Husqvarna 394xp build/mod

[RIDE-RED 250r]

So as some of you know, I'm kind of into saws. Yeah I use them for work at home and at my job, but they have become another hobby of sorts for me as well. Besides making a little side money overhauling a few for a local tree service, I have been learning how to port them from some of the pros in the business. Cool side effect is that I'm learning 2-stroke porting theory. Now mind you, compared to wheelers, bikes, and sleds, a saw is basically a one-trick-pony. It's meant to run strong at WOT. Whereas bikes and such a broader power curve is more desirable and I can plainly see the difference in the port layout with bikes and such being much more sophisticated with boost ports, windowed pistons, and the need for reed and rotary valves. I am gaining enough knowledge and tooling that I am building enough confidence to port my own 250r cylinder in the not too distant future.. But I digress.

I currently own all Husky's, a 346xp, 357xp (ported by me) 372xpw (75cc, ported by me) a 359 I built from a junk powerhead with a couple of simple mods, and finally got my mitts on a builder 394xp.

I got this blown 394 powerhead in leau of cash offered to me for my labor overhauling a couple of saws for the tree service I mentioned above. Pics below starting with how it looked when I got it to how it currently sits...

I went right through it from the crank bearings on up. The piston was scored pretty bad and there was piston material transferred onto the cylinder walls. These cylinders are nikisil plated and I learned that most often they can be cleaned right back up to good usable condition most times with simple sanding. My cylinder cleaned up good and I'm glad for that as nobody makes 394 spec cylinders any more, not even aftermarket. And to swap to a 395 top end while simple, involves swapping the whole intake tract over to 395 components as well.. Both saws are identical in most ways, but the intake tract is the biggest difference and adds several more parts to the list. Plus I wanted to maintain this saw as a true 394.

Couple pics:

[RIDE-RED 250r]

As the bottom end was coming together, I sent the cylinder to Shaun of Scarr Engineering to cut the squish band in the combustion chamber, cut the cylinder base (this is the typical mod done to raise compression) and raise my transfers for me to the correct height for the cylinder machine work. I opted to have this work farmed out because A: Being a 394 I wanted to mod this saw to the max this side of a true race saw and B: I do not (yet) have a lathe, Foredome drive and RA handpieces to be able to physically get in there and raise the transfers enough. I can do the exhaust and intake work myself with the tools I have already so I opted to do them myself.

Shaun did a great job and if anyone out there wants to mod their big bore Husky (particularly 394 and 395) and are interested, just let me know and I will put you in touch with him.

Couple pics of his and my cylinder work... First is his work on the transfers and squishband, second is my exhaust port. Forgot to snap a pic of the intake after I was done with it.. All said and done the cylinder is set at 98/116/80 for timing with 210 PSI compression... Stock these saws pull around 170-ish for compression. So yeah, definitely have to use the compression release when firing this beast up unles you want to replace copious amounts of starter components..

[RIDE-RED 250r]

So I ended up getting a new cylinder cover for it as I like the HD Hi-top air filter setup better on these bigger saws. I also modified the muffler with an extra exhaust port to help it breath and dissipate heat more efficiently with these mods. After initial assembly, I figured out I had a problem in the low speed circuit of the carb that I was unable to remedy despite my best efforts. I swapped in a carb from another good running 394 I have access to in order to confirm and presto! This thing runs FIERCE! These saw carbs whoop me occasionally, they have such tiny fuel circuits that can be very difficult to clear. So now I am waiting on my new carb and a few other bits and pieces. I can't wait to get some runtime in the woods with this fire breather!

[plastikosmd]

Very cool. Now I will have to look for a project saw. I won't tear into my home saw yet. I learned long ago, don't tear apart your "daily driver" without a plan!

[atc007]

LOVE this thread,keep us posted!

[atc300r]

This is a cool thread. I like working on saws and weedwackers and other small two strokes aswell. I pull weed wackers ,push mowers and snowblowers from the dump metal scrap dumpster if they are complete and get them running again . I don't find many saws. I haven't bought a snowblower or pushmower in years. .One of my Uncles told me years ago that a lot of people buy a saw,lawnmower ,weedwacker ect,ect,ect use it once or twice store it away for couple years when they get it out to use again it wont start and they throw it out and buy another one.Usually they just need a carb cleaning or spark plug and fresh gas.

[briano]

I'd like to start working on my Husy 2100 one day. It's from the 70's I believe, and 100cc's. I have a 56 inch bar on it, yes, 56 inches with an Alaskan 48 inch sawmill. It will cut through a three foot diameter pine log, 8 feet long in just about three minutes. I can't believe the torque it has, it don't matter how wide the log is that we cut, the saw never bogs down. We cut a bar top for my brothers garage that's 44 inches wide and 12 1/2 feet long, really nice piece of white pine with the natural edges left on it.

[plastikosmd]

^ post a pic of that beast

[RIDE-RED 250r]

I'd like to start working on my Husy 2100 one day. It's from the 70's I believe, and 100cc's. I have a 56 inch bar on it, yes, 56 inches with an Alaskan 48 inch sawmill. It will cut through a three foot diameter pine log, 8 feet long in just about three minutes. I can't believe the torque it has, it don't matter how wide the log is that we cut, the saw never bogs down. We cut a bar top for my brothers garage that's 44 inches wide and 12 1/2 feet long, really nice piece of white pine with the natural edges left on it.

Yes Sir, 99cc of Swedish muscle! And you are correct, introduced in late 70's, discontinued 1987.

My carb arrived in the mail today :D

[kiser]

I like it!! I have an old 066 I would like to warm up and this gives me motivation! Keep the info and pics coming! Post a video of it eating if you can!

[RIDE-RED 250r]

Absolutely will post a vid. I need to make one for my friends over on OPE Forum who have helped me out along the way with this build and I'll be sure and post it up here.

OPE forum has alot of knowledgeable members and well reputed porters over there. Any of you guys looking to learn about saws, everything from where to source that hard to find part to full on porting and compression mods, I would encourage you to join up and check it out. I go by RIDE-RED 350r over there and have 10+ page build thread on this 394. Alot of good 394/395 info in that thread posted by some very knowledgeable people. http://opeforum.com/

[RIDE-RED 250r]

Well I swapped in my new carb and got a preliminary no-load tune dialed in. This thing is a beast! The new carb cured the issue and she now runs perfectly! Once I get a chance to go stuff it into some hard maple, I'll make a vid and post it up

[RIDE-RED 250r]

I like it!! I have an old 066 I would like to warm up and this gives me motivation! Keep the info and pics coming! Post a video of it eating if you can!

I'm not as well read up on my Creamsicles as I am with my Huskies but I do know that it is a beast of a popular large displacement saw. About the size of a 394/5, 90-95cc??

[briano]

^ post a pic of that beast



I will get a pic of it next time I go to my parent's house. It's in my dad's garage.

[RIDE-RED 250r]

Well, I got a chance to give my newly overhauled and modded 394 a real stress test today. Came into some large sugar maple, AKA "hard" maple. This stuff is harder and more dense than any oak we have around here, arguably toughest of any species native to this area. It will give any saw a real workout.

So today I put the 36" bar on it and we did some noodling and blocking. I think it pulled it quite well. My brother was cutting with me using his ported 372xp X-Torq and let me tell ya, wood like this really shows the muscle the 394 has over the 372. Overall I am real pleased with how this beast came out.

Here is a couple of vids and pics.

https://www.youtube.com/watch?v=8aMMRjzRJ1I
https://www.youtube.com/watch?v=v45qaqZSv7o

Thinking my next overhaul/mod might be a 288xp or 390xp

[coolpool]

I love unique builds and this is just plain awesome. That saw doesn't even sound like it wants to slow down in your vids even when your cutting up the length and getting big chips. Very nice!

[RIDE-RED 250r]

Thanks man. This has been a fun and rewarding project through and through. The 394 is an impressive machine but it does wear on the operator. It's alot of saw but it's very useful in large hardwood.

About a year ago I did a 359 overhaul. It was a pile and missing several parts when I got it. Now it is mildly modded with just a base gasket delete and basic lower transfer work. Now it is a good running well mannered saw running an 18" bar with 3/8 full chisel. It's not a screaming banshee like my ported 357xp, but it has a wide torque curve and will pull well when dogged in. I find myself grabbing this saw fairly often.

Here is a pic of what it looked like when I received it and a couple pics of what it looks like now.

[plastikosmd]

Like the saw stand

[RIDE-RED 250r]

I like this one better ;)

[plastikosmd]

Struggling w a husky 124l weed wacker. A small stand like that would be nice. No spark, plug tester shows spark but I can't get enough to jump the gap on old or new coil. Both adjusted close to the magnets on flywheel. Maybe too close, sigh. I'm about to bend it around a tree.

[RIDE-RED 250r]

Should be a .010"-.012 coil/flywheel gap..at least that's the spec on saws anyway

[tripledog]

Struggling w a husky 124l weed wacker. A small stand like that would be nice. No spark, plug tester shows spark but I can't get enough to jump the gap on old or new coil. Both adjusted close to the magnets on flywheel. Maybe too close, sigh. I'm about to bend it around a tree.

I use a standard business card (not one that is embossed) as a feeler gauge to set the gap on my saws, and it works great. Make sure the magnet on the flywheel and the face of the pickup coil are clean before you set the air gap.

[plastikosmd]

Clean and set can't get old or new coil to fire plug but both fire tester and plug works in other machine. I can't use that coil in second machine as it is a different setup but plug works.
Old coil 1500 ohm and something huge like 1.5Mohm, only reads one way, otherwise OL
New is 370ohm 3500ohm. Seems more normal, gap is about a card. Can't get it closer. So confused, outside of magnets not having enough field or my new coil is also bad....

[tripledog]

Clean and set can't get old or new coil to fire plug but both fire tester and plug works in other machine. I can't use that coil in second machine as it is a different setup but plug works.
Old coil 1500 ohm and something huge like 1.5Mohm, only reads one way, otherwise OL
New is 370ohm 3500ohm. Seems more normal, gap is about a card. Can't get it closer. So confused, outside of magnets not having enough field or my new coil is also bad....

A friend of mine says he uses a piece of notebook paper to set the air gap. I wouldn't think that would work, but paper is thinner than card stock, so the gap would be closer.

[RIDE-RED 250r]

New coil aftermarket or OEM? It's possible to get a bad new coil, especially with aftermarket coils

[plastikosmd]

Aftermarket china

[B S]

Tell them it's a bad coil?

Have you tried to start it with the kill switch unhooked ?


Sent from my iPhone using Tapatalk

[plastikosmd]

Yes kill is disconnected
Coil was ordered via Amazon
I will see if I can find another local

[RIDE-RED 250r]

A coil that does not fire when the kill circuit is disconnected from it is indicative of a faulty coil. By default they should fire when the flywheel magnets pass by the armature. It is only by grounding them that ignition is disabled shutting down the engine....

As much as its nice to save money on parts, chinese parts, particularly electrical parts like coils can be very hit and miss. As I mentioned earlier in this thread, I am active on a couple of saw forums. Lots of back and forth on chinese parts and saws there. One very common theme I have read about id chinese coils failing prematurely, causing engine to not perform up to par, or not working at all. An OEM coil should be under $50 and in this case experience of others indicates you are better off with the OEM part. I'll look up your weedwacker and see if I can find a rough cost for your coil... Stand by.

[RIDE-RED 250r]

Ok, if you click this link: https://www.partstree.com/parts/husqvarna/trimmers-string-trimmer-brush-cutter/ You can see 4 or 5 links to your model but different year runs. I clicked the first and found that your coil is 38 bucks (number 40 in the diagram). I'm not sure what year your 124L is, but you should click the link appropriate for your model year to make sure you get the correct part.

Here is the diagram I looked at, again might not be your year. It's the 2006-05 parts listing.. https://www.partstree.com/parts/husqvarna/trimmers-string-trimmer-brush-cutter/124-l-husqvarna-string-trimmer-2006-05/engine-fuel-tank-ignition/

If you don't want to order from here, just jot down the part number to your coil and call your local Husky dealer.

[plastikosmd]

Thx for your hard work!
38 bucks, sigh. I should have guessed the other isn't worth it. Well I will return to amazon. Both old and new fire tester but as we all know that ain't enough.

[RIDE-RED 250r]

Not a problem, glad to help.

It does seem strange that both coils fire the tester but not the plug... But at this point given the testing you have conducted, especially disconnecting the kill wire, it's kind of hard to conjure up a solution other than a faulty coil. I would be surprised if a new OEM coil doesn't cure it.

Please do post up the results either way once you get your new coil installed.

[plastikosmd]

Agreed, nothing worse than a bad replacement part to drive you crazy

[RIDE-RED 250r]

I assume the new aftermarket coil came with a sparkplug wire already attached? Just want to make sure we aren't missing other possibilities like a bad wire or cap.

[plastikosmd]

Yep,attached 3500ohm resistance to coil core.not sure what spec is.old one was 1500 and primary was in the Megaohm range-bad

[plastikosmd]

Crap china coil

I called my local husky dealer who said that my current coil was covered under a lifetime guarantee. He ordered me a new one and it worked like a charm. I Will return the Chinese coil back to Amazon just based on principle

[RIDE-RED 250r]

Glad to hear you got it straightened out buddy! :) The aftermarket coils are very hit and miss with these things, much like aftermarket CDI's for our trikes, especially those of chinese origin.

Oh and my 394 is even nastier than the vids I posted depict. I had a binding issue with the throttle lock spring and throttle trigger. The spring kept working its way out of its slot on the throttle trigger and causing me to not have the last full 1/4 throttle to WFO! After addressing this issue, the saw is on a whole other level of beast. We don't have any bigger wood to take a vid with that does a saw like this justice. But when we get into some more I will take a vid and post it up. I did noodle a chunk of ash to try it out after fixing the throttle lockout spring. 36" bar buried and it doesn't know the meaning of slow down till the discharge plugs up with those long noodle chips. Once that happens the chain carries the noodles all the way around the clutch and stuffs them back into the cut, and that's the only thing that will slow it down. Crosscutting, it's an absolute beast.