Installing a carb kit basics.........

[STIHL-KID]

Ok, I have done some research on here and some of the information is overlapping when it comes to rebuilding a carburetor. I have a Walbro HD-18B model carb. I have put new carb kits in before, but seem to have difficulty with making them function correctly. I will openly admit that I'm still a rookie at tuning carbs and knowing little details about what to look for when troubleshooting carburetor problems. Basically, besides replacing the carb kit parts one for one.......what else should a person do to ensure trouble-free performance after putting one in? Any details or things I should be aware of while putting in a new carb kit? What should I be inspecting. Perhaps I'm asking obvious (no duh!!!) questions........but I figured some experienced guys would add in some worthwhile advice. Oh and maybe a wise-crack or two.

 

[PES+]

What problems have you had after installing kits?

It is pretty straight forward and a lot of people just don't remove the adjustment needles and clean the fuel passages.


It is not much help that Tillitson re-used the HD prefix on two very different carbs and that their site dowloadable service manuals are in Word
.doc

 

[bama]

Make sure the parts go in the right place!

I ended up learning the hard way to make sure you put the diaphram in the right place(on top of the gasket) on my 621. Darn thing wouldn't run worth anything, no matter how I adjusted it. I forgot the rule that if all else fails, check the directions(or the IPL).:bang:

 

[troutfisher]

Good Stuff!!!! I've messed up a few too,opcorn: opcorn: opcorn: opcorn: keep this thread going..

 

[PES+]

Don't feel bad bama...I had carbs assembled that way from three manufacturers right out of the box.....and all three claimed that every saw was started and performance verified before shipping

I didn't get jaded for nothing:angry2:

 

[ehgauss]

Carb Kit Installation

I'm certainly not going to be the most experienced responder to this question, but when I have to work on a carb, I DON"T do in in my garage or cellar. Any small part falling on the floor in either of those places would be lost for all of the rest of eternity. Instead, I lay out some paper toweling on the kitchen counter, sweep the floor, make sure the stopper is in the sink drain, and remove anything else that could hide anything, and then read the instructions. As I disassemble the carb, I lay everything out in the order in which it was removed, looking at each part carefully to set in my failing mind how each part was installed originally, and when all the removable pieces are out (except Welch plugs, unless necessary), and laid neatly out across the paper toweling, I read the instructions again. Next I blow the carb body out with compressed air, making sure that all passages are clear. If any deposits are noted that don't come off with the air, some spray carburetor cleaner usually does it. Next, I read the instructions again. Then I lay out the new kit parts in a row parallel to the row of removed parts. Then I read the instructions again. Now, I install the parts from the kit in the reverse order from which the old parts were removed, making sure that alighnment of screw holes, ports, etc., is correct and that the new parts are right side to. Tighten everything up, set the needle valves in accordance with the instructions, and reinstall the carburetor, making sure that linkages, etc are free and hoses are not split or crazed. One more read of the instructions to make sure I haven't forgotten anything, and then a couple of pulls on the starter rope usually does it, and after a suitable warmup, needle valve adjustment to get the right sound. I've only done a couple of them so far, but haven't screwed any up yet. Gene Gauss

 

[PES+]

You forgot to mention send the wife to the spa for the day

 

[chuckiehow]

I didn't have new kits for the Walbro carbs from my fleet of Stihl 025s but I commonly have trouble with them (especially the one screw adjust ones) and I take them apart and clean them thoroughly.

Had 3 of them apart and cleaned in the last 2 days, soaked the diaphrams in brake fluid overnite to limber them up and reinstalled. The needles all looked good and I stored them away in a baggie. The first one I used on a saw malfunctioned like every other one on that saw. I pressure checked the fuel line (with my mouth...is that permissible?...LOL), changed the sparkplug, fuel filter and cleaned the air filter and the flywheel contacts and it would still die and fail to restart...only run with the choke out for a short period..etc.

Then I remembered some good advice from this board to check the gasket between the carb and the jug. It was sealing around the port but had damage around the bolt holes. I wouldn't think that would matter (correct me if I'm wrong), and not having a new one, I put gasket sealer on it and it ran like a champ for 20 minutes tonight. Tomorrow may be a different story, but I think that was the problem. Been haunting me for 2 months.

 

[daemon2525]

The biggest tricks that I have are :

Remember (or RTFM) that the gaskets are opposite each other. On the fuel pump side, the gasket goes next to the cover, On the metering side, the gasket goes next to the carb body. (they are opposite each other).

The next tip is to use carb cleaner (Recommend genuine GUMOUT brand), to spray through each hole (EVERY TINY HOLE THAT YOU CAN SEE) until you can see it come out SOMEWHERE. On your first rebuild, if you have not used an entire large can of GUMOUT, then you have not tried hard enough.

DO NOT BLOW THROUGH THE HOLES WITH 120LBS of air pressure. You will ruin the main checkvalve under the welch plug. Use a generous volume of carb cleaner instead.

The metering lever must be bent correctly (according to the instructions), they are normally ALWAYS correct. DO NOT BEND THEM unless you are SURE that they are incorrect. (they are already correct in the kit).

Reassemble.....

Then set each H/L needle to 1 turn out from lightly seated.

And LASTLY>>>>>>>> If it still does not run... It might not be the carb.
Check your fuel filter, and fuel lines for cracks.

 

[Log Splitter]

I've done two now, so I'm no expert but I am dangerous.

Take pictures as you tear it down. That way you can be sure you get things back together in the right order.

And be careful to not let that spring on the metering lever go sailing into thin air. http://arboristsite.com/showthread.php?t=41585

 

[Indiana John]

Zama carb ?

On the subject of carb overhauling, I've got a Zama carb (C1Q) out of this Homelite Super 2 that needs redone. I noticed when I took it apart that it had a wedge-shaped welch plug on the metering side. The sealer around that plug was peeling out, and I'm wondering what folks use to seal these back up. Or does it hurt anything not to put sealer back around it? The problem I was having with it was flooding. I'm pretty experienced in Walbros, but don't really see many Zamas.

 

[chuckiehow]

DO NOT BLOW THROUGH THE HOLES WITH 120LBS of air pressure. You will ruin the main checkvalve under the welch plug. Use a generous volume of carb cleaner instead.

Oh my, you just destroyed my one avenue of hope and tranquility.
Ignorance was Bliss.....I hate to be enlightened....but...but

Howard

 

[daemon2525]

chuckie, If you disagree, thats cool!. Let me know why... We can all learn.

 

[STIHL-KID]

Has anyone ever heard of someone getting away with just changing the basic kit components without removing the needle-screws? I guess in order to make sure the carb is 100% clean, everything must be disassembled and cleaned throughly. I have been guilty of short cutting myself and skipping the step of removing the adjustment screws (figured if I don't tamper with them, my carb settings will stay intact). What I probably didn't realize is that debris and particles were gummed-up in these areas all along.

 

[daemon2525]

Never, If I was only going to do one thing, it would be to pull the adjust needles and clean them. That is often the ONLY thing that I do to get a saw running again.

OOOPS! EDIT. You should however, slowly screw them in and count how many turns (or partial turns) that it takes. Then put them back with the same number of turns.

 

[PES+]

Has anyone ever heard of someone getting away with just changing the basic kit components without removing the needle-screws? I guess in order to make sure the carb is 100% clean, everything must be disassembled and cleaned throughly. I have been guilty of short cutting myself and skipping the step of removing the adjustment screws (figured if I don't tamper with them, my carb settings will stay intact). What I probably didn't realize is that debris and particles were gummed-up in these areas all along.

Not usually....changing parts is only part of the job in any carburetor refurb

 

[Lakeside53]

Never, If I was only going to do one thing, it would be to pull the adjust needles and clean them. That is often the ONLY thing that I do to get a saw running again.

OOOPS! EDIT. You should however, slowly screw them in and count how many turns (or partial turns) that it takes. Then put them back with the same number of turns.

I would just use the manufacturer's recommended "turns out" for the initial starting postions, then tune from there. Restoring them to the prior postions just repeats the last mistaken or compromised tuning, and that was when you had a dirty or faulty carb.

With needles I take a paper towel and tightly polish the tips. You'd be amazed the varinsh crud that come soff.

 

[Lakeside53]

On the subject of carb overhauling, I've got a Zama carb (C1Q) out of this Homelite Super 2 that needs redone. I noticed when I took it apart that it had a wedge-shaped welch plug on the metering side. The sealer around that plug was peeling out, and I'm wondering what folks use to seal these back up. Or does it hurt anything not to put sealer back around it? The problem I was having with it was flooding. I'm pretty experienced in Walbros, but don't really see many Zamas.

Use no sealer... The sealer in all zama carbs has cost a lot of people good money... Just put them in "dry" then tap the center slighty. They stay put..

 

[stihl025]

I DON"T do in in my garage or cellar. Any small part falling on the floor in either of those places would be lost for all of the rest of eternity. Instead, I lay out some paper toweling on the kitchen counter, sweep the floor, make sure the stopper is in the sink drain, and remove anything else that could hide anything, and then read the instructions.

One thing I found to be very helpful was to put a small magnet under a coffee filter and stick those easily lost items to it. For one, they will not go anywhere because of the magnet, and two, it can be easily seen on a bright white filter. And three, the filter is cupped to stop any "runaways".

 

[chuckiehow]

chuckie, If you disagree, thats cool!. Let me know why... We can all learn.

No I don't disagree at all. You're probably right and that could be the reason I have so many uncompromising carburetors. Would less air pressure be permissible? I'm supposing there are many carbs cleaned that way. Thanks for sharing your expertise. I think I'm the one learning on here.....others do the teaching. Thanks