Signs bike is overheating

[sixfivezip]

Thanks to a few forum members I've made good progress on troubleshooting my 79 Special. The bike runs okay for 10 or so miles then craps out. I'm in the process of rebuilding some BS 38s as the current carbs are vac leaking from every nook and cranny.

It was suggested that lean conditions and high idle due to air leaks could be causing the engine to overheat.

What are some signs that the engine is overheating?

 

[jd750ace]

Fire, smoke, loss of compression, high oil consumption, Hole in piston, melted valve, melted white or ashy grey spark plug electrode, and won't kick over after it quits. Not necessarily in that order, but all are signs of overheating.
I'm sure there's more. You could just have an ancient coil giving up under the stress.

 

[TwoManyXS1Bs]

First signs of overheating that we observed down here were clattering engine, followed by the sensation of the rear brake being applied (imminent engine seizure)...

 

[sixfivezip]

Thanks for the replies. seems like overheating is more of a sudden failure leading to major damage rather than the bike temporarily running poorly until it cools.

 

[barelycompetent]

If the bike temporarily runs poorly till it cools off, its another problem not overheating. I would check the coil. I broke down on a ride a few weeks ago after getting stuck in traffic and overheating. When I shut the bike off it would not restart, even after cooling off. I pulled the original coil out and it had a HUGE crack running from the top of it to about half way down the front and around the spark plug wire. It only started acting up after getting good and hot though.

 

[DogBunny]

A sure sign that your bike is starting to overheat is when the ThermoDipStick reads greater than 260 degrees.

 

[weekendrider]

Hmmmmm and how long will the bike last if it does read over 260??
Say the Thermodipstick reads a solid 275 on a 30 mile trip with 90 degree days??
Or it runs a solid 290 in SW TX all day long? Will it make it home? I guess the mileage life is going to be short? How short? Is it going another 100 miles? 10 miles? 10,000 miles?
Are these bikes and riding styles so uniform you can set a "it dies now number" to them?
Now I'm sceerd to even get it off the kickstand.
Sorry for the poor quaility. The glare is bad but I bet you can finger it out.
Right click for properties and check the date.
OP I'm not trying to derail/hijack your thread.
Just saying there are so many variables no one answer may be the silver bullet.

 

[DogBunny]

Good to see your ThermoDipStick, and I also apologize for the threadjack.
I carefully worded my post. I said that 260 is a sign that it is STARTING to overheat. My engines start getting janky and the valve train starts getting clattery, and you can really feel excessive heat coming off of the engine at 260. And, I have correlated the ThermoDipStick temperature with head temp. measured at the spark plug, and I know that when the TDS reads 260, you are at the temp. where oil very quickly breaks down in the head. I know some bikes run hotter than others. I have a couple of bikes that run hot, I just haven't had time to figure out why. But, if my primary XS650 consistently ran at 260, and I couldn't get it lower by changing the timing or richening the fuel, then I would RUN to buy a real oil cooler (not the Heiden filter/cooler, which is excellent, but doesn't really cool).

 

[retiredgentleman]

Just move up to Canada, and all your over heating problems will be gone

 

[Tully]

Hi Guys Im running into an over heating issue. Cant get more than 10 miles out of my 77 it runs fine now. Can ride around town a 4 to 5 mile trip to my parents and back. Go anywjere further the bike is hot enough to worry about ruining my engine and than wont start for an hour or so. Any help would be great!

 

[DogBunny]

Did you re-jet for your exhaust? What do your plugs look like?

 

[jpdevol]

Hi Guys Im running into an over heating issue. Cant get more than 10 miles out of my 77 it runs fine now. Can ride around town a 4 to 5 mile trip to my parents and back. Go anywjere further the bike is hot enough to worry about ruining my engine and than wont start for an hour or so. Any help would be great!

There is actual running hot. And symptoms that act like hot or only appear when warm (electrical). As DB says: a plug pic may give a clue

 

[650Skull]

What is the oil your using??

 

[Tully]

I am running a 10/40 engine oil I cant remember the brand but it is for motorcycles. I was running lean I thought. The kit for my carbs came with a 135, a 137.5 and a 145 main jet. My exhaust now has cheap baffles and I am running air pods. I just installed the the 145 jet drove home and made it 10 miles and it was hot. And when I mean hot its burning excess oil and the paint hot. the pic of the plug is from the 137.5 jet yesterday.

 

[Tully]

I am running a 10/40 engine oil I cant remember the brand but it is for motorcycles. I was running lean I thought. The kit for my carbs came with a 135, a 137.5 and a 145 main jet. My exhaust now has cheap baffles and I am running air pods. I just installed the the 145 jet drove home and made it 10 miles and it was hot. And when I mean hot its burning excess oil and the paint hot. the pic of the plug is from the 137.5 jet yesterday.View attachment 223202

The kit also came with adjustable needles which are on the center setting. with the 137.5 jet I was having to back out my fuel adjustment screw 3.5 turns now with the 145 jet I am back out tje adjustment screw 3 turns to get a good decent low idle.

 

[jpdevol]

And when I mean hot its burning excess oil and the paint hot. the pic of the plug

The plug is not as conclusive as I'd hoped. There is some color there (brown) that would normally indicate good (slight rich) jetting. I also see some black specs that may be some oil.

Sorry - more questions:
You have oil consumption?
Do you see any exhaust smoke when hot?
Can you do compression or leak-down test?
Do you have infrared thermometer?
What type of paint on motor, and is it fairly fresh?

 

[Tully]

The plug is not as conclusive as I'd hoped. There is some color there (brown) that would normally indicate good (slight rich) jetting. I also see some black specs that may be some oil.

Sorry - more questions:
You have oil consumption?
Do you see any exhaust smoke when hot?
Can you do compression or leak-down test?
Do you have infrared thermometer?
What type of paint on motor, and is it fairly fresh?

It is fresh paint. I can do a compression test. I have never done a leak down test but can figure out how. No oil consumption at all. When the bike starts I cant see any oil burn from exhaust and the 2 times it did die and not start I wasnt able to see if it was burning oil through exhaust. And while I am drivimg it 60 MPH seems like I am asking a lot of the Bike RPM wise. I dont have a guage.

 

[jpdevol]

A leak-down takes a different instrument. A compression check is ok.

If you're not consuming oil or showing oil burning via exhaust......
If oil is getting past the rings (not indicated ATM) the oil should turn dark rather quickly (blow-by of combustion gases). Compression readings of interest.

FWIW, I've always used 20W50 in the XS650

To the uninitiated, the rpm does sound high @ 60

 

[Tully]

Will do a compression test and will have results soon.

 

[Jan_P]

Not sure if it matters but that sparkplug looks as a non standard plug