250-500cc dramas with a 2000 wr360

Hey all,

been sucking up the awesome knowledge on this site for a while now, but have a conundrum of my own now.

background:

2000 model husky, ate its top and bottom end up in a big way about 5 years ago. a mate got hold of it knowing this and eventually sent the complete engine down to R&D husky here in australia 6 months ago. Engine got a full top, bottom and jug (went near on 2k, whoa!) and when it was returned ran "good" for about 2hrs total running time.. last ride, it started bogging down badly at mid-high throttle, then died with no sign of life.
we've since been right thru the electrical system and verified it all good (not the first stator ive needed to check), stripped and cleaned the carb. (not the first carb... you get the picture ), tried fresh fuel and made sure air filter is clean (as in, actually cleaned and re-oiled because it was a bit grimey)
these are its current settings, we ride @ ~200-500m ASL, temps from 15-35 deg C.

Stock TMX Carb

6AEJ3-64 needle, top clip
primary - 30
main - 390
keep in mind, these settings were quite ridable previously

now, when we start the bike it will idle ok for a while (~3-4 mins), then eventually foul the plug till it stops.. using the throttle to rev it up some makes the foul come sooner. air screw and idle speed dont seem to do anything. (weird...)
pulling the plug, cleaning it with carb cleaner, clearing out the cylinder then refitting allows the same thing to happen next start. we've got it running then jumped on for a fang, plugs fouls quickly due to throttle usage.

Im after some ideas from you all here, as this is running towards the boundaries of my troubleshooting skills..
gut full of premix oil?
leaking floats (doent leak out of overflow, no matter how long u leave it parked with fuel on?)?
leaking gearbox-side seal?
act of god?

help me please guys, i want to experiance the howl of a 360 on full song.. ive ridden this thing years ago, its a buzz (as im sure you guys know!) and im keen to sample it again

cheers!

Act of a vengeful god.

I'm thinking leaking wet side seal. Try to determine if it is gear box oil.
Try an Iridium spark plug (they are more resistant to fouling) to see if you can run it long enough to figure out where the problem is. You could also go to a hotter plug for the same purpose but be mindful of running it at full load as you don't want to hurt it only trying to determine where the problem is.

I've had wet side seals leak before (KTM not Husky) and the exhaust also has a distinct 4 stroke smell. More pronounced if you are not using castor as a pre-mix.

thanks for a quick reply, gem, will throw it in the hat for the next session.. tbh, its where im leaning too..
the plan for next session is to pull the carb and reeds, give it a good squirt of degreaser or carb cleaner into the crankcase, then remove plug and run it down the driveway (200m long and downhill) in gear to blow all the junk out. just incase it somehow has got a case full of oil. hot plug in, then fire it up and try to diagnose whats next.

as always, any suggestions welcome

check the stator wire near the fly wheel behind the cover, mine had same problem after i had dropped the bike and pushed the exhaust into the frame.
turned out this had pushed the wires further into the stator area and the fly wheel was chewing into them and shorting out.
would start up but died when revved or left idling for more than a few seconds.

Don't waste your money on iridium plug because all you will do is foul them and at $30 a pop...better off buying BR8ES which are $4 a pop and use these until you getting the issues sorted (l still use a BR8ES on my 360).

Leaking crankcase seal - drop the gearbox oil and if it's milky then the seal is stuffed but l'm betting you would've checked this already, yeah?? You can do a leakdown test by blocking the exhaust, get a leakdown tester from supercheap and with the stator cover off, spray soapy water over the seals etc and if it bubbles then you have an air leak - especially check the base gasket which should show signs if it is leaking but With newly rebuilt motor from R&D l would doubt the seal has gone bung but you can always check.

Now, the problem is, from you description, is all jetting, have a read of PVDUKE's post as he explains well the whole jetting circuit.

http://www.cafehusky.com/threads/jetting-your-two-stroke.13934/#post-127854

You can also check the 2 stroke jetting database for idea's but l would get my head around what the carb is doing because , atm your bike is running too rich in the pilot circuit.

Also, l would recommend not wasting time with the TMX and order a new Keihin PWK 38mm Airstriker from the states (can get full Keihin, jetted and needles from JDJetting for $250 landed), as the PWK transforms the 360 somewhat as well as being a carb that isn't so sensitive to change in air pressure and temperature.

As l said, read PVDUKE's post and start to understand jetting and the carb circuit as someone's setting for one 360 will be slightly different to another.

Good luck and where abouts in Aust are you from?

as stated by others, use the non-wire non-race plug.

ya mightta over-oiled the bottom end during rebuild...or the tap was left on or....i've had bikes come in with crankcases full of gasoline. takes lots of fresh plugs to clean it out. get the standard types for your model, not the fine wires.

and, as stated, the wet side seal may be leaking- especially suspect if it was running fine prior to rebuild and no one diddled with the carb. if it was done 6 mos ago then, ya might be outta luck shop-warranty wise, sorry. i've never done one on that model, not sure if you can pop the flywheel and do it w/o splitting the cases. if ya can it's an easy job, just dont scratch the seal bore. then yer buggered. i fixed a scratched seal bore with JB Weld once. it was a b***h! but i saved the dood $$$.

also- don't over-oil the filter. i did that once. pretty funny after i figured it out and was scratching my head for a while going WTH? i just rebuilt it, now it's fouling plugs?! ...oh. hmm. oops. hehe. duh.

if the plug's rusty from sitting overnight ya gotta blown HG. coolant burning smell is unmistakeable so...that's prob not it.
if yer yer airbox is SPOTLESS, yank the filter, or install a dry one, light it up w/ a fresh plug and see if it'll clean out on the stand, dont ride it. if it shuts down and the plug is cleanish but wet/slippery you have a leaking wet side cank seal-usually accompanied by white smoke.
if it is wet and clean/inked and stinks like fuel ya left the tap on and the crank is fulla fuel- yank the pipe and invert the machine with the plug out and piston at BDC. hang the pipe stinger down so it drains. wait a day or two then refire, gently. do not rev the beans outa it or you'll hydrolock it. *bang* bent rod. yer done. stroking the kick lever gently can get some of the liquid out faster. i've had to pull the jug on some that were flat full of fluid and would not come around.

check yer plug cap/wire too while yer at it. don't usually foul plugs, but, since yer there. elec issues cause stalls, not fouling in 99% of cases. electrical stuff usualy either works or it dont.

LoL...l stumbled on this too..over sprayed the filter to the point it was leaking out the airboot (which identified a hole) and then spent 2 frustrating days fouling plugs, come the 3rd day and cleaned with and lightly sprayed, i haven't fouled a plug in 3 mths