My CB400 is a cold-blooded little sucker!

[Mikep328]

Went out for a ride today - bike hadn't been ridden in 4-5 weeks.  It took probably 10+ attempts to start before it would finally run for more than a second or two.  This was with choke full on/nursing it as necessary.  Once it started/sputtered for a few seconds it then fast idled properly with some fiddling with the fast idle/choke lever.  Once I got on the bike and started off, it ran perfectly.  But cold starts after sitting for an extended period are not its thing. 

Are they generally stubborn about cold starts or is it just mine? 

In any case, I rode for about 20 miles after adding some Stabil/filling the tank with normal pump E10 thinking that might be the last ride this year though we're thinking of taking a ride next week if the weather cooperates.

[Nurse Julie]

I hope that was a typo and meant E5 and not E10 🤔🤔🤔

[Mikep328]

No, no typo - E10.   

[Nurse Julie]

No, no typo - E10.   

😳😳😳😳OK, why not E5 low Ethanol? I can't see why E10 would be used when it's know to be very detrimental to long term storage.

[Mikep328]

Never thought about it - I just grab the "regular" petrol dispenser at the station where I typically buy fuel in town and it's E10! 

[Nurse Julie]

Never thought about it - I just grab the "regular" petrol dispenser at the station where I typically buy fuel in town and it's E10! 

E10 is the kiss of death at the best of times, for a bike that is either being stored or not ridden very regularly, it will cause major problems. The Ethanol absorbs water from the air, water in fuel systems can cause rusting of the tank , Nitrile O rings in the carbs will disintigrate and clogging of all the internal passages of the carbs and jets will happen.

[Nurse Julie]

Using E10 could be the problem for the bikes poor cold starting, maybe the idle jets and circuits are blocked, or partially blocked.

[Alexrayz]

Hey Julie and Mike!
How big a difference would you say E5 is compared to E10?
I stick to E5 for the reasons you mentioned but I wondered how big the difference is. I don’t ride my ride so regularly these days and I’m always worried the carbs are getting pooped.

Cheers!

[McCabe-Thiele (Ted)]

A lot of E5 was actually E0, E10 is just that 10% Ethanol, a lot of E5 is well below 5%.

Personally I have never used anything other that E5 since they started putting the Ethanol in petrol.

For quite a few years  Shell V power was Ethanol free as was Esso SUL that has changed in the last few years,  SUL in the south of England was E5, in the North it was E0 as the refinereies were older iirc, it might be that Shell is still E0 but they have to put the E5 label on the pumps by law.

[Mikep328]

Thanks NJ!  I've read that E10 can cause some hard starting on old vehicles so that could be the issue.  OTOH, I've used E10 in the USA for the last 8-10 years - since it became the "normal" fuel at the pump.  Haven't had any issues with it at all as long as StaBil (or equivalent product) is added for long-term storage.  As I posted in another thread, my 2019 Kawasaki Z900RS, with E10/StaBil in the tank, sat without running for two years and it started immediately/ran perfectly.  I didn't intend for it to sit for two years but it just worked out that way! 

I think carbureted engines are much more prone to ethanol issues because the fuel is exposed to fresh air via the venting for the fuel tank and the carburetors.  In FI systems there is far less exposure - essentially none when the engine's not running.    Although for winter storage, I add Stabil, my wife's 2019 Honda 750 has no issues with starting/operating on E10 during the riding season even if sitting for four or five weeks between rides but of course, it's fuel injected. 

I've decided I'm going to pull the carbs on the 400 and disassemble/see if there are any deposits/etc.  Depending on what I find, I may decide to add StaBil at every fill up since the bike can sit for several weeks at a time.  If E5 is available at the normal pumps I use here in the UK, I'll switch to that but I won't make any special effort to find it.  If I have to go out of my way, I'm too lazy to bother! 

[ka-ja]

Drain the carbs for long term storage, whether E5 or E10, ethanol can rot some metals over time.

[McCabe-Thiele (Ted)]

In modern times we have become accustomed to engines starting straight off the button with fuel injection.
With carbs if an engine is not used regularly they take some cranking over to pull the petrol through to where it's needed.

If you want your 400 to start immediately off the button that can be done - just squirt some easy start into the air intake, it will fire up almost instantly run for 5-10 seconds then splutter a bit as it starts to run on petrol.

Personally I like the idea of the engine cranking over as it pumps oil round the crank & cam before it starts running. I would not advocate the regular use of easy start type sprays.

[K2-K6]

Probably a good move to check the carbs for any untoward effects.

The first thing that should happen when cold starting is for the idle jets to go full "suck" against the vacuum created by choking the intake.

Sounds familiar, doesn't it  any impairment compromises that effect to take fuel delivery below target, making  it sub optimal. As they say in modern parlance 

The ancient art of stuffing an old rag into the intake was a historic way of "encouraging " the low fuel circuit to get up and go when reluctant. Probably to suck the chunks out of that circuit with any soft debris accumulated

[Mikep328]

Pulled/disassembled the carbs - all parts/passages as clean as they were when I had cleaned/adjusted them in late '21.  Float levels are not exactly the same as they were then but are all within a mm of their settings.  Bench sync settings are still as they were then so no issues with that.  IOW, I don't see the hard cold start issue I experienced yesterday being related to the carbs. 

FWIW, I started the bike today (fresh E10 yesterday) before removing the carbs and it started immediately with no issue at all.  So it appears to me that the starting difficulty yesterday was the E10 fuel.  As I said, it had been sitting for 4-5 weeks since the last run.  Maybe E10 needs stabilizer added for carbureted engines if it sits for more than couple of weeks!  On my wife's bike and my other bike (both fuel injected),  there is no issue with the same 4-5 week-old E 10.

[McCabe-Thiele (Ted)]

I use fuel stabiser in E5 in my bikes and our old Merc.

I also add Wynns Dry fuel for the winter into the bike tanks - the Merc has a plastic petrol tank so I dont worry about water pooling in the bottom.