cold starting

[K2-K6]

Extrapolation of effects in this case:- if fitted with stronger spring Or originally had no spring (correctly for that carb) then it will be richer running from straight off the bat to full power with this current spring fitted.

Failure to start and assuming spark is there (plugs verified) with that voltage while cranking test showing anything of use. Then rich can give no effective combustion as the mixture fails to ignite simply because the fuel droplets that are nucleus of combustion aren't volatile enough to start process going. Just gets worse the more it's cranked over. That verified by then cleaning the plug with heat gun.

If it's verified that they can run with no spring fitted, that would be a good assessment to gauge effective starting. I'd make sure that the plug was very tight onto it's gapping spec though, this to try and mitigate the "expected" flat spot that the revised spring is supposed to cope with, as that condition is, or should be, lean running. 

[McCabe-Thiele (Ted)]

The manual I looked at CB450 KO shows no spring on the carbs tops.

[mo goldie]

yes Ted you are right they did Not, But as Ashley told me that due to the flat spot around the 4,000 RPM that Honda got a kit out to Try to sort that out one of the things along with the jets needles etc was to fit a spring.

[K2-K6]

The question would be then "does it change anything in starting either springs removed ? " to find out IF there's an effect caused or propagated by them.

Then to bring other questions about running if there was positive change with that.

With electronic ignition (thought it was mentioned previously) some difference in fuel composition now to when that adaption was specified, what is the current situation.

[mo goldie]

yes that will be the next thing to try.......... oh and the fuel well what can I say dam E10 stuff all our old engines don't like that at all ha But I run all my bikes on the super UNleaded.....bring back 4 starr ...ok NOT then lol.

hope to do that some time next week when I get all the Hospital appointment done I will see how it all go`s thank till then.

[Toko_Jo]

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The manual I looked at CB450 KO shows no spring on the carbs tops.

[Oddjob]

Anyone notice the last paragraph, out for richer, in for weaker but is contrary to normal Honda practice, meaning it’s normally in for richer and out for weaker. Exactly what we all, well most of us, thought.

[mo goldie]

Hi all just and update again,

I took the tops off the carbs today and noticed that the left kept getting stuck in the top hat so after cleaning and a bit of polish they both now fall up and down freely with the springs on and off, one thing I did Not say is the springs that I have are honda but from anther bike as could Not get the ones that Honda did for the upgrade kit for the Bomber,

So if anyone has got any of the right ones part Number 6186-283-305 if they know what the lengths of them are as the ones that I have are 8cm long, they were 12cm long but I cut them down as they were far to strong to push up on the piston so I cut them down to counter act that. so if you know the true length I think that will help.

[K2-K6]

Hope you're well after hospital trip.

Ah ha, the springs are definitely suspect then.

Cutting them actually increases the spring strength, but reduces preload. Both of which you don't want in this situation.

Definitely try without them then, and would likely give some credence to your running observation of rich mixture (from having the spring too strong) it fundamentally alters the whole mixture landscape.

In effect, a stronger spring changes the vacuum under the airslide (by altering balance equation above and below) to suck too much fuel through the main jet, irrespective of it's size. Usually you'll get very quick response when you wind it on, even under load, but over fuelling that'll do for your oil by diluting it through washing past the piston rings the excess and unburnt fuel.

Interesting to here any significant change in response without the springs.

[Toko_Jo]

Spring Spec. for  16186-283-305

Spring Rate 1.3 gm/mm

Free length 71 mm

Wire size 0.55mm diameter.

Outside Diameter 17 mm

[K2-K6]

Do you also have the original jet size spec to compare with that modification sheet Toko_jo ?

I'm interested in what they've changed to gauge the effect they where delivering.

[Toko_Jo]

Do you also have the original jet size spec to compare with that modification sheet Toko_jo ?

I'm interested in what they've changed to gauge the effect they where delivering.

Some of the kits put together by Honda UK's UK Service Centre in Nottingham in the 1960s contained a #130 main jet (STD was  #125) Hope that helps!

[K2-K6]

Thank you, yes helpful.

Anything also on the idle jet details given too ?

[Toko_Jo]

Thank you, yes helpful.

Anything also on the idle jet details given too ?

Slow and pilot jets in the upgrade kit were both #35 size.

[mo goldie]

testing...