Topic: Cold starts - is there any tips or tricks

[Scott]

Hi there
I have had trouble last winter (Sydney winter) with cold starts on my CB750 K2.
Not real cold here in Sydney, maybe 8 to 10 celcius (46 to 50)
Latter on this year I will going for a ride and it may get down around 0 celcius (32)
If there is any thing that I can do in advance before going on my ride to hopefully make cold starts easier, then I will do it for sure.
Thanks for any tips or thoughts on preparation for cold starts

Scott

[TwoTired]

Turn off the lighting before hitting the start button or the kick starter.

Use 10w 40 Oil viscosity.

Have a recent tune up performed.

[tomkimberly]

Turn the throttle 2 - 3 times, then turn on the electrical, hit the starter button. It's a Honda, and should fire right up.


Tom

[70CB750]

Are you using the original air box? I dont but i understand the original setup is the best.

I do half choke, half throttle and start. When it runs I worked the throttle and the choke to make sure it stays running. When it warms a little I hit the road typically with choke on 1/3. The choke comes of at the first stop sign - 500 to 800 meters, depends which way I go.

[totty]

2 kicks full throttle with choke on and ignition switch off. Then start as normal.
I think this is in the manual, I've only done it to ensure easy starting when around freezing, but it probably would have started as normal anyway.

[trueblue]

I always turn the fuel tap on for a few minutes to ensure the carbs are full.  My 650 has an accelerator pump, so I give four twists on the throttle, pull the choke and press the button.  Always fires right up even if it has been sitting for a couple of months.  The K2 doesn't have an accelerator pump so don't bother fiddling with the throttle.  Make sure your engine is in perfect tune, valves set, points, timing, idle fuel mixture and carb sync.

[andy750]

For my CB750 K2 (and to an extent my K4), I dont have cold starts. The K2 fires right up and can be used within 30 secs even on cold days. No lag on acceleration. It has stock airbox, 40/120 jets, HM300 exhaust, stock carbs that are in perfect working order. The K4 takes a little longer (1-2 min) and then maybe 0.5 mile before it dosent lag on take off.

I think for the older CB750s with no accelerator pump "cold starts" are a function of the state of the carbs and not a characteristic of the bike.

good luck
Andy

[evanphi]

Around 0-5C, I use electric start after kicking twice at full throttle/choke with electrics off. Fires right up, and then just need to keep the throttle going for a minute or two to warm the engine up. Reduce to half choke, ride off, and work the choke down gradually over the next few minutes.

[Stev-o]

Be sure your battery is fully charged. Do you have a battery tender?

[bjatwood]

2 kicks full throttle with choke on and ignition switch off. Then start as normal.
I think this is in the manual, I've only done it to ensure easy starting when around freezing, but it probably would have started as normal anyway.

I would add to this, turn the fuel on for say a minute before doing the above procedure to "prime" it when you kick it. Not all CB's have a accelerator pump on their carbs.

[Scott]

Thanks for all the responses
 
The bike has standard air box and new points, plugs, leads, coils and valve clearances set. I put kits through the carbs a year or two ago myself.  I have another set here rebuilt by a specialist, I might put them on for a test of cold starting once the weather cools off a bit.

Batt is fairly new and has heaps of power to turn engine over.

I'll try the method of kicking it with ignition off then using electric start, once again when weather cools off a bit.

I'm not going for 3 months yet but just trying to get bike sorted before the last minute as is usually the case with me

Scott

 

[lrutt]

Turn the throttle 2 - 3 times, then turn on the electrical, hit the starter button. It's a Honda, and should fire right up.


Tom

K2 has no accel pump so cranking the throttle will do nothing. Only the K7 and K8 had accel pumps, at least in NA.

[Henning]

Stupid as it sounds, a new, well lubricated throttle cable makes it easier to start. Lets you dial in just the right amount of throttle to get it going.

[Black 750K8]

Turn the throttle 2 - 3 times, then turn on the electrical, hit the starter button. It's a Honda, and should fire right up.
Tom

Tom I know my bike with the accelerator pump pd 42b will benefit from turning the throttle 2 - 3 times But I don't see what this would do for non accelerator carbs. Just asking to learn.
 update Sorry I see irutt covered this.

[Geeto67]

I have a K5 and andy is right, the later K3-6 bikes tend to be more cold natured than some of the earlier bikes. I think it is how they re-tiuned them for emissions and has as much to do with cams and timing as it does with carbs. Honestly the best thing is a throttle lock. When I have to start my K5 and it is 30 degrees F or below out, I give it a power off priming kick (sometimes with the throttle WFO), and then kick it to life. It usually starts right up but won't idle. I then use the throttle lock to hold the bike at 2K rpm while I put my helmet and gloves on and give it a few minutes to warm up. When I am ready I release the throttle lock, set the choke at about half and ride off. No lag and by the time I hit the first stop light the bike is idling or close to and no choke. When it is warm out, that bike starts first kick every time. 

[AJK]

This is what i do with my 750 K2.

Turn fuel tap on, wait about say 30secs to 1 min. 1 minute is better if the bike has been sitting for a while.

Put choke on full. At the same time, hold the throttle 1/8th open and press the starter button. The bike should fire right up. Once fired up, immediately open the choke about say 10mm (press down on the choke lever by ~10mm) whilst continue holding the throttle 1/8th open. When you do this, you will hear the bike run nicer as its now getting some air.

I can leave the bike sitting for weeks and it always fires up first go using this method.

PS: I never find it necessary to twist the throttle beforehand, but it should help you fill the bowls quicker if you do. This is not really necessary as trueblue has mentioned.

[trueblue]

PS: I never find it necessary to twist the throttle beforehand, but it should help you fill the bowls quicker if you do. This is not really necessary as trueblue has mentioned.

It isn't on the early 750's, which I said if you read my post properly.  I was simply saying what I have to do for my 650.  If you don't prime it with some fuel it won't start from cold no matter how warm it is out.  Just the way it is.

[LesterPiglet]

I was surprised how easily my bike starts after installing Hondamans ignition system. I couldn't recommend it enough. I don't have a kickstart so it's always the electric boot. Never fails even after sitting for weeks in an unheated garage.

[AJK]

PS: I never find it necessary to twist the throttle beforehand, but it should help you fill the bowls quicker if you do. This is not really necessary as trueblue has mentioned.

It isn't on the early 750's, which I said if you read my post properly.  I was simply saying what I have to do for my 650.  If you don't prime it with some fuel it won't start from cold no matter how warm it is out.  Just the way it is.

Hi True blue, i was actually agreeing with you. 

[eastyork1977]

10w-40 is ideal for colder temps.

I've found about this small trick that works on most Hondas on a cold day, and I'm in Canada.

I usually kick start the bike or get it started with choke pulled all the way.

As the bike starts to warm I let the choke out gradually for about 1-2 min max.

After that I turn the bike off and wait for 1 min.

I then turn it back on and find the RPMs and idle is stable at close to 1000, I wait for another 3-4 minutes for it to drop a bit more.

If I rush and don't do this I find the bike takes about 10 minutes to warm up while I'm riding and I have to adjust the throttle stop on the fly.

[dave500]

id hate to have a kick only bike,mines well sorted and runs bloody well,even with the fuel on for a few minutes and proper choke use itll take a good spin on the starter to spin up and fire even in my location in queensland,it rarely gets below tee shirt and shorts weather here,ive never tried starting it from cold on the kicker,ill give it a shot.

i think a few novices whove only had fuel injected cars expect old bikes or cars to start on the button and idle straight away?most old carbed engines will need some sort of throttle use to hold a cold idle and wont settle down till properly hot?so many old cars had a certain way to start them from dead cold that if you did it wrong they wouldnt start at all,even with correct ignition settings etc,i think old chrysler sixes were the worst?

[70CB750]

You right about the carbs and people. I retrofitted TBI injection on my jeep in 99 and forgot all about car carburetors.
Than when I first tried to start Honda I would do it with closed throttle

[grcamna2]

This is what i do with my 750 K2.

Turn fuel tap on, wait about say 30secs to 1 min. 1 minute is better if the bike has been sitting for a while.

Put choke on full. At the same time, hold the throttle 1/8th open and press the starter button. The bike should fire right up. Once fired up, immediately open the choke about say 10mm (press down on the choke lever by ~10mm) whilst continue holding the throttle 1/8th open. When you do this, you will hear the bike run nicer as its now getting some air.

I can leave the bike sitting for weeks and it always fires up first go using this method.

PS: I never find it necessary to twist the throttle beforehand, but it should help you fill the bowls quicker if you do. This is not really necessary as trueblue has mentioned.

I like starting them w/ full choke(on some bikes w/ just a c-hair off of full.. )and then when I engage the starter I keep the throttle at the lowest setting I can(and adjust as she responds best)to fire it up.It helps me to keep a Very steady right hand on the setting of my throttle and even slightly close it another c-hair until she catches.
I think that the choke butterfly and the slide can act together to create enough vacuum to pull the fuel up from the bowls through the jets on non-accel. pump models.This new Ethanol fuel kind of makes me to want to drain that stuff from the bowls if I let her sit for too long.I like being able to kill the lights before starting on the older models.I think it's also good to keep your coil connections,ign. sw.,kill sw. black & white wires good and clean for a hotter spark when cold.
Has anyone used 10/30 oil in the extreme cold ? How's it worked for you ?

[Doggie]

My '78 CB750K has the choke on a spring return and I have trouble holding that out, turning the throttle, and pressing the start button. Not enough hands!! Anyone have the same problem or am I doing it wrong?
                                                Doug

[AJK]

This is slightly off topic, but somewhat on topic as well.

Years ago when i was a kid & mowing lawns, my father would always teach me to let the mower stop by turning off the fuel and just let it die by fuel starvation. This kept the carbs clean he said, so next time you start it up, it fires right up.

Having this in my mind all these years continues this habit on the sohc. About 500 metres from home, I turn off the tap & the bike usually just starts to die off as i'm in the driveway about to turn it off and park it.

Now, i don't think any of this actaully matters if you are using the bike fairly frequently as you generally always have fuel flowing through the system keeping it clean. But if your going to store the bike for some time, at least, the only thing that is going to gum up in this respect is likely only the fuel bowls and nothing else. Of course, the next time you go to start it, you will need extra time to allow the bowls to fill up, which is no big deal.

Anyhow, take it as you wish, but just something that i learnt years ago.