1928 JD Operating Temperature? Overheating Temperature?

[SteveAdventure]

I have a temperature sensor on my electronic speedo/odometer. I attached the sensor to the left rear piston head bolt. The operating range has been 210-250F at sea level here in KC with an air temperature of about 80 F. The question is when I am pushing the bike hard riding through the mountains on the Cannonball at what temperature will the engine be overheating? Any thoughts on operating temperatures would be appreciated!

[pete reeves]

Steve.
I’m also entered for this years Cannonball I’ve been out riding my 29 Jd today in 80F tempratures trying to get some miles on a fresh built motor I Have attached my temperature sensor under the front cylinder primer.
My temperature readings range from 265F when cruising at about 45 Miles per hour to 330F in traffic. I don’t know how accurate or significant these readings are but I don’t feel my motor is running any hotter than it should.
Pete Reeves 860

[SteveAdventure]

My bike uses the larger 18MM plugs and the factory said that if I cut the ring sensor that it would NOT read correctly and they told me to put it on the cylinder head as an alternative. I believe the temperatures could be 100 degrees hotter if the sensor were under the primer! I’ll try putting my sensor on my primer and report back!

[Rubone]

Running a factory head temperature sensor on a stock Shovelhead in the '80s I regularly saw over 400 degrees on it with zero issues. I found that the sensors were pretty useless as you could mount them in a variety of positions and get over 100 degrees of variation! Which doesn't give one a sense of security!
Robbie

[Jerry Wieland]

Passive air cooled motors basically run hot when it's and cold when it is cold. I make sure that the carburator and ignition are where they are supposed to be and run'em.

I cannot do much about the rest of it. Jerry

[c.o.]

I think along the lines of Jerry's post. Running these machines from coast to coast has been done for many moons. They did it back in the day and you guys will do just fine. This is no slight against the folks trying to keep tabs on engine heat though. I understand the concern for the well being of your old machines.

[Steve Slocombe]

I guess like the VLs these bikes run with the front cylinders hotter than the rear, because the flywheels rotate clockwise seen from the right hand side, throwing more oil in the rear cylinder and with no recirculating oil system. The VL Rider's Hand Book says "Don't keep motor running for more than one or two minutes at a time, while motorcycle is stopped." I guess that would need to be on a really hot day, and you guys should be on the move most of the time on the Cannonball Run. Have fun.

[sirhrmechanic]

Keep in mind that if the bike is running modern aluminum pistons (instead of the original cast iron pistons) it will be a lot more sensitive to both heat and oil supply. The cast iron pistons are much more forgiving to high temperature. If the aluminum pistons get too hot, they can start pulling metal onto the cylinder wall. Once they start scuffing like that... it's pretty much game over.

Just FYI. Not sure what my '27 runs for temperature but I never worry about it. It runs a lot cooler than shovelheads I've owned, at least based on the 'how hot is my damn leg' test.

Cheers,

Sirhr

[SteveAdventure]

I have a Vector Trail Tech unit and it only goes up to 299F. What model do you have? Do you agree with Steve Sclobe post that the front cylinder get’s hotter than the back?