Topic: CB500 won't start when wet/moist! Need help!

[ApolytonJS]

Hey everyone!

This is my first post on this forum, I'm seeking any and all wisdom anyone can pass down to me:) So here's the problem: I've had a '72 CB500/4 for ten years now, and since moving to San Francisco, the motorcycle will not start when it's wet/moist/foggy outside. It's foggy 95% of the time where I live, and I have to keep it stored outside, under a cover. I used to be able to ride it in the rain, & it would start up no problem.

I've replaced the spark plugs, spark plug covers, condensor, the battery has juice, it just won't start when there's any kind of moisture on it. I'm not sure what else I can do? Any help you Elders could give me, I'd GREATLY appreciate! Thanks again,

-Jonathan

[luap]

http://scootrs.com/tech.cfm?tip=weather
possible might help out a bit

[CoachDoc]

I'd change the spark plug leads. This made a huge difference on my 550 back in the 90's in the way it ran in the rain and damp conditions. Lots of threads here on how to do this by splicing to the OEM coils, or just get yourself new 5K ohm Dyna coils with new replaceable plug wires.

[TwoTired]

Look inside you points cover for moisture.  Make a neoprene gasket to replace the cork one for the points cover.  Neoprene is reusable.

Clean all the spark plug wires and coils with alcohol so there is no dirt or any "patina" on them.

Measure the battery voltage while starting the bike.  If it dips too low, spark becomes problematic.

Turn off the lights while starting.

Look at the bike coils and leads in the dark while it is running.  Spark "leaks" will be visible.

Measured voltage data would help us make better recommendations.

Cheers,

[NastyNip]

I've been living in the Outer Richmond for 7 years now, and it's just something that I've come to accept with living in this city (along with expensive everything  )

I've had mild success cleaning my idle jets real well and setting the mixture to be a little richer than factory

[ApolytonJS]

Hey, thanks everyone. I've changed the spark leads, & run it a little rich. I'm sure it's the coils that need to be replaced. I haven't been able to find any for less than $200, I'll just keep checking eBay. Thanks again!

To Shnitzel: I'm in Parkmerced, besides Charlie's Place, do you know of any other local places to get used SOHC Honda parts?

[DH]

When you have a dry day, and the bike starts good, try lightly "misting" different ignition componants one at a time.
Use an old squirt bottle filled with water, preferably with an adjustable spray pattern. Start with the plug wire caps.
LIGHTLY is the key word, and try to start the bike. If it starts good, mist the wires and see if that causes the problem.
If that sint it, mist up around the coils. If nothing so far has caused it, try misting around the points cover. If it's an electrical
issue that is aggraveted by moisture this simple trick will help
bring it out sometimes. Just don't get carried away with the water
and don't spray anything like the the points themselves.
Just FWIW....

[Tugboat]

Maybe a stupid question, but where can you get Neoprene to make a gasket with?

[TwoTired]

Maybe a stupid question, but where can you get Neoprene to make a gasket with?

Hardware store.  Around here, OSH has it.

[bollingball]

I ran a bead of silicone on the points cover. Let it cure 24 hrs. It has been on there 2 years now. Clean the area good first to get any oil off. Every time I take off the cover it stays on the cover. You can put it on either side but I found it easy to put it on the cover rather than the engine. Main thing is to let it cure completely.

Ken