1930 Chief engine temperatures

[Covey534]

After two years of gathering and making parts and pieces, my Chief is now running. It sounds good and takes throttle well (still on the stand) but I'm concerned about the high temperatures at the exhaust ports. The new steel header pipes have already turned blue all the way down to the exhaust pipe and sitting on the bike my right leg gets quite warm in a hurry. I'd really like to know the normal maximum temperatures at the exhaust port and/or headers. I have access to an IR temp reader. Can anyone help me with some numbers? Thanks. -Mike

[gww]

evening Mike, not sure this is what you want to hear, built a 30 a few yrs ago, was amazed at the heat she created. ran around with a hand held temp gun for a week thinking something was wrong. checking and re checking for intake leaks, timing, making sure she was oiling, and so on. wish i could remember temp readings but ive slept sense then. they were well above today's v twins, prob double at the exhaust nipple, and hotter than any flat heads i rode yrs ago. always fill like a sun burned leg while riding. cyls were painted (powder coated) not nickel-ed, course paint did not last long. runs good pulls good but prob. the hottest heat wise i ve ever ridden. it was very concerning for many miles, guess i got use to it. i know you will do the same as i did just to be safe. have about 6k miles now, 4k with a sidecar. best to you. gary

[Yellow53Chief]

Hi,
In the attached diagram, approximate internal engine temperatures are given. The diagram is old, but I think the temperatures are in the range still. Exhaust temperatures over 500 degrees Fahrenheit probably spell trouble. Fresh engines will always run hot; as the rings are breaking-in and friction is high. There is a thinking that a fresh engine should be broken-in with old crappy exhaust pipes. Once the engine in broken-in and the carburetor adjusted correctly (not too lean), the nice new shiny fresh chrome pipes can be safely installed with no fear of instant bluing.
I'm personally running a Keihin carburetor - which works 99% perfectly - but back in the day when I was running a Linkert, I tried to lean out the engine in order to get a few more miles per gallon of gasoline. I leaned the motor out until it just started to loose power, and I ran it that way for awhile. I was shocked to discover that my pipes had blued within just a few miles. After that, I adjusted the high-speed needle (turned it in) until I started to lose power, and then I opened the needle up about 3 clicks. Running lean will blue pipes. The 3 clicks richer from the lean needle position stopped the bluing problem. I ultimately switched to the Keihin because of the disturbing hot-start problem that my Linkert had. The Keihin set-up can sometimes be difficult to start when hot - but it always starts. With the Linkert, all I could do is wait until the motor cooled down before it would restart.
Temperatures in an air cooled engine.jpg

[Skirted]

Just a note on using IR sensors. You can get highly inaccurate readings when targeting a more reflective surface so unless the gun is a more expensive one with a feature to counteract this, incorrect readings will complicate the troubleshooting process. I have an IR gun but use a surface contact type pyrometer when accuracy is important.

[Covey534]

Thanks for the info, Gary. About two years ago when I had not much more than a frame, engine & tanks, you really helped me out with your old 19" rims- one of the harder things to find. Good to hear from you again. The folks on this forum and Kent Thompson (who I'm sure will never own a computer-but he does have a push button phone now- a great guy) have made this project a real pleasure. Thanks for everything. -
Mike McMains

[Covey534]

Thanks for the info & the chart. Your input is really appreciated. -Mike

[Covey534]

Jason- Good info to know. Thanks for your response. -Mike

[phillie]

I run Brad Penn Oil in my bikes has a zinc additive which helps cut friction thus lower engine temps. Might be something to consider.....