CB550F Main Jets

[K2-K6]

That doc,  linked above,  shows different id for needle set,  idle screw and filter to be paired with the #98 main jets.

Whether the carb set designated number changes for the whole bank setup,  and without body casting changes, is not apparent.  But I suppose it would be logical on production line and feed stock to identify the different spec externally if they where in production at the same time but destined for different markets.

[Nurse Julie]

I don't think that's correct, never seen or heard of a #78 main jet on any Honda, let alone a CB500/4 🤔🤔🤔🤔

Except for France, all CB500s on continental Europe had the #78 main jets. Again, see the parts lists. Also Honda listed the #78 main jets as a possible alternative for the standard #75 on the CB400F. See the CB400F parts list, p.17 http://www.honda4fun.com/pdf_parts_list/pdf_spac400/CB400F-F1-F2/CB400F-F1-F2.pdf

You're just confusing the issue Delta. It was a simple thread that has got stupidly complicated for no reason.

[deltarider]

I don't think that's correct, never seen or heard of a #78 main jet on any Honda, let alone a CB500/4 🤔🤔🤔🤔

Except for France, all CB500s on continental Europe had the #78 main jets. Again, see the parts lists. Also Honda listed the #78 main jets as a possible alternative for the standard #75 on the CB400F. See the CB400F parts list, p.17 http://www.honda4fun.com/pdf_parts_list/pdf_spac400/CB400F-F1-F2/CB400F-F1-F2.pdf

You're just confusing the issue Delta. It was a simple thread that has got stupidly complicated for no reason.

That's not fair, Julie. I did not start about the #78 jets that just happen to be in my overview  that was modestly attached as a PDF in reply #26. It was you yourself that opened it and then commented:
I don't think that's correct, never seen or heard of a #78 main jet on any Honda, let alone a CB500/4 🤔🤔🤔🤔.
That compelled me ofcourse to correct that again because, what is not corrected, lives on as truth eternally on the internet. Except for France, all CB500s*, no matter what year, on continental Europe had the #78 main jets and we're talking tens of thousands of bikes here, some of which may even have surfaced in the UK nowadays.
* The CB500K3 model being an exception ofcourse. That model had the PD carbs.

[deltarider]

...So, a 1971 500/4 has 627A, a 1972 CB500/4 has 627B's...

Does anybody know what may have been the difference between the 627A and the 627B carbs? Has anyone actually seen 627A carbs in real life?

[Nurse Julie]

I stick to my statement 'I don't think that's correct, never seen or heard of a #78 main jet on any Honda, let alone a CB500/4 🤔🤔🤔🤔.'. THINK being the important word. My little world of SOHC/4's is entirely UK models, therefore you will have to forgive the fact that I , unlike yourself, don't know everything or nor do I have the time or interest to recite documents or data that I have no interest in.

[deltarider]

Coolercoast, did you communicate what number carbs you have? See pic for where to look.

[cooleronthecoast]

I just checked, I actually have two sets of 4 carbs.  The ones on the bike are 087A and the others I have are 069A.  The plot thickens!

[Nurse Julie]

I just checked, I actually have two sets of 4 carbs.  The ones on the bike are 087A and the others I have are 069A.  The plot thickens!

069A's are early CB550/4 F 1 & 2 model (I think)

[deltarider]

087A carbs were exclusively on the CB550K2 model, marketed in 1976 in the US. I have no knowledge that this model has been in other markets than the US. These 087A carbs are a bit of a mystery because we don't know why they have that number. So far they seem 100% identical to the 022A that were on the previous models: CB550K and CB550K1. Please do me a favour. Unscrew one of the airscrews (in the side) and inform us if yours has the cross drilled, hollow tip airscrew or the solid tip ones that have no hole.
The 069A carbs were exclusively on the 550F, all models: CB550F, CB550F1 and CB550F2, not on any K model. There is indication that the F2 had a somewhat leaner initial setting of the airscrew (solid tip type) knowing ¹/₄ of a turn further out*. Probably it had to do with new legislation on emission.
*An American Honda booklet seems to suggest this.

[cooleronthecoast]

The carbs currently on the bike (087A) have the hollow point cross drilled jets, at least the No.1 outer carb has, I didn't check the others.


 When I get some free time, I'll check them all out on both the sets of carbs I have.

[deltarider]

Thank you. Your finding is in line with what others have reported. The 069A carbs will have the solid type airscrews. You don't have to unscrew them all, I mean: not for me. Tip: prior to unscrewing, turn them in (gently! do not exercise force!) and count the turns, so you can reposition them as they were.

[cooleronthecoast]

It looks to me that I might have a bit of a miss matched set up on the bike.  I inherited both sets of carbs from the previous owner, I'm thinking from what you guys have said, that he (or perhaps an earlier owner) swapped the 069A set for the 087A set. Mebbe someone bought the 087's and fitted those to the bike as something was amiss with the originals?   I don't know as I've not actually had the 069's fitted on the bike although the set seem complete apart from some idiot using a black sealant on the carb float bowls in place of the O ring rubbers.   

As I mentioned at the start of the thread there was a motley selection of main jets in the 087A set so I think it would be in my own interest to checkout the airscrews in both sets and see what I have. 

[deltarider]

... An indication also is that this F2 had a fast cam and the chokeknob on the handlebars...

The info I have given above, may be wrong! Any F2 owners that have that choke arrangement or did all F2s still had the chokelever under the tank?

[Nurse Julie]

... An indication also is that this F2 had a fast cam and the chokeknob on the handlebars...

The info I have given above, may be wrong! Any F2 owners that have that choke arrangement or did all F2s still had the chokelever under the tank?

Our F2 choke on carbs, not handlebars.

[cooleronthecoast]

Mines on the carbs.