The International CBX Owners Association

I have a interesting situation and maybe someone can shed light??

I cold start my CBX (1979) without an issue. It has a new battery with even better specs than OEM - I bought it two months ago because I wanted to eliminate a battery issue (old battery did the same as described below!). Once warmed up I'd ride a few km and then return home. After switching off and turning the tank tap off I usually wait for a minute or so and then start up again (like one would do at a filling station for fuel or air)... however the bike then seems to have much more compression (or something??) as the battery struggles to start the bike. After about 5 minutes it just starts up normally again. I checked the voltage during cold start: I indicates 12.8V and drops off to about 12V during startup. However when hot (about minute after switch off) the battery indicates 12.8V but now during startup falls to 9.8V.... As I mentioned the "old" OEM 18A/H battery did the same.

The starter seems just fine and the battery is charged while the motor is running - The volt meter indicates about 13.5V.

Your guess / comment??

Regards!

This sounds like a starter problem to me. Has it ever been serviced?

The starter was removed and inspected... I could not see issues there... After all it never has an issue apart from hot start up.... Regards!

The voltage drop indicates either a faulty battery or high resistance in the starter/circuit, including the grounds. The easy one to check is the current path to the starter. Start with shorting the solenoid with a screwdriver when it's hot, and if it repeats the problem, then it isn't the solenoid. Check resistance on the starter hot lead. Check the ground. Check the starter lead terminals, are they clean and tight? Remove the starter, skin it, and verify that the brush plate is making good solid contact with the starter body via the little ears on its edge, as that's how it grounds. Some electrical connection in your starter circuit is becoming weak/poor as a result of things heating up and spreading apart.

Thanks! Will check asap.

How will one know if the starter does not disengage after start-up but is for one or other reason running with the engine?? (if possible?) I do hear the starter "kick" in when starting up but a lot of times I hear that same (starter) sound when switching off after the engine ran....

I took the starter out. It seems to be in good condition. Included is a photo of the hole in the casing where the starter fits in. On can see the gear inside. I can rotate this gear with my finger - it engages going the opposite side, however the "free" side has some feel of resistance - like a course bearing - not rotating 100% freely... is this OK?? Regards!

There is no bendix on our starter, it is always engaged with that gear. The gear has a clutch and so you should be able to freewheel it fairly easily in one direction but not at all in the other. What electrical tests have you run?

As mentioned the starter clutch only hooks up one way as you say and is "fairly" free in the opposite direction (relatively free in the sense that I feel some slight friction with my finger). I took the starter to a bike shop that checked it out. From brushes, bushes, armature... Seems to be in good shape! I also connected it to 12V before installing again - it spun up all OK. No suspicious sounds or noises. Thanks!!

Did you short the solenoid and see if it spun normally? Inspect your grounds and cables?

Yes - I used a large screw driver for the solenoid. Cables are OK. I must say it seemed to start a little easier with the shorted solenoid.... I will check that again when the bike is hot. Thanks!

It might be a good idea to check voltage drop across the cables while cranking. I've seen them corrode internally while looking fine on the outside.

Thanks Rick. My cables are all new... and maybe a bit on the thinner side compared to the OEM ones...

Rick Pope wrote: ↑

Thu Nov 04, 2021 8:07 am

It might be a good idea to check voltage drop across the cables while cranking. I've seen them corrode internally while looking fine on the outside.

Especially any cables/wiring with crimped connectors vs soldered connectors. (That's why the Japanese auto went to solder long ago for certain cables and wiring. (And, subsequently, the US mfr.)

Agreed Larry! Thanks!

Larry Zimmer wrote: ↑

Thu Nov 04, 2021 11:52 am

Especially any cables/wiring with crimped connectors vs soldered connectors. (That's why the Japanese auto went to solder long ago for certain cables and wiring. (And, subsequently, the US mfr.)

Especially interesting because some big truck manufacturers (Volvo/Mack) only crimp, never solder. Something about making the wire susceptible to breaking.