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Another basic CB400 question - starting in cold weather

Posted: Wed May 15, 2013 12:38 pm
by Richh
After my last 'how do I use a fuel tap!?' post, I've got another basic bike question.

What's the correct procedure for starting the bike on a cold morning and using the choke.

Again, it's something I've never had to deal with before because my last bike was fuel injection, and whenever I pressed the start button it stared first time every time, no matter how long it had been stood or how cold it was.

I know the principals of how a choke works (restricts air intake to the carbs to make the fuel/air mixture leaner for easier starting) but this morning and yesterday morning I had a little trouble starting it up and only eventually got it going by trial and error and persistence - no set method. In the evenings when the air is warmer, it starts just fine, no choke needed at all.

So, from reading around the web this morning, this sounds like the way to do it is...

1) Engine in neutral
2) Choke 'on' full
3) Press start button with NO THROTTLE (I think this is where I was going wrong)
4) Hopefully that gets it going
5) Leave the bike for a minute, don't rev the engine or anything
6) Once it's warmed up for, turn 'off' the choke and away you go

That about right? I think my main issue this morning and yesterday I WAS giving it a little throttle while trying to start it, which I don't think it liked.

Also, how long should I turn the starter motor over before giving up and letting it have a rest? 2 seconds, 10 seconds? What's considered good practice. Any other CB400 Super Four specific tips!?

Thanks again everyone,
Rich

Re: Another basic CB400 question - starting in cold weather

Posted: Wed May 15, 2013 1:49 pm
by superv500
I always find each bike has it's own 'choke' technique.... keep using the choke and over a week you'll find that you'll have the art to starting it.

My old CB500 needed the choke fully out, a tiny blip of the throttle and a poke of the button and it would come to life.

Once it's started, get riding, it will reach normal operating temperature a lot quicker if you use it! (I had a massive argument about this with some tw@t who used to start his Subaru outside my house every morning at 6am and run it until it warmed up) Just ease the choke off as you ride.

I always pull the clutch in and make sure all electrics are off to give the engine the best condition to start in. I reckon a good 3 second push is more than enough.

Re: Another basic CB400 question - starting in cold weather

Posted: Wed May 22, 2013 9:18 am
by chricol
cb400 has Constant Velocity carbs which use a vacuum operated slide to richen mixture instead of a choke butterfly. For the choke to work correctly you need to set it before starting and then crank the engine with about 75% throttle. Retard the throttle (not the choke) as soon as the bike starts and the revs will seem to 'rest' on the choke. Think of the choke as a ratchet applied to the throttle. You can then adjust the choke to a reasonable high idle.
Ride normally after starting and you can remove all the choke after 2 or 3 blocks

Hope that helps