Topic: ‘78 CB 550 starter doesn’t work when hot

[RWWARD4]

My bike starts easily when cold but after it gets hot the starter acts like the battery is dead. Battery is new and it will kickstart. After it cools down the starter works fine. Help!


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[scunny]

Had that happen on my 650, turned out to be the solenoid.

[kerryb]

I had a very similar set of symptoms  with an '83 goldwing.  After rebuilding the starter (twice) and using a better battery, the problem was traced to a poor ground contact between the starter body and the engine block.  Cleaned the ccntact point with sandpaper and the problem went away.  It seems when the parts heated up and expanded the contact wasn't good enough, the starter would turn very slowly if at all.
I suggest you pull the starter and clean the bottom boss where it bolts to the engine block, then check/ clean the ground strap at the frame contact point too.

[RWWARD4]

Thanks-I will try the starter ground first and if it doesn’t work a solenoid is relatively cheap. I have rebuilt starters before so if I need to will try that last. Anyone else been through this too?


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[RAFster122s]

The CX500 uses the same starter I believe as the CB550 and they have traced some starter issues with the starter body and the ground of the starter to the case to the internals gets iffy and they have added a strap from the inside of the starter to the case with an added screw.  Let me see if that procedure for the rebuild is available with pics to see what I am talking about.


There are three tangs on the brush holder plate that ground that plate to the starter end cap. Those grounds get arcing and subsequently pit and make a dodgy connection with time. The fix the CX guys came up with was to extend the brush holder screw to the end cap with a pigtail braid of wire to the end cap or a bolt through the end cap to secure the brush holder from the outside.


Here’s a thread with images.  Originally I had seen the fix on ofpar’s site in the Netherlands but he discontinued his site so I had to pull it off the AUSTRALIAN CX forum site.
https://australiancx.asn.au/forum/index.php?topic=4459.0


They also found a secondary ground from the battery to the starter body and the end cap never hurt things either...

[Keith]

Back in the day I was a Vw Porsche Audi technician. It was common to trace poor cranking to a worn starter bushing. We would run a tap into the bushing and his would pull the worn bushing out. Could this happen on a honda engine?

[RWWARD4]

Update- removed and disassembled starter-all good. Checked battery when running-not charging. Don’t ride much and keep bike on tender so that is why I never noticed it. All 3 Stator coils about 1.7 ohms with no shorts to ground and rectifier (new)good. Could it be the coils are bad-cannot find what the resistance should be for this ‘78 K.


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[scunny]

Don't think it will be coils, motor would still crank over even if coils were shot, and they don't tend to fail.