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+--- Thread: clearing the jet in a 22FZB (/showthread.php?tid=9463)
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clearing the jet in a 22FZB - JonE - 10-07-2024
In the long brass 'tower', with a screw adjstment at top and the removeable jet section at base, the latter is firmly not showing light when viewing through the jet. I've been trying to rod it with the smallest wire of a gas nozzle cleaner set (I use them as small files) but it doesn't get anywhere. What could I try next?
I am also missing the bottom gauze which I understand sits there.... to prevent my stated problem. Are there any good solution for the filter effect in that tube?
RE: clearing the jet in a 22FZB - Howard Wright - 10-07-2024
Hi Jon
I’ve used very fine drill bits to clean and increase jet sizes. I believe the compensating jet (which I think is the one you are referring to) should be a 75 (0.75mm). You need a Dremel with a very small collet chuck to hold the drill bit. I prefer to gently hold it between thumb and finger.
Regarding a filter, I’ve never seen one here, only on the fuel intake to the float chamber.
Cheers
Howard
RE: clearing the jet in a 22FZB - JonE - 10-07-2024
great thankyou. I will search through the Dremel case...
The section at the bottom of the "cigarette" shape seems to have a visible rim with different patina down at the base, so there must have been something there once.
RE: clearing the jet in a 22FZB - Ruairidh Dunford - 10-07-2024
I think you are referring to the slow running jet.
It is normal practice to remove the filter in the bottom of these. To clean it you need to separate the top and the bottom from each other, hold the flats with a suitably small spanner and twist the top off with some pliers or other.
Once you have it apart you will be able to get a small jet cleaning wire into the hole and clear it.
The hole is much smaller than 75, this is normally the size of the main jet.
RE: clearing the jet in a 22FZB - Howard Wright - 11-07-2024
Hi Jon
You should get a copy of ‘Hints on Fitting and adjusting the Zenith Carburetter’. David Cochrane sells this small booklet. Much of it is reproduced on the Burlen Zenith carburettor web site.
My notes show the main jet as 70, the compensating as 75 and the slow running as 35 but I’m not sure where these came from and Ruaridh may be correct in that the main jet is 75.
Willie MacKenzie sells all three jets.
Cheers
Howard
RE: clearing the jet in a 22FZB - Ruairidh Dunford - 11-07-2024
70 is correct for a standard main jet.
RE: clearing the jet in a 22FZB - JonE - 11-07-2024
thanks both. I'll have a look on the Burlen site. This is is the one on the RIGHT... so that's 0.35mm? I wonder if a Dremel gets that small... cleaning wire is just bending so it needs something to redrill it after a long period of un-use. Carb cleaner was also ineffective over 12 hours soak.
RE: clearing the jet in a 22FZB - Howard Wright - 11-07-2024
Hi Jon
Yep that’s the slow running jet. You may find its size stamped on the side!
Be careful with drills this small. I would do it by hand as in my first post.
Cheers
Howard
RE: clearing the jet in a 22FZB - JonE - 11-07-2024
I was trying to work out whether you meant guide a slow running dremel with extra fingers around... or just use like a bradawl letting it cut with no pressure behind?
RE: clearing the jet in a 22FZB - Howard Wright - 11-07-2024
Hi Jon
I’ve found using the drill bit like a bradawl has worked for me.
Howard