Leaned the jetting, still rich/smokey. Other causes?

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RustyStuff
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Leaned the jetting, still rich/smokey. Other causes?

Post by RustyStuff »

OK I started doing the jetting today. Did as the jetting guide suggested, adjusting the Air screw and going for rides with every change( riding my gravel road). Using 40:1 mix. Stock 1172 needle on the 3rd clip. I live at 1350ft, temp was about 60* this evening. It starts first kick every time. It pulls well from the bottom( you can putter around at low rpm, and it will just get up and go once you open the throttle), and there's a pretty pronounced Hit at high RPM. Aside from the smoke, spooge and plug fouling it seems to run well.

Engine internals are stock as far as I know, aside from the FMF Fatty pipe, Clean air filter/no lid. Boysen RAD Block, Procircut silencer.

Bike came with a 145 Main,48 Pilot. Runs fairly well, but it wouldn't Idle, lots of smoke and spooge.
Decided to try the stock jetting just to see-
150 Main, 48 Pilot. It was super rich, some bogging, didn't want to rev. All around worse than before.

45P, 150 M. Was actually able to get a rough Idle, still pig rich at idle.lots of smoke on acceleration, some bogging and hesitation when you open the throttle.
40P,145M. Idle is smooth, much less smoke( But still rich smelling with some smoke), rev's even better. Didn't get a chance to ride it because the bike ran outta gas. When this happened it ran away( sitting at idle). Now, this makes me think that it's still way too rich( lean condition made it rev), even with a the leanest jets I have.

By the end of this, there was spooge all over the fender/ swing arm. I just cleaned and repacked the silencer last weekend. I don't seem to be losing any gearbox oil. The spooge isn't slick-oily, but kinda thin, dark black and ferociously sticky.

Aside from the jet's just plain being too large, What else could cause it to be this rich? I have not taken the kips apart. I'm going to pull the pipe and wash it out when I have a chance, to eliminate the spooge reservoir. Also going to get a different Synthetic oil just to see it that's part of the problem.

I've never used/tuned a 2 stroke, so this is all pretty new.
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Re: Leaned the jetting, still rich/smokey. Other causes?

Post by Corey »

I had a similar problem with my son's CR85. Did what you did, leaned out the carb. It too didn't seem to be losing any gearbox oil. I even bought a new carb for it thinking that the original one was somehow worn out. It still smoked badly. So I took the side cover off and the appropriate components to gain access to the crank seal and upon inspection the seals lips were thrashed. Bingo, there's the problem. Installed a new seal and jetted it fat fearing that is was too lean where I had it and gradually leaned it out again after I got it running. No more smoke and it idled and ran great. Lesson: It doesn't take much gear oil to make an engine run like it did.
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Re: Leaned the jetting, still rich/smokey. Other causes?

Post by Julien D »

There is a small rubber gasket between the jet block and main carb body. This can be ruined if the carb is soaked/dipped in any chemical cleaner, and cause exactly the issues you are describing.
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RustyStuff
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Leaned the jetting, still rich/smokey. Other causes?

Post by RustyStuff »

I ordered the Jet block o-ring. may as well replace it.

Pulled the stator cover and I found some milky stinky oil. So I've got bad crank seals. :toimonster:

All this work and I've only gotten to ride this F&*#ing bike once. :evil:

Can the crank seals be replaced with the engine in frame, or do I have to throw more money at this and split the cases? I Are the expensive fancy tools required?
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Re: Leaned the jetting, still rich/smokey. Other causes?

Post by doctord23 »

You have to split the cases to change the crank seals.
There are fancy tools, but it can be done with a steering wheel puller.
Might as well change the crank bearings as well.
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Re: Leaned the jetting, still rich/smokey. Other causes?

Post by ohgood »

RustyStuff wrote:I ordered the Jet block o-ring. may as well replace it.

Pulled the stator cover and I found some milky stinky oil. So I've got bad crank seals. :toimonster:

All this work and I've only gotten to ride this F&*#ing bike once. :evil:

Can the crank seals be replaced with the engine in frame, or do I have to throw more money at this and split the cases? I Are the expensive fancy tools required?
Clean out the stator cover and make sure it's bad seals. The stator wires can allow water/oil/fudge into the stator cover, along with chain lube.
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Re: Leaned the jetting, still rich/smokey. Other causes?

Post by Tedh98 »

How old is the bike?
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Re: Leaned the jetting, still rich/smokey. Other causes?

Post by RustyStuff »

Tedh98 wrote:How old is the bike?
It's a '90.

I guess 20 some odd years is a good run.

There is no internal engine difference among the different year E series right? If i order bearings for a 91 or a 92 it should fit? Weird but Rocky Mountain MC or Bike bandit only lists bearing kits back to 1991.
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Re: Leaned the jetting, still rich/smokey. Other causes?

Post by Tedh98 »

With the bike being that old, I would replace all the bearings inside the cases. I know it is more money now, but it won't be any fun having a tranny bearing go bad a year from now and you have to split the cases again.

Replace everything now and you'll be good to go for another 25 years.
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Re: Leaned the jetting, still rich/smokey. Other causes?

Post by RustyStuff »

Tedh98 wrote:With the bike being that old, I would replace all the bearings inside the cases. I know it is more money now, but it won't be any fun having a tranny bearing go bad a year from now and you have to split the cases again.

Replace everything now and you'll be good to go for another 25 years.

That's what I'm planning, as the Complete engine gasket kit is $75, so I really don't want to open it up multiple times.

This may snowball out of control. I keep thinking " While I have it apart, I should replace this, and that and those"....
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Re: Leaned the jetting, still rich/smokey. Other causes?

Post by Dekon »

I just went through the same thing with my '89. Crank seals were bad. I wound up splitting the cases, having the crank rebuilt, all new bearings throughout the motor. That led to getting a new cylinder and piston. So, yeah, your right, it snowballs out of control easily. But hopeful, I will not have to split the cases for another 26 years. Oh, and if the steel KIPS valves were available when I did it, I would have sprung for those too.
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Re: Leaned the jetting, still rich/smokey. Other causes?

Post by RustyStuff »

I'm really hoping the crank, bore and Kips are all fine. Otherwise this bike will cost more in engine parts, than I paid for it.
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Re: Leaned the jetting, still rich/smokey. Other causes?

Post by ohgood »

Tedh98 wrote:
Replace everything now and you'll be good to go for another 25 years.
i keep hearing this... then the next statement is "pull the head of every year and check the kips/piston/bore/etc" which kind of dilutes the earlier.
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Re: Leaned the jetting, still rich/smokey. Other causes?

Post by Tedh98 »

ohgood wrote:
Tedh98 wrote:
Replace everything now and you'll be good to go for another 25 years.
i keep hearing this... then the next statement is "pull the head of every year and check the kips/piston/bore/etc" which kind of dilutes the earlier.
You can't compare the top end to the bottom end. If splitting the cases was a quick job and easily accessible, then it would make sense to replace only the parts that have failed. But considering the time and expense involved each time you split them, I would want to do it as little as possible.

And unless you are riding mega hours each year, I'm not so sure you need to pull the head once a year on a KDX.
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