New To Me FE390 Maintenance Insights

So I did some work on the 390 over the 4th of July- big thanks to the Husaberg tribe and elders for posting all their experiences. Very helpful!

Here are some notes:

At 50 hours the spark plug had some mild corrosion forming. I will be spraying some air in there after water exposure.

The tank wasn't too bad to remove, but the air box design makes it more work than other bikes. I added reflective fiber tape to the bottom of the tank and wrapped the fuel lines.

I did not like how the wire bundle running next to the TPS blocks the rotation of the plug and adjustment, so I moved the bundle more towards the inside of the frame and TPS adjustment is better now. I played with the TPS a little but still need more experimentation. Will probably set to 0.601V and be done with it. Not sure how the idle screw works yet. Does it open an air bypass or does it adjust the butterfly?

Some connectors had dirt starting to enter the pins so I cleaned with alcohol and added dielectric grease.

I checked the valves and the exhaust were fine on the loose side. The intake had one a little tight and one loose, so I swapped some disks and got them close to each other more on the loose side of the spec. I don't use a feeler gauge much, so I hope I got it right. I had to kind-of saw the gauge or push it in pretty good at max spec and over, so I think it was ok. Same for the intakes. I should have recorded the engine sound before the work for comparison. I can hear the valve-train - hope that is normal. It's not loud, but you can hear it. Let me know if it sounds concerning. It for sure doesn't sound like the tensioner failures I have heard in vids. I had to take the ignition cover off to get to TDC due to the old ball actuated Rekluse (Z-start pro), then used the TDC bolt by removing the copper washer from the bolt on the clutch cover. Probably overkill because at TDC there is a couple degrees of free cam rotation for things to go boom.

I added the ZipTy fuel filter- seems pretty good and the way it integrates with the quick disconnect is worth the money. I took out the grey little inline filter in the ZipTy. My bike had the small inline filter at the elbow connection to the throttle body removed, already.

I added the dirt tricks tensioner. Pretty easy install when you lay the bike over. Otherwise, the piston keeps falling to full extension and you can't tighten the cap down. Well, you can, but it will damage stuff. Be careful of that.

The Sicass key-switch is pretty nice. I like the action of it. Easy to install, too.

The Hyde Racing Bash plate is pretty sweet.

The Profill fast fill filter sock is cool. Fills fast. : )

Changed the oil, filter, and cleaned the screens. The engine was very clean inside. The guy I bought it from only used Motorex and K&N filters. Seems to do the job, but it only has 50 hrs on it. Couldn't find the Motorex over the holiday, so used 20W50 Valvoline motorcycle oil. There seems to be more drag on the Rekluse at idle now. I will experiment and use Motorex next oil change.

I performed the weep hole mod. It was much easier to take the clutch side off to take the water pump shaft out vs. dicking around with prying the seal out. The seal was of course installed backwards from the factory like everyone says. I planned on reusing the seal, if possible, so taking the clutch side off is the way to go. If you are going to toss the seals, just drilling a couple small holes in the seals and using a drywall screw seems like it would work. If it gives you trouble you might just want to take the clutch side off with the bike on its side, or combine with an oil change. There was fine dirt between the two seals, also just like everyone says. I cleaned it all out and sanded the shaft with 600 grit a bit, then reinstalled the seals. It seemed to be leaking a bit at some point because there was calcium or whatever in the seal bore. Just a little bit. The seals have a little groove in the middle of the bore, so I put some grease in there and lightly greased the shaft. The weep hole was gummed up, so cleared that out. Next, the brass tube I bought was sanded down on the tip and I tapped it into the weep hole (just the tip), then slipped on some silicone tubing down to the bash plate where I loosely zip tied it. Dirt be gone!

I installed the dirt trix engine sprocket spring washer - took the sprocket off and greased the splines. Also put grease under the spring washer and extruded grease through the spines as I tightened the bolt exactly to spec. Pretty sure that torque spec is pretty critical no matter which spring washer is used. The blue spring washer looks pretty snazzy.

The bike will live at 7000 feet so riveted the factory fan on the radiator. Checked the coil connections while I was around there. I flushed out the old coolant with water, then two pours of Evens prep fluid, then two pours of Evans no boil coolant. I like how the little drain screw port on the water pump doesn't drain until the radiator cap is opened. It seems to be a low point, so I think most fluid drains out. One 64oz bottle is about two system fills, so I should have close to the required 97% concentration. Maybe I should have thrown some compressed air in the system but I got lazy. Should be fine.

The rear silencer joint leaks, so going to throw some RTV on that at some point. Maybe the front joint, too. The new springs come soon and I will refresh the fork oil, bushings, and seals when I do that. Not sure about the valves and shims. Maybe the next time.

That's all for now!

Thank you! This is an awesome contribution!

Nice work! You performed all that in one go which took me several months to achieve (in between rides of course.....). Well done sir. Swingarm bearings and shock bushes and fork service and she’ll be almost new again!! Oh, and new plastics and decal kit too.....

I'll have to take note to do most of those on my new FS.

Sounds like you are on the right path.

Consider doing one of the upgraded pumps of it was not already installed by the previous owner.

Maybe wrap the exhaust.

Thanks for the reminder..

NoClassic said:

Sounds like you are on the right path.

Consider doing one of the upgraded pumps of it was not already installed by the previous owner.

Maybe wrap the exhaust.

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I forgot to mention the new owner did have the pump changed due to the well known pump heat issue. While I had the tank off I did replace the in-tank large inline filter that is between the pump and the fuel line exit to the engine. I also inspected the filter basket at the base of the pump - it was clean. No issues. I did find a moderate to large issue: the plastic fuel lines, large inline filter, and quick disconnects add up to a pretty long set of hoses compared to the volume they need to be stuffed into. The line to the engine had actually been bent over and was kinked. Maybe when the pump was on it would straighten out, but the plastic was fatigued and would not stay straight on it's own anymore. I used a couple fuel system clamps, side by side, to make a splint of sorts. I can see this being a potential hidden issue on some bikes if the lines are just stuffed in there or through bad luck. If I ever go back into the tank I will change out the fuel lines to something better and more length appropriate. I see in the parts catalog there are some long and short options for those lines. I do not know if the short part number is long enough but maybe worth looking into. Also, I struggled with those quick disconnects a little bit until I realized you can use a small screw driver to individually push back each of the three locking tabs. Presto! I guess there is a special tool at auto shops, too, but it isn't needed.

The previous owner did wrap the pipe. I'm waiting on a carbon pipe gaurd for the front section. Something like that should have come from the factory - gets damn hot!

smbcj said:

Nice work! You performed all that in one go which took me several months to achieve (in between rides of course.....). Well done sir. Swingarm bearings and shock bushes and fork service and she’ll be almost new again!! Oh, and new plastics and decal kit too.....

Click to expand...

Good idea on the swing arm. I just ordered some bel-ray waterproof grease- will see how it works for the swing-arm and head. Reviews say they use it on the brake caliper pins, too.

Great!

I also have/had concerns about the in tank lines but could never really think of a good solution beyond completely reconfiguring them. I know there is a certain way they should go in but the manuals dont show that. I did end up completely removing the MAHLE inline filter on mine so that helped a bit with organizing things in there.

For the push lock fitting you should grab one of the ford fuel line QD tools. They work great and wont cause damage like a screwdriver can.

NoClassic said:

Great!

I also have/had concerns about the in tank lines but could never really think of a good solution beyond completely reconfiguring them. I know there is a certain way they should go in but the manuals dont show that. I did end up completely removing the MAHLE inline filter on mine so that helped a bit with organizing things in there.

For the push lock fitting you should grab one of the ford fuel line QD tools. They work great and wont cause damage like a screwdriver can.

Click to expand...

That big inline filter does seem to mess it all up.

One thing that is annoying is the pipe wrap holds water and steams. I had bought some foil faced fiber wrap that I had planned on gluing to the pipe with RTV. The plan was to brush on the RTV and embed the heat wrap in it, then wipe the excess. Then I realized that was not a-happening. I guess pipe removal requires the engine to come loose, but I was tired and decided to wait or never do it. Looking back, it seems like overkill, but overkill is underrated. At least that is how I rationalize it!

I will check out the Ford tool- thx.

I always make sure to run the bike until the wrap is dry.

Silicone is not going to hold up to the external exhaust tube temperature. I initially attempted to wrap mine using a silicone walled and fiberglass lined 2" tubing heat barrier. Even with the fiberglass liner the silicone was crispy and smoking in no time.

Steamer

NoClassic said:

I always make sure to run the bike until the wrap is dry.

Silicone is not going to hold up to the external exhaust tube temperature. I initially attempted to wrap mine using a silicone walled and fiberglass lined 2" tubing heat barrier. Even with the fiberglass liner the silicone was crispy and smoking in no time.

Click to expand...

Roger that. Glad I didn't waste my time. On the bright side, I guess I can steam some broccoli while on the trails.

Oh also you can remove the exhaust tube with the motor in. The rear shock needs to come out and the swing arm allowed to fall down a bit. You have to rotate the pipe around in some weird way but it will pass through the fame.

NoClassic said:

Oh also you can remove the exhaust tube with the motor in. The rear shock needs to come out and the swing arm allowed to fall down a bit. You have to rotate the pipe around in some weird way but it will pass through the fame.

Click to expand...

Ah, thanks for the tip.

NoClassic If you Ever remove that pipe again please take some pictures because when I do it I have remove the tank also. Thanks

The additional directions I had given were assuming the tank was already off.

Update

So I was insecure about my feeler gauge skills so I loosened the rear subframe tank, took off the main tank, rads, and checked the valves. The bike is new to me and I was dumb to not video the engine to compare when I initially adjusted them. There is some valve noise or some ticking, or at least I thought so. Anyway I pulled the valve cover and waited until it was cool out to measure again. The intakes are mid-high gap and in spec. The max in spec gauge would not push in for both, so I am satisfied there. At max gap the feeler would not go in one of the exhaust valves, and it was tight 0.01 below, then nice 0.02 below max. The other exhaust valve dragged medium hard at max spec and was good at 0.01 below max spec. I would have replaced that shim but I only had a kit with 0.05 increments. I tried turning the shim over but no luck. Anyway, I am done playing with it. I am confident now. I also played with the dirt tricks tensioner while the valve cover was off and I am comfortable with the installation. The piston when down one or two clicks. I cleaned out the spark plug bore real good and at 20nm the torque wrench hits firm resistance. Previously, tightening it seemed soft. There might have been some crud in there. The ticking seems better. Ha. The bike starts great hot or cold and I am a pro at taking the bike apart now.

I won't be messing around with the sub frame tank much. One rear fender side threaded insert spins, but doesn't appear to be a leak path. A small impact driver gets the screw out, for now. At some point I will have to dig out the insert and JB weld it. It appears to be a circular insert, which was a bad idea. The main subframe attachment points seem more beefy- time will tell. If a leak develops I guess sloshing around an interior coating might help.

Next up, I installed a Lexx silencer. It weighs about the same at the oem silencer but you can change the tips and it's a straight through silencer. I would say the quiet tip/arrestor that came with the Lexx is more quiet than the OEM silencer. Pretty close to call. I bought the other 34mm tip and the spark arrester to go with it. The 34mm tip and arrestor flow great and are not much louder at idle. The Lexx is a one size fits all silencer, so it takes some fiddling to get it setup where the rear wheel clears the silencer. There are two attachment bands that you can spin silencer in to get the right orientation. The Lexx comes with a small mid pipe. I tried to not use it, but best results came with it installed. Without the mid-pipe, the silencer is a bit loose on the rear pipe connection. The mid-pipe fits perfectly into the silencer and onto the pipe. The spring attachment points didn't make much sense, so I just used some hi-temp RTV. It all worked out and I am satisfied. There is an ultra quiet insert for sensitive areas. The tip points downward, which should help when I ride in the Sierras.

I set the TPS to 0.601 and was getting some pops so I installed the EJK tuner. Works awesome. The bike seems rad now. Can't wait to get the 390 on the trail with these mods.

Oh, and I put a cheap LED bulb in the headlight. It's better.

The radiator fan and waterless coolant work well. It was 95F and I was idling in place for a while without a problem. Not that it was a problem without them, but the bike will live at 7000ft. The fan, waterless coolant, tuner, and silencer seem to help, all combined. When the bike gets a bit warm I have been cracking the radiator cap to purge any water I left in the system during the waterless conversion. The first time a medium-low amount of pressure was released. It seemed less on later tries. Not sure if I am doing anything yet, but the waterless coolant is not supposed expand much, if at all. Thanks to all the others for posting their tips.

Until the next update..

Super useful! Thanks!

Re. the subframe: Apparently it's a somewhat special plastic. Cross-linked polyethylene iirc? Someone on here described it as basically one giant molecule. So it's rather unusual to work with, and I'm not sure any standard fuel tank coatings would stick to it. There are methods to work with it however, which have appeared on here and will be found when searched for.

the bike will live at 7000ft, it was 95F, and you're in Oakland? must not be the Oakland I was guessing.

tourist said:

Super useful! Thanks!

Re. the subframe: Apparently it's a somewhat special plastic. Cross-linked polyethylene iirc? Someone on here described it as basically one giant molecule. So it's rather unusual to work with, and I'm not sure any standard fuel tank coatings would stick to it. There are methods to work with it however, which have appeared on here and will be found when searched for.

Click to expand...

Yep, difficult to get anything to stick to that plastic!

Plastic

Ah, I also just read the Husaberg promo about it. It’s PEX, the same stuff used in plastic plumbing pipe. I’m familiar with PEX in radiant heat applications and it is very durable.

Are we sure the 70 degree subframe is also PEX? It looks different.