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.

[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!

[hikermikem]

Beautiful work Ed... really, really nice.

[chef1366]

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

[kingofvenus]

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!

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.