Strange Needle

Coyote · Post by **Coyote** » Sat Jan 24, 2015 10:11 am

Did Suzuki ever make any 'silver' needles? I am used to these being gold in color. All 3 have the same needle (as well they should). Note the totally unworn slide. All 3 are like this. I'm just not sure about that needle. The carbs are 341-11L, M and R.

Post by **Alan H** » Sat Jan 24, 2015 10:35 am

AFAIK, all needles are chromed, or in the 'old days' some were silver steel but this tends to wear the brass jets out faster. Doesn't matter so much on racing carbs where they get chopped regularly.

tz375 · Post by **tz375** » Sat Jan 24, 2015 10:47 am

I suspect that the needle is machined from aluminum. Most needles are silver.

What is the needle number? 5DH21 or 5DN1?

Coyote · Post by **Coyote** » Sat Jan 24, 2015 3:58 pm

5DH21 Is that good or are the 5DN1 preferable?

tz375 · Post by **tz375** » Sat Jan 24, 2015 6:07 pm

I don't know about "better". 5DH21 is what the spec calls for for 1975 IIRC.

J model crabs are 340-11 according to my notes and used that needle. Yours are 341 and that sounds right for the later ganged sets.

Mike Yeadon (UK market not sure of year) mentioned 5DN1 in a set of 346 carbs. I don't know if US models changed to the 5DN1 needle or not. Looks like maybe not.

Ian Sandy's GT550 guide says "Note there is still a lack of clarity about which carburettors were fitted and where. The Suzuki Service Data manual for 1973 lists a 34012 for non-EU countries and a 34600 for EU countries having different slide cutaways, different jet needles, pilot and main jets. The only parts manual I've been able to find does not list the 34600 carburettor - I'm sure additional material will surface over time."

Cam operated, ganged carburettors (carburettor designation 34110 which changed to 34111 ) now with one push and one pull cable only.

'L' jetting was standard in most countries having #97.5 left and right carburettor main jets, with a #95 centre main jet, and a #25 pilot jet
Throttle slides were 'handed' with the locator pin for the right side carburettor being on the opposite side to the middle and left carburettors
Note The 'L', per the parts manual at least, seems unique as only one carburettor version was fitted for both EU and non-EU markets

Coyote · Post by **Coyote** » Sat Jan 24, 2015 9:26 pm

Seems as though everything is correct on this set. 97.5's left and right. 95 center. None look like they had ever been removed. I got smart this time on pilot jet removal. shot some WD-40 in the cavity. All ran through, a good sign. Heated the tower with a propane torch for about 30 seconds. All three backed right out with no 'snick'. Screwdriver slot in perfect condition. They are 25's. Overall this set is in really good shape. I'm going to use these because I have no faith in the ones I already did. Remember the eroded main jet towers? And all the trouble I had with loose and tight main jet tubes? These will be a much better choice when finished.
Tough question. How critical is the spring tension on the float needles? These seem very weak and fully depress with the carbs inverted. I'm used to about half depressed when inverted.

tz375 · Post by **tz375** » Sat Jan 24, 2015 11:47 pm

If they are really weak the fuel level will be higher than stock leading to rich running. At 24 bucks I would get those Cruizin sets and throw most of the rest of the brass away. Mikuni charge that sort of money per float valve last time I got some.

Coyote · Post by **Coyote** » Sun Jan 25, 2015 7:16 am

Mikuni charge that sort of money per float valve last time I got some.

They are considerably higher now. $39.60 at Partzilla. I figured up the 4 items I need yesterday. The float needle / seat, the washers under it, the top o-rings and the bowl gaskets. Came to $154!

Coyote · Post by **Coyote** » Sun Jan 25, 2015 7:19 am

Coyote wrote:
Mikuni charge that sort of money per float valve last time I got some.

They are considerably higher now. $39.60 at Partzilla. I figured up the 4 items I need yesterday. The float needle / seat, the washers under it, the top o-rings and the bowl gaskets. Came to $154! That does not include shipping. I believe $10.95 on that amount.

yeadon_m · Post by **yeadon_m** » Sun Jan 25, 2015 11:15 am

550 ganged carbs seem a jetting lottery depending on the model and country. Extract from my confused notes:

"Manuals confirm that for a US 550L, NJ is a P-0 and the JN is 5DH21-4.
But, is this what my NOS carbs have? (I'd purchased a set from a guy who imported them decades ago from a dealer in Italy who was closing shop).
Nope, in my Italian NOS carbs NJ are O-9; JN are 5DH21-4.
By contrast, my UK 550B carb NJ are P-4 (larger); JN are 5DN1-3 (I read this means a steeper second angle). "

I am now using the Italian carbs with those JN/NJ and have upped the pilots to the the 30 and mains to the 105/102.5/105 that the UK nikasil bikes seem to like. Its very nice.

Cheers,
Mike

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