Show Posts
121
CB500/550 / Rough Running advice needed -- at wits end
« on: September 19, 2016, 08:30:46 AM »
My 500 Four is running like a pig and I am at my wits end trying to fix it !!
Symptoms are will not pull away from start properly and have to rev and slip clutch like hell to get going. It's so bad I cant ride it because it's dangerous when pulling in to traffic etc. I also think there is a lack of power overall, the motor just doesnt feel "zingy", feels really lumpy and feels underpowered.
Since my rebuild its got much worse. Things is have checked/changed
New Points
Timing spot on
New plugs
Good spark at all pots
Valve clearances spot on
Carbs well balanced
Float heights about 3mm below carb flange so also bang on
New pistons and rings so not a compression issue
I have come to the conclusion I have a carb problem but would like some thoughts and help. Other symptoms I have noticed are
Plugs 1,2 and 3 are very dark and sooty (rich) but plug 4 looks good
Advancing timing to nearly max advance point at tickover makes idle smoother
Moving air screw from 1/2 to 2 turns out seems to make absolutely no difference to behaviour
So bottom line she seems to be running very rich particularly at up to 1/2 throttle
When I did my rebuild I did not replace all the jets just cleaned them and replaced O rings so now I have ordered a full carb kit of all new jets, pilot screw, float valve etc so while i wait foe delivery I want to also to do more checks on the carb bodies.
Is it possible I may have a blocked idle circuit? If so how can I check there are no blocked passages anywhere in the carbs. I am not sure what hole connects to what as I cant find a Keihin eploded diagram. What holes should I squirt carb cleaner down to see if the passageways are clear and wher should it come out??
Symptoms are will not pull away from start properly and have to rev and slip clutch like hell to get going. It's so bad I cant ride it because it's dangerous when pulling in to traffic etc. I also think there is a lack of power overall, the motor just doesnt feel "zingy", feels really lumpy and feels underpowered.
Since my rebuild its got much worse. Things is have checked/changed
New Points
Timing spot on
New plugs
Good spark at all pots
Valve clearances spot on
Carbs well balanced
Float heights about 3mm below carb flange so also bang on
New pistons and rings so not a compression issue
I have come to the conclusion I have a carb problem but would like some thoughts and help. Other symptoms I have noticed are
Plugs 1,2 and 3 are very dark and sooty (rich) but plug 4 looks good
Advancing timing to nearly max advance point at tickover makes idle smoother
Moving air screw from 1/2 to 2 turns out seems to make absolutely no difference to behaviour
So bottom line she seems to be running very rich particularly at up to 1/2 throttle
When I did my rebuild I did not replace all the jets just cleaned them and replaced O rings so now I have ordered a full carb kit of all new jets, pilot screw, float valve etc so while i wait foe delivery I want to also to do more checks on the carb bodies.
Is it possible I may have a blocked idle circuit? If so how can I check there are no blocked passages anywhere in the carbs. I am not sure what hole connects to what as I cant find a Keihin eploded diagram. What holes should I squirt carb cleaner down to see if the passageways are clear and wher should it come out??