Help with cutting out/bogging
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  1. #1
    Junior Member Sunny's Avatar
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    Jul 2015
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    I have an 86 trx, so trying to solve the problem I’ve recently cleaned the air filter, cleaned the carb, checked the jets to make sure they’re clean, tried new spark plugs, cleaned the coil ground and replaced the coil, and checked the reeds. Noticed my oil was a little gray but checked my antifreeze levels and they haven’t changed. The main jet is 170 and and pilot is 48 with a uni air filter and fmf fatty pipe.The bike will start within a few kicks but won’t idle I have to constantly be in the throttle, and when trying to take off I have to feather the throttle to get it revved, enough to go. If I get it revved to about half throttle I can ride but if I push it any further it cuts out and will die. So basically I only have 1/2 throttle to work with. After running it until it’s hot if it stalls it won’t start again for awhile. I’m at a loss any thoughts are greatly appreciated.
    Last edited by Sunny; 10-26-2019 at 12:29 AM.
    1986 250r
    -cool head
    -FMF fatty
    -+2 a-arms
    -+2 swing arm
    -+2 axle
    -Renthal handle bars

  2. #2
    Senior Member american opel's Avatar
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    Sep 2012
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    ashtabula ohio
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    sounds like you have too large of jets.in stock cylinders i have ran a 38 pilot and a 140 main.

  3. #3
    Junior Member Sunny's Avatar
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    Jul 2015
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    Problem is I’m really not sure if it’s stock. Previous owner claimed it was a 310 but don’t know how much of that I believe, it does have a cool head though. Only issue i see with the jet theory is it was running fine on the current jets and then one day it just all of the sudden started doing this.
    1986 250r
    -cool head
    -FMF fatty
    -+2 a-arms
    -+2 swing arm
    -+2 axle
    -Renthal handle bars

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  5. #4
    Senior Member 2ndmoto's Avatar
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    Mar 2013
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    Check compression and check for air leaks.

  6. #5
    Senior Member american opel's Avatar
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    Sep 2012
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    ashtabula ohio
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    check the reeds.worn chipped reeds will make it act like it's rich.

  7. #6
    Junior Member Sunny's Avatar
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    Jul 2015
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    Quote Originally Posted by 2ndmoto View Post
    Check compression and check for air leaks.
    Wheres the most likely place to check for a leak? After firing it up today I did notice that Where the top end meets bottom end was wet like it was leaking. Guessing I’m going to have to replace a gasket. Could that be causing the issue?
    1986 250r
    -cool head
    -FMF fatty
    -+2 a-arms
    -+2 swing arm
    -+2 axle
    -Renthal handle bars

  8. #7
    Senior Member 2ndmoto's Avatar
    Join Date
    Mar 2013
    Posts
    576
    Proper way is to do a leak down test. Old school way is to clean it, start it up, then spray around the intake and base gaskets with carb cleaner. If it starts to rev higher then you have found your leak.

    Air leaks can come through the mains, center gasket, intake gaskets, base gaskets or cracks in the cylinder or center cases. I suggest investing in a leak down tester. There are write ups on how to build them from home Depot parts

  9. #8
    Senior Member acecarlos's Avatar
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    May 2010
    Location
    Alta Loma, California
    Posts
    12,459
    Quote Originally Posted by Sunny View Post
    I have an 86 trx, so trying to solve the problem I’ve recently cleaned the air filter, cleaned the carb, checked the jets to make sure they’re clean, tried new spark plugs, cleaned the coil ground and replaced the coil, and checked the reeds. Noticed my oil was a little gray but checked my antifreeze levels and they haven’t changed. The main jet is 170 and and pilot is 48 with a uni air filter and fmf fatty pipe.The bike will start within a few kicks but won’t idle I have to constantly be in the throttle, and when trying to take off I have to feather the throttle to get it revved, enough to go. If I get it revved to about half throttle I can ride but if I push it any further it cuts out and will die. So basically I only have 1/2 throttle to work with. After running it until it’s hot if it stalls it won’t start again for awhile. I’m at a loss any thoughts are greatly appreciated.
    It is always good to perform a complete check of your engine; air leak testing included, however; the issues you described are normally not related to engine leaks, unless the leaks are extremely severe, and easily noticeable. You need to look at the engines 'health', meaning; compression, fuel flow, carburetor/jetting, carburetor cleaning and IGN.

    From experience building 250R's daily I can assure you it's either carburetor, compression or IGN related. Start with compression check, clean carburetor-jets out well and perform a complete IGN test to Honda Manual specifications to start.

    Carlos
    Last edited by acecarlos; 10-28-2019 at 09:18 AM.

  10. #9
    Junior Member jon370r's Avatar
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    Aug 2009
    Posts
    5
    I hate to assume anything so I’ll throw this out there. Pull the carb slide out and verify the needle and particularly the needle clip are still properly in place. If the needle has dropped down it will plug off everything above the main jet.


 

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