250-500cc 1998 WR360: questions about carb and forks

First post, let's start with a small introduction.
I am a Dutch guy that likes to venture away from the black top now and then. I am not a racer or motocrosser. Before I got kids I did a lot of greenlaning, went to Morocco, etcetera. I did those things on bikes like Kawasaki KLX650R, KTM LC4 Adventure, etcetera.

After I got kids, motorcycling went on at a slower pace. I sold all the bikes and replaced them with a KTM 950 Adventure with an extra set of wheels equipped with knobby tires. That bike is simply amazing; I can ride it everywhere I want. Twisty roads chasing sports bikes, no problem. Muddy Dutch trails, no problem. Steep, slippery, rocky hills in France, can do. It takes 10 times as much energy as a lighter bike and in tight stuff I am slower than my friends on 450cc bikes, but I'll get there.

Last offroad riding trip to France I went down. A steep dowslope with lots of football-sized rocks and branches hanging over the trail. One of those branches got my handlebars, and down I went. Bike on top of me, foot rotated 180 degrees under the bike, unable to get out under it, had to wait for my friends to remove the bike. Not much physical damage done luckily; slightly sprained ankle only.

That day I was lucky to ride on a TTR600 from the local guy, and not on the 950.....


So, I went shopping for a lighter bike. Always wanted a 2-stroke just to see if I like them, and with old 4-strokes you always have problems with the head. Oil pumps wear, and the first part of the engine that suffers is the head. Been there, done that, multiple times. Makes that $1000 bike an expensive one.
Since I am mostly trail riding and not involved in any competition the KDX250 was my first choice, but these are rare in The Netherlands. Then I read about the Husqvarna WR360: 'A KDX on steroids'. Wide-range 6-speed gearbox, more bottom-end grunt. Sounds great.

So, after visiting a few sellers I got one:



Bike is a 1998 WR360 in fair condition that has 5500km on the odometer. Engine seems OK, but basically every bearing that comes in contact with water is shot. Like this:



Even the balls in the grease nipples have rotten away. I knew this when I bought the bike and used it to talk down the price.
So I am waiting for a LOT of bearings and seals to come in...

Also running in other small problems like this:



Already better:



Another small issue:



Fixed:



And so on. All parts seem to clean nicely and be quite undamaged or worn.



[/img]https://dl.dropboxusercontent.com/u/2762301/WR360/WR360_voorvorkschoon.jpg[/img]

I am not converting this bike into a beauty queen by the way, but unless you clean the parts well it is impossible to inspect them.


Now for the questions:

- I can find plenty of workshop manuals online, but not for the '97-'98 model. Most of the time this is not a problem, but it is for the 50mm conventional Marzocchi forks. I would need some service information for these forks. Things like air chamber length, basic setting of the rebound adjuster (and does it have a compression adjuster? Didn't find it yet unless it is under the bolt at the bottom of the forks). Also 'things to watch out for': I changed the oil, stroked the inner tube until no more air bubbles appeared, but now it seems to lack compression damping...

- The bike is not running well in the first 1/4 of the throttle range. It 'blubbers' and 4-strokes a lot, and I have to open the throttle a little to get it to start. I took the TM38 carburettor off, cleaned it (was not very dirty), assembled it making sure there were no air leaks, and did a few plug chops with fresh spark plugs gapped at 0,5mm.
2-strokes are fairly new to me, but it seems to be OK on tha main jet and needle.

Full throttle through all 6 gears:


At half throttle the plug is a bit darker, but not much.

I tried playing with the air screw, and it seems to run best at 2 1/4 turn out. When going further out the RPM's start to hang a bit before dropping back to idle, with the default 1 1/2 turn out the bike almost dies before coming back to idle. But also with 2 1/4 turn out I need to start without choke, throttle slightly opened, and it doesn't run well in the first 1/4 of the throttle.

I wonder what I shoudl do next?

Nice work & looks like you've been busy.

The forks look like marzocchi magnums, had the same on a 98 cr125.
Just google search for marzocchi magnum manual I'm sure it's out there.

If you get stuck I can always email it.

dont worry about what the plug looks like. looking at the plug can cause problems and is very inconsistent.
jet according to seat of the pants. good safe jetting is just lean enough to get rid of the four stroking. judging by all the work you have done to the bike, i assume the air filter is clean and properly oiled. this is key to jetting. make sure its not over oiled, i saturate them then squeeze out excess. also before starting jetwork, make sure the silencer has clean tight packing.
you need to verify what jets are in the carb, to see if any have been changed out. this will give to somewhere to start with tuning.
the needle jet could be worn in the carb, causing it to run a bit rich, or someone may have put in a larger pilot jet.

After visiting a few sellers? How many of those are there in Holland? How much did that cost? I want one.

Not quite finsihed yet, but I have the front together.
Second fork leg adjuster was far, far worse than the one pictured above. Totally stuck, mainly becuase the fork cap was machined badly to begin with. The hole in the 19,mm wrench part was offset to the inner thread, and the inner thread is slightly oval.

Managed to get it fixed somehow, although it still binds a little now and then and I lost the 'clicks'. Oh well, 1 turn is 6 clicks, I can memorize that.

I found Marzocchi Magnum user manual as scanned .jpg's. That one says that one fork leg contains the compression dampener and the other the rebound dampener. It might explain why I felt little compression dampening on the leg I serviced first.
The weird thing however, is that both of my fork caps are marked with 'R'?

If yours is different from this one, then yes please. My E-mail is dabit weird a sign icecoldcomputing point com.

Yes, once you are experienced that probably works. My experience with 2-strokes is from 10+ years back when I rode 50cc Honda MTX-50 mopeds and back then I hardly knew what the business end of a screwdriver was.
It runs fine with no hesitation or whatever, once you get past 1/4 throttle. Below 1/4 throttle is the only problem area, and according to the jetting tutorials I should look into the idle circuit.

But, if I turn out the airscrew more than 2 1/4 turn, the bike starts to show signs of lean running (hanging at a higher idle before returning to normal, riiinggg...ding.....ding...ding...).

Air filter is clean and oiled as it should. Didn't check the silencer packing though. Since everything on the bike is just the way it was when the bike left the factory, I suppose that the packing has never been serviced. Will look into that.

Ah, forgot to mention that. Sorry for that.

Carburettor: TM38
Main jet: 430
Clip position: 2nd from top
Pilot jet: 40
Airscrew: 2 1/4 turn out.

And as I said: I cleaned the carb with carbcleaner and compressed air, but it was already pretty clean. Normally I manage to remove a lot of brownish gunk from an old carb when cleaning, but strange enough not this one.

The emulsion tube (sorry for my English) looks undamaged with no wear marks and when I fitted a small rod inside there was no air gap present that would indicate ovalness. The same for the needle; it looks pristine by sight. But on the other hand: I replaced needles in the carbs of my KTM 950 that also looked fine, but with new needles gas mileage improved significantly..

I read a lot of bad things about the TM38 carburettor. Would it be wise to replace it with a PWK Air Striker instead of spending a fortune on parts and countless hours on the TM38? They cost around $320 here in The Netherlands. Quite a chunk of money, but jets and needles add up too.

Not that many; somehow I have a weakness for bikes that aren't available by the dozen.
I visited/test drove two and watched another one though a window and decided not to bother.

I paid EUR 1350 for mine. For the US guys that probably sounds expensive, but bikes and cars are expensive here due to the additional taxes.
Add ~300 euros to that for swingarm/steering head/linksystem/wheel bearings, thing here, repair there, and I have a nice play bike for not too much money.
Here is another one. That bike probably goes for 1000 euros or so, but it lacks all the lighting equipment, it also has bad linksystem bearings and the engine makes much more noise which may or may not be a problem.

If you find a nice bike in The Netherlands, I am willing to help.

as for the tm38, this carb also came standard on my 95 360. it ran well and started easily using jetting that was fairly close to book spec. after some time i ordered a lectron carb and fitted this, and was a major improvement in several areas. i would say the tm isnt causing your problems, but there is a gain to be had by switching to the airstriker or lectron. i LOVE the lectron, as its very simple and very easy to adjust, but also capable of very fine tuning and is mostly unaffected by weather and altitude.after setting up the lectron on my 360, i would have a hard time spending money on any other carb.
you say you dont know what youre doing when it comes to carbs, but it sounds like you do. if you want to watch the plug thats up to you. just be aware it can be a trap, as many bikes have dark plugs but are in fact jetted great for power and economy. in my opinion, it takes much more experience to "read" plugs. spark plugs last me all year, and only get changed perhaps once a year out of pity.

welcome to the site
i have had 4 360's and still have 2
great bikes
my 99 and 93 both came with what appears to be the same TM Mikuni and the 99 is junk
replaced it with a Lectron, works well

Another plug for the Lectron carb. Kelly, on these forums as Motosports, sells them set up and ready to go for a very reasonable price. I've put them on my '96 WXE360 and on my '87 WR430. I'm getting ~ 38 mpg while dual sporting the 360. Both carbs were easy to install and tune. Good luck with your project!

I am also convinced that the TM38 itself is not my problem, but either something in the carb or further downstream. The carb is a really, really simple one only a few channels
From another guy I received the tip to double-check the choke and see if it doesn't hang open a bit. Sounds plausible as as possible cause for this issue.

OK, clear.

I only dealt with Keihins, Mikunis and the occcasional Dell'orto. And so far I have not enough experience with Dell'orto to say meaningful things about them, I love Keihins and I hate Mikunis.
I never seem to be able to get them working equally well as their Keihin counterpart. In my 4-stroke experience a TM40 works fine but an FCR39 works much, much better and gets far better fuel mileage. A CVK40 is fairly nice carb while a BST-40 is a POS. The 43mm Keihin CV carbs on my 950 never ever let me down and handle summer, winter, sealevel and altitude well. Etcetera.

Did hear about the Lectrons but thought they were a bit obscure. Seems I have some reading to do about them.

Well, I am not new to wrenching on bikes, and I did tune carburettors on my 4st singles. I did that almost like you said: find a piece of straight abandoned road with no traffic, mount a small homebrew datalogger that captures RPM vs time, make a run in the throttle opening area of interest, tweak, compare graph and seat of pants, tweak, repeat.

I didn't use that technique with the new-to-me 2st, afraid to blow up the engine I guess. I got the 'read the plug' wisdom mainly from the various jetting tutorials available on the internet.

38mpg . That would be nice!
What would a PWK do under the same conditions?

I'll contact Kelly/Motorsportz to see how much these Lectron things cost and do some reading about them although I don't think the round-breasted chief of finances will let me spend the money now. ('So, your gonna buy another bike? Hmm. How much does it cost this time? OK, and how much are you going to spend when you have it?' 'Not much honey, really. Only a bit of maintenance').

Then there is still the forks.
- Were the fork caps meant to be labeled with 'C' and 'R' and is there something weird going on, or were they both labeled 'R' from the factory?
- Does anyone know an approximate default setting of the compression/rebound clickers? I cannot find much about it on the Internet and it is much faster to start from a known starting point and deviate from there than to start at zero.

i would not get too bogged down with mileage numbers, the selling point in my case due to riding in the mountains is that it altitude compensates

We don't have much elevation changes in The Netherlands (unfortunately). Riding offroad (actually more dual-sport) in The Netherlands is all about slippery grass, sand, mud, farming roads, (illegal) forest trails and the unavoidable stretches of asphalt to connect the trails.
Once or twice a year I get to ride at changing elevations, but that is still limited to say 600 meters/2000ft of change in a riding day. Bike will be prepared and receive maintenance before leaving on such a trip anyway so changing out a few jets is not a big deal. Same with temperature changes: if I have to rejet for winter and for summer, no big deal.
What I prefer not to do is open the carburetor to stick in other jets or change the needle position on a riding day itself. I hate opening up critical parts of the bike when there is sand and mud everywhere. IMHO that is by far the best way to wear down a good bike in a very short time.

Mileage is somewhat important because I need to be able to ride ca. 120kms/75mi before having to visit the gas station again. A little extra would be nice since riding on the last two liters / half a gallon of fuel is not very comfortable between the ears. Of course, plenty of solutions exist to carry more fuel, but none of them are zero-cost. And there is also fuel cost. A liter of gasoline and Motul 800 oil mixed at 1:40 costs $2.72 at the moment, which is $10.34/gallon for you US guys. And fuel prices are low at the moment; I don't expect them to stay that way.

I am more concerned with smiles per mile than fuel cost or having to carry some extra fuel now and then, but a significant improvement in mileage might pay for a more expensive carburetor pretty quickly....

My advice is to strip the current plastics off, packing to in a box and send to me in Australia and l'll send you back a set of 2K plastics

What needle is in the carb ? Husky had a propietary needle that would make the 360s run great but it was not the stock needle. You are correct about the fork caps one should be "c" and one should be "r".

I am not sure you want my plastics; these have seen, uhm, 'good use'

But are these plastic parts so hard to get then? No alternatives?
If so, it might be wise to pull a mold from them or probe them on my CNC mill before I shatter them completely so I can reproduce them in carbon/kevlar or glass when needed.

No idea, but since everything on that bike is still the way it was delivered 16 years ago except for tires and chain/sprockets I expect the needle to be OEM too.

Hmm, so something weird is going on. Once you start digging.....

What makes it especially weird is that the entire bike seems original and none of the previous owners seemed to have modified or serviced anything except air filter, gearbox oil, chain and tires. I replaced the oil in the forks when I had them out, and the old oil came out as a total stinking mess. Didn't look like it was replaced this century. And fork caps are not something that is easily damaged in a getoff to the point where one needs to replace it.

I should probably give the forks (and shock) full service instead of only replacing oil, but I prefer to send them out to the suspension tuner for that. That guy is worth every cent I have to pay him, but it still isn't cheap and the budget is not there yet. Plus I still need to ride a few hundred miles to find out if the valving and spring rates needs adjustment to my liking. First things first.

As far as I can tell the forks match the drawing in the parts manual pretty well, but is it possible that I do not have Marzocchi Magnums but another type that does not use compression adjustment in one leg and rebound in the other?

I just looked at the pics again and the forks on your bike are in fact magnums, but the cap in your pic is for the shivers. The magnum caps have blue adjuster knobs on the top, it looks like someone mixed parts on your forks.

What fuel octane rating are you running?
Also i jetted my tm all over the place and the thing still wouldnt run right sometimes i believe a carb can wear out.
I have jets and a complete tm38 if you want it just pm me i will send it over to you.

Pilot @40 seems a bit big for a low climate try a 30 as that may improve your 1/4 blubber.
I may even have one hanging about if your willing to wait for post.

20,25,35 yours if you want them
20 and 25 are spanking.

Absolutely!!! Those plastics are hard to find as those fluroish yellow/greenish front/rear guards, once started life as yellow. Those tank guards, the edges where the decals don't wrap over, become brittle over time expecially the rear sideplates which many rip the plastic mounting anchors off the plastic.

Mate, if you a CNC and can make a mold of those plastics and in turn produce new plastics that fit well, you may have a growing market in selling these plastics!!

All in all, they are a great bike, pull the chain adjuster bolts off and apply anti seize on them - drilled out a few seized husky adjusters PITA!!

I run a Keihin 38mm PWK, ditch the TM38 and either grab a PWK off a KTM or something similiar, there is plenty of info in cafehusky about these carbs as with the Lectron which is the top of the list in terms of carbs for any 2 stroke.

Front magnum marzocchi, pull off and keep them aside and find a set of 45mm Marzocchi Shivers(2t or 4t) and triple clamps, again a heap of info about these forks on the site..if you can find a set of KYB's from newer models even better. The rear shock is a sachs unit, again plenty of info on the site and pay attention to the top shock bearing as they can lock up/seize easily and snap off.

Aside from the airboot and engine, just about every part of the 360 is compatible with 250's, some 125's and some of the 4t's , from 1994 right up to 2004+.

Hmm, weird. It it is only the caps I don't care. But the millin-dollar question is still 'why would someone do that?'

Currently RON98, mainly because the 'premium' RON98 fuel is of higher quality and contains less ethanol than the RON95 fuel.
RON95 would be 91 in the US, so RON98 would translate to ca. 93 in the US I think.

I have only seen emulsion tubes becoming oval, needles wearing out, membranes becoming brittle, and floats becoming saturated. The body seems not to wear.
Have a look at the BMW 2-valve airhead people for example; they pop in new brass now and then and run their Bings for decades and several 100.000 miles.

But for the 2-stroke carbs: if you have to buy new brass, new needle, new emulsion tube, new whatever, you might as well buy a new carburetor.

Currenly I'm leaning toward the Lectron from Motosportz; so many votes for that carb.
However, importing one of those in The Netherlands is an expensive business. Would cost me over $600, which is quite a big chunk of money.
On the other hand, if it consumes less fuel and just works smoothly without constant fiddling I usually forget that it was an expensive thing pretty quickly.

I'll decide if I go Lectron/PWK or not first.
I do have a 35 pilot jet to try and the others are not terribly expensive either at the local dealer (~$9/pc). Might beat shipping cost to just buy them locally.

I am pretty sure that Acerbis/Polisport/UFO/whatever makes front/rear guards that fit or can easily be made to fit. Same for the headlight; plenty of choice. Sometimes I wonder what Husqvarna actually did to this bike, all I see is Cagiva and Acerbis marked on the parts

Side panels and tank guards are less universal.

[quite]Mate, if you a CNC and can make a mold of those plastics and in turn produce new plastics that fit well, you may have a growing market in selling these plastics!![/quote]

That entire CNC-mill business is another hobby that grew a bit out of hand. It originated from the fact that I hate searching the Internet for ours to find that one part I need and then facing delivery times, minimum order quantities, etcetera. All local hardware stores carry the same cheap Chinese sh*t nowadays, and they only carry stuff that many people need. If you are looking for an irregular size or model of something you are out of luck.
It started out with motorizing the cross slides of a drill press and ended with a fully functional 3-axis CNC mill capable of doing all materials including titanium, stainless steel, etc. designed and built from the ground up. Of course it has been used many times to whip up special motorcycle parts. Like this/this for example. I can also anodize small parts now. As I said, it's getting out of hand .

It it still hobby though and performed in my garage; I do not own or work for a business that does these things.

Currently I am developing a new 3D probe for the machine so the panels might be a nice test case to get these in CAD. Probing those panels takes hours and hours of continous probing, a good test to see if the design lives up to it's expectations.
Getting the panels in CAD would be needed anyway; my plastics are too damaged to pull a mold of them directly.

The easiest way to reproduce them in low quantities is to put a large chunk of plastic on the table and convert 98% of that chunk into chips. Won't make them very cheap unfortunately. I do not have to make a living out of this, but the raw material costs money and the machine consumes a lot of energy/endmills/coolant/etc and wears.
Milling a mold first and doing a hand-layup of carbon/kevlar (glass is a bit too sensitive to tearing; kevlar combined with a slightly flexible epoxy makes it almost unbreakable and carbon just adds bling and hides the ugly kevlar) is the other method. Very time consuming though, and that is why all carbon parts are so terribly expensive usually.

We'll see. Let's get the bike running and dirty and finish other ongoing projects first.

While I am waiting for the linksystem and rear wheel bearings to arrive I am dripping penetrating oil on them daily. So far no luck. Heat and violence are next..

I'll leave the shock in for a while until I am ready to perform full service on that. Not going to check that bearing either; sometimes not knowing is better
It is just a money and time issue; cannot do everything at once.

Same with the forks; one day I'll run against a nice set of forks for a nice price if I want other forks. But somehow I seem to prefer conventional forks; also ran a set of forks off a DR-Z400E on a SV650 to allroad conversion (154kg/340lbs with half a tank of fuel..) and really liked them. So if I can get those Magnums to work decently I might prefer that.


OK, yesterday I ran against another issue; the lock nut in the rear wheel that keeps the two 6004 bearings at the sprocket side in place seized. We are talking about this nut, part# 800064863:



I could only remove that nut by destroying it; years and years of water and debris welded the hub and nut together.
Tried to order a new one, but after checking the dealer told me that nut was not available anymore .

Two questions:
- What exactly is the benefit of this nut, except maybe for keeping the seal ring in place? I have never seen this locknut construction before and I do not see the benefits either. Bearings are held in place by the wheel axle and spacers anyway.
- Since Husqvarna seems to use standard industrial size parts wherever they can: is this nut a standard item?

If not I'll copy it, but at this moment I rather spend my time putting things back together since the weather is becoming beautifully bad