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Mike Anhalt

CHT question

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On my SIP speedo/tach I was hitting about 360f on the CHT (at the plug) while running at WOT @ around 6600rpm

 

Not having run a CHT for an everyday bike I was wondering if that sounds inline with what others have found?

 

RT205, 19deg btdc, PHBL24 95main, 22 needle on 3rd clip down, ram air, MDB big bore exhaust.

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Yeah. running wide open at relatively lower RPM like 6600 sounds about right..  if you were to increase the revs you'd see it drop.

 

I always cool it down if it hits 400.. some guys go up to 450 but I'm in no hurry to seize a top end... and don't find myself at or over 400 that often.

 

Have you got an EGT on that bike?

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No, wish I did. If I could figure out the values on the for the CHT in the speedo, I think I could add a resistor in the circuit to make it handle the higher numbers for the EGT. Then just know what the multiplier is and it would be good to go.

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That would be nice.. but you have to pay attention to the thermocoupler.. there are ones for analog, others for digital, grounded, ungrounded etc..  compatibility is key.. here's a nice info source..

EGT reacts much quicker though.. much quicker.. it's def worth the investment. 

 

 http://www.alcorinc.com/index.php/learning-center/

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Bell's book says you can pull max power up until 205C/401F, but in his wording he appears to call 218C/424F and above entering the meltdown zone. Pretty much in accordance to what Vader says. Anything above 400F I would consider danger.

 

The one thing I like about measuring at the spark plug is that it's a solid and repeatable connection to accurately compare notes between riders and bikes. I'll be adding them to several bikes this season, so hopefully learn a lot more on temps. I've read various opinions, pro and con, on both CHT and EGT gauges. They both seem to have their strong and weak points. 

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 They both seem to have their strong and weak points. 

I agree... as we know.. best is to just have both.  

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Bell's book says you can pull max power up until 205C/401F, but in his wording he appears to call 218C/424F and above entering the meltdown zone. Pretty much in accordance to what Vader says. Anything above 400F I would consider danger.

 

The one thing I like about measuring at the spark plug is that it's a solid and repeatable connection to accurately compare notes between riders and bikes. I'll be adding them to several bikes this season, so hopefully learn a lot more on temps. I've read various opinions, pro and con, on both CHT and EGT gauges. They both seem to have their strong and weak points. 

 

Ok good to know because I'm hard on the throttle and 360f is the highest temp so far. Doing 1 mile + straights. Feels crisp in the response also with no loading up or weak spots. I only have 68 miles on the top end so I still have a little way to go before it's broken in.

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If I downshift at 50mph for a hill my CHT drops 50 plus degrees. At top of hill doing 60mph temp are back up near 400 F. A quick downshift and some clutching / blimping thrortle to cool it down I coast down hill while leaving throttle at half or higher using rear brake to keep speeds down.

All of which you do I bet

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For my own edification, I'm going to do a test with these two CHT sensors.. one is the 10mm type on a cylinder stud, and the other is screwed directly into the head..  I want to see what difference I get.. then I may get a 14mm plug ring and compare that to each of the others..  I have had the plug sensors come loose and never liked them.. I'll need to mill a little area for the 14mm sensor, as they can be a hassle to screw the plug in..  Also, I don't like using the 14mm type with the plug's crush washer as the sensor raises the plug all that much further out of the dome.. and I don't like cutting the crush washer off the plug to compensate either, as the sensor ring really doesn't act the same as the plug's crush washer.. 

 

Anyway, when I get to it, I'll report my findings.. a fried on another forum did extensive testing between sensors on all 4 studs, the spark plug and I think direct into the head.. IIRC the biggest difference between spark plug sensor and stud mounted was 15 or 17 degrees (the stud furthest from the center of the head) and the least difference was 3 or 5 degrees (the stud closest to the center of the head) Don't quote me on those numbers.. I need to find the thread.. but I think I'm correct.

 

RBCHTSensors_zpsa0b0aa3c.jpg

 

ps.. Thanks to Travis for the use of his custom tap.. the sensor screw is a weird size... not a standard size 

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I'm not sure how much material are on other Lamrbetta heads like stock or BGMB RT etc... but the RB has a good healthy, thick section right there next to the plug that was a perfect candidate to be drilled and tapped.  I'm looking forward to seeing simultaneous comparative readings.

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I'm not sure how much material are on other Lamrbetta heads like stock or BGMB RT etc... but the RB has a good healthy, thick section right there next to the plug that was a perfect candidate to be drilled and tapped.  I'm looking forward to seeing simultaneous comparative readings.

 

The rt head has a lot of material to it

 

I run up to 426 degrees

That sounds a little on the high side according to everyone else. Hows the plug look?

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I would think that the flash point of whatever 2T you use should be considered when choosing your "max CHT" to run at.

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I would think that the flash point of whatever 2T you use should be considered when choosing your "max CHT" to run at.

The flash point of Motul 710 is only 190.4F ... pretty low in comparison to what the heads get up to at times.

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Vader - Love the sensor install and can't wait to see the data from the study you are conducting! A multi-channel data recorder would be great to get all data points simultaneously...

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The flash point of Motul 710 is only 190.4F ... pretty low in comparison to what the heads get up to at times.

Which is partly why I run Motul 800 Road Racing (Flash Point 525 F)

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With 4.84 final drive I hit a solid 69 mph (ran out of road) and 360f on the CHT. That was sustained WOT for over a mile.

I'd say it's jetted correct now. I could probabbly bump that temp up by jetting changes and gain a little top speed but to what end? It's fast enough for the riding I like and starts 1-2 kicks every time.

Also on the topic of oil

Yamalube R2 at 32:1 every time

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Which is partly why I run Motul 800 Road Racing (Flash Point 525 F)

Copy that.. If I were running HARD all the time, I'd use 800, but for street riding the 710 does just fine.. and the lower flash point means it gets vaporized and I don't get gummed up.. I hear what you're saying.. I'd be interested in trying something with a flashpoint somewhere in the middle of 190 and 525.. that's a big jump.  The Yamalube 2R is lower at 149F.

Thanks GP Kevo

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I have been using the yamalube R2 as well, consistently and at a little under 3%(full mix cup).

With a better sense of jetting i have had absolutely no problems.(knock on metal)

My machines get ridden pretty hard. My fav is sitting on the freeway for mile after mile at speed. I like where my bikes are set now.

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YMD-65081-01.jpg   Is this the stuff you are referring to ?

No sir.

I havnt seen that bottle.

Mine is red label with a couple dirt bikes racing on it.

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Same here,

The thing to realize is Yamaha are/were at the height of two stroke technology. It's the same oil their race team used. I've used it for years and years. No problems and cheaper than most any other.

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Cheers, the search will continue then, and this stuff certainly isn't cheaper. 

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