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I have a project bike, it was running well but started to overheat after putting a new thermostat in. I also took off the mufflers so the bike would be louder. (Yes I realize now, I shouldn’t have done that.) Well it was running for a bit like this. Just an hour at most. The bike started to overheat again so I removed the thermostat and realized my idiocy with the mufflers and put them back on. Now the bike will not idle. I have to hold the throttle to keep it running or it immediately dies.

I am about to cut off the fuel and run the carbs till empty. Any help is beneficial because I’m stumped.
 

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  1. The mufflers have nothing to do with idling or overheating, so you can rule that out of the equation.
  2. Be sure you have the correct stat, working stat, and installed stat, and that should fix the overheating. Flushing out the cooling system is important if you haven't done so yet.
  3. Sounds like the carbs are dirty, run them until they work out the debris by chance or remove them and rebuild.
 

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Discussion Starter #3
  1. The mufflers have nothing to do with idling or overheating, so you can rule that out of the equation.
  2. Be sure you have the correct stat, working stat, and installed stat, and that should fix the overheating. Flushing out the cooling system is important if you haven't done so yet.
  3. Sounds like the carbs are dirty, run them until they work out the debris by chance or remove them and rebuild.
Thank you, and I had flushed it out previously and it looks clean, ALOT better than it did before it was overheating. I had taken out the thermostat and I don’t have an overheating problem now, might’ve been a bad stat. The carbs I believe I am going to have to rebuild because they do not respond to carb cleaner when sprayed directly into them. So that’s my next step! Thank you very much!!
 

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A properly working tstat is necessary for several reasons, even though the engine may seem to run okay without one. You should reinstall one. They can be "kitchen tested" in a pot of hot water, should open before water boils. Not sure if they can be installed backwards or not, but if in backwards it likely wont work correctly either.
 

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'84 CX650E that is evolving into a GL500
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Lack of mufflers actually can raise the temperature at the exhaust valves a bit so it could have a slight effect on the engine temperature but it shouldn't be much.
Changes to the exhaust can also affect the idle speed so if you adjusted it with no mufflers and the idle decreased when you put them back on you may need to re-adjust the idle to compensate.

If it was overheating with the thermostat and is not without it you either had it installed backwards or it is defective or the wrong one. It might be worth re-installing the old one temporarily to see what happens.

BTW: Welcome to the forum. Please add your location and your bike's model and model year to your profile so that you don't have to remember to tell us every time and we don't have to keep asking when you forget (see Forum Settings link in my signature).

And welcome to the world of antique vehicle ownership (they own us, not the other way around). Your bike is over 4 decades old and the Previous Owners may or may not have done the maintenance necessary to keep it safe & reliable so it is highly recommended to download the Factory Shop Manual for your model (available through the CX Wiki - link in my signature) and go through all of the service procedures, regardless of whether your bike has reached the specified mileage.
I also recommend looking on all rubber parts with suspicion because rubber does not age gracefully. Check the date codes on your tires and replace them if they are over 5 years old no matter how good they look & feel (old rubber simply cannot flow around the irregularities in the asphalt well enough to grip, especially if it is cool or wet). If your bike still has the original rubber brake line(s) (should be replaced every 2 or 3 fluid changes = 5 or 6 years) I recommend shopping for modern stainless braided ones (they last practically forever and double the life of the fluid). And don't forget things like the rad hoses and the boot between the engine and swingarm (they can crack on the bottom where you don't see it).

You haven't said what kind of project but if you are planning to make any modifications the best advice anyone can give you about customizing any vehicle is to get it safe & reliable in more or less original condition and use it for a while before you start making any changes so it can tell you what changes it needs to make it do what you want/need better. That approach almost always results in something you actually want to keep and use but making changes based on style or on what someone else (who may or may not really understand how the changes affect the way it works) has done often results in a piece of expensive yard art that you can't stand sitting on for more than a few minutes and might even be dangerous.
 
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