Running temp

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Nine_Iron

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Hey guys, I have a 1975 XS650B. It's bone stock except for the Pamco high output electronic ignition. I was wondering if you guys knew what an optimal running temp would be? Where should it be checked? I have a nice fancy laser temp gun so I can check it anywhere but I'm not sure what's a good check point and what it should run at. Any idea what these bikes ran fresh off the line in 75?

Thanks and great site!!!:wink2:
 
Optimum running temp is 200f. The best way to check would be the bottom of the crank case and the head front and back. There's a lot of threads on this and i believe xsjohn has some what of a guide for doing the best temp check.

You shouldn't worry about it, though. These bikes will only overheat in the most extreme circumstances and they are good and warmed up after 10 minutes.
 
did a lot of checking head temps testing xsjohns needle usually ran between 220 and 240's when really hot out, check cylinder close to sparkplug hottest part of the running engine
 
Nine_Iron said:
Hey guys, I have a 1975 XS650B. It's bone stock except for the Pamco high output electronic ignition. I was wondering if you guys knew what an optimal running temp would be? Where should it be checked? I have a nice fancy laser temp gun so I can check it anywhere but I'm not sure what's a good check point and what it should run at. Any idea what these bikes ran fresh off the line in 75?

Thanks and great site!!!:wink2:
Click to expand...

Why do you care? It's not like you can control it other than choosing the weather you drive in. Is it because you got a new tool? Just ride it.
 
You can and should control your running temp. You do that with correct timing and correct jetting. These items are important with aircooled engines. If you read some of XSJohns wisdom and experimentation, you would see he had high milages engines by accually running cooler than stock. He did this by retarding his timing, lowering compression ratio, and optimizing the jetting. He even went so far as to have custom needles made.

There is alot to be said about running open pipes and pod airfilters. This promotes leanness and higher temps.

My bike was running around 210 degs., and felt lean when on the throttle. I raised my needles a notch and now on even hotter days, I'm running almost 195 left cylinder, and 200 on the right cylinder. XSJohn always said right cyl runs hotter, hence his custom needles. I also run 2 liter aircooled VW motors here in AZ and have no hot running issues by following this simple advice. Just food for thought.
 
Thanks Ben I agree with you.

I have also noticed my right cylinder a bit hotter and was wondering if that was norm on these bikes. It's good to know it is normal.

I forgot to mention I am running pod filters with stock jets and needles. I checked temps tonight after a run and was upwards of 240 degrees. Maybe I should notch up on my needles to enrich the mixture a bit?
 
I was able to have my carbs so rich (accidentally) that they were smoking, just by adjusting the float. '81, BS34 with stock everything I believe...
 
Nine_Iron said:
Thanks Ben I agree with you.

I have also noticed my right cylinder a bit hotter and was wondering if that was norm on these bikes. It's good to know it is normal.

I forgot to mention I am running pod filters with stock jets and needles. I checked temps tonight after a run and was upwards of 240 degrees. Maybe I should notch up on my needles to enrich the mixture a bit?
Click to expand...


absolutely.
 
Yes, raise them. I went to a 140 main jet, one size bigger idle jet, and have my needles at the lowest notch. I running pods and some mufflers that are pretty free flowing. I'm at approximately 2800 ft. above sea level. Your adjustments my vary, but if you get your temps down to 200, you'll be in the ballpark.
 
An oil cooler can drop the head and cylinder temps by as much as 50 degrees.
 
Yes they can, esp. the one that you modify the right side cover for. I believe that was/is on the Oz site.
The right side is hotter because of the clutch basket and all on that side. John's needle's helped with that, but his, or mine, never ran cooler then the left. But, both were within 15 degree's F. of each other. As Jayel stated, shoot the beam right at the lowest piont on the spark plug, for an accurate head temp reading. On R.R radial engines, the sensor for cyl. temp guage was actually the spark plug washer.. Each engine had two, one at 9 o'clock, the other at 3. One on the front plug, the other on the rear.
 
Gordon, A temp gauge with a sensor under the plug would work great on our XS's. Do you know of anyone making one like that? I find plenty that have a senser that screws into the water jacket on an engine.
The oil cooler set up I use has the modded side cover. The cooler radiator is almost the exact same size as the one Mike's sells, so I'm sure you will get about the same cooling.
The one thing I did notice is it not only dropped the cylinder and head temps but evened them out too. Before the difference was like 20 degrees, after it was hardley detectable.
 
You can get thermo-couple wires with ends on them for many different size sparks plugs though aviation supply houses. Also the cylinder head temp guage that I bought for my VW had a spark plug ring that is the same 14mm plug thread as the XS.
 
Like he said. You could also google cyl. head temp guages, and try Stewart Warner. I use to be able to get them from JC Whitney, but not anymore I guess. I just tried before I came on here to answer that question for you, even tried in the old VW section,cause thats where I used to get them from. Used them on a Honda CB750, had a real high compression on that one so,,,
 
i just installed this oil temp gauge dipstick


DSC05513.jpg


project still under construction
 

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