# Need help understanding why people replace their carbs



## wmazz (Jun 1, 2020)

My name is bill, and I used to be a pro watercraft mechanic, and
I specialized in float diaphragm carbs, engine tuning and pipes.

I used to manufacture Goped pipes, and did a lot of work with
Zenoah engines, carbs, and I have a brake style dyno for small
gas engines. 

I would like to help some other people on a different forum, but
my problem is that there is a big difference between my experience
with Walbro and what people seem to go through to fix their carbs.
It seems like most people just give up, and purchase new carbs?

I am looking for help to understand why people tend to purchase
new Walbro carbs, rather than rebuilding them?

I am also curious if some problems seem to be common with
Chinese Walbro clones?

Thank you


Bill M.


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## ammoaddict (Jun 1, 2020)

I rebuilt the walbro on my old Husqvarna 50. Made in 1985. It had a bad diaphragm. A new carb like that was over $100. The walbro kit was $12. The Chinese carbs are hit and miss. I have a couple on clone saws I built. I don't think they all have the same problems. I think it's a quality control issue and some have problems and some don't.

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## wmazz (Jun 1, 2020)

It seems like a lot of people do not know how to test the float diaphragm,
but people are telling me that they use a rebuild kit and it does not help.
That leads me to believe that their problem is a leaking carb base, insulator
gasket, a vacuum leak from somewhere else, or pressure/vacuum leak, or
the main jet check valve is bad, and it was not replaced because it is not
part of the rebuild kit?

But I have never needed to replace a main jet check valve before.

Perhaps there is counterfeit Walbro rebuild kits out there?

Bill M.


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## ammoaddict (Jun 1, 2020)

There are aftermarket kits for walbro carbs and there are genuine walbro kits. Never heard of a counterfeit. 

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## CausticUC (Jun 1, 2020)

Sometimes it is the kit cost vs replaced or clone, however, it is my understanding that most people change their carbs because someone else told them to or that they do not understand how jets work or that they come in different sizes.


That is just my opinion mind you.


Myself, I buy carbs for one of two reasons: 
1) I want a backup carb that is clean and ready to-go or incase certain parts get hard to find. 
2) I am going up in size either for performance or stability. This includes carbs I know have a wide array of jets available as a preference. 

As an aside and since you did cross post in chainsaws; typically for my Stihls I try to swap for the Tillotson carbs specified in the Euro versions of the saws. Reason being is that they are speced higher in power.


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## wmazz (Jun 1, 2020)

ammoaddict said:


> There are aftermarket kits for walbro carbs and there are genuine walbro kits. Never heard of a counterfeit.


I have known people (back in the late 90's) that serviced HP printers, and
they sold Chinese product in genuine HP boxes. I don't know if people
do that with Walbro products, but it wouldn't be difficult to do so.

Are clone Walbro carbs obvious? Do they have any tell-tale features?

If a clone Walbro has a Walbro name as part of the casting, that carb
could be considered counterfeit.

Bill M.


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## CausticUC (Jun 1, 2020)

wmazz said:


> I have known people (back in the late 90's) that serviced HP printers, and
> they sold Chinese product in genuine HP boxes. I don't know if people
> do that with Walbro products, but it wouldn't be difficult to do so.
> 
> Bill M.


They dont need to; in the worst case thay are spec failed production that gets sold off as oem. Walbro moved their small engine carbs to China quite a while ago.


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## MacAttack (Jun 1, 2020)

I wouldn't replace one of my old Walbro carbs unless I had no choice. However, I have a few cheap weed eaters with "Zama" carbs (or Chinese clones of Zamas), in which a carb repair kit costs $6... but for $10 I can get an entire new carb, with fuel lines and a filter. How could I not justify buying a whole carb?


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## RED-85-Z51 (Jun 2, 2020)

In my shop if its an older unit with a Tillotson or Walbro carb, or even a zama c1u, most stuff with a hi and low needle...ill try a clean and kit.

Stuff with rotary valve carbs, or the newer stihl carbs, fixed jet carbs...i toss on a new aftermarket carb and call it a day. Ive wasted too many days of my career trying to hold those carbs hands and make them work..only to put on a 12 dollar carb and it functions like new. One day i had an echo 210 with a Zama k54A i think it was. Would idle but not rev. Drilled the plugs and adjusted...no change. New kit and time in the sonic cleaner...no change. Vac and press tested the case...perfect. Pop tested the carb...perfect. Swapped every part off the body with known good parts...no change. Bolted on an Amazon carb..small tweak on the needles and she purred. Some carbs are just not worth the time and the equipment isnt worth an oem carb.

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## buzz sawyer (Jun 2, 2020)

MacAttack said:


> I wouldn't replace one of my old Walbro carbs unless I had no choice. However, I have a few cheap weed eaters with "Zama" carbs (or Chinese clones of Zamas), in which a carb repair kit costs $6... but for $10 I can get an entire new carb, with fuel lines and a filter. How could I not justify buying a whole carb?


I agree, depends on the carb. Tilly HL, no problem. Zama, sometimes you get dirt or old gas residue that is a pain to clean out. As for the cheap replacements, I've had a couple that needed internal adjustment out of the box but for the most part, no problems. You also sometimes get new primer bulbs and air filters.


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## wmazz (Jun 2, 2020)

CausticUC said:


> Walbro moved their small engine carbs to China quite a while ago.



I knew that, but why are some carbs still coming with the 
made in japan logo? (Japan spelled as a circle).



CausticUC said:


> They dont need to; in the worst case thay are spec failed production that gets sold off as oem.



I suspected that. There was a rumor going around that all starting and 
idling problems were caused by metal shavings stuck in the low speed
by-pass holes. 

Metal shavings could really cause problems, and a possible source is
when the low speed adjustment screw hole was tapped. But Walbro 
would have caught the problem, and then possibly sell a bad (or 
questionable) batch of carbs to a Chinese engine company for cheap. 

I really doubt there are large quantities of different part numbers with
the same metal shavings problem. 

Bill M.


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## ammoaddict (Jun 2, 2020)

wmazz said:


> I have known people (back in the late 90's) that serviced HP printers, and
> they sold Chinese product in genuine HP boxes. I don't know if people
> do that with Walbro products, but it wouldn't be difficult to do so.
> 
> ...


Neve seen a cheap Chinese carb with walbro cast into it.

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## CausticUC (Jun 2, 2020)

The ones with the Japanese symbol could be for various different reasons, my guess would be that they are branded versions of someone else's patent. Mikuni and Yoshi still both manufacture in Japan.

As for Walbro selling off bad stock... it is possible, but unlikely. Things at Chinese factories have a way of disappearing from the defect/scrap areas.


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## Ted Jenkins (Jun 2, 2020)

WM welcome hopefully you will have fun at this site and not be too sensitive when some one does not agree with your take. I worked with Kawasaki on the early jetski before personal water craft was thought of. Our dyno back then were quite crude, but did perform. The chainsaw carburetors are wildly different than the PC diaphragm carburetors you are used to. The big difference is size and the environment. Saw carburetors are exposed to sawdust and every thing else so they can get plugged up easy making them less than perfect. On my saws most of the time some compressed air and put it back together. Some times after being taken apart a couple times you have a torn gasket or a wrinkled diaphram and a new kit is needed. Some times a carb become useless because of all kind of things like abuse. Some buy used carbs for spares and others buy new ones with no concern for cost. Then there are after market carburetors that can fir several different saws that can be made to work well. I like to use economic applications that will meet my needs. Then there are folks who are in the middle and constantly have problems when they are not thorough. Thanks


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## Freudianfloyd (Jun 2, 2020)

wmazz said:


> It seems like a lot of people do not know how to test the float diaphragm,
> but people are telling me that they use a rebuild kit and it does not help.
> That leads me to believe that their problem is a leaking carb base, insulator
> gasket, a vacuum leak from somewhere else, or pressure/vacuum leak, or
> ...


I attempt to repair/rebuild them all the time. Sometimes they just don't like to work. Sometimes, as in the case with some Stihl equipment, the rebuild kit is $20 and the carb was around $35. It doesn't always make financial sense to rebuild them in those cases. Also, some don't have the required tools to rebuild them, or more importantly, clean them properly.

I would honestly love a thorough video on rebuilding these carbs that goes more in depth than just replacing diaphragms. If there was one that went into setting metering lever heights, testing diaphragms, insulator gaskets etc. I would definitely watch it.


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## Mad Professor (Jun 2, 2020)

If you are cleaning carbs a sonocator is a good investment. 

Get one big enough to do stuff bigger than saw carbs.


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## dmb2613 (Jun 2, 2020)

an oil thread oh no a carb thread lol


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## RogerD (Jun 26, 2020)

We run mostly Stihl stuff with Zama carbs and I have had a few that I just couldn't get to work after rebuilds/cleaning so I installed a new carb. Problem is usually Lo speed circuit that seems to bleed fuel, screw only being 0-1/4 turn out and even then seeming too rich. When you clean/rebuild carb do you remove the aluminum caps inside carb? I never have. Could this be part of my issues? Also, can you see wear on the diaphrams like you can on a watercraft - those usually will have creases in them? I don't always replace those either as I don't usually have kits for every type of unit we have ( City Public Works).


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