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Thread: Bike carbs running rough on 4age red top..

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    Bodger zaks's Avatar

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    Bike carbs running rough on 4age red top..

    I installed r1 carbs on my redtop, got it to idle and run but after running for a few minutes, it began to run rough and the motor will stumble from idle going to the main jet. I adjusted the float level and it was better, but it began to run rough again, same problem as before..I replaced the pump to a low psi type, same thing, I cleaned the carb thoroughly, same thing, repalced main jet from 1.80 to 1.40, same thing, no overflow issues or dirt, any ideas what could be causing it to run rough? I'm at my wits end!

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    Re: Bike carbs running rough on 4age red top..

    Are you using the original bike pump? If not they will run crap.

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    Re: Bike carbs running rough on 4age red top..

    Theres a thread on oldskoolford about bike carbs n he was having similar problems with his if youre a member have a look I dont know how to do links his was something to do with air correction jets.another thing to check is for air leaks on hoses I run a pinto on thunderace carbs with 130 bhp and main jets are 155 also use facet fuel pump restricted by filterking to 3psi and they run spot on had them checked on rolling road.

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    Re: Bike carbs running rough on 4age red top..

    Quote Originally Posted by scooter View Post
    Theres a thread on oldskoolford about bike carbs n he was having similar problems with his if youre a member have a look I dont know how to do links his was something to do with air correction jets.another thing to check is for air leaks on hoses I run a pinto on thunderace carbs with 130 bhp and main jets are 155 also use facet fuel pump restricted by filterking to 3psi and they run spot on had them checked on rolling road.

    Hiall, I am thinking of checking the coil as leaks and psi issues are all spot on, Im using a bike pump and no issues with overflow and transition when engine is cold..I'm thinking that when the copil heats up that is when the engine falters, I'm at a loss however if the 4ac coil is 9 or 12volts? many says that all 4k and 4ac's use 9V coils..

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    Re: Bike carbs running rough on 4age red top..

    years ago when most cars ran on 9v coils with ballast it wasnt rare for the ballast to fail and be bypassed, the only issue with that was the points/condensor would suffer due to running on 12v the whole time, it rarely effected the coil. you could certainly try another coil without making any other changes, coil failure due to running 12v wont happen overnight

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