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CB466f
Erwin83:
--- Quote from: kevski on April 30, 2017, 06:57:23 AM ---I just see you are running open pipes, this can affect the running as no back pressure, you may need to increase the size of the pilot jets to compensate, the information for the air screws is correct and turning them in will increase the fuel at low engine speeds but may not be enough.
--- End quote ---
Thanks Kevski! Quite helpful.
I think i have the screws all leaned out now at 2,5 out.
So let me first try to make idle somewhat richer by turning everything in again. After syncing, i have not played with the air screws at all.
With regards to the lack of back pressure, isn't that something that especially plays a role at higher revs?
I'm actually quite happy with how she runs higher up.
kevski:
The air screws are what the pilot circuit is metered by with them maxed out and open exhaust you are leaned right out giving you the poor running at low revs take them in a bit at a time and see what it gives you, you need some back pressure even at low revs to run smoothly.
Erwin83:
Changed the float level to 24mm now..... And we've got reliable idle!
Also a nice coffee brown color on the plug.
Turns out i also had a broken coil lead on pot 2. Did a bush-fix with a small screw, will order new replacement coils with new leads as all are very rigid and old.
Still with a hot engine (seriously hot), it drowns on pick up from idle to any throttle.
Will look into the air screws a bit see what that does.
With my friend's 500 four, out playing together:
Erwin83:
Last week I installed a new set of (aftermarket) coils, after I broke a lead, just after selling my spare coils. Ah well...
The settings of my little 400 is juuuuuuuuust about perfect now. 8)
I don't have any hick-ups while riding, and both constant speeds as full throttle I'm getting a healthy response and good sounds.
Even the dreaded camchain noise has reduced significantly since I pushed the rod down according to known methods...
The only thing is still the idle at warm / hot engine.
Since I synced the carbs, she runs idle very well and sounds sweet but a few seconds in and she drops below 1000 rpm and ends up stalling, unless I blip the throttle again.
In order to avoid endless carb setting tinkering, could this be related to another setting or a defective components?
Points setting, ignition timing, condensors, advancer?
andut:
Good to hear that you're getting some progress Erwin !
Does the idle speed increase before it dies and do you still have the air screws at 2.5 turns ? If it isn't increasing in speed before stalling, it could be overfuelling slightly, so you may want to try running it a little weaker via the air screw adjustment and see if it improves - do the plugs look wet immediately after it stalls ?
You'd expect to wind the air screws out to weaken it - more air = leaner mix, but I read an equally plausible description of the 400's Keihin idle circuit as posted by Hondaman on the US site that makes some sense and suggests winding the mixture screw out will actually richen the mixture as it's the air bleed that draws the fuel into the idle jet, and the greater flow or air would draw more fuel. Regardless of the theory, it's an easy experiment to do, so it would be worth trying an adjustment in small steps in either direction to see how the bike reacts. - and then let us know how you get on !
It's also worth thinking about plugs - have a look at Julie's recent 400 idle issues thread that appear to have been improved by a change in plugs.
Andy
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