks good. Runs super well. It's 75 degrees out, and kinda muggy. Buddies call you up in the fall and want you to go ride. It's 40 degrees, clear and crisp. You were on the edge before at 70 degrees. You go blasting down the field now and you could very well be over the edge. Having a pyro to glance at may save you a piston and a rebuild.


I stand corrected and informed,

Thank you.

[hoser]

Give this a read, keep in mind some of the links wont work unless your a member of my site. http://12.227.214.171/tech/wetline.htm

http://12.227.214.171/tech/wetline_files/wetline.jpg

Also give this a close read http://12.227.214.171/BillGivensjetting.htm