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Author Topic: Carb problems solved! Valuable lesson learned!  (Read 1293 times)

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Offline 1timduke

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Carb problems solved! Valuable lesson learned!
« on: September 09, 2010, 07:22:17 PM »
Yeah... I've been trying to tune the carbs on this bike for years...never quite right.   Rideable, but left some to be desired.

Finally figured out it's the wrong carb.  :P

Wow, I really thought I'd checked that.   Figured it out yesterday.   I was frustrated with always trying to get it right and wanted to just sell the bike, I figured I really didn't have the time or the space to tinker any more and I let it sit too many great riding days.  

Maybe I shoulda just looked at those little stamp marks...  :-\

Bottom line... if your having trouble, or rough running, or just feel a little flat spot, or especially checking out a new bike, check the engine # to the frame # to the carb chart here...



Anyways, I got a decent set of 627B carbs for a '71-'73 cb500 to trade for (or just purchase) an equally decent (or better) set of 022A carbs for the '75 cb550K.

I know feebay is overpriced and unreliable, but there is a nice cycle salvage yard near me with boxes of cb carbs.   Question of the day is how much should one expect to ultimately pay for a dirty but usable set of carbs?   I'm assuming new jets and new rubber all around is not to be factored in b/c I'll do that later.   I'm thinking no more than $100 from a salvage yard.... Is that in the ballpark?

-Tim
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a700guy

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Re: Carb problems solved! Valuable lesson learned!
« Reply #1 on: September 09, 2010, 08:00:52 PM »
so what was the problem?
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Online Stev-o

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Re: Carb problems solved! Valuable lesson learned!
« Reply #2 on: September 09, 2010, 08:31:55 PM »
Quote from: a700guy on September 09, 2010, 08:00:52 PM
so what was the problem?

Finally figured out it's the wrong carb.   ???
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Offline Hush

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Re: Carb problems solved! Valuable lesson learned!
« Reply #3 on: September 09, 2010, 09:00:52 PM »
I paid $50 for a full rack of 650 carbs and we pay way more here in NZ than you guys do for stuff so beat them down. ;)
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a700guy

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Re: Carb problems solved! Valuable lesson learned!
« Reply #4 on: September 09, 2010, 09:23:53 PM »
engine doesn't know what carbs are on it, only if they are set correctly
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Offline mystic_1

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Re: Carb problems solved! Valuable lesson learned!
« Reply #5 on: September 09, 2010, 11:12:57 PM »
Quote from: a700guy on September 09, 2010, 09:23:53 PM
engine doesn't know what carbs are on it, only if they are set correctly

Jet needles and air screw settings appear to be different between the carbs in question, based on the posted chart.

mystic_1
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Offline dave500

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Re: Carb problems solved! Valuable lesson learned!
« Reply #6 on: September 10, 2010, 12:45:42 AM »
jet the carbs to suit any bike.
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Offline MRieck

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Re: Carb problems solved! Valuable lesson learned!
« Reply #7 on: September 10, 2010, 05:32:27 AM »
Quote from: dave500 on September 10, 2010, 12:45:42 AM
jet the carbs to suit any bike.
I agree
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Offline mystic_1

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Re: Carb problems solved! Valuable lesson learned!
« Reply #8 on: September 10, 2010, 06:40:07 AM »
What I'm getting at is that it sounds like the OP tuned the carbs as appropriate to his year of bike ( I suppose that's an assumption) but still got inadequate performance.  Different jet needles and air screw settings suggest there may be differences in the carbs that he didn't take into account.  The chart also shows different tapers on the air screws for some models, so it's possible he's got the screws with tapers that don't match the carb's casting in there.

I don't see anything wrong with going back to a known starting point, especially for non-experts.  Sure you can, in theory, make just about any carb work on just about any bike, but the amount of skill and work it takes can be excessive for the layman.

mystic_1
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Offline 1timduke

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Re: Carb problems solved! Valuable lesson learned!
« Reply #9 on: September 10, 2010, 11:29:34 AM »
Yeah, I live in an apartment now and I don't have a decent place to sit and tune it.   I've tried and tried with several different jets and settings and it runs okay, just not optimal.   I could buy more jets and keep trying but the obvious solution to me is to return the bike to stock as it was designed.   

-Tim
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Offline Duanob

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Re: Carb problems solved! Valuable lesson learned!
« Reply #10 on: September 10, 2010, 12:39:37 PM »
$100 at a junk yard? Feebay is cheaper than that. There was a set for $49 that had no bids. I think the guy relisted them but I didn't follow up. Another set of 'professionally cleaned/rebuilt' carbs sold for less than $200. Considering rebuild kits alone X4 will cost you more than $100 that's a pretty good price.
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Offline 1timduke

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Re: Carb problems solved! Valuable lesson learned!
« Reply #11 on: September 11, 2010, 02:23:52 PM »
Found em!   Paid $75 for the set.   Got to open them up and look inside too.   Other than a little varnish and a slightly bent throttle cable plate they look real nice.   I could've tried sleazebay but it's so hit or miss.   The last time I found something good on ebay it opened up in the mail and I got a letter later saying that my package was found... just the package... no contents.... and no insurance.   It's worth my time to poke in the carb bins for the best set I can find, at least then I kinda know what I'm getting.   

As far as rebuild kits I found some I'd bought a long time ago in my pile of "bike crap".   :)

SO!   If anybody needs a set of 627Bs I'll let em go for a reasonable price.

-Tim
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