My first post! Question regarding CB550 main jets.

[Brian.]

Good afternoon all!  I hope you are all enjoying the sunshine today.

I have a question regarding 1974 CB550 K1 main jets, to which I cannot find the answer anywhere:-

The main jets have the jet size (38) stamped on the flat face of the jet.  When they are fitted to the carb, should that face of the jet be visible?  Or does it go in the other way please, ie stamped face butting up to the bottom of the needle jet?

Thank you very much.

Brian.

[Trigger]

Your main jet should be stamped 100 and your slow running jet 38. The 38 screws in and the 100 pushes in at the o ring end and then the black spring clip 

[Brian.]

Your main jet should be stamped 100 and your slow running jet 38. The 38 screws in and the 100 pushes in at the o ring end and then the black spring clip 

Thank you Trigger; yup you are right, I was mixing the sizes of the two up, I meant 100 for the main jet.  I shall try to keep up 

So can I ask, when the main jets are fitted in place correctly, should the end of the jet marked "100" be visible, or should that end be the one that's pushed into the carb body and the unmarked end be visible please?

As I see it, it is possible to fit them either way because there are two grooves; one for the O-ring and one for the spring clip.

There is a reason why I'm asking!

Thank you again.

Brian.

[Trigger]

Larger hole face the float bowl

First pic right, second wrong


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[Brian.]

Thank you for that Trigger.  I'm almost certain that mine are in the correct way round then.

I can only positively remember that mine have the numbers not showing when fitted but I do think coincidentally they are correct as per your first picture.  Thank you.

It's a longish boring story about my bike but essentially I removed the jets, cleaned them and refitted them as they were but I am beginning to realise that just about everything has been messed about with in an effort to get it to run properly so they could have been wrong when I removed them.

It just seemed odd to me that the jet size is invisible unless you actually remove the jet.

Hey ho.  There will no doubt be another carburettor question coming from me in due course then!

Thank you for your prompt responses, I do appreciate it.

Brian.

[Trigger]

You can't go on where the number is stamped as, some manufactures have the numbers on the end 

[Brian.]

You can't go on where the number is stamped as, some manufactures have the numbers on the end 

Now I certainly hadn't thought of that.

I know that mine are all the same way round, I think I'll take one float bowl off just to check to eliminate that.

Thank you again Trigger.

Brian.