Hi Guys,

I got my Zenoah to run good after finding the gauze filter inside the acrb was full of crap. I cleaned it out and a few days later went to the lake with it. It ran on the water for about 10 meters and then cut out.

When we got home the filter was a little blocked but not completely like before. So my dad attacked the carb with compressed air (not disassembled) and the priming bubble burst when he blew air in through the outlet on the top.

I got a new bubble but now the carb wont prime at all. The fuel moves up the tube very slowly then stops once it reaches the inlet nipple. A tiny amount gets up to the bubble but no further.

I blocked the inlet nipple with my tounge and pushed the bubble but there was no suction (something which worked even when the filter was totally clogged).

Im guessing something inside the carb got damaged by the compressed air???








All the best,
Brandon.

make sure you have put the diaphram and gasket back in the correct way!!!!!!!!!!!

If that's a 644 (which it sure looks like) and you attacked with with compressed air, you more than likely blew the check valve in it. Seen many guys trying to figure out why their carbs no longer worked after doing a maintenance on them... most of not all of the guys that used compressed air blew the check valve. It will never pump gas.

Its a little insert in the carb with a hole in the middle of it. It's about 3/16" diameter with a small hole about 1/16" in it. Inside you should see the hole blocked by a rubber flapper, flush against the opening. If you don't see that, or is out of shape, you have to replace that part or chuck the carb. That valve is pressed into the body.

Surprisingly, not many people know about this. I would be curious to know how many perfectly good carbs went to the garbage bin because of this! lol

I took a pic to show you. It located under the metering diaphragm. In the picture the valve is at about 4 Oclock.

The 257 carbs don't have this.

Thanks Marc,

I looked into the hole in the valve and can only see bare metal so I'm guessing the rubber flap is gone. Any Ideas on how to get it out of the case....I'll probably have to destroy it yes???

Hi Guys,

I'm just wondering which rebuild kit to get. Should I get the K20-WAT or is the K10-WAT sufficient and does anyone know if either of them contain the check valve I need.

Is this the check valve I need???


Or this one??


All the best,

Brandon.

This link should help you out. I'd say the first pic you showed looks more like it.

www.ereplacementparts.com/walb...818_141493.html

I've replaced the check valve in a few carbs, and had to destroy it to get it out...mind you it's already destroyed! Just don't mess up the body where it seats. Might be faster to just get a new carb though.

Thanks again Marc.

I will order a new carb aswell as the rebuild kit just in case. Be handy to have the spare anyway.

Any ideas on which rebuild kit to get??

All the best,

Brandon

Rebuild kit...depends on what you want to change in the carb. They have the appropriate kits listed on that page I posted.

K24 would be the complete kit for this carb
K10 would be for a 257 carb

I don't buy much of these complete kits unless I really need them. Most of the time all we change is the diaphragm, and you can buy those in packs of 10 or more... very good idea to have these handy!

This is all so confusing dont see why they cant make one kit for each carb instead of one for all full of stuff you dont need.

Anyway, thanks for the advice Marc.

A lot of the kits have some interchangeable parts. I agree though it does get confusing at times. Scott S on here has a wealth of knowledge on these and can possibly shed more light on this subject if he sees this thread.