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-   -   Zama needle settings (http://www.rcuniverse.com/forum/engine-conversions-92/10995323-zama-needle-settings.html)

gr8flyer55 03-11-2012 07:28 AM

Zama needle settings
 
What are the initial needle settings for a Zama carb?
I have a few new ones that I replaced diaphragms and regulator flap valves and have no base settings for either needles or regulator levers. I know what they were set at when I bought them. Low was at 3 turns out which was way too rich cause it floods the engine trying to choke and start my engine. High speed was set at over 2 turns out, which never let it rev past 5,000 rpms. Converted engine is a small Kioritz, 16cc.
Any help would be appreciated.

John

rangerfredbob 03-11-2012 07:40 AM

RE: Zama needle settings
 
a good starting point on both Zama and Walbro are 1.5 turns out, and they should be around there for best running, any less than one turn out and more than 3 turns out and you get similar results to what you are seeing, if this doesn't get the engine running decent there is either a diaphragm problem or the regulator lever needs tweaked.

gr8flyer55 03-11-2012 08:13 AM

RE: Zama needle settings
 
I have the carb apart right now looking at the lever. I'm trying to determine the height for the pump diaphragm center button contact. Seems like anything above level with the inside base height and it floods out at an idle, wetting the plug. If I set it at exact level it won't pump a darned drop. Maybe there is a problem with the metering needle or seat?
I'll pull the needle and have a look. Everything is new as I mentioned, never been mounted or had gas in it till now. I have one on a Ryobi 31cc that seems to work perfect, and it also was brand new like the problem carb. Needle settings on the one that is working are as you said, 1 1/2 low and 1 3/4 high and lever level with base. Kinda stumped on this one though. Actually, I pulled off the fuel line from the carb, dried the plug, and a few flips it'll start and run till reservoir is dry. Kinda tells me it is way too rich. The bore size is the same as the Walbro the engine came with, so it should be fine if I get this sorted out.

John

av8tor1977 03-11-2012 08:58 AM

RE: Zama needle settings
 
The best way to fix a Zama carb is to exchange it for a Walbro. ;)

There is very little tech info available for Zama carbs, the kits for them are usually around 3 times or more the price of one for a Walbro, and I have found the diaphrams to be more sensitive to alcohol.

They work fine when set up properly though.

Just my two cents....
AV8TOR

gr8flyer55 03-11-2012 09:22 AM

RE: Zama needle settings
 
I may have found a potential problem with the metering needle. Took the screw out that holds the lever and spring. After lifting the assembly out, I looked at the needle tip and saw some sort of green plastic substance that looked like green locktite wrapped around the needle's rubber tip! Looking at the hold down screw, I found the same thing on it. Looks like an over abundance of locktite was used and excess got down into the needle seat. I think maybe it held it off the seat, causing my flooding problem. Thing was, after choking one time, it would continue to drip gas out of the carb till I flipped the prop. Never had one do that before!

So a word to the wise, look extremely close at your needles for debris collected, even on a brand new carb!

Thanks for needle info for initial settings. Hoping to have a successful engine run this afternoon.

John


gr8flyer55 03-11-2012 12:19 PM

RE: Zama needle settings
 
Just reset the needles and fired up the engine with the Zama carb. After a little tweaking of the low needle (open) it has excellent transition and nice steady idle with no more flooding. High end is better than I expected at 7400 on this 20cc engine with a MA classic 16-10 prop. Tried a new timing curve written by Nyemi for my timer and now also get one finger flip starts when warmed up. No tendency for kickback at all. What a wonderful day it turned out to be!

I have alot of ignition boards and new advance boards made up if anyone is interested. All they require is an ignition coil which should be available from Adrian at CH Ignitions with your choice of shielded plug cap. Pm me if interested in a setup for your conversion engines.

John

pe reivers 03-11-2012 02:26 PM

RE: Zama needle settings
 
I don't agree. Zama carbs are just as good or better than Walbro, depending on where walbro was made. In my part of the world, kit prices are about the same, and resistance to ethanol is not an issue.

PS
Loctite residue on needls seats, and all over other parts has plagued all pumper carbs since time memorial. It is good advice to look for clean carb internals if a new carb acts up.
Quote:

ORIGINAL: av8tor1977

The best way to fix a Zama carb is to exchange it for a Walbro. ;)

There is very little tech info available for Zama carbs, the kits for them are usually around 3 times or more the price of one for a Walbro, and I have found the diaphrams to be more sensitive to alcohol.

They work fine when set up properly though.

Just my two cents....
AV8TOR

bluejets 03-11-2012 05:25 PM

RE: Zama needle settings
 
http://www.zamacarb.com/pdfs/TechGuide_2007.pdf

gr8flyer55 03-11-2012 05:58 PM

RE: Zama needle settings
 
Wow!
Wish I had looked a little harder for tech info on the Zama before I tore it apart!
As always Jeff, you came up with an excellent source of info!
This sure dispells the thoughts there wasn't much info on these little gems.
Much appreciated information for sure. Now there is no excuse for lack of knowledge. I think they did a great job of producing the much needed technical data and pictorials.

Thanks again Jeff for the super find!

John

av8tor1977 03-12-2012 08:06 AM

RE: Zama needle settings
 
Very nice tech info. Thanks!

AV8TOR

CH Ignitions 03-20-2012 07:02 PM

RE: Zama needle settings
 
Hi John,

All Zama Carbs I am using I start at 1 1/4 turns.


Raise the the RPMS to 4000 with the screw for throttle adjustment then play first the high needle , turn it till you get a nice "round" sound and engine pics RPMS. then do the same with Low needle. After that back out the adjustment screw to your desire idle.
Then go and check how it transition and how it runs on WOT. If you want ...then try to lean uot till you get the highest RPMS then go back on rich side till around 200 rpms are dropped. You do not want to run it to lean.
If carb does not have a accelerator pump you will want to run it a bit rich at idle.( turn the needle on the rich side till you drop around 200 rpms.and try transition again.

I am not sure if this make any sense to you ...but I domoust by ear and feel.
Zama has all the technical data for all egines on theyr site.

http://www.zamacarb.com/prod_lookup.cfm , select the carb series then the model.

Hope it helps.

Adrian

gr8flyer55 03-21-2012 03:17 AM

RE: Zama needle settings
 
Hi Adrian.
I like your needle setting method. I also tune by ear and have good luck setting carbs when internals are setup correctly. The metering needle problem on mine is fixed now and I have it close to perfect for my engine. My other Zama carbs are going on some Echo engines and should be a good match.

John

av8tor1977 03-21-2012 07:48 AM

RE: Zama needle settings
 
I've actually had good luck with Zama carbs. It just irritates me that the kits cost double what they do for a Walbro.

The real junk carbs are the "Rui Ing" carbs... I have made some money off of them though. I had two "Mini Harley" small chopper motorcycles given to me because the owners were disgusted with not being able to get them to run, or run consistently. I took the Rui Ing carbs off, put a Zama on one and a Walbro on the other. They then ran great, and I sold the motorcycles for 200 bucks each!

AV8TOR


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