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Help me learn to use a uni-syn

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livinginthepast

livinginthepast

Jedi Trainee
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Will someone please point me to 'for dummies' instructional material for using a uni-syn, or give me a brief run down?

I'm not talking about all the carb specific tasks (disconnect throttle shaft, choke, and so on) - I mean just the basics on how to position and adjust the uni-syn on the carbs to get a reading (should the glass/plastic tube be positioned vertically? Horizontally? What to look for when contrasting results between carbs, etc. Really basic stuff for a someone who has never used one before. Assume I know nothing. Cuz I don't. :smile:
 
Tube is vertical. On first carb adjust so float is at a mark on tube.

On second carb adjust idle to the same mark.\

All done, wasn't that easy, now button it up by tightening the throttle rod between the carbs and fine tune the idle.
 
I'll take a stab at it.
I used one for the first time a couple weeks ago, prior to that I had used the "tube to the ear" method, I wasn't too far off with the tube according to the unisyn. You need to turn the middle round thing with the bumps on the perimeter to let more or less air flow through, you don't want it too "closed" so the carb is starved for air (and the red plastic pellet is way high) nor to you want it so open that the pellet is too low. I set mine so the pellet was on the lower third, then move the thing to the other carb and adjust the carb until the pellet is at the same place it was on the first carb.
 
Thanks; this is exactly what I needed!
 
There is a John Twist video on YouTube demonstration how to tune dual SU's. Don't have a link but he is using the Uni-Syn.
 
Don't waste too much time on the Unisyn- it only sets your idle but has virtually no bearing on the engine above idle. I have one and use it occasionally but usually to verify that the carbs are the same at idle. If you readjust the idle then all of your Unisyn time is wasted and you need to start over.
It is a fun toy but almost useless.
BillM
 
If they're synched at idle, then locked together, they should stay together pretty much, no? I can see how with all the variables that they won't be perfect at 3,000 rpm anymore but then again, they could be more perfect.
 
What it does is tie the butterflys together so they open the same. Important at all RPMs.
 
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