Braapp-Shack/SCARR Engineering 394 build, DONE :)

[RIDE-RED 350r]

When I put the carb kit in, I set the metering lever with my Walbro metering lever gauge. Gauge says the metering lever is a little below the carb body. I raised it a little bit from that position twice. It made a difference but it was minor.

 

[RIDE-RED 350r]

Pull the Welch plugs they aren't hard to replace.

What's underneath?

 

[Sty57]

What's underneath?

Welch's Grape juice........

 

[beaglebriar]

What's underneath?

A couple small holes that you can clean with a fine wire and you know that tiny brass screen that's in the kit? That is where it goes.

I'm thinking tillotson but the walbros are similar.

 

[XP_Slinger]

That's definitely worth a look Joe. Had I not been so distracted with my little project today I might have thought about it before you left. That screen under the Welch plug is what was screwing over that Jred 920 carb when I was fighting with adjustments on it a few years ago.

 

[beaglebriar]

Here's my method : carefully drill a small hole in the center of the plug, take a sturdy pick and pry it out. To install I'm sure there's proper tools but I use a socket of the correct size to start then give the plug a good tap in the center using a punch and hammer. Don't flatten it though, it needs to be a little concave.

 

[XP_Slinger]

Here's my method : carefully drill a small hole in the center of the plug, take a sturdy pick and pry it out. To install I'm sure there's proper tools but I use a socket of the correct size to start then give the plug a good tap in the center using a punch and hammer. Don't flatten it though, it needs to be a little concave.

A socket is what I use as well...works like a charm

 

[RIDE-RED 350r]

Well I got it out using the method I found in a youtube video posted by Walbro, but not realizing how shallow that pocket is I ruined the damned carb. Lesson learned... gotta get a new carb now.

 

[beaglebriar]

Oh that's not good.

 

[RIDE-RED 350r]

Live and learn.... Not everything goes the way it's supposed to first time around. Now I know..

 

[RIDE-RED 350r]

Well, just ordered a new wj-71., $55 shipped. Not too bad I don't think.

Should arrive by the end of the week.

 

[srcarr52]

I will use 78 if the exhaust is 101+
At 98 you need more intake or you waisted your time raising it that far.
Intake duration won't hurt these saws,since Shaun raised then that far I'm sure he had around 80 and 98.5 to 99 on the exhaust.
Your to far under square.

I usually run 79 on the intake and 99 on the exhaust. I'd widen the intake a little bit don't go way overboard with it.

 

[jmssaws]

I usually run 79 on the intake and 99 on the exhaust. I'd widen the intake a little bit don't go way overboard with it.

Yessir the intake is plenty big on these saws.
I like around 160 degrees of duration on both with 16-18 degrees of blow down,that with a couple hundred lbs of compression make a pretty good running saw.

 

[RIDE-RED 350r]

Honestly, I was thoroughly impressed with how the thing ran up top yesterday as-is albeit I wasn't able to run it in wood at the time. Fierce is the word that comes to mind.

I ran a compression check before first startup and of course there was oil in the cylinder. It pulled 210 psi. Squish came in at .024". I imagine squish tightened up a tad after final assembly with full torque on the cylinder bolts. I have only ever ran 394's with a simple BG delete and a stock 395 so to say I'm impressed with my 394 thus far is a understatement. But I WILL be going back in and lowering that intake some based on the advice given by you guys. Too tempting not to.

And not to sound like a broken record, but I can't thank you guys enough for the guidance.

 

[RIDE-RED 350r]

Well boys, I'm happy to report good things this evening.

I lowered the intake to 80 deg for final timing numbers of 98/116/80, easy enough.

So then I swapped in the known working carb from the 394 owned by my employer for testing purposes.....Saw runs PERFECT with that carb! So now I'm just waiting for the new WJ-71 I ordered to arrive.

Also figured out that both my fuel and oil caps leak. No big deal, I like the newer style anyway. Other than that it's just things I don't necessarily need but want plus a 28" Sugi or TSB Light and Tough. It has the OEM 24" GB bar that came on my 372 currently.

I can't wait to button this thing up and stuff it into some big hard maple! Unfortunately I don't have any of that on hand yet, we haven't started our tree work for this year at work yet. I usually get some loads of firewood logs when the property owners don't keep the wood.

 

[srcarr52]

The new flip caps from the 562 work on the 394 oil and fuel tank.

 

[RIDE-RED 350r]

So I learned one other thing the other night, a hardware store replacement nut doesn't work for a flywheel nut. Too big on the outside and rubs on the recoil hub.

So I'm waiting on a correct flywheel nut along with the carb.

 

[srcarr52]

Just grind it down.

 

[RIDE-RED 350r]

So Jason, I have been thinking about our conversation about "square" port timing layout and it makes good sense to me... Being an aspiring porter, I am wondering how transfer timing plays into that theme if at all. Or is it simply a matter of setting them for the desired amount of blowdown after setting your exhaust?

Another thing I have been thinking about, 2-stroke port layout pretty much does what a cam profile and valve sizes do for a 4-stroke engine. With 4-stroke engines, the intake valve and ports are always larger than the exhaust valve and ports which stands to reason with me as you are taking in more than you are pushing out after the combustion mix is burned. Going back to the "squareness" of intake duration relative to exhaust duration, I can't help but wonder if it would be beneficial to have a bit more intake duration than exhaust duration?? Or is this picked up by intake area instead?? I do notice that intake ports are larger overall than exhaust ports. And I can see where too much intake duration will cause your transfer velocity to be reduced.

Just thinking about this stuff alot lately and wondering your thoughts.. You too Shaun and Mike.

@jmssaws @srcarr52 @mdavlee

 

[mdavlee]

I like more exhaust myself. You can't burn what you can't get above the piston into the chamber.

With that said transfers are the key. I'll run 94 on exhaust if that gets my transfers where I want them with the blowdown