Author Topic: CB550F Main Jets  (Read 3040 times)

Offline cooleronthecoast

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CB550F Main Jets
« on: November 11, 2019, 01:11:19 PM »
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?
Now where did I put that 10mm socket?

Offline davidrsmith

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Re: CB550F Main Jets
« Reply #1 on: November 11, 2019, 01:21:42 PM »
Hi

I got my new jets etc from nrp-carbs.co.uk, they may have what you are looking for.

Dave

Offline Johnwebley

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Re: CB550F Main Jets
« Reply #2 on: November 11, 2019, 01:37:26 PM »
If you need a rebuild kit.check
Www.cruzinimage.net
Great carb  kit. Quick delivery and good prices

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Offline deltarider

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Re: CB550F Main Jets
« Reply #3 on: November 11, 2019, 02:51:33 PM »
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?

Offline Johnwebley

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Re: CB550F Main Jets
« Reply #4 on: November 11, 2019, 02:55:13 PM »
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

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Offline Nurse Julie

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Re: CB550F Main Jets
« Reply #5 on: November 11, 2019, 02:56:03 PM »
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.
LINK TO MY EBAY PAGE. As many of you know already, I give 10% discount and do post at cost to forum members if you PM me direct.
https://www.ebay.co.uk/sch/julies9731/m.html?item=165142672569&rt=nc&_trksid=p2047675.m3561.l2562

LINK TO MY CB400/4 ENGINE STRIP / ASSESSMENT AND REBUILD...NOW COMPLETE
http://www.sohc.co.uk/index.php/topic,14049.msg112691/topicseen.html#new

Offline cooleronthecoast

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Re: CB550F Main Jets
« Reply #6 on: November 11, 2019, 03:42:48 PM »
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.
« Last Edit: November 13, 2019, 06:43:00 PM by cooleronthecoast »
Now where did I put that 10mm socket?

Offline Nurse Julie

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Re: CB550F Main Jets
« Reply #7 on: November 11, 2019, 04:04:59 PM »
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.
« Last Edit: November 11, 2019, 04:06:33 PM by Nurse Julie »
LINK TO MY EBAY PAGE. As many of you know already, I give 10% discount and do post at cost to forum members if you PM me direct.
https://www.ebay.co.uk/sch/julies9731/m.html?item=165142672569&rt=nc&_trksid=p2047675.m3561.l2562

LINK TO MY CB400/4 ENGINE STRIP / ASSESSMENT AND REBUILD...NOW COMPLETE
http://www.sohc.co.uk/index.php/topic,14049.msg112691/topicseen.html#new

Offline cooleronthecoast

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Re: CB550F Main Jets
« Reply #8 on: November 13, 2019, 06:37:48 PM »
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.    :)
Now where did I put that 10mm socket?

Offline Moleskins

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Re: CB550F Main Jets
« Reply #9 on: November 13, 2019, 07:19:05 PM »
Try NRP Carbs in Manchester.
+44 (0)161 832 8646

Offline deltarider

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Re: CB550F Main Jets
« Reply #10 on: November 13, 2019, 09:55:47 PM »
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.

Offline cooleronthecoast

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Re: CB550F Main Jets
« Reply #11 on: November 14, 2019, 08:46:37 AM »
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
Now where did I put that 10mm socket?

Online K2-K6

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Re: CB550F Main Jets
« Reply #12 on: November 14, 2019, 09:05:00 AM »
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.

Offline deltarider

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Re: CB550F Main Jets
« Reply #13 on: November 14, 2019, 11:03:52 AM »
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.

Offline Nurse Julie

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Re: CB550F Main Jets
« Reply #14 on: November 14, 2019, 05:05:16 PM »
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.
« Last Edit: November 14, 2019, 05:07:27 PM by Nurse Julie »
LINK TO MY EBAY PAGE. As many of you know already, I give 10% discount and do post at cost to forum members if you PM me direct.
https://www.ebay.co.uk/sch/julies9731/m.html?item=165142672569&rt=nc&_trksid=p2047675.m3561.l2562

LINK TO MY CB400/4 ENGINE STRIP / ASSESSMENT AND REBUILD...NOW COMPLETE
http://www.sohc.co.uk/index.php/topic,14049.msg112691/topicseen.html#new

 

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