Topic: Bike will not start when it is cold....

[gearsoup]

So, I have an '82 CB650. I got it used, and I spent a bunch of time on it. I took the carbs out, gave them a thorough cleaning, replaced all the o-rings, and all the vacuum lines, as well as the fuel lines. (yes, I did split all the carbs apart) Now, since then, it's run really well. I know that my carbs are probably out of sync, since they were completely apart, but it ran just fine. Fast foward to the colder days.....

Now, when I go out at 5 in the morning to ride to work, it will not start. Sure, it will turn over and cough right away, but that is the extent of what it will do. I have tried all positions of choke, as well as playing with the throttle. The only way I have found to start it up is to pull out the two accessible spark plugs, spray some starting fluid in, and crank her ver again. That usually works.
Any idea what I could be facing? I'm not ready to put the bike up for the season just yet....
It does have: 10-40 oil, new filter, air filter is clean, new plugs and wires. I checked the lash of the valves, as well as the cam chain. I don't have a timing light, so I just did a static check, per the Clymer's manual.....

[Gordon]

One thing I've found is that a decent build-up of carbon in the combustion chamber will make these bikes (or any engine for that matter) much more difficult to start when cold.  But before you go delving into the head to clean it out, make sure you're getting a good spark. 
Is the battery holding a full charge?  How's the compression?  You've checked pretty much everything else I can think of.   

[gearsoup]

I don't have a compression tester. It doesn't burn oiil, but it does leak a little around the headgasket. The battery is new.

Perahps someone has a CB650 manual and would be willing to share the recommended start up procedure?

[eurban]

Bypass the vacuum operated fuel safety device (if you haven't already) and see if that helps things.  This is the gadget that is bolted to the top of the carb bank that has the fuel hose from the petcock going to it and then has a fuel hose going to the carb bank.  It also has a vacuum hose connected to it.  It is supposed to only allow fuel to flow when the engine is running/cranking and thus applying vacuum to it.  These can be testy sometimes particularly as they age.  All you need to do to bypass it is to run a fuel line straight from the petcock to the fuel inlet down on the carb rack.  Plug the vacuum hose if you actually remove the device from the carb rack.  Without the device, make sure to turn your petcock to the "off" position when you park the bike to prevent fuel from dumping on the garage floor if the floats hang up for some reason.  Good luck.

[gearsoup]

I've been thinking it was a fuel issue......
That would make sense. I'll try that tomorrow. Thanks!