won't start via solenoid but will run

[riddmkidd]

hi all, trying to troubleshoot my 65 cb77. ran errands after a nice ride up to the local reservoir and back, a good 100 miles in the mtns. she wouldn't start (fortunately at home) though and all I got was a single CLICK from the solenoid. bridging the terminals on the solenoid does nothing. the battery is strong, I confirmed power getting into the solenoid but the feed line heading to the starter shows nothing. she will run via kick starting at least. what do I look for next? double checked the wires in the headlamp housing and everything looks "normal", though I'm new to working on electrical issues.

I removed the solenoid (talk about fiddly) and was able to get the lid open part way to see inside and the black thin wire (12+?) seemed loose. unfortunately I can't get the wire clamp undone and I don't want to risk doing any unnecessary damage. any tips on getting the housing off? if it's a disconnected wire I'm comfortable with resoldering if I have to but I feel like I'm walking in to a room blindfolded at this point.

could it also be my starter? this is a 13k mi. full restoration that I've put 1000 miles on since last August. avid rider here...

[riddmkidd]

would this work as a replacement? pending mounting adjustments of course...

https://www.common-motor.com/honda-elec ... LcEALw_wcB

[Tim Allman]

These relays (solenoids) are quite rebuildable. Often they just get gunked up with dust and corrosion so a cleaning will bring them back.

The two screws on the front of the relay are all that hold it together. The front piece will slide off although rust may make it difficult. The wire clamp (I assume you mean the sheet metal part that wraps around the wires) can be opened up with needle nodes pliers. There are tiny grommets that seal the wire holes. If they are in good shape the wires should slide through them as you pull off the front cover. Don't bother removing the terminals on the wires as all you need is room to work on the inside of the relay. (My grommets were in bad shape. I looked for reasonable replacements but to no avail so I just removed them and sealed the wires into the holes with black silicone when I reassembled it.)

Check the coil itself by touching the wires to the battery. If the polarity is correct you will see the centre contact push out on top of a small rod. If nothing happens, switch the polarity. If nothing happens again, it means that there is a problem with the coil. I have never disassembled the relay beyond this point so I can't help although I think you probably need to replace it.

Clean the large contacts. Steel wool or fine sandpaper work well. The contacts on the large terminals can be removed to make cleaning easier but be sure to keep track of where the nuts and washers go. The fibre washers are important for electrical isolation. Messing up here could lead to a nice fireworks display.

Reassemble and reinstall.

Start bike and have fun.

[Tim Allman]

It just occurred to me that, of course, the problem could lie in any of the connections, large and small, at the solenoid and at the starter motor. If the solenoid is not the problem It's probably the starter motor. Let me know.

There's a service manual (along with some other interesting things) in this directory on Google drive.

https://drive.google.com/drive/folders/ ... drive_link

[riddmkidd]

my collar that holds the wires together is crimped on so right I can't get the needle now pliers in there to bend them back. tried for 20 minutes yesterday. but the rest is very helpful thank you! I'll keep plugging away at it.

[riddmkidd]

update:

I connected the solenoid directly to the battery and it works fine. I can hear the switch move every time I made contact (stripped a couple lengths of wire while the battery was disconnected from the bike).

my led taillight arrived so I installed that (from super bright LEDs dot com) and kicked her over just to see what would happen and the high beam was modulating a lot more severely than before. gunning the throttle made the head lamp go very bright until it blew the filament. oops... does this mean my rectifier is to failing or did the led bulb's lower power usage send more power to the headlamp?

I've got a sparck moto reg/rec but I'm feeling intimidated by the installation and writing conversion. I may take it to my local mechanic to do that job.

while my battery tests fine what are the odds it's not strong enough to run the starter motor?

[Tim Allman]

The sound of the solenoid is a good start but I'm still wondering about your battery. If it fits the battery box the capacity should be fine if it is in good condition.

I would try disconnecting the big cables from the solenoid and connect them momentarily. This makes a direct connection from your battery to the starter motor and it should turn over the engine immediately. If nothing happens, the problem is elsewhere, perhaps the ground cable from the battery, the starter or the starter itself. If it turns over, but weakly, I would guess that the battery is not charged.

Installing a rectifier/regulator is probably the best thing you can do for the electrics. As manufactured, the only voltage regulation is done by the battery. It's not great when the battery is new and gets worse as it is used. This again points to the battery as this is the main reason for blown bulbs. If you take your bike to your mechanic to install the regulator maybe he or she can have a look at the starting problem.

Here is a directory on Google drive containing manuals etc. that I have accumulated. You may find it helpful.

https://drive.google.com/drive/folders/ ... drive_link