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Discussion Starter #1
Hello everyone im new to this forum I'm hoping some one can answer a quick question for me. I just got a 2005 crf50 it wouldn't idle well and the ROMs would hang for a few seconds so I tore the carb down and cleaned the heck out of the pilot jet and now it idles perfectly. But I am getting a odd sounding sputter when holding a constant throttle say like 1/4 throttle riding it has a odd sound like a sputter but I can't really feel it in the movement of the bike. I need to check the air filter and change the plug. But while I was tinkering I popped the muffler cap and there's no screen and no muffler packing. I know it should have a screen but should there be packing in it? If so would that cause it to run a little off? I'll add a pic if my little dude after his first race on his old bike it was a 99 jr50 he's 3
 

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Hanging RPM's can be caused by an air leak. Sputter can also be caused by an air leak as it messes with your fuel mixture.

The lack of an exhaust screen shouldn't cause the RPM's to hang.

Awesome pic of your son! Very cute and very awesome. It's good to see a new generation of riders! Kudos on making him wear earplugs.
 

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Discussion Starter #3
Sorry I'm not very goo with my writing I got the hanging rpm fixed with cleaning the pilot jet. The new issue is the sputter I put a new air filter in last night after the post and I pulled the plug it was dark black I'm gonna grab a new plug and see what that does. I was winder if the muffler is supposed to have packing like my 450 does or is it just the chamber with a screen? The little bike is rather loud for a tiny thing. I do like the sound tho and my son loves that it's throaty sounding. On a different subject I'm super surprised at the after market support if this little bike I saw a place making 117cc kits for it. His little Jr50 had no after market support that I could find
 

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Sorry I'm actually terrible at writing. I will look for air leaks any reason I can't do the old brake cleaner trick for that? And I ment to say I was wondering if there is supposed to be packing in the muffler or is it just a chamber muffler
 

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Discussion Starter #6
If I remember right it's closer to 1.5 I let it warm up and ran it around a bit then I turned it in till the idle started dropping then went the other way and did the same and set it right in the middle at the highest rpm and adjusted the idle to what I thought sounds right
 

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Discussion Starter #7
Ok update I did a new plug and it's still doing the odd running so I let it run maybe 10 min and never choked it when I started it and the plug is black soot so I'm guessing I need to check jets and see what it has and figure out what it should have also something I should mention is when I cleaned the pilot I drilled a tiny drill bit up through the bottom just enough to get the finest sewing needle I had through it.
 

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If you drilled the pilot out, that is most likely the cause of the richness. A good thing for cleaning the pilot jet is the smallest guitar string (.009 or .010" diameter) That size wire is just big enough to fit through. You may be able to adjust the air screw out to compensate, but if not, a new jet is in order.
 

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Discussion Starter #9
Does the pilot jet have any effect after idle? I can lean it out with the mixture screw till it sputters and almost dies
 

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Does the pilot jet have any effect after idle? I can lean it out with the mixture screw till it sputters and almost dies
The pilot controls idle and affects about the first 1/4 of the throttle. Be sure you are screwing out (counter-clockwise) to get leaner. The other thing often missed with these carbs is the tiny orifice in the carb just behind the main jet on the floor of the carb throat. You can see it by pulling the slide out and looking down the barrel. Once again a guitar string can be pushed through this hole. The other place to check is your needle for a thin band of gunk near the top. Also be sure and take out all of the brass parts on the main jet. There is another brass part above the main jet (the emulsion tube) that needs to have the tiny holes in it poked out. Can't remember offhand if the emulsion tube has to be pressed out, but if so, it is simple enough, just pushing out the brass part the needle slides into. You just pull the slide and put a brass or aluminum piece of rod into the barrel and tap it lightly with a hammer. The main jet has to be out to do this, but it should just fall out the bottom. With everything out, blast every hole you can find with compressed air. Good luck!
 

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To answer you question about the exhaust packing, the stock exhaust has none. its not like full size mx bike that use fiberglass packing.
 

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Discussion Starter #12
For some reason I didn't get any email notification about this. I'm gonna pull the carb apart if I have time shortly and check it all out again thank you guys for all the reponses
 
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