I've got a Poulan 42cc converted to gas/glow with a Walbro 11.11mm carb. I would like to replace it with a 13.5mm carb? Would any of the Walbro WA or WT series carbs with 13.5mm venturi and High and Low needles be OK? I'd like to go ahead and get one off the auction site that's been mentioned here recently. I'd like for it to have a primer bulb too, but that's not mandatory. Thanks.

I have a WT498A from a Stihl. It has a H/L needle and is 13.5. Hope this helps.

Either a WT-540 or a WT-660 are good carbs if you can find them. 13.5mm venturi, two adjustment needles, and an accelerator pump.

Good carb(s).

AV8TOR

AV8TOR, I just pulled the 40cc poulan 2-stroke out of the saw and it has a Zama w26b, 63a printed on it. Also has C1M cast on it. Can you tell me anything about this carb. and is this one that doesn't like gas/glow? Thanks. Plasticmaster, I am using a WT644 on my 31cc Ryobi. The venturi is 12.7 and has two needles. it works really well.

I just purchased the WT-540. AV8TOR, are you sure you meant WT-660? I looked on Walbro's site and it specs it as a 7.94mm venturi. Thanks for the replies.

I have never checked to see if there is a Zama website with all the info on their carbs....

I had trouble with two different Zama carbs and Gas/Glow fuel. The only reason I was using them was that I was working on my Super Tiger .90, and being that the Zama carbs are a touch smaller physically, they fit better. But after I had trouble with those two Zama carbs, I modified things enough to put a Walbro on the .90. No more problems.

AV8TOR

Ha! That´s interesting. It is a mistake on their website. If you type in WT-540, it says to use WT-660. If you type in WT-660, you are right, that comes up as a 7.94mm carb.

Good catch on that.

The WT-610 is the number I should have posted along with the WT-540.

AV8TOR

Well, I found the Zama web site and it lists the carb I have but it shows a range of venturi sizes for the C1M. No way to tell which one I have. I'll contact Poulan and see what they tell me.

Well, the Poulan people tell me the venturi size on this Zama is 8 throttle bore is 14. Seems small to me. Just wondering if there is any, "rule of thumb" when it comes to venturi and throttle bore and jet size? Maybe less air is wanted for a carb that is needed to run richer? Sorry if this is a stupid question.

I use an 11mm venturi for 21 to 25cc engines, (sometimes on 30cc too), a 12.7 for 30cc engines, and a 13.5 for 40 to 50cc. A good 50cc might make good use of a 15mm venturi.

AV8TOR