Hey guys I'm a dyna guy myself but I have a buddy who Has a 99 sportster which has been overheating after he rides it for about 1-2hrs, it overheats where the heads and whole engine is really hot. Has anybody here had the same problem or have an suggestions on what to do? Would his oil be the cause of this maybe wrong weight or if he has not changed it for awhile?

 

Maybe running too lean, the first thing I would be looking at.

They all get hot and maybe he just thinks it overheating and isn't really hotter then normal.

 

The Heads & Engine are going to be hot of course. So how have you guys actually determined that it's "overheating" or excessively hot?

 

Here are my recommendations:

1. Check spark plugs. What you are looking for is the plug to be white; if this is the case, the bike is running way too lean causing excessive heat or "overheating" as he believes. If plugs look to be ok move on-

2. Have your friend purchase a dipstick with a built in temperature gauge. This way you will actually know what the oil temperature is. Operating oil temperature for these engines range from 190* to 220*. These numbers are dependent on the outside temperature as well, being that these are air cooled engines. For instance, if it's 40* outside you will not get to 200*. Honestly, you'll be lucky to hit 180* with that outside temperature. 220* is the highest my oil temperature has ever displayed; that's a 85* day just backing off from a 120 MPH run. Pretty much running it very hard.

3. Change to a good quality oil if he hasn't already. Please, do not start an oil debate. I personally use Mobil 1 20W-50 V-Twin oil. There are many manufacturers who produce quality 20W-50 oil recommended for our bikes.

Oil filter is your preference as well; I run a K&N.

After this has been completed, you will know whether or not the engine is actually overheating. If oil temp is shown to be 240* or higher then yes, he has a problem. Without knowing what the spark plugs look like or the oil temp, anything said is a guess until you do.

 

As suggested, start with the basics. If he has only owned the bike for a short time then do a thorough service, by the book, to ensure oils and filter are new, not donkey's years old, change spark plugs for the same reason, clean or replace the air filter.

Check ignition timing and if necessary strip and clean the carb. Running hot can be caused by various things, such as poor ignition timing or poor carb set-up. So check timing and if necessary strip and clean the carb, checking float level. As you can see there are lots of things that can affect running, so get the basics sorted first, before looking for more unusual things.

 

Maybe you can borrow an infrared temp gun, and you can check just how "hot" those heads and cylinders really are. Oil temp dipstick gauge is really good to have as well.

Check plug color first, that should indicate a lean condition. Looking for tan/brown insulator and gray ground electrode for proper fuel mix, white insulator indicates lean.

John

 

Hot??? Compared to what?

Really a stupid thread

Sorry for the rant.