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Old 07-16-2010, 09:05 PM   #286
Renner
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my carburetors are giving me fits!
at least I think it's the carbs. symptoms being unpredictable surging and stumbling at first 1/4 of throttle action.

I suspect the idle air passages are not wholly clear of debris, been working on that, blaming all on the PO.

Anyway, the carbs in question are 64/32/323 & 324
Bing catalog shows these as applicable to R80
Same catalog indicates R80ST carbs are 64/32/351 & 352

I don't think it matters much but I'm curious which are more commonly found on our STs, an informal survey please.

What model Bings are on your R80ST?
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Old 07-17-2010, 12:22 AM   #287
England-Kev OP
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My ST has new carbs fitted so not much help, but the important number in the sequence is the 64, as that is the spec for the 80 series carbs with regard needle position and jet size, the 32 is the size, and the 323/324 just means left and right.
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Old 07-17-2010, 07:26 AM   #288
Airhead Wrangler
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Quote:
Originally Posted by Renner
I don't think it matters much but I'm curious which are more commonly found on our STs, an informal survey please.
I think they changed between the '83 and '84 models, the only difference being a leaner 135 main jet on the '84s and all other settings identical IIRC.
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Old 07-17-2010, 08:55 AM   #289
Renner
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Looking at the Bing catalog, all carburetors from the R45 up to the R100 are prefixed with the 64, and the 32 refers 32mm of the throat diameter.

I'm guessing the last three are essential the Bing carburetor model number. I know when I've called Bing the fellow wants the whole series of numbers.

I've read that the main jet size changed somewhere in the production run... may have heard that 135 was a US spec, perhaps Euro models never came equipped with the smaller jets?
This bike went down the assembly line somewhat early and currently has the 150 jets.

My ST has a moderately annoying stumble or lack of predictable response in the first 20% of throttle range or off-idle transition, which I would first suspect as debris in the idle air passages and possibly idle jet as well. I've been working to clear all this. While puttering and stumbling along, if I roll on throttle rapidly then the bike accelerates smoothly with good enthusiasm.

The Bing catalog shows my 323/324 (left & right) use a 40 idle jet which it has. The 351/352 is specific to the R80ST (according to Bing) and runs a 45 jet.
I'm actually considering moving up to the 45.
The Bing book also shows initial idle mix setting at .5 for both model carbs.

That seems extremely lean to me; the idle mix sweet spot on my bike is about 1.13 turns at which the stumble while running at low revs is pretty bad. Right now I'm using a richer setting of 1.5 and off-idle response stumbles less and is tolerable but well rich of the sweet spot when making adjustments at idle.
The plugs indicate a too lean condition... maybe that's a result of our modern gas formulas, or perhaps not.

I wish I knew more about this particular bike's history. Quite possibly the carburetors are not original to this bike, which is why I'm asking what model carburetors are on the other R80STs in this small survey.

I'd guess most are 64/32/351 -352 with maybe a few 64/32/323 -324 like mine.
I don't doubt they're interchangeable.
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Old 07-17-2010, 09:00 AM   #290
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Quote:
Originally Posted by England-Kev
My ST has new carbs fitted ...
Kevin, I'm curious what carburetors did you fit up?

I've been considering this myself.
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Old 07-27-2010, 10:35 PM   #291
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Here's mine , bought last week and riden 500 miles home .She's smooth and sweet , my first BeeM . I like the 100GS tank and might add a GS single seat ,subframe and some decent sized panniers .


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Old 07-28-2010, 05:15 AM   #292
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nice
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Old 07-28-2010, 12:39 PM   #293
mark1305
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Carb Serial Numbers

Just to add to the confusion, my ST has 64/32/327 & 328 carbs. All the jets were model correct when I went through the carbs last year. But I did increase the idle jets from #40 to #45 which helped cold starting, cold idling, and stable transition to warm idling.

When servicing these carbs, don't forget to check and if needed clean out the tiny little jets in the bottom corner of the float bowls. I had to very very carefully clean mine out with cleaner and judicious application of welding tip cleaning probes. I'm sure that helped my carbs. Someone else on here mentioned those jets as well - they are so small they can get aluminum oxie crystals around them that close them off eventually.
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Old 07-28-2010, 01:28 PM   #294
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Thanks for those carb model numbers Mark.

Like you, I also managed to improve low-end throttle response by replacing 40 idle jets with 45s.
I'm thinking 50s would be better still, but my fuel economy would suffer.

+1 also on the jets in the bowl corners.
I believe they're choke/enrichener jets.
Those are sometimes slotted for removal: standard 3/16" flat blade screwdriver IIRC.
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Old 07-28-2010, 02:37 PM   #295
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Quote:
Originally Posted by Renner
I believe they're choke/enrichener jets.
Right you are, sir. It took me a little while to realize why my enrichener circuit wasn't working well when I first brought my airhead back to life.
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Old 08-01-2010, 05:08 AM   #296
Sibbo
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Seat height

A question fellas ...........My bum is very close to the ground cos I'm 5'7'' .Is there anyway to lower the seat height on an ST ? I'm planning a 100GS single seat cos the one I tried was so comfortable .

Any suggestion ?
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Old 08-01-2010, 05:22 AM   #297
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Hey Sibbo, how did the boots go, keep your feet from freezing. Here is a ST i shipped back from the States and built the luggage for. Locky.

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Old 08-01-2010, 05:53 AM   #298
Sibbo
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Boots !

They were brilliant Locky , a good fit with 2 pair of socks .... no cold feet at all .It was a good trip mainly around 11C with about 7 in the mornings .The ST is a very smooth touring machine ,great brakes and pretty reasonable fuel consumption .


I've used up all available cash with the purchase and have to sell another bike to pay the Visa ! So I reckon I'll be trying to make up a set of panniers like that for myself ...I like yours ! Beautifully made but it going to have to be the poor man's version for me ! I wish I could ally weld .
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Old 08-01-2010, 07:29 AM   #299
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Sibbo, As for seat height, when I bought my ST it included both stock seat and a Corbin that was cut way lower. It was so low that although it was the more comfortable seat, it caused my knees to hurt from the extra bending required. So I sold it. It did lower my riding position noticeably, though.

Look around on the internet. I've seen a few lowered Corbins from time to time.
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Old 08-01-2010, 03:41 PM   #300
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Corbin ? thanks Mark I haven't seen one here but I'll look around .
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