Smoky exhaust... Losing engine oil... Bad crank seals? 1996 KDX200

Rob84KDX200 · May 23, 2010

Here's a lil video clip. I took the bike out again today, had it idling for about 5-10 minutes.

http://www.dailymotion.com/video/xdeogs_1996-kdx200-at-idle_auto

However, I'm a lil concerned with the smoke.

Why am I concerned? Well, I had put in about 800ml of Castrol MTX gearbox oil. After the idle session today, I drained the engine oil. Wanting to refill with fresh oil. After a quick drain, I had measured only a touch under 700mls drained. "Where did that 100mls go?" - I'm wondering. Definitely not out through the crankcase vent tube. That's still as clean as a whistle, no oil exiting through there whatsoever.

I'm 'hoping' it's not due to bad crank seals. Would bad crank seals be evident at idle? In my case it doesn't seem to be. As you can see in the video, it is quite acceptable at idle. Very little smoke. It's only when opening up the throttle that the smoke is probably a bit too much.

What do you think? Your thoughts? Would the color of the smoke and/or sound of the engine indicate burning engine oil? Is it possible for the engine to retain 100mls of engine oil after draining? I had the bike on a lift stand when draining the oil, so it was vertical.

Or is it a simple case of leaning the main jet even more from where it's at now? (@ 155 - 152? - 150?) For those who've not been following - I'm running 155 main, 45 pilot, Boyesen Power Reeds, FMF exhaust/muffler, airbox lid/snorkel intact. Castrol TTS at 40:1 with 98 octane.

Many thanks in advance.

Sandman 2.0 · May 24, 2010

From my experience burning trans oil has a very distinct smell. Nothing like 2 stroke oil. KDX's tend to be a bit smokey partially due to rich factory jetting and if you had stock exhaust (Which you don't), the muffler tends to collect oil. Your jetting should be fine as that's what I'm running although my lid is cut. I'm not sure what Castrol MTX is or what weight it is. I run just regular 10W40 castrol in my trans. Usually a leaky seal will smoke more the more you open your throttle.

Rob84KDX200 · May 24, 2010

Castrol MTX is a 75W/80 gearbox oil. Yeah I noticed it gets more smoky the more the throttle is opened up. Have you seen the vid? My main concern is the loss in gearbox oil. And I'm unsure what the distinct smell is, comparing burnt gearbox oil to 2 stroke oil. I've not had that much exposure to dirt bike riding to know. Help!

julien_d · May 24, 2010

99% chance the crank seals are bad.

sr5bidder · May 24, 2010

julien_d said:
99% chance the crank seals are bad.

hey easy JD.... think

you can retain 100 ml of oil very easily when you drain from vertical, i always drain on the kick stand and when it slows down I tip the bike from side to side to get even more oil out..

....think.. FMF pipe,, airbox lid,, and snorkel... why not loose the airbox lid and snorkel give it a try and let us know..

I had a blaster (200cc 2T) that ran decent on the stock pipe and air box lid on and when i installed an fmf pipe and took her out it ran like crap/ smoked like hell and then I remembered I left the air box lid on ...once I took the lid off the smoke was lessened and 3rd gear wheelies where easy

.also try the clip in the second from top on the needle.

also just id'ling for 5- 10 minutes then trying to rev will give my kdx smoke every day, get out and wring the piss out of it to clear all that oil out ....mine will run like crap at first but I definatly know when she clears only takes 10-15 seconds.

excess oil builds in the cases while idleing

sr5bidder · May 24, 2010

high float level will cause that too.
my kx suffered a smokey break-in ...way more smokey that that video.

so in addition to loosing the airbox lid check your floats

julien_d · May 25, 2010

Points well taken, lol. I must have been half asleep......

You could very well end up around 42/152 on your jetting, depending on mods and the condition of the engine. Dropping the needle is a good step too, just see if that improves the situation.

Different oil might not be a bad choice either, some 2t oil will smoke much more than others. I have no experience with the Castrol, so I would not know what to expect with it.

I'll drop it to 75% chance? :nener:

sr5bidder · May 25, 2010

Castrol is pretty good cheap 2 t oil I used it for about 1 1/2 years on my kdx 40:1

I found lucas 2t oil at o'riely for 6.99 so I have been using it and it tends to smoke a bit less and spoog about 1/2 less and it gave the engine a zingy lighter feel. course at the time of oil change I also dropped the needle to pos 2 and Had basically a brand new engine due to sinking it in a mud hole

I'm not paying 14.99 for brands like Motul or honda hp1, matter fact I try to not buy any oils or fluids from bike shops the only thing I might be buying is some no-tiol filter oil

Dirtdame · May 26, 2010

I used Pennzoil Two Stroke oil for years at 40 to 1. It ran pretty clean and my engine parts lasted a long time. I also ran a couple different formulas of Silkolene at 32 to 1 and 40 to 1. I ran a few other brands of oil along the way through the years. I finally broke down and shelled out the $$$ for Motorex which I run at 60 to 1. The engine parts show minimal wear so I don't have to rebuild as often, almost no carbon buildup, the exhaust is very low on smokiness (and smells great). Been using it for five years and don't plan to switch. :cool:

julien_d · May 27, 2010

I'm on Amsoil Dominator.. Pretty fond of it. Top end looks good when I have it apart, and the bike runs well with minimal smoke and spooge. I would run Amsoil Interceptor, if it was available around here.

The reason I'm pressing on the crank seal issue.... The bike is a 96, right? There's a good chance that the bearings now have play in them and have worn the seals out. You can check for play in the LH main bearing by jiggling the flywheel around. If it moves up/down or side/side at all, then there is excessive play in the main bearing. When the bearings have play in them, the crank ends will move in an oblong pattern rather than spinning perfectly. This will cause the seals to break contact with the crank end, and a leak follows.

The LH is usually the first to go because of the weight of the flywheel, but once it goes, the RH must follow shortly due to the non linear motion of the crank caused by the LH having slack. At least check it out the best you can. It may or may not be your problem, but it's worth a proper look!

Rob84KDX200 · May 29, 2010

Another update... I've since removed the snorkel from the airbox lid. I decided to leave the airbox lid in place, unaltered. Re-adjusted the pilot air screw to 1 1/2 turns out. Everything else is the same as previous.

I had a peek inside the flywheel/stator cover for any signs of petrol/gas in that area. There was a 'very small' amount sitting in the bottom. And I also checked the flywheel, wiggled it left-right-up-down-in-out to check for main bearing play. No play whatsoever, which would be a good sign.

I re-filled the engine with 850ml (approx 1 quart) of fresh Castol MTX 75W/80 gearbox oil.

Started up the bike no problem, and re-adjusted the idle thumb screw. Brought it down slightly, reducing the idle speed. This was suggested by my local bike mechanic after he viewed my Dailymotion vid (posted via link in this thread).

So I took it for a quick 15 minute ride. Up and down my local park, going through the gears it pulled through quite nice. Very strong power delivery, no real flat spots. It did smoke a lil, I'd look behind me to see a thin haze of smoke. But nothing that would suggest that transmission oil is burning. I've no idea on what that would smell like compared to 2 stroke oil burning. And actually riding the bike has I think cleared up some of that excess smoke/oil.

I will keep an eye on the oil level. After a good solid 15 minutes riding time, it's still well above the level markers on the sight glass.

Now another question. I asked my mechanic about this very problem (ie. possible leaking crank seals), and he thinks that the crank seals can be replaced easily without splitting the cases. According to him, the KXs 'do' require case splitting, the KDXs 'do not' require case splitting. I've seen conflicting answers on this and other sites, as well as many a web search in between. What's the definitive answer on this? I'd hate to be spiltting cases just to be changing seals, if the main bearing is still good with no play.

Dirtdame · May 29, 2010

Haven't had to split the cases on my newer KDX, but my older one, 86 C1 has to have the cases split to replace the main seals, and all the older models prior to that one had to have the cases split as well. A quick look at the technical manual for my 2003 model shows that the seals go in from the crank assembly side, so it would appear that the later models need to have the cases split as well.

julien_d · May 29, 2010

You have to split the cases to replace the seals. Sorry. The seals are pressed in from the inside until they hit the stop that is cast into the case on the outside. I have thought that I could grind the cast stops off, and drill and tap a few holes for some removable seal stops, but haven't been brave enough to try it. You could conceivable do this without splitting the cases. Really not worth the effort though. It's a KDX. Split it once, replace ALL the bearings and seals and anything else that looks worn, and you'll likely never have to tear into it again as long as you own the bike.

You'll need to find out definitively if the seals are leaking before you worry about all that, obviously. Sounds like you might have gotten it sorted out. Keep in mind it is a 96, and it is a KDX, so it's probably lived through some pretty rough years.

I just re-watched your video. That bike is incredibly clean for a 96, very nice! Maybe you got lucky and it's been cared for in the past. That is a lot of white smoke. Can't tell for sure from the video if you have problems with the motor, or problems with the jetting.

sr5bidder · May 29, 2010

JD is right your mech. is mixed up the kx's seals can be replaced without a split the kdx's cannot,

my kx was smoking like a bitch after rebuild and I took it out to ride/tune today at a place with fire roads and 2 reack and once I really got it really warmed up and wrang it out I think I got the rings seated and no more heavy smoke!!... a few light heat cycles didn't do it in the n'hood..
LSS I got the bitch tuned pretty freakin good

why so stubburn about the lid man ???

Rob84KDX200 · May 30, 2010

I figured that removing only the snorkel would be a compromise, opening up the air intake a lil, but still keeping that dirt out of the airbox. Yeah it's definitely not smoking as much as it was in the original vid. I've a big ride coming up in two weeks, so I'll definitely keep some gearbox oil handy, and hopefully by then we'll know for sure if it's leaking crank seals. Am considering a leakdown test in the meantime. But from what I've been told and have read, it could be a lil diificult to determine proper readings. Due to the KIPS valve.

sr5bidder · May 30, 2010

you wil still get dirt in your air box, you could get a set of panty hose and come up with a pre filter by pulling them over the top of the box

Dirtdame · May 30, 2010

Rob84KDX200 said:
Am considering a leakdown test in the meantime. But from what I've been told and have read, it could be a lil diificult to determine proper readings. Due to the KIPS valve.

A leakdown test is not going to be able to tell you if you have bad crank seals anyway. The leakdown is supposed to be performed with the motor set at TDC (on four strokes on compression stroke) It is a test best done to four stroke engines, because it can be performed dry or wet (A tablespoon of oil poured in through the sparkplug hole) to help determine if the top end is suffering from worn rings or damged valves.

Two stroke engines only need a compression tester to tell what is going on with the top end. You would have to seal off the intake and the exhaust completely and I am still not sure if anybody has a leakdown percentage spec value to go by anyway.

julien_d · May 30, 2010

Yep, it should be able to hold 6 -8psi for about 10 minutes without a noticeable drop in pressure. Leaking through the powervalve linkage is however a concern, but you should be able to seal it up temporarily.

Leak down tests are important for a 2 stroke, even more so than a 4t IMO. An air leak in a 2 stroke is bad news.

julien_d · Jun 2, 2010

Oh yeah,

With a leakdown test on a 2 stroke, you introduce pressure to the crankcase via the intake manifold. The pressure should equalize between the top and bottom end relatively quickly, but the components you're specifically testing are in the bottom end. This is nothing at all like a leak down test for a four stroke where you are trying to find leaky valves or head gasket. Totally different procedure. A two stroke top and bottom end is not sealed off from each other the way a 4 stroke is.

A two stroke utilizes the crankcase volume to pull intake charge through the intake manifold, and then force the charge into the combustion chamber. This is accomplished in the 4 stroke using valves in the combustion chamber. This is why the leakdown test is done in a different way and for a different reason for 2t vs 4t. Obviously, the results of a leak down test would provide no indication as to the condition of crank seals on the 4t, but for the 2t it certainly will.

Just felt it was important to elaborate, lol.

reepicheep · Jun 4, 2010

I'm running with the lid, and thinking seriously about putting the snorkel back in and doing a thorough jetting excercise to quiet things down and get better low end tunability. I think the "pull the airbox lid" mod is way over rated. The air still has to pass through the carb and the reed valve, both of which are much smaller then the top of the airbox, and probably both smaller then the area of the snorkel.

Putting a "great big hole" before a little hole doesn't help you. And if Kawasaki worked out the resonant frequencies to get the right reflections of the shock wave, making the hole bigger would make the bike run worse.

julien_d · Jun 4, 2010

reepicheep said:
I'm running with the lid, and thinking seriously about putting the snorkel back in and doing a thorough jetting excercise to quiet things down and get better low end tunability. I think the "pull the airbox lid" mod is way over rated. The air still has to pass through the carb and the reed valve, both of which are much smaller then the top of the airbox, and probably both smaller then the area of the snorkel.

Putting a "great big hole" before a little hole doesn't help you. And if Kawasaki worked out the resonant frequencies to get the right reflections of the shock wave, making the hole bigger would make the bike run worse.

Looks pretty good on paper, but still incorrect. Think about it a bit more.....

shockwave.... lol.

sr5bidder · Jun 6, 2010

dont ask me how but an after market exhuast will flow alot more air out and with the lid on runs like crap at least it did on my 2t 200 blaster stock pipe air box lid on runs good ...changed to fmf pipe wouldnt rev... took lid off pulled hard and clean, 3rd gear wheelies.

reepicheep · Jun 7, 2010

I had that same experience... But swapping the pipe throws the jetting way off. So did it run like crap because the airbox was a restriction, or because the jetting was off?

So clearly, if you use "Internet wisdom" for jetting, pull the snorkel, and do the normal Boyesen / FMF expansion / FMF silencer path, you will have a decent running bike.

But if you put on the aftermarket exhaust, then properly dialed in the jetting but with the snorkel in, I wonder what would happen then? I don't know, but I wonder, mainly because I am having a fussy time trying to dial in the jetting on my FMF / Eric Gorr 225 / setup. It's close, but not perfect, and in all my thrashing (no 4 gas analyzer, so my changes are basically groping around in a dark room) showed me just how dramatic a difference "jetted right" versus "jetted wrong" can make.

The fact that I recently drowned my Saab 9-3 in a flash flood may be a factor as well. I have a newly found respect for water versus motors. ;)

sr5bidder · Jun 7, 2010

used to be I would jump right in a mud hole just to see if I could make it out...well not anymore after I sunk the kdx and had to rebuild...I'm not going to make a snorkle that sicks out past the handlebars...I steer clear of water and if its a river/creek crossing I will walk it first...hell I'm gonna get wet anyhow right??

Smoky exhaust... Losing engine oil... Bad crank seals? 1996 KDX200

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