Topic: '71 CB500 dies :(

[tjhva]

I have a '71 CB500 that likes to sputter out randomly 5 minutes into a ride then start right back up again and run strong and not die again.


So far I've replaced for various reasons: New coils (from cycle-recycle), Hondaman Ignition, Rectifier, Voltage Regulator (from oregon motor), Stater solenoid and fresh D7EA plugs (gaped to .065mm)


With the bike running at 2,000rpm I get 14.5 volts and with the head light on it's around 13.5 volts. This problem is really puzzling to me especially after I checked all of the connections.

Could these two problems that I notice be the cause of the problem?: A lot of the time the gas tank likes to hiss quietly, even not when its hot out. And there seems to be some oil collecting near the spark plugs, I've read the "pucks" are bad?


Hopefully I can get some direction on what to do next!

[TwoTired]

Is the gas tank cap vent clear?

[1timduke]

Is the gas tank cap vent clear?

Beat me to it TT!!

Welcome to the forum, don't forget to introduce yourself here--->   http://forums.sohc4.net/index.php?board=58.0

-Tim

[tjhva]

Thanks for the reply! I realize it's not preferred to have people pop with one post asking questions.


I'm not 100% sure what you mean by is the vent cap clear? Do you mean is it clogged? Here are photos of my cap:

http://www.flickr.com/photos/44345172@N00/3879856289/in/photostream/
http://www.flickr.com/photos/44345172@N00/3880653228/in/photostream/

<a href="http://www.flickr.com/photos/44345172@N00/3880653228/" title="IMG_0512 by killedinstereo, on Flickr"><img src="http://farm3.static.flickr.com/2619/3880653228_ef38526910.jpg" width="500" height="375" alt="IMG_0512" />[/url]

<a href="http://www.flickr.com/photos/44345172@N00/3879856289/" title="IMG_0511 by killedinstereo, on Flickr"><img src="http://farm4.static.flickr.com/3547/3879856289_caf4729ee8.jpg" width="500" height="375" alt="IMG_0511" />[/url]

[TwoTired]

It does look clear. But, you should test it.   I think there is an internal flap valve that can get stuck. That hole in the cap underside must allow the tank to "breathe" with the atmosphere.

[Spanner 1]

Slow fuel delivery....rust or old fuel ' globs' sitting in the tank fuel inlet.....imo

[tjhva]

The tank is thankfully perfect. It was two tanks welded back together.

I do have some questionable in-line fuel filters that I need to just take out. What size fuel line should I seek out at the auto store?

[TwoTired]

It takes 5mm fuel line that auto stores don't carry.  You can get the proper fuel line at Motorcycle shops.  I got some "bulk hose" and my Honda dealer.

You can make other sizes "fit" but you will either need hose clamps, or have a real wrestle job getting them on.

The nipples were made for 5mm hose which is pretty near 7/32 inch.  Auto shops don't carry fuel resistant hose in that size.  Do NOT get vacuum hose.

[1timduke]

Inline fuel filters shouldn't be necessary if your petcock filter screen is intact and clear (as well as the inside of the tank).   They're kinda redundant and may impede flow.

-Tim