Shimming CV carb needles ? never fails to amaze?

[Nessism]

My recently licensed 1000 project bike is finally road worthy so I?ve been taking it out for short rides while shaking out the bugs. The bike was running like a dog when cold and required a lot of choke and clutch slipping to get moving until it warmed up some. Shimmed the needles this morning and now the bike is running great! It?s amazing how simple this mod is, and how effective. As far as I?m concern it should be mandatory for everyone with CV carbs using the stock airbox and exhaust. Suzuki jetted these bikes LEAN, and a simple matter of lifting the needles 1 mm makes a world of difference. Do it, you won't be sorry.:dancing:

 

[Matchless]

Ed,
That bike looks like it just came from the factory!!! Excellent job!

Its going to attract a lot of attention.

 

[old_chopper]

Nice looking ride!

 

[Guest]

Beautiful work Ed... really, really nice.

 

[Guest]

Needles smeedles
You just wanted to show off your ride.
Very nice indeed!

 

[Guest]

Wow, Yes, you do great work. That looks show room fresh.

 

[doctorgonzo]

If there was ever somebody made to restore bikes to bone stock beauty it's the grumpy old engineer.

 

[KitKat]

is there a guide to shimming needles? I'm sure i'll need one and can't find it on bikecliff's site

 

[BassCliff]

The grumpy engineer strikes again!

The grumpy engineer strikes again!

Ed, you are a wizard! The West Coast's Grand Poo-Baa of GS restorative prestidigitation! Another excellent build! Thanks for showing it off.


Thank you for your indulgence,

BassCliff

 

[BassCliff]

is there a guide to shimming needles? I'm sure i'll need one and can't find it on bikecliff's site

Here are some notes that I've collected. There's plenty more in the SEARCH feature.

Shimming The Needle



Thank you for your indulgence,

BassCliff

 

[rapidray]

You can get the shims/washers at a Radio Shack. Ray.

 

[KEITH KRAUSE]

The bike looks great and I'm glad it's running as you say.
However, I gotta say, Suzuki wouldn't release a bike that was so lean that it would take launching efforts as you describe. They wouldn't sell 3 of them. Were they on the lean side? Yes. But not so much that it would require you to lift the jet needles approx' .040" to get good performance. That much lift is close to 1 full position richer if the needles were adjustable. Believe me, 1 position is a significant step with no intake/exhaust changes and the motor tuned correctly/maintained well.
I think something or a combination of things are involved here that make that normally too-rich needle position work for you. The needle is compensating for something else. I can't tell you what it could be because I don't know the bikes history but in most cases it could be many things.
I don't want you to think I'm arguing. From previous posts I know you have a firm way of believing things. But I don't think other owners should be advised to just run out and re-jet their bikes based on your info.
I think it will cause more trouble than good.

 

[doctorgonzo]

I believe they were so lean Keith for emissions reasons. They optimized the jetting for emissions not for performance. The average buyer didn't know the difference, the bike ran fine, and they just had no idea it could run great.

 

[salty_monk]

Ed's at Sea level that's one thing....

Also I believe that motor is made up from Parts, the head is not the original & neither are the Cams & I don't think the carbs are off an S model so I guess it's possible that could also require a slightly different setup. The exhaust is also off a 781000 from memory, all things that could have some effect.

I agree with Ed though, lifting the needle by a couple of washers does seem to make a good bit of difference round here on the couple of stock bikes that I have played with.

Dan

 

[Nessism]

I read in Cycle magazine how they routinely took their GS test bikes and removed the plastic spacer on top of the clip in order to raise the needle in order get them to run properly. The amount I raised the needles is about 1/2 the height of the spacer and it made a huge improvement. I did the same thing on all the CV carb GS's I've rebuilt and in each and every case it transformed the bike from a cold blooded beast to one that could be ridden away from a cold start almost immediately with only a small or no choke depending on the temps outside. This is one of the most worthwhile mods there is and I highly recommend it to everybody with CV carbs.

 

[Nessism]

Ed's at Sea level that's one thing....

Also I believe that motor is made up from Parts, the head is not the original & neither are the Cams & I don't think the carbs are off an S model so I guess it's possible that could also require a slightly different setup. The exhaust is also off a 781000 from memory, all things that could have some effect.

I agree with Ed though, lifting the needle by a couple of washers does seem to make a good bit of difference round here on the couple of stock bikes that I have played with.

Dan

Thanks for defending me Dan but no need. The head on this bike is from a 1000G, which is identical (same part number) as the 1000E and 1000S head for 1980. The cams are likewise from a 1000G, which again are identical to the 1000S parts. The only thing on this bike that is not 100% stock is the carb jets which I think are K&L parts and the exhaust pipes which are regular C/N/E pipes. The jet could have something to do with the issue but I doubt it.

Keith's memory is foggy, or maybe he's never ridden a bone stock 1000 with CV carbs on a cold morning.

 

[tfb]

What a glorious-looking machine!

 

[posplayr]

Ed,
Real nice. I have not see this machine close up but if it is anything like that GS750 you did then I know it is immaculate. I know enough now that this kind of detail only comes from the experience of the other builds you under your belt. Also I don't think you sent a ton of money on PC, so most all of this was refinished DIY but with professional results.
Congrats
Jim.

P.S. I have been planning to shim the CV's on my bone stock Ca 81 GS750. It runs a little lean as well.

 

[KEITH KRAUSE]

Ed, like I said, I'm not trying to argue. Nothing to defend against. Nothing intended as an attack on your knowledge.
I simply find it hard to believe Suzuki sold all those bikes and eveyone had to go through what you said you do just to get them rolling. Their jetting could be off but not so much as you believe. Nobody would buy the bikes. I certainly wouldn't.
I still think there's other factors involved here that worsen the existing condition and create the need for your suggested change, that's all.
See?? Lots of smilies.

 

[Nessism]

Ed,
Real nice. I have not see this machine close up but if it is anything like that GS750 you did then I know it is immaculate. I know enough now that this kind of detail only comes from the experience of the other builds you under your belt. Also I don't think you sent a ton of money on PC, so most all of this was refinished DIY but with professional results.
Congrats
Jim.

P.S. I have been planning to shim the CV's on my bone stock Ca 81 GS750. It runs a little lean as well.

Thanks Jim. Shim those needles, you will be amazed what 1 mm will do.

Something to keep in mind regarding this mod is that the needle height is dictated by the spacer on top of the needle clip. This is contrary to what some might think but you have to realize that there is a spring under the needle clip that pushes up so how far up the needle goes depends on what's above the clip, not what's below.

Radio Shack sells a bag of washers that are the proper size from what people have said. What I did was take some washers with the proper ID and stack them on a small screw with a nut, and then chuck up the assembly in a drill motor to spin them so the OD can be reduced with a file. Works great if you are too lazy to drive to Radio Shack.

Regarding my bike, I used POR-15 paints on most parts after bead blasting in my ebay procured blast cabinet (great purchase). The paint seems pretty tough, particularly the Hardnose stuff which is two part catalyzed. One other great purchase which made this restoration easier was a Caswell Plating zinc home plating kit. This kit was not cheap but it's really nice to have nice shiny hardware to use when bolting everything back together.