What am I doing wrong with carb rebuilds?

[LAWN BOY]

So I’ve rebuilt a few 2 stroke carbs. First was a Walbro WT26 on a Ryan 263 weed trimmer years ago, I was much younger and it was my first one, leaked gas and wouldn’t idle, I was so young it could‘ve been a bad fuel line or I didn’t even try adjusting the screws, I’ll have to dig that project back out one of these days. I also did a Walbro carb from my Homelite EZ automatic chainsaw, saw runs ok, but carb leaks fuel all over into carb/intake bay of throttle handle…. Then I did a Walbro carb off one of my Homelite 150s, this is the only one I used a cheap kit in, saw ran good for a while, but now after a month it seems like it needs to be rebuilt again. I recently won an ultrasonic cleaner so I used purple power in it for my most recent rebuilt, the carb off my grandpa’s Homelite 360 chainsaw. Now that saw floods like crazy, vomits fuel out of the muffler. I take lots of pictures through every carb rebuild and the only one I used a non-genuine Walbro kit on was the Homelite 150. Does anyone have an idea as to what I’m doing wrong?

 

[ammoaddict]

Metering lever height? Low screw too rich?

 

[LAWN BOY]

Metering lever height? Low screw too rich?

I adjusted the screws in various ways including factory setting. Metering lever height could be the problem. In the 360 carb it felt like the metering lever was stuck kinda high…. Any suggestions on how to reinstall metering levers and springs better guys?

 

[ammoaddict]

I adjusted the screws in various ways including factory setting. Metering lever height could be the problem. In the 360 carb it felt like the metering lever was stuck kinda high…. Any suggestions on how to reinstall metering levers and springs better guys?

You should be able to get the lever height from the walbro website.

 

[Ketchup]

People disagreed with me last time I said this but USC’s kill the check valves in Walbro main nozzles. Carb cleaner and gentle air is often all you need.

 

[hacskaroly]

Metering lever height could be the problem. In the 360 carb it felt like the metering lever was stuck kinda high…. Any suggestions on how to reinstall metering levers and springs better guys?

Zama and Walbro have tools that you can use to get the metering lever at the correct height, they come in handy:

Amazon - Zama and Walbro Metering Lever Adjustment Tools

If you have a Tillotson or other type, then you might need to look and see what they do specifically for their carbs.

 

[LAWN BOY]

You should be able to get the lever height from the walbro website.

Ok, I’ll check that out. But how would I adjust the height?

People disagreed with me last time I said this but USC’s kill the check valves in Walbro main nozzles. Carb cleaner and gentle air is often all you need.

Interesting. I will try only spray cleaner and a compressed air gently with my McCulloch PM6 I suppose, new diahpram also tho cuz she’s crusty.

Zama and Walbro have tools that you can use to get the metering lever at the correct height, they come in handy:

Amazon - Zama and Walbro Metering Lever Adjustment Tools

If you have a Tillotson or other type, then you might need to look and see what they do specifically for their carbs.

I’ll look into those, thanks.

 

[ammoaddict]

Ok, I’ll check that out. But how would I adjust the height?

Interesting. I will try only spray cleaner and a compressed air gently with my McCulloch PM6 I suppose, new diahpram also tho cuz she’s crusty.

I’ll look into those, thanks.

You have to bend it to get the height correct.

 

[EFSM]

People disagreed with me last time I said this but USC’s kill the check valves in Walbro main nozzles.

Totally possible. Depends some on what detergent and temperature you're using.

 

[EFSM]

Zama and Walbro have tools

Zama's are set level with the metering diaphragm mounting surface. Walbro's are set even with the chamber floor.

 

[Sloughfoot]

Ok, I’ll check that out. But how would I adjust the height?

Interesting. I will try only spray cleaner and a compressed air gently with my McCulloch PM6 I suppose, new diahpram also tho cuz she’s crusty.

I’ll look into those, thanks.

There are pumps on Feebay for ~$30 that come with Zama and Walbro gauges. You need a pump if you're going to work on carburetors.

 

[Sloughfoot]

Zama's are set level with the metering diaphragm mounting surface. Walbro's are set even with the chamber floor.

I believe Tillotsons are set with the chamber floor also. The few I've piddled with were anyway.

 

[Coupe]

All the info the guys have told you on here is corect. Make sure your
metering diafram is not the type that locks into your needle valve.
If so make sure when you put carb back togeather you have not just set
it on top of needle valve if so that will make it flood. Just had a Homelite
mighty lite blower given to me (chinese) to find here in New Zealand to
find we cannot get repair kits out here for them have to buy new carby.
The metering diaphragm had gone super hard so looking at a diaphragm
out of a F10-WAT kit and grinding the centre pin down with a dremal to the
same height as the old one and was in business. Look any carby can be a
handfull more so diaphragm carbs but I find when doing them take thwm apart
and lay them out and put them back together the same way and plenty of carby cleaner
cause a lot of the time they play up can be blocked inside somewhere.
I have a set of jet cleaners and use them a lot of the time.
And last job I do and if you don't own one a mityvac presure tester a great tool
for testing crankcase seals and so on. Get a bit of fuel line put it on
carb intake bit of gas in it and apply a bit of pressure on it. Should be no leakage
what so ever if so that can be a problem as well. If you do start playing with the metering
lever be very careful with your ajustments as you can get a sorts of problems doing that.
The normal is with the small flat end of a stainless steel ruler it should be flush with the carby
body.
As I have done these little blighters up for years it does come second nature but sometimes
if carb has been left for years and really crappy inside you have to bit the bullet get the
wallet out and buy new.
Hope this helps in some way.

 

[LAWN BOY]

All the info the guys have told you on here is corect. Make sure your
metering diafram is not the type that locks into your needle valve.
If so make sure when you put carb back togeather you have not just set
it on top of needle valve if so that will make it flood. Just had a Homelite
mighty lite blower given to me (chinese) to find here in New Zealand to
find we cannot get repair kits out here for them have to buy new carby.
The metering diaphragm had gone super hard so looking at a diaphragm
out of a F10-WAT kit and grinding the centre pin down with a dremal to the
same height as the old one and was in business. Look any carby can be a
handfull more so diaphragm carbs but I find when doing them take thwm apart
and lay them out and put them back together the same way and plenty of carby cleaner
cause a lot of the time they play up can be blocked inside somewhere.
I have a set of jet cleaners and use them a lot of the time.
And last job I do and if you don't own one a mityvac presure tester a great tool
for testing crankcase seals and so on. Get a bit of fuel line put it on
carb intake bit of gas in it and apply a bit of pressure on it. Should be no leakage
what so ever if so that can be a problem as well. If you do start playing with the metering
lever be very careful with your ajustments as you can get a sorts of problems doing that.
The normal is with the small flat end of a stainless steel ruler it should be flush with the carby
body.
As I have done these little blighters up for years it does come second nature but sometimes
if carb has been left for years and really crappy inside you have to bit the bullet get the
wallet out and buy new.
Hope this helps in some way.

Thanks for the info! I was not aware that the bump on the diaphragm is supposed to sit in the hole on the valve thingy. That's probably why the 360 floods.

 

[Sloughfoot]

Thanks for the info! I was not aware that the bump on the diaphragm is supposed to sit in the hole on the valve thingy. That's probably why the 360 floods.

That may do it. Which goes first, gasket or diaphram is different on one side than the other too, in case you didn't know.

Learned that one the hard way.

 

[Coupe]

The main thing is if you do not already have one is a preasure tester
and before you strip a carby down test the intake side of you carby.
If it holds preasure it means your needle valve should be good but
if it loses preasure needle is leaking or you have a leak somewhere else
in your carby.
The possibly mean the carby is getting old and most likely time for
a new one.
As you will know by now you can get half or full rebuild kits.
I most of the time go for a full kit as has a new needle valve
in there..
As I said in my first thread most carby the metering lever sits on
top of the needle but there is some it does not and there is a
grove in the needle and a slot in the metering diaphram that
fits in the needle.
This will not cause them to flood but does the opposite and
not let gas through.
Main thing as I said keep everything clean and put togeather as you took it apart.
Ask some of the guys on here about pressure tester and what types but I have a Mityvac
9000 and the come with all the hoses and fitting you will need to test carbys.

 

[Kiwioilboiler]

The main thing is if you do not already have one is a preasure tester
and before you strip a carby down test the intake side of you carby.
If it holds preasure it means your needle valve should be good but
if it loses preasure needle is leaking or you have a leak somewhere else
in your carby.
The possibly mean the carby is getting old and most likely time for
a new one.
As you will know by now you can get half or full rebuild kits.
I most of the time go for a full kit as has a new needle valve
in there..
As I said in my first thread most carby the metering lever sits on
top of the needle but there is some it does not and there is a
grove in the needle and a slot in the metering diaphram that
fits in the needle.
This will not cause them to flood but does the opposite and
not let gas through.
Main thing as I said keep everything clean and put togeather as you took it apart.
Ask some of the guys on here about pressure tester and what types but I have a Mityvac
9000 and the come with all the hoses and fitting you will need to test carbys.

Hey Coupe. Where in NZ are you ehoa?

 

[Czed]

I've always used brake cleaner and use it very gently
High pressure kills carbs it's that simple.

 

[Likesaws]

I would recommend you watch some YouTube. I think Walbro might show some rebuilds.

 

[Al Smith]

Two things could go wrong .One being the spacer gasket on the wrong side of the main diaphragm .Two being the type of diaphragm .The setting of the lever is dead level with the fuel cavity but two types of diaphragms ,one with a little knob and the other that hooks the lever .On the later if it just sits on the lever not hooked it will fail and probabley never start .If it will start at all it won't stay running very long .Simple but often over looked which once again I've done it myself .