Which needle will I use in my BS32SS carbs

[Guest]

As a few of you know I have just got my 550/650 motor back together and now am going through the carbs i bought for the conversion. They look to be in really good nick, no wear in the throttle shafts can be felt, etc. But thought I should still give them a good going over before I put them on even though they would have probably run OK.

I have dipped the first carb body (#4) and it came out looking good. I was surprised how thick the solid aluminium plug was that was sitting in top of the mixture screw. Took a while to get through it with the drill.

Anyway to my question:

The standard jet needle for the GS650E is a 5C45, but I also have a set of 5C32 needles that have the 5 grooves in them for adjustment.

My question for those who know about these things: "Is there much difference in these needles? Can I swap to the grooved needles without upsetting the throttle response?"

I like the idea of adjustable needles, but do not want to swap if the taper is too different and is going to cause tuning problems.

BTW These 5C32 needles did come out of BS32SS carbs, but I think they were off a 750GSX (Australian model).

The other thing I found surprising when pulling the Aussie carbs to pieces was that the needle was held in place in exactly the same way as the needles that are non-adjustable. With a plastic spacer on top of the small needle circlip, then a small washer and spring under the circlip. I thought the needle would have been help positively in place by an arrangement that secured the needle circlip without all the spacers, washers and springs. Well there you go.






Photos for your perusal. Is the taper the same?

[Suzuki_Don]

What To Do With Starter Plunger

Oh! ONE MORE QUESTION:

What do I do with the choke plunger once it has been taken out of the carb? I guess I cannot put it in the dip, that would ruin the rubber insert on the inner end of the plunger. Is it just a wipe over with carb cleaner fluid on a rag and then put back together with a new "O" ring?

SORRY: TWO QUESTIONS:

Do I wipe the diaphraigm with WD40 and the piston as well and that's enough? Anything else to do?

[chef1366]

With the needles I'd use the adjustable. Line the needles up and put the clip one notch lower than the non adjustable needle. The 5C means they are the same needle. You can play with the adjustable.
I just wipe the diaphram with a towel and take off the dust cover on the choke plunger cap.

[Suzuki_Don]

With the needles I'd use the adjustable. Line the needles up and put the clip one notch lower than the non adjustable needle. The 5C means they are the same needle. You can play with the adjustable.
I just wipe the diaphram with a towel and take off the dust cover on the choke plunger cap.

So Bill does the 5C mean both needles have the same taper/profile. If so what does the 45 & 32 stand for?

Sorry for asking for extra detail on the choke plunger, but what do you do with the plunger after the rubber dust cap is removed? I put the big brass nut off the choke plunger in the dip after removing dust cap and "O" ring. That cleaned up really good. How do I clean the plunger itself?

[posplayr]

So Bill does the 5C mean both needles have the same taper/profile. If so what does the 45 & 32 stand for?

Sorry for asking for extra detail on the choke plunger, but what do you do with the plunger after the rubber dust cap is removed? I put the big brass nut off the choke plunger in the dip after removing dust cap and "O" ring. That cleaned up really good. How do I clean the plunger itself?

Don, Ive just been reading the Sudco catalog and the 5C relates to the thickest part of the taper which is what drives the needle jet size (emulsion tube). The tapers are different although either uses the same emulsion tube.

Unless you did alot of modifications and are looking for more power, why not use the stock needle? You can put washers on the single groove needle to raise it (go richer).

[Suzuki_Don]

Don, Ive just been reading the Sudco catalog and the 5C relates to the thickest part of the taper which is what drives the needle jet size (emulsion tube). The tapers are different although either uses the same emulsion tube.

Unless you did alot of modifications and are looking for more power, why not use the stock needle? You can put washers on the single groove needle to raise it (go richer).

Yes Jim I am thinking that might be the safest way to go. I bought washers the other day from JAYCAR here in Sydney. It takes five of them to make up the same depth as the plastic spacer on top of the needle circlip. By removing two (leaving three in place) it means I am raising the needles by .037" which I think should be about right.

Just thought I would use the adjustable needles if they did not alter the mixture too much. But I don't want to pull the carbs down again if things aren't quite right. It's been almost two years on this project now so i just want it on the road.

On another point; if the main jets are a few sizes too large (should be 97.5 and are actually 110) will this affect the running of the motor except at full throttle. I don't do full throttle much.

[1_v8_merc]

Where do you even GET new needles at?

Everybody says to stay away from the cheap Carb Rebuild Kits out there, but I couldn't find any other needle jets for sale anywhere including z1 enterprises!

[chef1366]

Where do you even GET new needles at?

Everybody says to stay away from the cheap Carb Rebuild Kits out there, but I couldn't find any other needle jets for sale anywhere including z1 enterprises!

What needles do you need? The numbers are stamped on the needle.

[waterman]

Don, check out this page.

http://www.motorcyclecarbs.com/Mikuni_Jet_Needle_Dimension_Ch_W121C37.cfm

From what I can understand, the two needles you have are nearly identical with the exception of the grooves.

Either one would most likely be fine. I would throw the adjustable ones in.

Try the 110 main jet, at worst it will be too rich. No harm in that.

And what is this BS about not doing full throttle much, why go to trouble of modifying 550 to 650 without enjoying fruits of labor?

[posplayr]

Yes Jim I am thinking that might be the safest way to go. I bought washers the other day from JAYCAR here in Sydney. It takes five of them to make up the same depth as the plastic spacer on top of the needle circlip. By removing two (leaving three in place) it means I am raising the needles by .037" which I think should be about right.

Just thought I would use the adjustable needles if they did not alter the mixture too much. But I don't want to pull the carbs down again if things aren't quite right. It's been almost two years on this project now so i just want it on the road.

On another point; if the main jets are a few sizes too large (should be 97.5 and are actually 110) will this affect the running of the motor except at full throttle. I don't do full throttle much.

Don, I spoke with Bill, he thinks the number diff might just be the fact that it has grooves v.s. single groove (i.e. same taper). Needles are tapered and they bench mark them every 10mm, so if you are careful and use a caliper you can compare thicknesses along the length in a couple of spots to confirm what Bill is saying.

The suggested tuning is to get the mains set by pulling hard full throttle to redline. Then adjust the needle height, to adjust for any flat spots or bobbling in the mid range. Bill taught me everything I know and I still don't know what he does.

[Suzuki_Don]

Don, check out this page.

http://www.motorcyclecarbs.com/Mikuni_Jet_Needle_Dimension_Ch_W121C37.cfm

From what I can understand, the two needles you have are nearly identical with the exception of the grooves.

Either one would most likely be fine. I would throw the adjustable ones in.

Try the 110 main jet, at worst it will be too rich. No harm in that.

And what is this BS about not doing full throttle much, why go to trouble of modifying 550 to 650 without enjoying fruits of labor?

Tongue in cheek, my man, tongue in cheek.

[Suzuki_Don]

Bill taught me everything I know and I still don't know what he does.

He bakes cakes doesn't he.

[1_v8_merc]

What needles do you need? The numbers are stamped on the needle.

My mistake, i meant that I can't find Float Pins....not float needles.

All the float pins I see don't include my bike.....not sure if pins from another bike are swappable.

It's for a 82 650g

[chef1366]

My mistake, i meant that I can't find Float Pins....not float needles.

All the float pins I see don't include my bike.....not sure if pins from another bike are swappable.

It's for a 82 650g

I have float needles.

[chef1366]

Don, I spoke with Bill, he thinks the number diff might just be the fact that it has grooves v.s. single groove (i.e. same taper). Needles are tapered and they bench mark them every 10mm, so if you are careful and use a caliper you can compare thicknesses along the length in a couple of spots to confirm what Bill is saying.

The suggested tuning is to get the mains set by pulling hard full throttle to redline. Then adjust the needle height, to adjust for any flat spots or bobbling in the mid range. Bill taught me everything I know and I still don't know what he does.

And vise versa.