Carb rebuild

[Multiman]

Hi all
Here's wishing you all a very happy New Year.

Laverdaroo has done a spectacular job on refurbing my carbs and so it's on to refitting. Thanks again Roo!

I had already bought some new throttle cables from Wemoto and fitted them beforehand.

Unfortunately when I split the right hand switch gear to do the job, I discovered a red and yellow wire in mid air.

After checking the wiring diagram, I disassembled the lower starter motor switch further and soldered the red and yellow back onto the small contact mounted on the tiny bit of U shaped insulation board.

Put every thing back together (oh to be an octopus) and whilst the starter works it has no "feel" and I'm worried might vibrate into contact whilst the engine is running.

So to cut a very long story short I've lost the spring that must live in there behind the starter button.
I've spent and hour on my hands and knees but can't find it, if it ever existed.

Two questions,
1. anyone got a spare starter button spring, or got dimensions of one?

2. Could someone describe how the parts go together as there is no exploded diagram I can find in manual or parts book and I'd like to be sure.

Many thanks

Cheers

Tim

[Bryanj]

If the 400 grounds to the bars go to the 500K0 parts fiche on cmsnl and there is a part number for both spring and button

500 spring part number is 35318259000

[Multiman]

Ah thats good info.
I shall take a look, thanks.
Tim

[McCabe-Thiele (Ted)]

Tim I have a complete switch that has had the wiring cut off plus a section has been cut off the lower case to allow the wiring to be external on bars. The starter action seems good. If you PM your e-mail address the unit is  all yours f.o.c. just postage cost.
Cheers Ted

[Multiman]

Ted thanks incredibly kind.
I'll pm you
Best
Tim

[Multiman]

Teds switch assembly has arrived and the interior is completely unmolested.
This so useful as it shows all the original cable/insulation layout which will enable me to fix mine and get it to go back together properly.
Cheers Ted, a legend.

[McCabe-Thiele (Ted)]

Teds switch assembly has arrived and the interior is completely unmolested.
This so useful as it shows all the original cable/insulation layout which will enable me to fix mine and get it to go back together properly.
Cheers Ted, a legend.

The switch came with a bunch of parts when I bought my spare carbs & engine from a member here "Pops400" he was going to rebuild his  fathers old 400 but the frame was badly damaged,  the bike was sold off for spares shortly after his father & brother had died. He is a really nice bloke who had a small lock-up unit near his home where he stored his main passion - 1950/60s  American Cars.

[Multiman]

The story so far....

Bought my 400/4 last may whilst I was learning to ride.
Got 2 mates to ride who gave it the thumbs up and it sounded and ran sweet.

Didn't take my A lic till November but passed at the tender age of 65.

Took the bike out for a run and it was awful.

Carbs flooded and the bike was jerky and stalled at junctions.

Roo came and helped me whip the carbs off, took them away to strip, clean and generally fettle. What a gent.

Got the carbs back a refitted.
To cut a long story short it was still not running well, flooded on fuel on, revs hanging etc etc

I started fettling other aspects of the bike and trying other obvious things that might affect the bad running.

Eventually I had the carbs off again and found discrepancies with the float bowl needle valve seats.
Replacing them cured the flooding.

But the rev hanging still persisted.

So carbs off again and a full strip.

More discrepancies in the main jet and emulsion tubes, so sourced some old brass and fitted.

I've made a short video which documents the main issues
Let em know what you think
Cheers

Tim

[McCabe-Thiele (Ted)]

Enjoyed the movie never seen so much fuel leaking from carbs before. Hope it's sorted for good now.

I might just have been lucky with my 400 carbs - only time they have ever leaked is when I ran out of fuel on a journey - I came to a stop - switched on the reserve and petrol poured out of one carb in particular - I just shook the bike from side to side & it stopped pretty much instantly. I suspect the float /valve  had stuck down due to the acute angle.

[Oddjob]

Impressive film making skills, really liked that, didn't spot any Ewoks though, maybe get Roo in the film, he looks like one of those bar aliens in Star Wars, you can mutter at him "These are not the Yorkshiremen you're looking for, Oh and by the way it's your round"

Not 100% sure you got the ignition timing right, I seem to recall someone saying they need to be timed at full advance as they don't have an advance unit? Could be wrong, never fitted an electronic setup to a SOHC before. Someone will advise if I'm wrong.

Some stuff I spotted. Emulsion tube was drilled off centre, if that's the state of the others I'd have changed them all not just No3. Clearly someone has replaced the entire set of brass and it's poor quality brass at that. Remove the throttle cables and see if the hanging carries on, blip the throttle with the butterfly.

[Matt_Harrington]

Well done Tim. Do I take it that the ol' bike is now running well?

[Nurse Julie]

Great video Tim. I admire your restraint, I'm usually kicking things and swearing like a trooper with issues like that. You certainly had a mish mash of brass ware fitted that's for sure. Well done.

[McCabe-Thiele (Ted)]

I have a decent set of four original  emulsion tubes - PM me if you are interested (not asking daft money).
I replaced mine together with the floats for no good reason when I refurbished the carbs in 2020.

Out of interest on your electronic ignition can you check the timing for 1-4 & 2-3 as I see no sensors that are adjustable for each pair of cylinders?

[Multiman]

Thanks for the comments guys.

I should be able to make a quick video as I work in TV for a living.
My defence for the slightly weird captions etc is I haven't done any actual editing in decades, I mainly look after the colour correction side of things. My offspring say I do the colouring in.
I just had a quick go on iMovie as thats what I've got and it is a crap bit of software.
I'm going to teach myself another program called Resolve.
Once I've got my head round that, look out for the Directors Cut, it will be a belter.

I made a selection of the emulsion tubes that all looked the same and had same position shoulders etc when checked with a vernier.
Only one had the drilling off centre and it was really easy to spot if a shocking bit of QC.

The electronic ignition has no built in advance curve like some other more impressive systems eg Tri Spark but the bike still has the centrifugal mechanical unit advancing the aluminium rotor that contains the magnets that trigger the signal. I checked it was advancing with the strobe and all good.

There is no separate adjustment for 1-4 vs 2-3 on the EI system, they are simply built with the transducers at 180° to each other. Not sure if this is a disadvantage?

Julie I have wanted to kick the thing more than once but I always do my ranting off camera. Think Basil Faulty birching his car...

Is it going well now?
So off I went in the sunshine, pottered round the estate to the main road, got onto a straight and applied considerable beanage.
Lush.
However she didn't want to slow down, throttle was jammed open sort of.
By the top of the hill it was sorted so maybe just settling in?
Then next straight the same.
Traffic lights fumbling with crazy reving thing between my legs and driver up my arse.
Not happy.
To cut a long story short, I managed to get the revs to drop and slowly made it home whilst trying to think of what I hadn't done right?
Throttle cable anchor not tightened perhaps, didn't feel like fueling but some carb mechanical thing.

Took the tank off at home.
Throttle cables all good.
Then it became obvious.
Some dickhead hadn't tightened the throttle stop pin which was free to rotate and jam the butterfly partially open. Randomly.
At least it was an easy, if embarrassing, fix.
Note to self.
Never think its sorted till you do a road test, blipping the throttle in the garage hadn't shown it.

Then I went a did a very enjoyable 35miles and came back grinning like a Cheshire Cat.
Everything works and there will obviously be a few tweaks, but the engine is running really well.

Roo is threatening to come over sometime and I'll get him to take it out for a second opinion.

Ted thanks for the offer of emulsion tubes, but as the engine is going well I think you should hang on to them. Cheers mate.

Its been said more than once own here that the old brass works better and I think I proved this too myself.
But it raises the question of what is right and what is wrong.
How do you know if you buy a carb service kit that the parts are right?
Are there and drawings available for the parts? I guess not, but it would be really useful to have some basic dimensions of components to be able to check.
Thoughts?

[K2-K6]

"There is no separate adjustment for 1-4 vs 2-3 on the EI system, they are simply built with the transducers at 180° to each other. Not sure if this is a disadvantage?"

No disadvantage at all, in my view. The original points are separately adjustable to remove production tolerance in their own manufacturing process, so to take care of any potential error they built in. Also, their rubbing block/heel wear that may also change this aspect.

Electronic triggered by the same singular spindle, as long as it's accurately assembled in regard to pickup point, shouldn't have variance or reason/need to adjust.

Looks fine in video clip.