Honda-SOHC

Update on this topic - I found company which will manufacture D rings up to specification (79x2.6), from NBR material.

Tomorrow I'm going to place order - is there somebody else interested too?
Expected cost is 5-6 euro/pc depending final qty.

Let me know asap if interested

Shipping from Slovakia to UK is normally quite cheap in bubble envelope

It is definitely D shape, groove is unusually wide (to accomodate flat part of ring). I assume it is to better seal as per my googling: "The flat geometry on the base of the D-ring stops the seal from twisting and rolling, preventing spiral failure often seen when O-rings are used in reciprocating applications"

I sent email to banrwell, let's see if they answer something

Pm sent

My experience with carbs rebuilt by Gerben, it was for 022A set, jets 40/100. All brass original Keihin.
As said here, Gerben work looks very good (even I'm not a fan of polished bowls).

However, funcionally vise I was never able to achieve good idling despite a lot of sync tries. Additionally, behaviour at lower RPMs not good (felt like too rich). First I replaced slow jets from 40 to 38 (new NOS Keihins). It improved a little but still, running engine between 2500-3000 felt too rich and rough.
Having cabs off the bike this spring and reading some forum thread pointing to sensitivity of emulsification tubes plus fact that my tubes were falling off the carb bodies when main jet is removed, I checked them into detail and compared with keyster replicas I bought some time ago.
Guess what - I found internal surface of hole rough / corroded.

As all outside dimensions and size/position of holes on tubes were the same as on Keyster replicas, I decided to put them in (I had to push them inside with some force, so they do not fall out by themselves). I did not change needles that required additional dissassmbly.

After bench sync only (bearing balls method) carbs installed - whoola! Bike idles much better, chain rattle almost gone. Additionaly runs great, smooth on lower RPMs, I can easily "cruise" on ~2500 RPMs and engine picks up easily w/o hesitation. So only simple change of tubes change bike behaviour a lot!

=> before deciding to use original old used tubes, check them inside. In this specific case originals are not always better than alternatives

Attached pic comparing new Keyster (left) with OEM Keihin

Thanks for advices

Your last sentence is still question in my mind - why on full stock bike (only exception is aftermarket air filter element from cmsnl) it runs fine (close to ideal) with 115 jets instead of 100

Update on this topic, finally jets arrived, I replaced stock 100 by aftermarket 115 (in reality they seems to have size around 133-114). Full trottle acceleration improved. Bike runs smooth on low RPM, I can easily cruise around 2500-3000. (of course battery is no charged wirh headlight on)

Checked plugs for color, it looks to me still lean, especially plug no1 (plugs on the picture are sorted from left). Wondering if I should go one step more wirh jets (120?) or let it be.
Using Shell V-power racing petrol, as this one still has "just" 5% of bioshit (E5). Others are E10 here. Maybe plugs color can be explained also by petrol used?

Just measured Keyster needle (declared for carbs 022A) - it has 2.520mm that somehow corresponds to original Keyster 2.515mm.
Replacing them will (to me) make mix even more lean.

With regars to fuel - I only use premium fuels to my bikes where possible, usually 100 octan, with 5% of ethanol max (E5). Standard fules here have 10% (E10)

I still suspect too lean issue might come from tubes being too small ID (Keyster). Need to check that before hassling with MJ and/or needles