XR4 smoking...any ideas out there?

[MadLawnGnome]

I've got a 01 xr4 w/ maybe 100 miles on it. Yesterday it started smoking, but only when I let off the throttle. The valves are ticking just a tad bit, which I do know means they need adjustment. The only thing I have done mechanically is cleaned and re-oiled the air filter.....Did I use too much oil or could the auto-decomp need adjustment too? Any ideas would sure help me out, thanks in advance.

MLG

 

[Russ]

I'm inclined to say it's a ring problem but don't want to jump to any conclusions. Is it an oil type smoke? Does it smell that way, or does it smell rich in fuel and black in color? If the air filter is dripping, then yeah, there's too much oil on it. If you really want to rule it out...clean it and stick it back on without any oil...not to ride...just to fire it up and see what you have.

I don't know that you can make any adjustments to the auto decompression, but you CAN adjust the manual one. Make sure there is play at the lever mounted on the engine, not just the hand lever.

Usually, not always, valves tend to tighten as the valve wears into the head rather than loosen. Anyway, you're going to get SOME ticking even if the valves ARE adjusted properly. It's better to have them a hair loose than too tight.

Are you able to due a compression test? I believe Honda has to sets of readings for you bike...decompression effected and not effected. Then you can do the spoon in oil thing.

Well...you asked for ideas and these are mine! Hope you hear from some others too.

Russ

 

[Bliz]

Don't mess with it until you talk to the dealer. It should still be under warranty.

 

[Dr.billZ]

What did you do when you "oiled your filter". IF you didn't wring it out very well it could very well be from that.
I had an XR400 that smoke EVERYTIME it was first started, then after about 15 seconds it was fine. That is "normal" (valve guide seal leak ? ).
I'd re-clean and re-oil the filter and see if it still happens. If your bike smokes when it's warmed up, then there is a problem.

 

[TexKDX]

I'd be suspect of filter over-oiling too. Normally oil and fuel smoke smell and look differently. Oil more blue, fuel more black in color. Oil smells like a '70 panel van with worn rings and guides, fuel like an '83 panel van with a stuck choke.

I helped prep a new KDX the other day a bud brought over. The filter had NO oil at all! It's easy to over-oil and make the bike run rich.

It is also possible things have not seated in yet. When does it smoke? Startup? Running under load? Deceleration?

 

[Russ]

Come to think of it, my XR400 (96) smoked a bit too every once in a while. This was usually just on start up and then went away. I really DO hope it is the filter. I would want to know HOW MUCH SMOKE we are talking about here. I mean, does it fog out the garage? I'm really curious about this because my dealer told me that there has been a ring problem with some of the 2001 XR's, however, nobody on this site has heard of such a thing and neither has another Honda dealer I spoke with.

 

[MadLawnGnome]

Well, when I oiled the filter I used Maxima FFT and it was never sopping wet with oil. I put about 1/3 cup of FFT in a zip-lock with the filter and worked it in real good. When the filter was wrung out it never really oozed any oil out, but that Maxima FFT is some really stick SH!T.

The smoke is a bluish color, but it has a funny smell to it(not like burning motor oil, at least burning motor oil i have smelled). Again it only smokes when I let off the throttle, it whisps out a lil "stream" smoke and then it's gone, until the next time I get into it.......and then let off. It doesn't seen to matter if the bike is warmed up or cold, it just started doing it and when i noticed it the bike was already at normal operating temps.

The bike has about 2 more months of warranty left. So to be on the safe side i'll let them check it out.

MLG

 

[Mianjet2001]

I also have an 96 XR400 and mine also smokes when it's initially started. The reason is the pump has a check valve in it to prevent oil from running from the frame into the lower end and this check valve sometimes leaks. the oil has a tendancy to get sucked up into the combustion chamber and smokes when starting. To check this you should let the bike idle 30 seconds after it's warm, turn it off and check the oil level. The oil level should be correct. Let it sit a couple of days and without srarting it, check the oil level. If the oil level has dropped from the previous check then it's the check valve leaking. If this is the case there is nothing wrong with the valves or seals. Mine has done this for 3 years and I just live with it. I will fix it at about 50,000 miles. (maybe). Also this is very common with XR400"s. :D

 

[MadLawnGnome]

Well, it seems that the problem has cleared up. I went riding today and it didn't whisp a single dtrem of smoke.......I guess it was a tad bit too much filter oil.

Now I have a flat tire to deal with.....

MLG