Changing jets MKI concentric in place

It seems that I remember changing the main jets through the float bowl many years ago rather than removing them. Well, I long ago lost my jet wrench so bought a new one. It binds up when unscrewing the jet so, am I miss remembering what I did years ago or is the wrench too fat?

You can remove the main jets through the float bowl drain plug.
I suspect what might be happening is that the jet holder, into which the main jet is screwed, may be unscrewing itself from the carburettor body, instead of the jet coming out of the jet holder. The jet holder is I think too big to come out of the float drain hole, and this may be your problem.
If this is the case, you will have to remove the float bowl to change the main jet.

+1 I'm sure that explanation is exactly what's happening.

The jet doesn't have to be all that tight to seal properly so tighten up the jet holder quite snugly and then just run in the jet until it just tightens a bit.

I realize "snugly" and "just tightens a bit" is not particularly scientific... But the point is to be sure the jet is less tight than the jet holder. There may be some torque specs for this in the manual but I never noticed them or, for that matter, looked for them. Back in the old days, with my first Commando (71) I changed jets at the track on a regular basis so once you get the "tight ratio" right, it will work just fine.

Reggie said:

You can remove the main jets through the float bowl drain plug.
I suspect what might be happening is that the jet holder, into which the main jet is screwed, may be unscrewing itself from the carburettor body, instead of the jet coming out of the jet holder. The jet holder is I think too big to come out of the float drain hole, and this may be your problem.
If this is the case, you will have to remove the float bowl to change the main jet.

Click to expand...

Indeed this is one option.

Another one I have run into is that the access hole in the bowl is not accurately central to the main jet - and especially if the jet removal box spanner is a bit thickwalled it will bind against the float bowl.

I checked mine with the carbs off the bike and had to grind a bit off the spanner wall.