91 FX overheating at idle
07-03-2006, 07:56 AM
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91 FX overheating at idle
Hi,
This is probably a stupid question but my 91FX is overheating in idle, is this normal or it is probably a too lean idle adjustment??
The engine is in inverted position so I did adjust the idel screw to have a good transition but it is overheating in idle then when I push the throttle to max it rev ups and dies.
Thanks for your help
This is probably a stupid question but my 91FX is overheating in idle, is this normal or it is probably a too lean idle adjustment??
The engine is in inverted position so I did adjust the idel screw to have a good transition but it is overheating in idle then when I push the throttle to max it rev ups and dies.
Thanks for your help
07-05-2006, 11:45 AM
#2
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RE: 91 FX overheating at idle
Unless your engine is getting absolutely NO airflow, and you're using some kind of very 'hot' fuel, we'd find it very hard to conceive of how your engine could overheat when running at idle. That's nearly impossible.
Your problem is that the carburetor is not adjusted correctly. If you throttle-up and the engine dies, then the idle is too rich or too lean. There is not enough information in your post to determine what.
Put the engine on a test stand and run it. Start out with the idle set too rich, and the high-speed needle set very rich. Start the engine and advance to full throttle. Then set the high-speed needle first. Only then slow the engine and work on setting the idle RPM and mixture.
Your problem is that the carburetor is not adjusted correctly. If you throttle-up and the engine dies, then the idle is too rich or too lean. There is not enough information in your post to determine what.
Put the engine on a test stand and run it. Start out with the idle set too rich, and the high-speed needle set very rich. Start the engine and advance to full throttle. Then set the high-speed needle first. Only then slow the engine and work on setting the idle RPM and mixture.
07-06-2006, 01:59 PM
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RE: 91 FX overheating at idle
Thanks Bax, I'll do what you suggest, also will change fuel brand because I had this same problem with a OS 108 a few weeks ago and I suspect this fuel don't have enough oil content so the engines are overheating.
07-07-2006, 06:19 PM
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RE: 91 FX overheating at idle
bax can you tell me more about the hot fuel thing. my 91 fx 2 stroke overheated on my pt-19 with the cowl on. i have plenty of airflow into and out of the cowl i think. i run omega fuel 10%. thanks
07-10-2006, 11:18 AM
#5
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RE: 91 FX overheating at idle
"Hot" fuel means over 20% nitro in an engine that's not tuned for it.
Airflow into and out of a cowl means nothing if the air doesn't actually pass THROUGH the fins of the cylinder and head. Usually, if you can see the air outlet when you look into the air inlet, and the cylinder is mostly not in the way, or there's a lot of room between the engine and the cowl, you can bet that the air's not cooling the engine. With any model, you must make sure that any air going in actually passes through the engine's cooling fins. This means you may need to make a baffle to insure that.
Airflow into and out of a cowl means nothing if the air doesn't actually pass THROUGH the fins of the cylinder and head. Usually, if you can see the air outlet when you look into the air inlet, and the cylinder is mostly not in the way, or there's a lot of room between the engine and the cowl, you can bet that the air's not cooling the engine. With any model, you must make sure that any air going in actually passes through the engine's cooling fins. This means you may need to make a baffle to insure that.
