Topic: 78 CB550K stalls

[jturner8]

First - thanks to all for helping me sort out some problems with a cold-natured bike.  Switching out the plugs from 8s to 7s worked very well, and adjusting the valves and (duh) helped as well.

Now I've got another issue.  The bike ran very well for 300 miles then developed the problem of stalling once I was on the road.  This has happened twice.  The bike stalls and then has no power even though the battery is new.  After charging the battery it starts first push on the starter but once on the road stalls with a loss of power again.  When the bike first stalled with loss of power I figured the main fuse needed to be replaced but it was fine. 

I'm now thinking that the problem lies in the charging system - perhaps the AC condensor.  Any ideas.

[martino1972]

define "stalling"
are you putting around town and she suddenly dies,or are you on the highway doing 70 mph when she cuts out,etc. we need more detail info on the problem..

[TwoTired]

If the bike runs okay with a fresh battery charge, then it is time scrutinize your charging system.

Charge the battery, then start the bike (kick), and then make battery voltage measurements at idle, 2000, 3000, 4000, and 5000 RPM.

The stock bike (you didn't say if the bike has any mods) draws about 120 watts with the keyswitch on. The alternator makes about 50 W at idle and 150 watts at 5000 rpm if all is well.

This means if you left it idle long enough, there won't be enough power left in the battery to fire the spark plugs.  If you spend more time below the RPM where the alternator does charge the battery vs the time spend at RPMs where it does, the engine will stop.

If you added a higher wattage headlight, you have exacerbated the issue.

perhaps the AC condensor

 
I never heard of a 550 with air conditioning.  Where does the compressor get driven from?
Show us a picture!

Cheers,

[martino1972]

I never heard of a 550 with air conditioning.  Where does the compressor get driven from?
Show us a picture!

Cheers,

  i was thinking the excact same thing,but didnt wanne reply on that,happy you did,awesome!!!

[jturner8]

Thanks for the replies.  The bike has no mods - all original and proud of it.  Any yes, the bike is principally an around town vehicle, rarely seeing rpms above 5K.  It's kinda sad b/c the bike REALLY likes to run all out.

[martino1972]

now we still dont know what excacly it is doing....
tell in detail what happens,and you will get alot of help...