how to set up SU carbies

**AdsLandies** · 27th April 2012, 03:38 PM

Originally Posted by pdd1098

They are 175 CD's but made by Zenith!
I just assumed all those style of carbs were SU's!

They don't appear to have the adjusting nuts on the bottom like SU's
I need to retitle this as "how to set up Zenith 175CD's?"

Anyone out there know how to weaken them a bit? I can't see anything other than the idle speed screws.
Thanks
Dave

Yep, I assumed you meant the 175CD's. The only way to weaken the mixture is by adjusting the depth of that needle down the dashpot using the special tool.

**pdd1098** · 30th April 2012, 10:29 AM

Heres how it went....I'm too impatient to wait for tools, so I took off the top of each carb, removed the pistons and cleaned everything up.
The adjusters on each carb is different! one was an allen head which is now mauled beyond repair(by previous mechanic)! the other is an inverted slot, sort of. So I made an adjusting tool for the slot one. The adjusters are left hand thread so counter clock screws the needle down to lean it. I turned it so the needle was a full millimeter longer. The other couldn't be turned but he needle is held by a grub screw, so I just dropped it by 1mm to match the other.
Back together , all good.
Went for a cold stert next day, normally no choke, no throttle. (it was obviously so rich!) now needs choke starts and runs fine after warm up, long test drive today and all is good.
Thanks for all the help

Dave

**Davo** · 30th April 2012, 09:57 PM

As the saying goes, "It's only a bodge if it doesn't work!". Good effort there, and in the meantime look for some good carbies you can rebuild in case you need them.

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