Jetting: - Not another jetting question!

[OldTimer]

Not another jetting question!

Yep, I just bought a Husky 360. It sputters after about 1/2 to 3/4 throttle and leaves TONS of unburned fuel on the plug and out the exhaust. I've repacked the silencer and calibrated the power valve, now I'm sure (well, almost) that it's time to start experimenting with smaller main jets. The bike has the stock Mikuni 430 main jet (TMX38 carb BTW).
My question is, how many sizes should I drop down for a starting point for a bike that's too rich to run properly?
And, if I get too lean, could even a short test run be enough to damage the engine?

 

[COLEMANAPP]

For my '02, it was suggested that I go with the 430 main, 35 pilot, 6aej164 w/needle clip in 4th position and air screw at 1.5 turns out. I had a 93 that never fouled plugs either. I can't remember how it was set but I'll email the current owner (good friend) and see what I had in that. It had an aftermarket pipe, silencer, ignition, and reeds though. All use the Mikuni TMX38.
Bob

 

[OldTimer]

Well, I tried a 410 main jet and now the only part of the insulator that's white is the base. The plug is already about four ranges hotter than called for and the plug is still wet.
Admittedly, test conditions weren't very good, but I let the bike warm up as much as possible and ran it down the road a couple of times. Still too much sputter to get a good loading for a "plug chop", but I gave it what I could get out of it.

 

[COLEMANAPP]

How's your spark?

 

[OldTimer]

I seriously doubt that there's a problem with ignition.
It's been sitting for at least a week in cold weather and it started on the first kick.
An article I read elsewhere said that most all bikes have too much spark advance.
I have considered turning it back a degree or two but that would be shootin' in the dark and there's a perfect little circle on the ground electrode directly above, and the same shape as, the center electrode. Doesn't that indicate that the spark advance is in the right place? At least that's what I gleened from the acticle. If I can find where I read it I'll post it here.
hmm, lemme go check the post script.....

 

[OldTimer]

Ah, here it is...
I don't know how to post a hyperlinq so you may have to cut/paste.
http://www.strappe.com/plugs.html
the phots don't show the detail intended, so just close your eyes and pretend.

 

[DanAKAL]

OldTimer,

I'm coming in a little late here and don't really know what you have done up to this point. However, I'll try to throw in something useful here. Or at least my .02 anyway. Were this my bike I think that I would do a compression test or leak down test first. Just to see if anything is getting by the piston. I'm not familiar with your Husky but this is a 2 stroke, right? Anyway, assuming it is then a compression or leak down test could tell you a lot about why you are very rich on the high end. I don't know what your compression should be but hopefully someone here knows. If compression is satisfactory I would next look at the carb. Have a look here at http://www.mandolyn.com/RSG/jetting.htm There is some good info about tuning your carb regardless what kind it is. Be sure to folow the links at the bottom of the page. I would probably put the needle in the mid position and then start working with the jets. You may have already done some or all of this but this is where I would start. Hope some of this helps.

Dan

 

[pcahbrown]

chuck the mikuni

Hi I have just spent the last 6 weeks trying to solve the same problem .
mine was a little more sever but the same problem. throw away the mikuni and kit a PWK Keihin . dont pass go dont collect $200 just do it . my tmx mikuni looked fine float hight OK jets OK but somewhere inside it it had cracked and allowed excessive fuel past the piolet jet. Read my Thread
WR 360 blows smoke fouls plugs
Good luck Paul

 

[OldTimer]

Paul,
How's that Keihin fit? The Mikuni's float bowl rubs against the crank case in my '96 360 (I guess it's stock). If the Keihin was even a little longer it would never fit in there, but if it were a little shorter then I'd rather have it in there for that reason alone.
Seems like I looked at the dimensions for Keihin and the over height was bigger than the Mikuni.

Also, as in the original post, would jetting a little too lean wreck the top end in short order? (how short?)

 

[Vince Stokes]

If your running 4 grades hoter plug than standard,if I read right,and you do the carb swop I would
definatly go to a stock plug.One grade is not much 4 is a lot.

 

[pcahbrown]

keihin fits fine

Hi
the keihin is about 5mm shorter in the float bowl. so it misses the casing by about 4 mm. my Mikuni rubed on the casing too. the only real diff is that the keihin is 10 mm longer and the airbox side boot needs a little nic out of it as it slides all the way up to the slider housing and float bowl. i have found a good jetting combo. 42 piolet and 170 main. also do as Vince said and go back to the B8EGV plug ( NGK ) good luck Paul

 

[COLEMANAPP]

I tried to attach the photo. Pcah's plan with the airboot sounds easier but I had the float bowl modified to fit. Cut a section out of the float bowl on front left corner and reweld a flat section in there. PM your email and I'll send you a photo. Fit fine after that.

 

[OldTimer]

Thanks guys,
I went ahead and lowered the needle to the last notch yesterday and it seems to have done the trick!
75 degree temps and dry air may have helped also.
I have yet to take a look at the plug, but I anticipate going colder. I'll prob. stick with the Mikuni til it gives just one cough, then I'll leave it on the doorstep of the Honda shop where it belongs!

Here's one more thingy though:
When I got the bike it had that 80 weight tranny oil Honda sells for 2 stroke engines. I drained it and put in some... I think it's Mobile? synthetic 20w50. Anyhow, when I first crank the bike the clutch plates are stuck together and I have to get a rolling start to get into first gear. As the crankcase warms up the clutch frees up.
I'd rather have sticky plates than slippy ones, but do you guys think I'm heading for trouble if I don't do something else with the lubrication? Maybe I should just wash it out real good to avoid having a mixture of synthetic with the residuals of the 80 weight?(washing might be a nightmare in itself)

 

[COLEMANAPP]

I've had same problems with the plates sticking on my 87, 88 and 93 husky. I used the 93 a lot more and the more I changed the oil, the less sticking. The other bikes don't get ridden much and seem to always stick initially. It should go away as you ride the bike more and change the oil. Maybe it just sat for a long time til you got it. I wouldn't think your choice in oils would have as much to do with it as how clean your oil is. Sounds like your getting your jetting close. I've gone back and forth with the Keihin and Mikuni carb but eventually settled on the Mikuni, it was tamer.
Bob

 

[pcahbrown]

gearbox oil

Hi use 100% fully synthetic 2 stroke trans oil and i have to give the clutch lever at least 10 good pulls after i start my bike cold before i can go into gear. and my 93 360 did the same thing . it is just a husky thing ,once you have moved 20 metres or so the clutch is fine.
if you don't know what oil to use just buy mobil 1 it contains no teflon so wont coat the clutch plates.
Cheer go luck
Paul

 

[maddmack]

just drop one size then go from there jets are cheap