More carb troubles, engine won't return to idle revs

[Matt_Harrington]

Bill, I'm currently rebuilding a spare set of carbs and I'm reading this with interest (sorry I can help yet!) and I will be interested to see what the outcome is.
Matt

[Sesman]

Get them built Matt and lend them to him?

[Matt_Harrington]

Get them built Matt and lend them to him?

Ha! I have to admit that I could have chosen from 2 sets of spare carbs to rebuild and I chose the wrong set! Parts missing ,damaged or just wrong - still I'm almost there but I have to admit they are quite complicated compared to other carbs I have restored!
Matt

[Sesman]

Hey Scottish nadger. When you cleaned the carbs did you remove the air screws and float bowls? I’m sure you know, but it pays dividends to understand the three orifices in the pilot jet pathway. Eg carb inlet, air screw and drilling in the main Venturi on the engine side of the slide. By judicious use of your fingers it’s possible to block of the routes in sequence and thus force carb cleaner and high pressure air through the pathways. Have you tried that with the carbs off the bike?

[Sesman]

Er badger, not nadger🤔

[Orcade-Ian]

Going back to Bill's problem of the bike refusing to return to idle, I think I've read all replies to your original post (hope I didn't miss any!). I hope you will forgive me if I'm stating the 'bleedin' obvious' but is the FB spring in the middle of the bank between 2&3 present, correctly attached and not badly stretched?

Ian

[Sesman]

Good shout Ian.SB says the slides snap shut (closed). Worth checking again I suppose?

Are you back home from your jaunt? If so I’ll post the gods on Thursday.

[Orcade-Ian]

Not back just yet, was supposed to be on the boat tomorrow evening but due to adverse weather it's been re-scheduled for 13.15 - no chance of making that from Aberdeenshire, so have moved it to Wednesday.  One of the joys of living on an Island!  PM me with the total cost with P&P and I'll fire some brass to you. Hope Bill gets sorted.

Ian

[billdn]

Going back to Bill's problem of the bike refusing to return to idle, I think I've read all replies to your original post (hope I didn't miss any!). I hope you will forgive me if I'm stating the 'bleedin' obvious' but is the FB spring in the middle of the bank between 2&3 present, correctly attached and not badly stretched?

Ian

Return spring between 2 and 3 carbs is in place and snaps back really fiercely, when operating by hand have to mind your fingers!

[Orcade-Ian]

That's good Bill,
It was just a 'clutching at straws' thought.  I've recently done 2 sets (one 350/4 and one 400/4) right down to completely bare carb bodies without problems, so have been racking my (admittedly rather old) brains to figure what might be wrong with yours.
Ian

[billdn]

Going to go for full strip down,  re clean and reassemble. In meantime I'll recheck tappets and timing in case it's slipped but shouldn't be problem 😉

[Oddjob]

Did you replace the o-rings in the manifolds Bill?

[Scottish Badger]

Sesman, yes, fully stripped for ultrasonic cleaning and all ports blasted through with compressed air afterwards.

[billdn]

Did you replace the o-rings in the manifolds Bill?

All new o rings everywhere in carb including manifold. 🤔 you can see why I'm confused , seem to have done everything right, obviously not but as to what it's a mystery!

[McCabe-Thiele (Ted)]

Sesman, yes, fully stripped for ultrasonic cleaning and all ports blasted through with compressed air afterwards.

Not sure if this is relevant but:-

When it does not return to idle revs does unscrewing the knurled main throttle screw adjuster reduce the idle to normal now or is it still as it was at the start of your post?