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Walbro HD Carb

Wigglesworth

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Now you know why I keep a supply of Zamas on hand and I don't drink the "bash Zama" kool-aid.

Lol. I got a pile of bad Zama's too. :p

On the HD's, this is the third one in a row that the pop off pressure was too high, and the needle still isn't seating. I ain't done with it yet though....
 

mweba

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Lol. I got a pile of bad Zama's too. :p

On the HD's, this is the third one in a row that the pop off pressure was too high, and the needle still isn't seating. I ain't done with it yet though....

Find some small Q-tips, apply metal polish to the tip and rotate it against the seat. If you can't find a Q-tip that fits, I've used the old needle before with some success.

The zama carbs do run more consistently but for my own saws, I spend the time on the walbro. Customers get new zama.
 

jacob j.

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Lol. I got a pile of bad Zama's too. :p

On the HD's, this is the third one in a row that the pop off pressure was too high, and the needle still isn't seating. I ain't done with it yet though....

I've found the failure rate with the HD's much higher than any other "modern" carb I've messed with. WJs are a close second. HDAs are up there too.
I've got a couple Zamas in the junk pile but about 18 HDs accumulated from the same number of machines in the same time period. Even trips through
the ultrasonic cleaner did no good. The SDC series is wonderful though with many putting in thousands of hours of service.

Find some small Q-tips, apply metal polish to the tip and rotate it against the seat. If you can't find a Q-tip that fits, I've used the old needle before with some success.

The zama carbs do run more consistently but for my own saws, I spend the time on the walbro. Customers get new zama.

Yeah, I've seen the seat wear down so far that the metering lever would actually strike the body of the carb. I fixed one by shortening the lever slightly- that only lasted about 6 weeks and then
it was time for a new Zama and I had told the customer that. I didn't charge him any labor though to swap the Zama in.
 

mweba

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This is stuff I use. Also use it on the cylinder fins, think its good for a tenth

 

Wigglesworth

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Find some small Q-tips, apply metal polish to the tip and rotate it against the seat. If you can't find a Q-tip that fits, I've used the old needle before with some success.

The zama carbs do run more consistently but for my own saws, I spend the time on the walbro. Customers get new zama.

Dun did already. I went as far on the last 046 carb to install a new seat in it, wit no luck.

I WILL FIX THIS CARB, IF ITS THE LAST THING I DO!!!!
 

TK

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Given your history we all probably shouldn't hold our breath and sit in front of the computer for an update...... :evilgrin:


Is this a stock carb or one that's been modded? What saw does it go on?
 

Wigglesworth

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Given your history we all probably shouldn't hold our breath and sit in front of the computer for an update...... :evilgrin:


Is this a stock carb or one that's been modded? What saw does it go on?

Stock Walbro HD 34 off on a ms361.

And no, don't hold ur breath. Haha
 

TK

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Stock Walbro HD 34 off on a ms361.

And no, don't hold ur breath. Haha

It's a creamy carb :jesterlaugh: Pop a new on on that bad boy and be done with it. I've got caught up myself in a few things that "I'm just going to fix, I've got to fix this!" and it turns out a money and time pit.

Latest case Jred 670. I'm gonna drop a list of parts in that thread soon, people be thinking I'm nuts LOL
 

Wigglesworth

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Pop-off is at 20psi, and seats and holds at 10psi now. Still wants to flood at idle, and is too lean up top.

And yes, saw vac/pressure tested good. Stoopid HD's...
 

motomedik

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Most carbs I understand pretty fully. Diaphragm carbs, not so much, but for the most part a kit and a cleaning, is all you gotta do. But lately I have got a few that are annoyingly setting in the corner, ran out of time to mess with them after not being successful the first few times. One is a friend's 460 that is rich as heck down low and lean on top. The other is a 272 of my own that goes lean after you run it a while. Messed with the tank vent, new line, filter, new bearings and seals, etc. Pretty much knew both have carb issues, but wasn't sure how to fix them. So I think I'll have to fool with the inlet needles and seats.
Would anyone be willing to explain the proper procedure for checking "popoff" to me? I don't think I'm doing it right, or not sure what I need to be checking or even how to properly perform the test. Thanks guys, it would help me alot.
 

Wigglesworth

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One is a friend's 460 that is rich as heck down low and lean on top........

Would anyone be willing to explain the proper procedure for checking "popoff" to me? I don't think I'm doing it right, or not sure what I need to be checking or even how to properly perform the test. Thanks guys, it would help me alot.

Exact same thing this carb is doing. I messed with it for a little while this morning, but still, no dice. :(

Here is a good video of testing pop-off. I do it a bit different, with the metering cover off and the carb submerged in WD40. Its just easier to see the bubbles.

[video=youtube;OaFvtlGzCB8]http://www.youtube.com/watch?v=OaFvtlGzCB8[/video]
 

Wigglesworth

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you unbroked these carbs yet? :wave:

Nope. I did find out that the HD-34 has an accelerator pump in it. This one was stuck, but freeing it up didn't help anything.

I swapped all the shafts with a HD5 out of an 029. Ran pretty good then. Still loading up a bit at idle, but it was runnable. I'm not real happy with swapping the shafts though, as it wasn't exactly a direct swap. Gonna have to mess with it a bit more before I'm happy.


Until then....

 

mweba

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So the shafts were worn? Stays fat up top now?
 

Cut4fun

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I got a 361 being dropped off Mon. Man I sure up it isnt carb issues like you are talking. :eek2:
 

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