394xp carb problems

[huskihl]

My 394 has a walbro wj39 on it. Before the MI gtg, I picked up a k10 wj kit for it but the Welch plug and screen weren't the right size. But I mainly got it to replace the diaphragms anyway. So I used everything else in the kit and cleaned out the screen.

After sitting for a month, today I got it ready to cut wood this weekend. It was lean on the low side, so I gave it 1/4 turn, and then another, and another. Still lean. Took it apart again and cleaned everything by eye, spraying brake cleaner into the holes and watching it come out the bore passages. I bent the needle lever up maybe .010 or .020 to attempt to allow more fuel in.
After reassembly, I gained a slight bit of L adjustment, but I'm too rich on the H needle. If I turn the H in tight, it'll still run, 4 stroking heavily. This is how it ran when I originally put it together, and why I installed the kit.
I'm not a carb guru at all, just what I pick up on here. Any help is appreciated

 

[5000+]

The rich H could be a leaking welch plug. You may have a damaged check valve.

 

[Chainsaw Jim]

Make sure your gaskets and surfaces on the intake flange and block are acceptable and torqued down right.
You may also be dealing with a bad crankcase seal.
Raising the metering lever will cause a high idle. Make sure it is flush with the bottom of the pan.

 

[backhoelover]

Make sure your gaskets and surfaces on the intake flange and block are acceptable and torqued down right.
You may also be dealing with a bad crankcase seal.
Raising the metering lever will cause a high idle. Make sure it is flush with the bottom of the pan.

second that.
plus i have seen where the nozzle check valve was acting up put a new one it and all was fine. that was even after running it through the ultra sonic cleaner. there so small you can see any problems even if you try taking them apart

 

[Warped5]

The rich H could be a leaking welch plug. You may have a damaged check valve.

Don't try to blow out the carb with compressed air. This could damage check valves. A good long soak in solvent is your safest bet.

Make sure your gaskets and surfaces on the intake flange and block are acceptable and torqued down right.
You may also be dealing with a bad crankcase seal.
Raising the metering lever will cause a high idle. Make sure it is flush with the bottom of the pan.

+2!

 

[srcarr52]

Make sure you have the metering diaphragm groove in the metering arm correctly. When the H side needle can be shut off and it will still 4 stroke is a symptom of too little pop off pressure, metering level too high or incorrectly installed diaphragm. You could have the wrong spring under the metering lever.

 

[Chainsaw Jim]

I've had check valves go faulty because they get a little bit of debris trapped in them. I've gone from a bad leaky valve to holding pressure without drop after blowing them out with carb cleaner and then drying them off with a low pressure shot of air.

 

[Chainsaw Jim]

Make sure you have the metering diaphragm groove in the metering arm correctly. When the H side needle can be shut off and it will still 4 stroke is a symptom of too little pop off pressure, metering level too high or incorrectly installed diaphragm. You could have the wrong spring under the metering lever.

Have you noticed how the diaphragm tab that hooks into the notch on the lever will bottom out and not allow the entire diaphragm to reach full depth?
I file that little thing down to the main tab and it'll sit flat allowing the metering pin to fully open at wot. The hook really serves no purpose as the spring returns the lever to original position.

 

[huskihl]

Make sure you have the metering diaphragm groove in the metering arm correctly. When the H side needle can be shut off and it will still 4 stroke is a symptom of too little pop off pressure, metering level too high or incorrectly installed diaphragm. You could have the wrong spring under the metering lever.

Since the first kit didn't have the correct welch plug, I ordered another kit last night from HLS. Hopefully it'll have the right stuff in it.
The diaphragms are in correctly, tit is in the groove on the lever

 

[jmssaws]

Intake block upside down?

 

[huskihl]

Intake block upside down?

I dont think so. Impulse is on top.

 

[jmssaws]

A 394 and 395 kinda have a lean lope sound at a idle.
I've had the metering arm to high and couldn't lean the high enough.