hey everybody, i have a triple su set up as you can see below and they definitely aren't in tune even though i have taken them to be tuned twice in the last 6 months. could anyone tell me or direct me to an article that could tell me how to go about it? i know its an art form that takes a while to master, but i'm having trouble finding anyone who knows how to do it.

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Classic, not plastic

Tuning SUs is as much an art as it is a science. Here's the manufacturer website; they offer an excellent service manual you should have, as well as all parts and tuning pieces. This book and this one are likewise strongly recommended. (I find one of them for sale more locally to you Here.)

Once you've got the basic ideas down, you will need some way to observe the mixture. A Gunson Colortune will get you a fair long way down the right road. You will also need a carburettor synchroniser to make sure all the carbs are sucking the same amount of air at the same time. Here is an Australian eBay auction that includes a whackload of SU tuning and service tools, including a Colortune, a synchroniser, jet-centring tool, etc. Suggest you buy!

SUs are tuned by changing jet needles; there are MANY hundreds (thousands?) of different needle profiles. Swapping the needles is not difficult, keeping track of which ones you've tried is. This computer program will make the initial selection and sequential replacement much, much easier.

Of course, all of this assumes the carbies are in fundamentally good condition. If the throttle shafts have any appreciable slop, for example, it won't matter how much you tweak and tune them; they'll still run poorly and give poor economy.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

What exactly do you mean by "aren't in tune"?
Not synchronized?
Not jetted correctly?
Both?
What are the carbs from?
What needles are in them now?
What color springs?
What was done when they were tuned?

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