ZAMA CARB MOD-CLIFF NOTE VERSION

[Poleman]

Sorry to hear they Bob.....I've had to drill one out myself. Check with Definitive Dave....Im sure he has them. Its the same as the Husky 362-365-372, it will have a larger choke hole but that's not an issue...it will be the same Carb.
If you didn't get the jet out and just nipped off the sides the Carb should still be good....and no the After market jets don't fit.....slightly larger.

 

[rmihalek]

Thanks for the tip for Definitive Dave. He had one carb listed on his ebay site so I just scooped it up. I'll give it another try.

 

[Poleman]

Great!!! It should work better for you.

I could have told you how to mod it without pulling the jet but this is a better way, and you can check the small diaphragm under the carb also to make sure its in place.

 

[drf255]

Great thread. Thank you.

How do you clean the shards out after drilling? Do u fully disassemble afterwards and reassemble, carb cleaner, compressed air?

 

[Poleman]

Most are so tiny they cause no problems....I just keep blowing off as I drill with lung power. The only issue I've ever had is dislodging the membrane in the jet itself...another reason for pulling main jet to inspect when drilling the bleed hole.
I've changed the way I drill them to only have a small amount of drill exposed when drilling as no to penetrate through the jet as before when drilling. I only have the drill bit exposed 1/8 of an inch or so now and haven't had any problems with the membrane since.

 

[rmihalek]

I got the carb from Definitive Dave. Looks like the ones that are shown earlier in this thread. I'm thinking I should grind away some material from around the main jet first, so I can get a better grip on it. Also, got a second ZAMA C3M for $10 off eBay. The set up looks totally different. Can these be made to work on a big bore Dolmar?

 

[Poleman]

The one on the right is the one that can be modded. It has the brass jets that can be enlarged. The one on the left looks like a Stihl carb that can not be modded...... I believe the linkages can be changed over to make the Stihl carb modded if both are Zama build. A Walbro and Zama linkage shafts are different sizes and are not compatible. To use on a Stihl the fuel inlet needs to be moved and the inpulse line plugged because stihls use it off the pump diaphragm.

 

[lambs]

I have my friend's 250 right now trying to get it to run right. It has LA and H adjusting screws only.....is that a Zama thing, or is there some other way to verify what carb he has?

This saw bogs down at odd times. Starts fine, but may bog immediately, may not. I tried my fuel in it but that did not matter. Next thing I'm going to do is run it with a full tank of gas to see if that matters. To my eye, the fuel body seems to stick up a bit and I'm wondering if it is sucking air at times as the fuel level drops. Or the fuel line may have a crack in it.

If that doesn't reveal anything, I'm going to switch spark plugs, although I doubt a bad plug would misfire only some of the time. Cheap enough to find out.

You guys got any ideas beyond that? This saw is about 7 years old and probably has 10 hours on it tops. It's pristine, the bar still looks new.

Thanks.

 

[Poleman]

Several carbs are listed...most Zama C1Q's but Walbro WT's were on that model also. (WT 215, WT 215 BR, WT 286A). From what you are describing it sounds like a carb issue...dirty, hard diaphragms not pumping properly to move the fuel then starvation. I believe a new carb from a Stihl dealer can be had for $25 which includes a H screw for better adjustment.

Being several years old the line (fuel-impulse) may need checked along with the fuel filter. A carb rebuild could also be in order if any ethanol fuel was used and left in the saw for any period of time. Not knowing the background there are more items to check and eliminate.

 

[wexcw]

Can these mods be made to the walbro hd carb as well?

 

[Poleman]

They can be but not as user friendly. If this is for a Stihl 044/440-046/460 finding an older Zama carb from one and converting it is easier than using the Walbro. There is a TON of tinkering that needs to be done on the Walbro and each saw is different. You'll be adjusting needle height, needle spring and such as each saw is a lot of trial and error.
That's the reason its easier and more consistent to modify a Zama twin jet then convert it over to the Stihl specs. It to is more time and patients but more consistent with good results. It's also easier for me to tune in as I've done so many its easier to read and adjust.

 

[wexcw]

I was going to try it on my husky 365, i went through my scrap pile and coukdnt find any of the zama carb that is listed in the post im sure ill come across one at some point then i will give this a go

 

[Poleman]

The Zama works good on the 365/372....just don't go too big. But if you do JB weld and redrill. If you hit .40 on the Auxiliary jet you'll need to block the H air bleed or you high as itwill be way to rich(closed) in most cases and loose adjustability.

 

[Jacklefty]

Where abouts did you get the micro drill bits and the pin vise?

 

[wexcw]

The Zama works good on the 365/372....just don't go too big. But if you do JB weld and redrill. If you hit .40 on the Auxiliary jet you'll need to block the H air bleed or you high as itwill be way to rich(closed) in most cases and loose adjustability.

Thanks for the advice..been working on saws for a couole years now, but never tried any mods..this forum has been full of great info

 

[Poleman]

I got the carb from Definitive Dave. Looks like the ones that are shown earlier in this thread. I'm thinking I should grind away some material from around the main jet first, so I can get a better grip on it. Also, got a second ZAMA C3M for $10 off eBay. The set up looks totally different. Can these be made to work on a big bore Dolmar?View attachment 491474 View attachment 491475

No the first carb doesn't have the Jets to enlarge like the Zama does. You'll want to use the Zama to increase performance for your application.
They do/did make the twin jets Zama copy that worked good but now the AM suppliers are shipping no or 1 jet carbs that are harder to modify and touching to set up than the twin jets carbs. I've done a lot of work with them and it's just not worth the time. Also I've found you can't switch the carb from one saw to another without more time to get it to run right. Little differences in saws make a huge difference with them. The two jet are more stable and user friendly and a LOT more consistent.

 

[Poleman]

Just do a micro drill search on ebay....youll9 find them. They sell a number size and millimeter size....I use the mm size for mostly but if I'm trying to split sizes I break out the numbered ones as I can move the drill size slightly up or down if I'm doing something special.

 

[usmcbuckwild]

@Poleman

Resurrecting an oldie but goodie;

So I attempted to drill the main jet and my bit broke. While trying to use a reverse bit to back out the broken piece I succeeded in drilling it through the main jet and through the venturi. So now I have a .030 hole through the main and into the venturi. Is this carb now junk? Oh, yeah, I used a pair of modified nippers exactly like you have and still can’t get the main jet out. Am I fooked? Or is this carb fooked?

 

[Leafy]

Double resurrection.

How does the flow work in there? The mixing jet (left side jet) goes right to under the oval Welch plug to the 3 "idle" nozzles, the L jet (right side) goes to the L needle and then to under the Welch plug. And the top jet goes right through to the venturi nozzle and there's an area for the fuel from the H needle (that's fed from the big hole top left) to join that fuel.

Do I have that right?

Also all the fuel from the pump side gets there through the needle valve that's controlled by the metering lever right?