Step by step

The use of the term ?push-pull? for the 2-way throttle thingy sounds kind of weird to me. A cable never can
push - whilst the term ?desmodromic? seems to work alright here, as you control both, opening and closing.

OK, enough nit-picking ?
;) 8)
 
Jo said:
The use of the term ?push-pull? for the 2-way throttle thingy sounds kind of weird to me. A cable never can
push - whilst the term ?desmodromic? seems to work alright here, as you control both, opening and closing.

OK, enough nit-picking ?
;) 8)
Click to expand...

Jo,

look at the throttle cables of old Jap Fours, i.e. Honda CB 350-750, push/pull action.

Good luck with your projects around the 3C

Gerald
 
Technically it's not controlled closing. You are controlling the connecting bar through the carbs but the slide is attached by a wire or rod or similar and the slide can still get jammed up in the bore of the carb body and no amount of twisting of the throttle will close it if it's jammed (DAMHIK).
 
Agree ? you can?t have total control. Total control is an illusion anyway (from a philosophical point of view).
I feel slightly better with the 2-way concept though ...
:D 8)

Again I?d to look up another abbreviation. How did the story end?

Cheers
Jo
 
Grant said:
Technically it's not controlled closing. You are controlling the connecting bar through the carbs but the slide is attached by a wire or rod or similar and the slide can still get jammed up in the bore of the carb body and no amount of twisting of the throttle will close it if it's jammed (DAMHIK).
Click to expand...

Thats true for a Dellorto where it's just a spring against a lifting cable or rod which has no retention in the slide in a downwards direction (so can't possibly 'push').  But doesn't an RS Mikuni have a sort of a con-rod type arrangement between the lever and the slide?  I've not worked on many, perhaps I'm vagueing out.  My recollection was that the only return spring/s are on the throttle shaft, and the slides are mechanically linked to it.  With a 'twin pull' throttle that system would be pretty much as close to 'positive close' as you can get.
 
Correct, Steve. Certainly for FCR Keihins. One of the reasons the spring action is so light. You can even opt for a softer spring.
Also light because (with FCRs) the slide is supported on four little rollers (looks like a little model train rolling stock when it's out) - stunning design.
 
The Mikunis have an adjustment for spring pull strength,thankfully Mark reduced mine at Reds shed as doing the blip for gearchanges was stupidly heavy right out of the box. Very easy now.
 
Jo said:
The use of the term ?push-pull? for the 2-way throttle thingy sounds kind of weird to me. A cable never can
push - whilst the term ?desmodromic? seems to work alright here, as you control both, opening and closing.

OK, enough nit-picking ?
;) 8)
Click to expand...

You're quite right Jo. I was having similar thoughts, but decided not to comment for fear of exposing my obsessive pedantry to ridicule. :D



 
I've said it before and I will say it again - it is a pull - pull operation, no push involved. The return, or down throttle cable actually does f/a as the carb spring returns the throttle to idle. It is probably only there as an emergency device if the throttle needs to be deactivated, eg in case of a jammed something.
 
Dellortoman said:
You're quite right Jo. I was having similar thoughts, but decided not to comment for fear of exposing my obsessive pedantry to ridicule. :D
Click to expand...

:D
That was what I thought in the first place. As non-native it is sometimes tricky trying  to be ironic, witty or
sarcastic ? could quickly go in the wrong direction ?
8)

breganzane said:
Thats true for a Dellorto where it's just a spring against a lifting cable or rod which has no retention in the slide in a downwards direction (so can't possibly 'push').  But doesn't an RS Mikuni have a sort of a con-rod type arrangement between the lever and the slide?  I've not worked on many, perhaps I'm vagueing out.  My recollection was that the only return spring/s are on the throttle shaft, and the slides are mechanically linked to it.  With a 'twin pull' throttle that system would be pretty much as close to 'positive close' as you can get.
Click to expand...

This is correct Steve. I found an exploded view which shows the set-up:
28339908327_27affd29c7_o.jpg


There is a direct connection from the shaft via a kind of knuckle/rod directly to the slide. However, also this is not
an insurance that the slide never could be jammed ?


Cheers
Jo
 
Jo said:
:D
That was what I thought in the first place. As non-native it is sometimes tricky trying  to be ironic, witty or
sarcastic ? could quickly go in the wrong direction ?
8)

This is correct Steve. I found an exploded view which shows the set-up:
28339908327_27affd29c7_o.jpg


There is a direct connection from the shaft via a kind of knuckle/rod directly to the slide. However, also this is not
an insurance that the slide never could be jammed ?


Cheers
Jo
Click to expand...

And the screw which attaches the knuckle/rod directly to the slide - 17 in the diagram above - works loose on 120 engine middle carbs due to the vibration when riding the North Coast 500. DAMHIK. ;)

?
Dick
 
VanguardontheLav said:
And the screw which attaches the knuckle/rod directly to the slide - 17 in the diagram above - works loose on 120 engine middle carbs due to the vibration when riding the North Coast 500. DAMHIK. ;)

?
Dick
Click to expand...

Hello Dick,
could you fix it en route? Is it worth to secure it with Loctite?

Cheers
Jo
 
Piranha Brother 2 said:
Correct, Steve. Certainly for FCR Keihins. One of the reasons the spring action is so light. You can even opt for a softer spring.
Also light because (with FCRs) the slide is supported on four little rollers (looks like a little model train rolling stock when it's out) - stunning design.
Click to expand...
Work of art actually say where do you source the softer springs for them and for that matter different size throttle ramps.
Love my FCR's  :P

Re the Screw on Dell's have noticed over the years working on the odd Lav that they can work loose... also I always when syncing carbs, loosen them off and make sure that them all off, ensure that all three are set the same and then retorque , find once torqued they don't seem to reloosen... if you use Loctite be careful not to use too much of the damn stuff will ya.
 
When I build the Mikuni sets for customers I always Loctite the middle screw with medium grade Loctite
but not the two outside screws with the adjuster nut


 
Brett said:
Work of art actually say where do you source the softer springs for them and for that matter different size throttle ramps.
Love my FCR's  :P
Click to expand...
Hey Brett, I've found that Webike (https://japan.webike.net/) in Japan are by far the best source of bits for the FCRs. I had to convert a set of four into two x two and needed all sorts of little bits. Also got my jets and needles, T pieces, springs and the like from them. They source the stuff in. Shipping was expensive but think they've rejigged their system - I for one gave very negative feedback on their shipping prices.
 
Jo said:
Hello Dick,
could you fix it en route? Is it worth to secure it with Loctite?

Cheers
Jo
Click to expand...

As Red says (and he diagnosed my problem from Oz when it happened!) Loctite that screw!

I dismantled the carbs in the car park at the B&B I limped the bike to on two cylinders, and fixed it - right pain, as it?s right below the frame top tube so not possible to fix without taking the carbs off the bike...

?
Dick
 
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