Carb Question for Stihl 032 AV?

[djohnm]

Hi Guys-

This is my first post on the forum, but I've been lurking around this site for a while now and am really impressed by all the helpful knowledge that gets shared around here...

I have an 032 AV that wound up with a problem bogging down when hot. I took it to a local shop (that had a real good Stihl man, I thought) who installed a kit and could never really get it to perform properly when hot. It would die in the log and could not be adjusted out. He had installed a carburetor kit, but came to the conclusion that I needed a carb. According to the kit he installed, I would need an HU-51A, but he could not locate one. The saw sat for a while, I wound up buying a MS361, and that’s been several years ago. I’m feeling guilty about having the 032 (which was a really good saw) just sitting around, and am now looking for a carb to hopefully get it running again. I’m likewise having a problem locating a carb.

Can y'all tell me, perhaps, what the difference is between the HU-51A and the HU-51B? I understand that both were fitted to the 032 AV, but are they interchangeable?

Thanks, folks!

-Dave

 

[brad1000s]

Yes, either will work. I think the HU-51A,B have been replaced with a HU-51C. Stihl part # 1113 120 0604. From your description of your problem, I would look else where. I would pop the muffler and check the piston and cylinder for scoring (I have seen them run with wasted pistons). If all checks good there I would then look at the ignition system. That's my two cents.

 

[OREGONLOGGER]

You can find a carb off a 031 will work just fine. Get a Walbro WA-2C I have one on my 032 and it screams and it's off a 031..good luck!!

 

[HILLBILLYREDNEC]

Let me know what carb number is on the saw, I have a good parts saw in that has a good carb.

 

[Rustynutz]

Sounds a bit odd "your Stihl man" that is!

first off get it pressure tested cold and hot that will tell you if the jug and pot are OK if your getting good pressure there.

most auto shops have testers if you haven't got one

report back to us on that if you do it!

I would be surprised if the carbs completely U/S more like badly serviced and not set up properly (I've seen some pretty canky looking carbs that still work fine) the pop off test is easy to do and all you need is an air pump with a gauge!

I would be looking for leaks, seals, gaskets etc
If its electrical then it will fail both in or out of the cut

 

[Rustynutz]

OWW BTW Welcome to our site!

 

[Rookie1]

Welcome to AS. I think you need to check all the basics first. Is the saw a points model? Like Brad said check the ignition. Ive worked on a couple of 031s that wouldnt rev and it seemed to be the carb but was a bad condenser.

 

[Fish]

My vote is ignition too!

 

[Rookie1]

My vote is ignition too!

Just for the record Fish was my first friend on AS. Glad to see he agrees with us on the ignition.

 

[Fish]

You are my AS BFF!!!!!!!!!

Wait, that doesn't look right..............

 

[djohnm]

Thanks for all the great suggestions, guys! Sorry for the delay getting back, but I just got back from a road trip last night.

I was a little suspect about that carburetor diagnosis, myself, so I appreciate the advice to start with the basics. I'll eyeball the jug and cylinder and check on the ignition and go from there.

I know four stroke engines well, but have never messed with 2-cycles. When you say, Rustynutz:

first off get it pressure tested cold and hot that will tell you if the jug and pot are OK if your getting good pressure there.

most auto shops have testers if you haven't got one

report back to us on that if you do it!

I would be surprised if the carbs completely U/S more like badly serviced and not set up properly (I've seen some pretty canky looking carbs that still work fine) the pop off test is easy to do and all you need is an air pump with a gauge!

I would be looking for leaks, seals, gaskets etc

are you talking about the procedure outlined in this thread http://www.arboristsite.com/chainsaw/42768.htm??

Thanks again, guys.

 

[Rustynutz]

not exactly, i got hold of a bicycle pump with a gauge cut off a bit of brass stem from an old lorry inner tube and got a push connector to go to the fuel pipe, and tested as follows..

Small Engine Diaphragm Carburettor Tests
QUICK TEST
Prove metering system works
Put 10psi on fuel inlet and see it hold there, (will creep down slowly) put tube on diaphragm vent hole and blow, watch inlet pressure drop
If it holds and drops that’s working

Test Main jet and Check Valve
Screw low Needle in until snug fit (Do Not Over tighten you will damage seat) then remove High Needle, get red nylon tube from WD40 spray can or similar and place in jet hole (takes some fiddling to get a good seal) when you think you are in the jet blow then suck you should feel the valve opening and closing as you do this (easy to blow harder to suck) if your not getting a response try sucking and blowing a little faster, if still not noticeable attach your WD40 and squirt some in (look in chamber and you should see it come out of the main jet, then try the suck blow test again (remember to clean the tube or you will get a mouthful)

Test Low Jets
Remove L needle put tube in and spray with WD40, look in chamber you should see it coming out of both holes.

NB
Using WD40 like this is OK for short periods (Don’t leave it in there for to long) I usually flush through with petrol after the test, A Quick blow on the supply tube will prove fuel can get there.
Put both needles back in till snug then back off 1 and ¼ turns (most working Carb’s will start at this setting)

General Notes
Main jet is in the centre of the chamber. Low Jets are each side of the throttle butterfly (Engine end). The H high needle (shorter one) is always closest to the air filter end and the L low needle (Longer one)is always closest to the engine. I made my pressure tester with a bicycle pump that had a gauge or you could use a car tyre pump and make an adaptor with an old valve stem and some fuel line (just remember not to go over 10psi or you might damage the diaphragm)

If it passes all these tests it should start and run now???

Set up the low jet first to get the engine ticking over nicely.
Increase the tick over screw so the engine runs without stalling, now by moving the L Jet in till it starts to die then back ¼ turn should be ok, now turn the T O screw till the engine runs a nice speed below the clutch cut in speed. Now open throttle and adjust H needle till you get a nice response as the engine speeds up and down (H needle should be set with a hot engine) now this will probly be to lean a mix, with full throttle screw in till engine starts to falter (4 stroke) then turn screw back ¼ turn. (this should be somewhere handy)
Now I usually run a couple of tanks through just to get everything to stabilise then reset everything again. Just remember to rich it might flood or foul the plug but to lean will kill your engine (so get it right!)

Quick Tip
Most carb faults are caused by storing machines with fuel in, I found if your lucky and its not damaged just clogged up, you can warm it up with an air dryer then flush through with WD40 followed by petrol, found this to work well on a lot of carbs without dismantling anything.

Hope this helps!
Russ…

 

[djohnm]

This is great, Russ, thanks! I'll run these tests, adjust per directions, try to run a couple of tankfuls and see how it goes. I'll go ahead and check the P&C and compression while I'm at it.

I'll do my best not to get a drink of WD-40 while I'm testing...:biggrin:

 

[Rustynutz]

Best of luck with that.

one thing forgot to say there was all saws have a manufacturers recommended max RPM setting, and if you have access to a tacho thats the best and safest way to set up the H jet, if not then as above.

 

[Warped5]

Just something to be aware of if you're thinking of swapping in a WA-2C off an 031 ....

That carb has Stihl-proprietary sized diaphragms on one side, the K10-WAT and K20-WAT diaphragms don't fit, they are too small.

I am waiting a week now for my kit to arrive at the dealer.

Just my $.02 .... :bang:

 

[Fish]

Just something to be aware of if you're thinking of swapping in a WA-2C off an 031 ....

That carb has Stihl-proprietary sized diaphragms on one side, the K10-WAT and K20-WAT diaphragms don't fit, they are too small.

I am waiting a week now for my kit to arrive at the dealer.

Just my $.02 .... :bang:

Huh?

 

[Fish]

Just something to be aware of if you're thinking of swapping in a WA-2C off an 031 ....

That carb has Stihl-proprietary sized diaphragms on one side, the K10-WAT and K20-WAT diaphragms don't fit, they are too small.

I am waiting a week now for my kit to arrive at the dealer.

Just my $.02 .... :bang:

There was 3 shooters on the grassy knoll... Too.....

 

[Warped5]

There was 3 shooters on the grassy knoll... Too.....

Nope, only one on the grassy knoll; Oswald was in the warehouse but the shooter on the knoll was a 'backup plan' that Oswald had no knowledge of.

Seriously. The K10-WAT is the kit that Walbro specs out. I happened to have a K20-WAT kit on hand as well.

None of the diaphragms that would be used on the one side fit; they were ALL too small.

Q: How else would you explain that Stihl does not have a full rebuild kit listed in the IPL, only the two diaphragms and one gasket that are used on one side?

 

[Fish]

I have been around the block many, many times...

Never heard that one......










never

 

[Fish]

elvis will chime in soon, it is his "destiny"