CM450 carb problems
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From: novascroller on 28 Jun 2007 10:36 its an 1984 honda cm450e. it has VB22 carbs (CV) I'm having hesitation/stuttering at about 1/4 to 1/2 throttle. the carbs have been professionally cleaned and synced. the slides move easily in the bore. once past this "stuttering" it runs fine. i just had the carbs apart again to doublecheck and couldn't find any dirt in the jets. these aren't the original carbs for the bike but every jet has been properly sized as per the service manual. what am i missing?? thanks.
From: Ed Cregger on 28 Jun 2007 11:39 "novascroller" <novascroller(a)gmail.com> wrote in message news:7hh783l8ubgjbq4uttnfkng8bec77o3g74(a)4ax.com... > its an 1984 honda cm450e. it has VB22 carbs (CV) I'm having > hesitation/stuttering at about 1/4 to 1/2 throttle. the carbs have > been professionally cleaned and synced. the slides move easily > in the bore. once past this "stuttering" it runs fine. i just had > the carbs apart again to doublecheck and couldn't find any dirt in the > jets. these aren't the original carbs for the bike but every jet > has been properly sized as per the service manual. what am i > missing?? thanks. Weak spark. Ed Cregger
From: novascroller on 28 Jun 2007 12:02 On Thu, 28 Jun 2007 11:39:45 -0400, "Ed Cregger" <ecregger(a)bellsouff.net> wrote: > >"novascroller" <novascroller(a)gmail.com> wrote in message >news:7hh783l8ubgjbq4uttnfkng8bec77o3g74(a)4ax.com... >> its an 1984 honda cm450e. it has VB22 carbs (CV) I'm having >> hesitation/stuttering at about 1/4 to 1/2 throttle. the carbs have >> been professionally cleaned and synced. the slides move easily >> in the bore. once past this "stuttering" it runs fine. i just had >> the carbs apart again to doublecheck and couldn't find any dirt in the >> jets. these aren't the original carbs for the bike but every jet >> has been properly sized as per the service manual. what am i >> missing?? thanks. > > >Weak spark. > >Ed Cregger > spark fat and blue, new plugs, coils measure fine.
From: Albrecht via MotorcycleKB.com on 28 Jun 2007 13:34 novascroller wrote: >its an 1984 honda cm450e. it has VB22 carbs (CV) I'm having >hesitation/stuttering at about 1/4 to 1/2 throttle. Are the spark plugs all covered with fluffy black soot? If so, your problem is rich idle mixture, caused by: 1. Incorrect idle mixture screw adjustment. If the idle mixture screw is turned out too far, the idle mixture becomes too rich and the inexperienced mechanic turns the master idle knob up to compensate for slow idle RPM. This uncovers the transition ports downstream of the throttle butterfly and the engine get a rich mixture and fires every other stroke, This is called "stuttering" or "8-stroking". 2. Float level set too high. The engine is able to suck fuel out of the float bowls too easily and the engine stutters until the excess gas is cleared out. 3. Float valve sticks, making the float level too high and the idle mixture to rich. -- Message posted via http://www.motorcyclekb.com
From: novascroller on 28 Jun 2007 14:03
>1. Incorrect idle mixture screw adjustment. If the idle mixture screw is >turned out too far, the idle mixture becomes too rich and the inexperienced >mechanic turns the master idle knob up to compensate for slow idle RPM. This >uncovers the transition ports downstream of the throttle butterfly and the >engine get a rich mixture and fires every other stroke, This is called >"stuttering" or "8-stroking". > >2. Float level set too high. The engine is able to suck fuel out of the float >bowls too easily and the engine stutters until the excess gas is cleared out. > >3. Float valve sticks, making the float level too high and the idle mixture >to rich checked the plugs, the tips are light gray in color and the insulator is a very light brown. . |