07 250r. Having hard time shimming
  • Tm85cc07
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    by Tm85cc07 » Sun May 15, 2016 6:56 am

    Are the pilots the same or is there a certain size I need?
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    JimDirt
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    by JimDirt » Sun May 15, 2016 3:23 pm

    The one that is in it (its the long skinny jet not the fat short one , its towards the front of the carb)should be a 42 , that is usually the size you want for about any elevation , the Main Jet is the larger number (170 or so)and is what you change for different elevations or temperature conditions , along with Needle Position

    You also want to make sure your Fuel Screw is set properly , *after you replace the Pilot jet to make sure its flowing clear* , (the fuel screw is located on the underside of the carb at the front , it goes thru the bowl at the very front center underneath) , it should be set between 1-3/4 to 2-1/2 turns out from "lightly" seated , if you need to go more than 2-1/2 turns out to get it to idle well without popping then you need the next size Larger on Pilot Jet , if you need to go less than 1-3/4 turns out then you need the next Smaller Pilot Jet , ........ though as i mentioned , the standard 42 Pilot Jet is what you will need unless your in extreme altitude or temperature situations *like below zero , etc*

    What is your elevation ?? (where you will be mostly riding it and/or where you live) , and what is the temperature range you will mostly ride in ??
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  • Tm85cc07
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    by Tm85cc07 » Sun May 15, 2016 4:57 pm

    We are 610' above sea level. Our riding season is typically 50 F- 85F.
  • Tm85cc07
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    by Tm85cc07 » Sun May 15, 2016 4:57 pm

    We live in michigan
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    JimDirt
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    by JimDirt » Sun May 15, 2016 6:01 pm

    OK , you want a

    42 - Pilot Jet

    175 - Main Jet

    2-1/4 - Out on Fuel Screw (then adjust slightly from there , in or out as needed)

    3rd groove from top - Needle Clip Position

    Fresh Gas - 91 Octane , (non Ethanol if possible , it will last longer)

    That should get you set up fairly well
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    Weiser , Idaho
  • Tm85cc07
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    by Tm85cc07 » Sun May 15, 2016 6:19 pm

    Pulled both jets. They indeed were what you sugested. I blew them out with compressed air and drained gas. Put back together and adjusted screw out 2 1/4. Fired up after 4 kicks. Seemed to idle fine... When it was cold and I twist throttle seems to fall on its face... I almost think this may be normal until bike is warm. Thanks for all the help!
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    JimDirt
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    by JimDirt » Sun May 15, 2016 7:33 pm

    Revving the bike on the stand will sometimes bog or pop thru muffler , what it does under a load/while riding is what is important , the stand has no load so its easier to notice things
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  • Tm85cc07
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    by Tm85cc07 » Wed May 18, 2016 6:18 am

    So by turning the screw "in". Is that letting less fuel in carb therefore creating leaner mix? Also if you go down numbers on pilot jet is that also make mixture lean?
    Just trying to get a better understanding of how these carbs work.
    Thanks
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    JimDirt
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    by JimDirt » Wed May 18, 2016 8:32 am

    Correct on both , Larger number on jet (Pilot and Main) is more fuel , Smaller is Less Fuel , Out on the FUEL Screw (not like a Air Screw like with a 2 Stroke) means More Fuel/Richer , In means Less Fuel/Leaner , so your Opening Up the Fuel Screw , and Closing off the Fuel Screw

    The screws do basically the same thing , but with different results , the Air Screw , when turned in Closes Off the Air Circuit and therefor makes it Richer , because it allows More Fuel and Less Air into the system , the Fuel Screw does the same thing , except it is regulating the Fuel Circuit , so it Closes Off Fuel coming into the circuit , so it Leans the system because it is allowing more Air and Less Fuel .....follow ??

    The Needle does kind of the same as the Fuel Screw , it closes off the Main Jet , as the throttle is twisted , the Needle Raises , the Quicker it raises (by the position of the Clip on the Needle) the richer it becomes , sooner in the throttle movement , the taper of the needle as well as the clip position is what determines how much and when the fuel flows , so when you Raise the Needle Clip Position , you are Lowering the needle farther into the Main Jet , so it takes longer to come out , because more of it is in the Main Jet , so it Leans the Mixture until you reach Full or close to full throttle , when you Lower the Clip Position , it Raises the Needle Farther out of the Main Jet , so it takes Less Movement of the throttle to allow more fuel to flow thru the Main Jet ... Follow ??
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  • Tm85cc07
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    by Tm85cc07 » Fri Jun 17, 2016 11:04 am

    So bike ran good first two rides after rebuild. Let bike sit 1 1/2 weeks-2 weeks and next time I rode it. It was backfiring like crazy any time I twisted the throttle. Brought it home and check valves again and they are perfect. Any ideas?
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    JimDirt
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    by JimDirt » Fri Jun 17, 2016 12:50 pm

    I would say the Pilot is clogged again , instead of "cleaning" the pilot jet by blowing it out , it would be better to just replace it , they are about $6 or so , also confirm that your Hot Start is working properly , the lever should "snap" back , if it seems to have a lot of slack in the lever , it could mean the Hot Start Plunger is stuck and it will cause a Lean Condition if its stuck Open(like as if the lever was pulled, if it stuck in the open position , it would ADD air and lean the system)

    Try both of those and report back with findings

    Just to be absolutely sure , check the connections on the exhaust , mainly where the header connects to the head , and where the header and muffler join together , if you have a candle handy , light it and hold it near the joints/connections while the bike is idling , if the candle flickers or blows out , you have a leak , which will also cause the symptoms of a lean condition by backfiring thru the muffler

    Better yet , if you have Stick Incense , light it and do the same , the smoke will flutter and tell if there is a leak , and you can hold it closer into areas where you cant get the candle and the smoke is more visual so you will definitely notice if it flutters
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    Weiser , Idaho
  • Tm85cc07
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    by Tm85cc07 » Fri Jun 17, 2016 1:28 pm

    Why does it continually clog? Is gas that bad nowadays? Will a new one clog too?
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    JimDirt
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    by JimDirt » Fri Jun 17, 2016 2:04 pm

    Yes the gas is that bad , you can thank Ethanol and the EPA for that crap , all it does is make you buy a gallon of gas at a exorbitant price when your only actually getting 3 quarts of gas and the rest water and Alcohol , that is why cars drip WATER out of the tailpipes , because WATER does NOT burn ! , it is what causes the jet to clog and the inside of the carb bowl to turn green , if you want to stop the clogging (at least for a few months instead of barely 1) , then get NON Ethanol gas , 91 octane or better , i personally use Non Ethanol mixed with 110 octane Sunoco Race Fuel , or when i can't get that , then i use Av Gas from the local (small private planes) Airport , either will set you back about $8 a gallon or more (for the Av Gas and Race Fuel , not the Non Ethanol Premium , its about the same cost as Premium *slightly higher*)

    What i personally do , is buy 5 gallons of each , then i mix up 2.5 gallon jugs , i put 1/2 gallon of Sunoco or Av Gas , and the other 2 gallons of Non Ethanol Premium , the bikes like this mixture as they idle better and start easier , and run cooler as well , since higher octane lowers combustion chamber heat , so the engine runs more efficiently , when i race i run 1 gallon of Sunoco/Av Gas , to 1.5 of Non Ethanol Premium

    The only other thing you can use is Star Tron Enzyme Fuel Treatment http://www.starbrite.com/startron (you can find it at Wal-Mart or any Automotive Parts Store) , it works far better than Sta-Bil
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    Weiser , Idaho
  • Tm85cc07
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    by Tm85cc07 » Sat Jun 18, 2016 6:46 pm

    I adjusted the screw until it ran better. Now it's only 1 1/2 turns out. Instead of 2. 1/2. Smoothed right out.
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    JimDirt
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    by JimDirt » Sat Jun 18, 2016 7:03 pm

    OK , maybe raise the Needle Clip Position to the number 2 spot (from the top) from the 3rd clip position , this will lean it down a bit on the bottom end , and might get your Fuel Screw back closer to where it needs to be , doing this will fine tune it a bit more , you will have to readjust the Fuel Screw , but most likely going OUT just slightly to get it close as you can to 2 turns out , that way you will be in the middle of the adjustment and can go in or out when changing elevations , and have a better elevation operating range

    Or if it suits your needs and is running good in whatever your doing , then you could just leave it alone and have fun riding ...
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    Weiser , Idaho

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