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| | | | Joined: Nov 2007 Posts: 131 Certified Bolt Nut | | Certified Bolt Nut Joined: Nov 2007 Posts: 131 | I'm in the process of getting my 250 up and going smooth and noticed there was a spring broke on a weighted flap of some kind located just under the carb on the exhaust manifold. I know I'm going to sound silly with this question, but I'm a nut/bolt guy, not an engine guy (yet) | | | | | Joined: Jul 2003 Posts: 252 Shop Shark | | Shop Shark Joined: Jul 2003 Posts: 252 | Heat Riser.....Bi Metal Spring opens and closes flap based on temperature. Provides heat to floor of intake manifold under carb so gasoline doesnt condense back into liquid form inside the intake. Thats the basics, others can elaborate..... | | | | | Joined: Mar 2002 Posts: 9,115 'Bolter | | 'Bolter Joined: Mar 2002 Posts: 9,115 | That is called the heat riser valve. It's purpose is to provide heat to the intake manifold while the engine is warming up. That spring is a thermostatic spring so you will at least need a new spring. | | | | | Joined: Nov 2007 Posts: 131 Certified Bolt Nut | | Certified Bolt Nut Joined: Nov 2007 Posts: 131 | So I guess this could be the cause of it running poorly at idol? When it is reved up it cleans up, but seems to run rich at idol. | | | | | Joined: Feb 2000 Posts: 5,198 'Bolter | | 'Bolter Joined: Feb 2000 Posts: 5,198 | If its cold out, that could very well be the problem. Try moving the shaft to see if the flap is loose or not. Most of them stick in the closed position (heat going out the pipe). If it is loose, turn it opposite what it is now and wire it in that position. You may have to clamp some vise grips to it and then wire it in the open position.
If its stuck, start spraying the shaft now and everyday for a week or so, then keep working the shaft a little at a time. It should come loose after a while. The side opposite of the spring, has a small cap (freeze plug type) over the shaft end, you can drill a small 1/8" hole in the cap so you can get your oil into the shaft area. Joe | | |
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