Felt washers, swinging arm (500) and carbs.

[Bryanj]

Emy, i did try the choke felts that ken made but attrition rate was about 50% as they broke up easily. If we could get impregnated felt it may well be easier as the grease/oil would hold the felt together

[Oddjob]

I'll try and source another grade of felt Erny, I've broken quite a few on the choke arms BUT the last ones were much better. Bryan found them easy to break BUT TBH I found them ok but then I've had far more practice with how the break, what causes them to break so I can understand why Bryan found them hard to fit.

Watch this space.

No harm in asking the firm I suppose but it could be a problem if say they make a few hundred for you and then you find they also break easily and then you're stuck with a set of really small, really expensive doilies. 

[Matt_Harrington]

I'm not sure if the felt is going to last but you can get 13mm diameter felt buffing wheels for a Dremel. I sliced mine to a suitable thickness with a very sharp blade and then punched out a central hole. Just a thought as a source. (Fleabay etc)
Matt

[Erny]

I'll try and source another grade of felt Erny, I've broken quite a few on the choke arms BUT the last ones were much better. Bryan found them easy to break BUT TBH I found them ok but then I've had far more practice with how the break, what causes them to break so I can understand why Bryan found them hard to fit.

Watch this space.

No harm in asking the firm I suppose but it could be a problem if say they make a few hundred for you and then you find they also break easily and then you're stuck with a set of really small, really expensive doilies.

I'll ask them - not sure I missed some info, did not find it quicky - what are required dimensions I shall ask please?

[Oddjob]

9.6 x 8mm Erny.

[Erny]

Ok, so just 1,6mm wide "wall' really small - let's see what they say
Do you know also "thickness"?

[Matt_Harrington]

Whilst we are talking about felt seals on the throttle shafts, does the 'flanged washer' retain the felt seal? If so, is the flange on the outside?
(Hope I have described that correctly!)
Matt

[Oddjob]

IIRC the sequence for the throttle shafts, starting from the throttle arm itself is Cupped washer, spring, flat washer, flanged washer, felt washer and on the inside of the carb boy there is a nylon washer. Just off memory. The cupped washer retains the spring, the flat washer is for the spring to sit against, flanged washer presses against the felt washer which fits inside a recess in the carb body, So I tend to fit the felt washer first after soaking it in light oil so it lubes the shaft running through it and also aids in dust retention and sealing, the flanged washer is the same size as the felt washer so no it doesn't sit on it, the flanged washer is to centralise the shaft of the throttle lifter and also to keep the felt washer pressed into place. The flange faces inside toward the carb body.

[Oddjob]

Ok, so just 1,6mm wide "wall' really small - let's see what they say
Do you know also "thickness"?

I'm using around 1.5mm felt Erny, and yes the wall is the problem, I did get the measurements wrong though, slightly confused myself with the throttle lifter shafts as well.

The choke shaft is actually 7mm wide at the part where it sits inside the felt washer, the recess in the carb body is actually a fraction over 9mm. So you'd need a 9 x 7mm washer. That leaves a 1mm wall each side, which is where the problem lies, it's so thin it just breaks when any stress is put on it, the threads on the choke shafts can catch it as it passes through and just rip it to bits. IMO, the way to fit them it to slide the first felt washer over the choke shaft, fit the shaft into the carb body and then slide the next one on. You can then poke it into position with a very thin screwdriver and finally fit the rest. I'd soak them in light oil first to see if that helps to strengthen them, a small amount of movement of the choke shaft would have to be made to ensure the first felt washer sat down into position before trying to fit the second.

I did just that on my 500 carbs and had almost no problems but I had to use a larger diameter washer at 10mm not 9mm due to how my cutter works, explained above in post 27. This makes them harder to fit as you need to compress the washers at 10mm into a 9mm opening but it's just felt and it compresses easily. Harder felt may be the answer but may make it worse as trying to compress that could make getting it into position harder. Ideally you want 9 x 7 but I cannot cut that size due to limitations in the cutter design.

Hope that helps.

[Matt_Harrington]

IIRC the sequence for the throttle shafts, starting from the throttle arm itself is Cupped washer, spring, flat washer, flanged washer, felt washer and on the inside of the carb boy there is a nylon washer. Just off memory. The cupped washer retains the spring, the flat washer is for the spring to sit against, flanged washer presses against the felt washer which fits inside a recess in the carb body, So I tend to fit the felt washer first after soaking it in light oil so it lubes the shaft running through it and also aids in dust retention and sealing, the flanged washer is the same size as the felt washer so no it doesn't sit on it, the flanged washer is to centralise the shaft of the throttle lifter and also to keep the felt washer pressed into place. The flange faces inside toward the carb body.

Mmm, I think I have used the wrong terminology! I'm referring to the smaller felt washers on the butterfly shafts.....
Matt

[Oddjob]

That's the choke Matt.

[Matt_Harrington]

That's the choke Matt.

Of course it is! 
So, does the little flanged washer on these spindle 'trap' the felt washer? Looks like that is the way it should be.....
Matt

[Oddjob]

Can't say for certain Matt as I don't have a set of 400 carbs, the 500/550 uses the same choke type mechanism though so I'd say so unless someone else can say for certain.

[McCabe-Thiele (Ted)]

This shows pretty much everything on the 400 carbs.

https://www.vintagebikebuilder.com/cb350-400f-carb-rebuild-demonstration.html

[Matt_Harrington]

This shows pretty much everything on the 400 carbs.

https://www.vintagebikebuilder.com/cb350-400f-carb-rebuild-demonstration.html

Ted, I read that a while back, however the carbs were never fully dismantled - ie the butterflies were not taken apart so I could not establish the correct orientation of felt washer etc etc.
This video, although not the same carb, I think, points me in the right direction.
https://www.youtube.com/watch?v=sXAn0SVSk9E&t=799s&ab_channel=Dude%27sGarage

Matt