Honda-SOHC
SOHC.co.uk Forums => CB500/550 => Topic started by: cooleronthecoast on November 11, 2019, 01:11:19 PM
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According to my Haynes manual, my CB550F2 should have 98 size main jets. I stripped down the carbs this morning to find I've got 3 100's and a 75 which I think is a CB400F size! I'm looking to buy a set of 4 98's, but I can't find any on ebay or on Dave Silvers website.
Can anyone point me in the direction of where I can get some please?
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Hi
I got my new jets etc from nrp-carbs.co.uk, they may have what you are looking for.
Dave
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If you need a rebuild kit.check
Www.cruzinimage.net
Great carb kit. Quick delivery and good prices
Sent from my SM-A750FN using Tapatalk
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If you need a rebuild kit.check
Www.cruzinimage.net
Great carb kit. Quick delivery and good prices
But isn't that the infamous Keyster set?
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If you need a rebuild kit.check
Www.cruzinimage.net
Great carb kit. Quick delivery and good prices
But isn't that the infamous Keyster set?
Don't think so.
I have had a couple of sets. For different bikes.
Always been good.
I know several on here that use them
Sent from my SM-A750FN using Tapatalk
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I always use the Cruzinimage carb kits, well, the brass bits anyway, I just ditch the O rings that come in the kits and upgrade them to Viton.
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Hi
I got my new jets etc from nrp-carbs.co.uk, they may have what you are looking for.
Dave
Thanks Dave
I had a look at their site and they quote a 108 Jet for the 550F
http://www.nrp-carbs.co.uk/shop/index.php?route=product/product&path=45&product_id=5233
and a 110 for the 550K so I'm a bit confused now. I've left the 3 100's I have in 3 of the carbs and I found a 98 for the 4th one, but I would like to get the correct ones.
I have the Delcavic exhaust fitted which I'm guessing is more free flowing than the original system, so perhaps the main jets in size 100 might be a better bet? I'd be grateful for members advice on that one.
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Delkevic advise standard jetting for their exhaust systems. I have an original Yoshimura 4 into 1 on my CB550/4 F mongrel, with standard airbox and filter and a minute push in baffle but with no silencer and I still have the standard jetting fitted to the carbs. It's usually a case of changing jets if you remove the standard air box and fit pods or velocity stacks instead.
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I've refitted the 3 x 100 jets I already had together with a 98 in the 4th carb, its already running much better than before and I haven't set up the balance with the vac gauges yet. :)
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Try NRP Carbs in Manchester.
+44 (0)161 832 8646
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I've refitted the 3 x 100 jets I already had together with a 98 in the 4th carb, its already running much better than before and I haven't set up the balance with the vac gauges yet. :)
Realise that changing the main jets, does not require a new synchronisation. Also realise that synchronisation only effects the idle and say a raised idle.
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I've refitted the 3 x 100 jets I already had together with a 98 in the 4th carb, its already running much better than before and I haven't set up the balance with the vac gauges yet. :)
Realise that changing the main jets, does not require a new synchronisation. Also realise that synchronisation only effects the idle and say a raised idle.
Believe me, in this case it does. When I got the bike, I got a 'spare' set of Keihin carbs with it. I think a former owner has been mix and matching out of the two sets and I put the gauges on a while ago and the reading s are all over the place. :o
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I've refitted the 3 x 100 jets I already had together with a 98 in the 4th carb, its already running much better than before and I haven't set up the balance with the vac gauges yet. :)
Realise that changing the main jets, does not require a new synchronisation. Also realise that synchronisation only effects the idle and say a raised idle.
I'd respectfully disagree with that too deltarider, if they've been synchronised with one odd jet then it's likely that slide would have been set to effect some sort of compromise.
Synchronisation is definitely not for idle parity, that's simply a byproduct of the process on carb banks linked with a bar. The fundamental reason is to get absolute parity at maximum torque to prevent unwanted stress at the most critical point of engine performance, tickover smoothness will benefit from that process but idle parity is ultimately refined with the aircrews, assuming the main slides are matched.
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An engine is basically an air pump. In our case 4 cylinders join their effort on one crank. Correct me if I'm wrong, but I'd say whatever cylinder has a less than ideal mixture, its piston will be forced up and down nonetheless, creating a vacuum in the intake tract all the same. When I've experimented with it, I found no change in vacuum readings when I had altered the mixture. Although I'm not an expert on this, I tend to disagree with your assumption that sychronisation is aimed to have the best result at max torque. Decades ago a Swiss race mechanic explained me that they never used clocks to sync the carbs, but just bench synced them. Reason: they were not interested in a nice idle and bench syncing was OK to have good results in racing, operating their engines near max power all the time. I wonder how you will be able to measure differences in vacuum at say cruising rpm, let alone at max torque. But make no mistake, I'm open to learn something new. I always read your posts with interest.
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I have never, ever synced a set of carbs by vaccum gauges. I bench sync and get bike running then get spot on running and performance by adjusting mixture screw as a result of plug colour, therefore obtaining perfect parity throughout the entire rev range from idle, to maximum torque. All my bike perform perfectly.
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Its all interesting stuff guys and gals, but does anyone have a single 100 main jet sitting on a shelf they can sell me so I can have 4 that match?
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Thats great mate. I'll have those please. I'll pm you with my address details later today and if you have Paypal let me know your addy and I'll sort out the money too. If not just let me know how you want me to pay.
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I've just removed 98's from my 500 carbs to fit 105's. If you drop me your address you can have them.
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I've just removed 98's from my 500 carbs to fit 105's. If you drop me your address you can have them.
Thanks mate, I've asked Oddjob for the ones he offered so I should be fixed up shortly.
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Sorry they were 100's. Would not surprise me if these are 550 carbs, the more I do on this "500" the more I find wrong!!
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Did we not ascertain a while back that the CB500/4 and the CB550/4 F model (non PD's which are on the 550/4 K's) are exactly the same carbs, just with different jets fitted. I know both myself and Trig have had plenty of both through our hands and have never, ever found a difference.... other than the jet sizes that were fitted by Keihin at manufacture. So, a 1971 500/4 has 627A, a 1972 CB500/4 has 627B's and a CB550/4 has 069A's fitted, which are identical carbs, all but for jetting.
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Julie, do you know why the 550F has 98 size main jets whilst the 550K has 100's? At least thats what my Haynes manual tells me. I was thinking because of the different exhausts but I haven't got a clue really.
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I know diddly squat about jetting really and can only assume it has to do with the CB550/4 K having Keihin PD carbs fitted which run very, very lean. The K3 was built primarily for the USA market and the bikes had to fit in with their strict emission regulations.
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Maybe you like to consult this.
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I don't think that's correct, never seen or heard of a #78 main jet on any Honda, let alone a CB500/4 🤔🤔🤔🤔
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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
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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.
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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.
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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.
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...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?
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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.
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Coolercoast, did you communicate what number carbs you have? See pic for where to look.
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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!
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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)
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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.
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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.
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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.
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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.
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... 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?
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... 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.
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Mines on the carbs.
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Thanks both of you. I'll modify the post. I am 100% sure I have seen a F2 once with that choke knob in the dash. I began to doubt when I didn't see it mentioned in the F2 parts list. So I take it the one I've seen must have been a F2/K3 bastard. Nowadays we see different parts ending up on different models.
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... 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?
All 550F's had choke lever on the carbs. The PD on the K3 carbs had a choke cable