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kpi103

Hanging idle

11 posts in this topic

Hi, just got done rejetting my 450. I have a 170 main, and a 48 pilot. Was going to put a 75 starter jet in also, but the dealer gave me the wrong one ( Too big). Anyway, bike seems to run excellent,except I have a hanging idle. So first thought was my pilot system is still too lean. It is really cold here right now (30-40 degrees) and my elevation is around 1000 feet. Should I go bigger? The strange part is if I pull the choke the idle shoots up like I pulled the hot start. &%$#@!? I would've thought the idle would've dropped. I've had the fuel screw closed and in 1/4 turn increments opened it up to 3 turns with no difference in the hanging idle. Any suggestions? Thanks

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Did you change the pilot? If so , go back to the last one you ran. Sounds like it is still lean, any popping on deceleration?

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Thanks for the tip on the valve clearances, I'll check them tomorrow hopefully. The choke thing is really confusing me a little, and the bike doesn't really have any popping on decel. I know its cold here, but anything bigger then a 48 just seems to big to me. I cecked for intake leaks and found nothing. Any help would be greatly appreciated. Thanks

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Hi, just got done rejetting my 450. I have a 170 main, and a 48 pilot. Was going to put a 75 starter jet in also, but the dealer gave me the wrong one ( Too big). Anyway, bike seems to run excellent,except I have a hanging idle. So first thought was my pilot system is still too lean. It is really cold here right now (30-40 degrees) and my elevation is around 1000 feet. Should I go bigger? The strange part is if I pull the choke the idle shoots up like I pulled the hot start. &%$#@!? I would've thought the idle would've dropped. I've had the fuel screw closed and in 1/4 turn increments opened it up to 3 turns with no difference in the hanging idle. Any suggestions? Thanks

Check the adjustment of the throttle cables also.

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Didn't get a chance to check clearances yet, but I will this week sometime. Bike probably only has 5+ hours on it, but I was going to check them soon anyway. Does my jetting sound about right? Guess I'll just have to see what the clearances look like and go from there. Thanks for all of your input so far.

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also try backing down the idle. If you have it to high, it will surge.

This is true, which also brings up a very good point.

This engine runs on fuel. In other words, in order for the idle to go up, additional fuel has to be going into the engine and that means that you don't have to look any further than the source itself - the carb.

Now, when the slide of the carb is closed, (an idle setting) an engine can still rev if it can find additional air from a source other than under the slide. When this extra air is present, additional fuel can be drawn up from the idle or pilot circuit even when the slide is in an idle position. So yes, an air leak can cause an engine to idle high. Common sources are cracked boots around the choke and hot start levers.

But I think you're problem is an idle or pilot circuit that is too rich, which would follow suit with the colder air and the higher altitude.

With the bike fully warmed, you may want to turn in the fuel mixture screw and then reset the idle as necessary. If this does not remedy the matter, lower the pilot jet until you can get an adjustable range from the fuel screw.

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I was wondering if you fixed the problem yet? Mine does the same thing??

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