Carb Guru? WJ-69 and Clone comparison

[Definitive Dave]

So I took apart an OEM Walboro WJ-69 and a Zama produced clone today.
The clones have been giving users uneven results, some have been fine and others don't seem to be able to tune the H in far enough.
Pics of the carbs which look identical externally except for the limiter cap/needle areas.

 

[Definitive Dave]

I removed the H needle from both carbs, using the Stihl tool which makes it really easy for the red limiter.
Guys ask all the time, it is a left handed thread of the proper size and you simply screw it in until it pops the cap straight out, no mess, no fuss and it keeps the cap pristine for re-use.
The needles are decidedly different in length and shape.
So now I find myself wondering what the heck I actually learned of any use.
Would the Zama work better with a different shape needle?
All I accomplished was taking them apart, hmmmm

If there is a carb guru here who would be willing to take a look inside and tell me if these clones are really clones or just some nonsense the vendor foisted on me I will gladly send the OEM and limiter tool and a handful of the clones for dissection. Send me a Pm if this is you please, I yearn to learn

 

[Gunn]

Based on the side by side photos of the needles you know these are not internally the same.

 

[Definitive Dave]

that is my thought as well, but I was told they had the same size for all the orifices just a different style of needle and needle enclosure
I asked for the same specs without limiter caps.
If the carb needles can be replaced and make good running carbs I would be happy with that but also want to know if this vendor who I do a lot of business with is jerking me around.
On one occasion in the past I got 100 carb kits with completely the wrong welch plug in all the kits, they made good on it, but I wondered if they just ran out of the right thing and tossed something else in hoping I wouldn't notice.
The hit or miss nature with this batch of carbs has me baffled.

 

[Redfin]

some have been fine and others don't seem to be able to tune the H in far enough.

D Dog Dave. Does this mean the users are not able to lean out the saw as needed?

 

[Definitive Dave]

That seems to be the case for at least two guys who let me know about it recently.
Its almost like I went along to tune the saw for them

 

[psuiewalsh]

Does the knockoff bottom out the spring before it seats the needle?

Sent from my XT1585 using Tapatalk

 

[Definitive Dave]

Does the knockoff bottom out the spring before it seats the needle?

Sent from my XT1585 using Tapatalk

I will grab a screwdriver tomorrow and test this to be sure.

 

[Redfin]

Its almost like I went along to tune the saw for them

Like a little orange screwdriver proxy?

 

[Redfin]

Can the brass looking washer be moved farther up towards the spring?

 

[Definitive Dave]

I'm in my damn jammies
Sleepy-time Dave

 

[Redfin]

Yeah me too DD. I guess your customers will just have to wait.

 

[Terry Syd]

I've run into the 'bottoming spring' issue before, so it should be checked. I looked at the ends of the tapers of your needles and it 'appears' from the picture that there is a mark or discoloration at the same distance along the taper where the needle may have bottomed. I don't know, but you may want to check it with the long taper needle. Perhaps put a bit of spray paint or something that you have available and then run the needle in - see where the needle bottoms.

The Chinese carbs can be perfect copies or 'close' copies. I've run into some with different size air bleed/transition holes and with the holes drilled vertically instead of at an angle (saves machining set-up). Also the metering spring is often different. One other thing to check is the size of the metering orifice, if it is, say, smaller it will give you a slower ramp in of the fuel and may be the reason the metering spring is different.

 

[Poleman]

Dave, I'm wondering if the internals are different which could be causing the issues.

 

[Time's Standing Stihl]

Are Impulse barbs different sizes? Looks like the i.d. is different

Sent from my SM-G900R4 using Tapatalk

 

[Chainsaw Jim]

It's a clone of the older wj carbs.

 

[jmssaws]

Dave sent me 3 of them and I had no high tuning problems,they all 3 ran great and made good power but wouldn't tune for a decent idle,either fat or lean at a idle.
Not sure what causes that but I couldn't fix it.

Are the carb kits you got with the wrong Welch plug for a wj?

 

[Terry Syd]

Did you try putting in a fresh pump diaphragm? There's a 'pulse chamber' between the exit valve on the diaphragm and the metering valve seat. The small diaphragm on the pulse chamber takes a hammering and is the first thing to wear out. You can see it on old diaphragms, the pulse chamber portion is more distorted than the pump section.

The pulse chamber absorbs the shock when the metering valve closes. If it is worn out, then the idle mixture can bounce all over the place.

The next time I get a worn out diaphragm, I'm going to put a metering spring between the lid and the pulse chamber - maybe it will give me an even better idle than a new diaphragm.

 

[Definitive Dave]

Dave sent me 3 of them and I had no high tuning problems,they all 3 ran great and made good power but wouldn't tune for a decent idle,either fat or lean at a idle.
Not sure what causes that but I couldn't fix it.

Are the carb kits you got with the wrong Welch plug for a wj?

It was a long time ago I think they were one of the batches of the rb-69 for the 200t carbs, one of my commercial customers let me know pretty quick.
Carbs are sorcery to me

 

[Definitive Dave]

Dave, I'm wondering if the internals are different which could be causing the issues.

Yours was one of the ones that wouldn't lean the h far enough right?