Koso EGT meter sensor into 2 stroke pipe

Ronald j · Nov 3, 2018

How many inches from the piston have you been drilling into the 2 stroke pipe to place the temperature sensor. All the info I can find shows where to place it if you have a 2 cylinder snowmobile engine. I’d really like to do this correctly the first time as I am going to weld an adapter onto the pipe. Thanks.

TYFOON · Nov 3, 2018

I spent 8 years selling and supporting EGT indications on aircraft engines. In aircraft motors 1.5” to 3” was the goal. Higher on the exhaust the better. To be in the flame exiting the valve was the idea. There we were monitoring for max power or max efficiency. Max power came at 100 degrees on the rich side of peak EGT. How are you tuning for a 2T? I ask because I don’t know. Interesting though! Are you using thermocouples?

portgrinder · Nov 3, 2018

6in or so. Doesn’t matter that much. Could be 5 could be 7

Ronald j · Nov 3, 2018

I have never done this before so I don’t really know what I am doing. I have a Koso EGT meter and I will be installing a thermocouple about four inches from the piston unless I hear differently. I have been told that I should be looking for a temperature of around 1100 degrees and that is being on the safe side, I don’t want to burn anything up looking for a little more power. I have a Lectron on this 300 engine so my plan is to dial up the power jet until I’m running in this range. Please feel free to give me any practical advice, this is all new to me.

TYFOON · Nov 3, 2018

This got me thinking. You really need to know what EGT is indicative of max hp and torque. Any leaner and all you’ll gain is higher temps with diminishing power.
If you are able to discern where max hp is relative to EGT then you should be able to dial the lectron to create that EGT roughly, therefore making max hp for your riding conditions ambient temps, altitude etc right?

CATSLEDMAN1 · Nov 4, 2018

how hot how far how can I trust it

Distance from the face of the piston/combustion chamber is the issue. on our wooped sleds we found 4" from the face of the piston worked, that's
pretty close to the start of the pipe.

So how hot ? where you place the pyrometer and how rich or lean your carb is delivering gas can make a big difference in temp reading. In the wrong situation a 25% rich condition in the combustion chamber will send gas going out the pipe and still burning, often 6" or more down the pipe you will have a hot condition 1350 degrees, but a cold over rich condition in the combustion chamber.

Too lean in the combustion chamber, no unburned gas escapes down the pipe and 6" out it reads cold 850 degrees, don't be fooled, going leaner will chunk da piston.

So the Pyro's can help you and give another opinion, but learn to recognize deto, lots of visual looks at piston top............tough on bikes, how to read deto on plugs.
In the end, Lectron and EFI will show different temp/plug/burn color than the leaky MIC/Keihin

When you know your jetting is near spot on, the pyros are good to tell that up one or down one jet, tells you not to chop the throttle at the top of a long steep climb, lots of interesting information, just don't hit a tree or off a drop while reading the temp gauge.

Used to be lots of good write ups on pyros on two stroke sleds, and good info from the dyno guys, and it mostly came down to tuning and avoiding deto looking for good power.

cbc76am · Nov 4, 2018

6" is the documented distance from the piston skirt in the manual on your EGT. 4 inches is for a Y adapter header for 2 to 1 pipes on twin snowmobiles. it's to keep the other piston from reading on the meter and have them not end up right at the Y junction. 6 will be the right placement on the pipe. Should be just before on on the initla bend of the pipe.

wellfed777 · Nov 5, 2018

so on an FMF Gnarly pipe for a CR500 6'' from piston
have someone tig weld the bung
figuring it'll probably mess up coating around weld but
oh well right ?

cbc76am · Nov 5, 2018

Gnarly

Why would you run a gnarly pipe on a snowbike... And use an EGT? Egt only works for wide open, otherwise the read is meaningless... Not trying to be a dick, just pointing out the delta in the logic.

Nickel plated pipes lose tons of hp to raw steel in the dyno also btw. The gnarly also crack under the protective plate on the right side bend at high rpm soon into life on a snowbike.

Pro circuit works finish, custom cpi, bills when the make a limited run... All better option IMO and the dynos.

2smokin · Nov 6, 2018

cbc76am said:
Why would you run a gnarly pipe on a snowbike... And use an EGT? Egt only works for wide open, otherwise the read is meaningless... Not trying to be a dick, just pointing out the delta in the logic.

Nickel plated pipes lose tons of hp to raw steel in the dyno also btw. The gnarly also crack under the protective plate on the right side bend at high rpm soon into life on a snowbike.

Pro circuit works finish, custom cpi, bills when the make a limited run... All better option IMO and the dynos.

How does the nickel coating lose hp??

cbc76am · Nov 6, 2018

Pipes are made to run at given temp, about 625 deg in the mid up to 1450 or so on the top. That is what controls the speed of the ultra sonic wave that regulates the pulse to the carburetor through the cylinder. Hotter gases are faster to travel through, so the wave speeds up. Ceramic or Nickle coating is an insulation. So longer to heat, slower to cool, and higher overall temps. That makes the sonic wave travel at a higher speed, and carries more heat back to the piston, the hot metal then repels the new charge coming into the engine. The sonic wave returns too soon to charge the cylinder when the gases are super heated in an engine is tuned to make maximum horsepower at high RPM. Every one who has a dyno will be able to verify this. Raw Steel pipes at cooler temperatures will yield better and more consistent power over coated pipes at higher RPMs.

Ever see a professional motocross racer running a platinum pipe? Nope. Woods/enduro that tune the engine for torque (gnarley pipe as well) they get a hotter pipe at lower RPM and that favors the motor build they have for that kind of racing with plating.

Ceramic on snowmobiles loses HP also, but super consistent pipe temperatures are critical for clutch tuning to hold the engine at maximum HP at a specific RPM. If the pipe temp changes that target could vary a few hundred RPM and the clutching is no longer inline with the engine's peak output. So sacrificing some HP to have stable RPM/peak HP maintained is a reasonable middle ground.

Snowbikes, specifically I've learn in the past few seasons don't need grunt. They are geared so low that any hard pack is a walk in the park for any size engine. But deep powder and long high altitude runs at speed require high RPM HP. Hence why 4 strokes that rev to 12k are winning popularity over the two strokes out there that rev to 8-9k... yet I dropped my 17 450 KTM for a CR500 this year - cause I'm a 2 smoke lovin A-hole.

I hope that helps break it down.

Sheetmetalfab · Nov 6, 2018

cbc76am said:
Pipes are made to run at given temp, about 625 deg in the mid up to 1450 or so on the top. That is what controls the speed of the ultra sonic wave that regulates the pulse to the carburetor through the cylinder. Hotter gases are faster to travel through, so the wave speeds up. Ceramic or Nickle coating is an insulation. So longer to heat, slower to cool, and higher overall temps. That makes the sonic wave travel at a higher speed, and carries more heat back to the piston, the hot metal then repels the new charge coming into the engine. The sonic wave returns too soon to charge the cylinder when the gases are super heated in an engine is tuned to make maximum horsepower at high RPM. Every one who has a dyno will be able to verify this. Raw Steel pipes at cooler temperatures will yield better and more consistent power over coated pipes at higher RPMs.

Ever see a professional motocross racer running a platinum pipe? Nope. Woods/enduro that tune the engine for torque (gnarley pipe as well) they get a hotter pipe at lower RPM and that favors the motor build they have for that kind of racing with plating.

Ceramic on snowmobiles loses HP also, but super consistent pipe temperatures are critical for clutch tuning to hold the engine at maximum HP at a specific RPM. If the pipe temp changes that target could vary a few hundred RPM and the clutching is no longer inline with the engine's peak output. So sacrificing some HP to have stable RPM/peak HP maintained is a reasonable middle ground.

Snowbikes, specifically I've learn in the past few seasons don't need grunt. They are geared so low that any hard pack is a walk in the park for any size engine. But deep powder and long high altitude runs at speed require high RPM HP. Hence why 4 strokes that rev to 12k are winning popularity over the two strokes out there that rev to 8-9k... yet I dropped my 17 450 KTM for a CR500 this year - cause I'm a 2 smoke lovin A-hole.

I hope that helps break it down.

So the 2 stroke pipe being in constant contact with snow isn’t going to drop below a temperature that makes decent power?

cbc76am · Nov 6, 2018

yeah, that's what I've been told by the pipe builders. I wanted to ceramic coat my pipe that CPI is making me and he shot that idea down as loosing 15HP at peak RPM. I then called another two stroke wizard friend and he confirmed that... let it be ice cold and you'll get better performance over all. The temp drops in powder that I was worried about shouldn't matter unless you are way too rich on your jetting is the overall feedback I've received.

Hope this forum gets a few more opinions into the mix. I've been advised high temp clear coat is all you would want to do to a steel pipe for maximum HP even in deep snow conditions.

Answ3r · Nov 6, 2018

Funny in that post apparently NPP learned something but they haven't said what.

Definitely looking forward for some real world data.

https://www.snowest.com/forum/showthread.php?t=406968

portgrinder · Nov 6, 2018

You’re way over thinking it.

Drill your hole somewhere around 6in out. If your lazy, don’t go above 1200 at any throttle or load. If you want to do it right, read the plug at different speeds and see what temps you can go to

Never seen coatings etc make any different power than raw. The ceramic does look faded after awhile but it’s better than rust. Been using stainless recently.

wellfed777 · Nov 7, 2018

my CR500 build is kinda low buck I focussed on engine being
gone through and fresh i'm doing tunnel cooler and carb heater
everything else is what i had or sourced cheap
the kit is a 14 ts 120 old school :face-icon-small-hap
gnarly is what i have so i'm using it i got a used koso gauge so thought i'd do EGT and have water temp together but haven't decided yet
i'm super pumped to get it out this winter I've had this 500 for 15+years I used to ride it a lot but it's just been sitting for years so figured snowbike time

as to wide open i guess i'll have to see
i know on my crf450 I've never been wide open on a dirt bike ever as i have with SB so maybe the CR will be similar ?

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Koso EGT meter sensor into 2 stroke pipe

Ronald j

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portgrinder

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