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Running Hot

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Hauula Pan
Posts: 402
Joined: Sun Dec 21, 2008 2:15 am
Bikes: 1952 FL
Location: California

Running Hot

#1

Post by Hauula Pan » Fri Oct 02, 2009 10:13 pm

Aloha, Well I finally got my 52 back together and took it out for a test ride. Starts right up cold and hot too, if you catch it just right. Ran ok but did not like low RPM, it ran a bit rough just off idle but smoothed right out and flew if I gave it 1/2 or more throttle. The big problem is after running about 7 miles in town, when I got home it was so hot I could not put my hand on the dash or tanks, they were so hot. Granted it was also a hot day temps. in the high 90's but I've never had this problem before. My 1st thought was I might be too lean, too advanced, or have an intake leak. Someone told me it might be too retarded instead of too advanced. I always thought advancing the timing made the engine run hotter, but a couple people said that retarding the timing would make it run hot. Now I'm confused?? Any ideas????? I hate to move the timing too much because right now it starts both cold & hot & moving the timing usually messes that up. Could I just be way too lean????? Here is a pic. 9 months of hard work in a very cold and very hot garage, Dec. - Aug. Now I want to put on some miles before the snow returns but I sure don't want to burn it up. Appreciate any ideas, Thanks.
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Ripley/Fla
Ex-member
Posts: 103
Joined: Wed Nov 21, 2007 1:27 am

Re: Running Hot

#2

Post by Ripley/Fla » Fri Oct 02, 2009 10:26 pm

Nice scooter! Why would checking the timing mess anything up? Take all the lash out and see where it is with a simple bulb - or use a timing light. At least you know where it was once before adjustment.

King
Posts: 387
Joined: Fri Apr 02, 2004 5:05 pm

Re: Running Hot

#3

Post by King » Mon Oct 05, 2009 4:26 pm

Hauula Pan

I would check the timing, carb. settings, and very importantly look for manifold leaks. But you say it starts well both hot and cold and runs well so I think all the adjustables are OK. Has the top end recently been rebuilt? If so that could be the cause of your "hots'. After my last rebuild the top end was tight and ran hot. I ran the motor for 20 minuite runs let it cool off and repeated. This was on flat roads and never letting it lug. I did this for about ten hours and the over heating went away and it has run cool ever since.

Best of luck

King

Hauula Pan
Posts: 402
Joined: Sun Dec 21, 2008 2:15 am
Bikes: 1952 FL
Location: California

Re: Running Hot

#4

Post by Hauula Pan » Mon Oct 05, 2009 7:03 pm

Thanks for the tips, Yeah the motor was recently completely rebuilt bottom & top and I'm also .090 over. When I set the timing I brought the timing mark about 1/8" into the hole and also measured from the piston top to the top of the cylinder and dropped the timer in at that setting. I'll double check the timing and check for intake leaks tonight. Also will try richer idle/mix on the S&S carb. I didn't think the motor was all that tight but it may be, I'll also do a compression check. Never ran hot before and it worries me. Also after about 7 miles when it got pretty hot the oil light came on. I figured that was the after market sending unit and normal panhead low pressure at running temp. and after it cooled off and I restarted it the light went out as it normally does. (Can anyone tell me if advancing the timing makes it run hotter or does retarding it make it hotter, or do both affect the temp.??????)

john HD
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Re: Running Hot

#5

Post by john HD » Mon Oct 05, 2009 11:07 pm

i tried the 1/8" in the hole with my FL per the harley manual. and it ran too hot.

move it to the center of the hole and set the points to break at full advance.

i think these motors will run hot if they are out of time either way, too much advance or retard is not good.

john

Bosheff
Posts: 1225
Joined: Fri Jul 03, 2009 8:23 pm
Bikes: 65 FLH 82 FLH
Location: Michigan

Re: Running Hot

#6

Post by Bosheff » Mon Oct 05, 2009 11:10 pm

Running with the timing retarded will cause the engine to run hot, but usually if the timing is that far out, the engine will misfire as you try to accelerate, and not have any power to speak of. I'm curious about yer .090 overbore. Are ya talkin .090 over 74" cylinders, or are ya talkin .030 over 80" cylinders? If yer running .090 over 74" cylinders I can understand why the thing is tryin to melt itself. It has always been my understandin' that anything over .070 on a stock 74" cylinder was gettin a little thin, which could cause the engine to run extremely hot. I've never experienced an engine runnin so hot that it made the dash set-up overly hot to the touch....bosheff

duoglide58
Posts: 117
Joined: Mon Apr 09, 2007 7:08 pm
Location: Oklahoma City

Re: Running Hot

#7

Post by duoglide58 » Tue Oct 06, 2009 5:21 am

Will advanced or retarded timing cause overheating? I posed the same question to an automotive engineer that did his masters on I.C. engines. He confirmed that retarded timing leads to high temps. In auto's, the factory used to retard the timing to warm the engine up faster and burn more of the hydrocarbons. You will hear pinging with advanced timing before it really heats the engine up.

A lean carburetor or vacuum leak could also be causing high temps. Looking at your picture, I cannot tell for sure if you have a manual advance "circuit breaker or an auto advance unit. If it is a autor advance unit, is the mechanism free and advancing the unit with increased engine speed?
Doug

Cotten
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Joined: Mon Aug 26, 2002 9:09 am
Location: Central Illinois

Re: Running Hot

#8

Post by Cotten » Tue Oct 06, 2009 3:48 pm

Never does only one then go wrong at a time.

Vacuum leaks are the #1 cause of overheating, so test it:
http://virtualindian.org/11techleaktest.html
When that variable is eliminated, go on to the next.

Timing is not arbitrary.
Put a strobe on it if you must, and use the middle of the hole.

On to the overbore concern:
At .090" overbore (or .030" 80"), the spigots of the cylinders will flex inward as much as .003" and outward as much as .003" for a differential of .006" out of round when the base nuts are torqued.

Even if you run fat clearances, you will still rub the piston skirt on the spigots!

The solution is to hone-fit for the piston with the cylinder already stressed upon a plate.
Then the cylinder will be round when you bolt it down!

....Cotten
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Bosheff
Posts: 1225
Joined: Fri Jul 03, 2009 8:23 pm
Bikes: 65 FLH 82 FLH
Location: Michigan

Re: Running Hot

#9

Post by Bosheff » Tue Oct 06, 2009 10:57 pm

Hay Cotton, I follow yer drift on the cylinder distortion when bored that far over, but whats yer thought on the heat/excessive over bore thing? What do ya consider safe over bore on a 74" or 80" cylinder?....bosheff

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