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Runs smoother at night?

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Hey guys... I may be going crazy, just want an opinion here.

 

I've got a 2010 SM, FCR39 installed.

 

The way I have it jetted, it runs pretty good, and pulls alright, during the day (70-80F), but it seems to run way smoother and more powerful at night (55 F ish). I understand its cooler and the air is denser and all that.

 

What I'm wondering, if your guys' opinion, am I possibly jetted a bit too rich? Or is this just a magic situation I'll only get when its cool, dense air? 

 

 

 

 

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All engines prefer colder, denser air to run. Same as all engines have a optimum operating temperature. You'll know when the engines making power and when its not. 

If you jetting is dead on during the day, with air temps of 70F, it will still run cleaner when the air temp drops to 55F, but of course, this doesn't take into account extreme temperature changes.

If that difference is very noticeable like described then chances are you are running the bike richer than it needs to be and a re-jet is a possibility.

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All engines prefer colder, denser air to run. Same as all engines have a optimum operating temperature. You'll know when the engines making power and when its not. 

If you jetting is dead on during the day, with air temps of 70F, it will still run cleaner when the air temp drops to 55F, but of course, this doesn't take into account extreme temperature changes.

If that difference is very noticeable like described then chances are you are running the bike richer than it needs to be and a re-jet is a possibility.

 

Thanks, that's what I was getting at and you explained it well. I think it is a bit rich, I'll try dropping the needle one notch and maybe bringing the main jet down a bit.

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What elevation are you at? And what jetting do you have? At night the cooler air will make your bike run crisper.chances are you are rich for the elevation and location your at

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Try taking the airbox door off during the day and see if it runs stronger.  That is part of the procedure to set up jetting.

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Try taking the airbox door off during the day and see if it runs stronger.  That is part of the procedure to set up jetting.

 

I always forget this trick, thanks, I'll try that out.

 

I can't recall my jetting... it's been a year and a few beers since I last changed it  :goofy: I'll write it down this time 

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