Smoking breather hose, won't idle.

[numbski]

Surprised no one is concerned about me spraying down the engine - no concern that water has gotten into the head somehow? With that sock filter, I started wondering if maybe that's what's going on here - that I'd saturated the sock filter with water, which in turn somehow got through the carb and into the head.

On the off chance I'm right about that, what could I do? Just tear it down and wipe it out?

[Rebel]

oil gets into the combustion chamber if there is a problem with the rings or the valves. Seems you have done the right thing with the rings having it honed. If a machine shop doesn't know how to hone they are not much of a machine shop, seems like a high price to pay for the job though.

So look for a top end problem, how many total miles on the head?

water goes away pretty fast after it is started backup. heat from the motor will dry it off.

in the old days though when cars had points in the ignition system, water could easily keep it from starting up. I'm not saying it is a good thing to spray water into the carb, or on a hot motor. A hot motor with cold water sprayed on it can crack something. And cold does not have to be very cold in relationship to the motor and how hot it gets.

[numbski]

1100 miles total on the head. Sounds like one way or another I need to pull the head off to inspect it fully.

[Rebel]

well make sure you've checked everything before taking the head off. Look for some kind of oil leak anyplace possible.

And to think about it, with just 100 miles on a new big bore kit, you might not have run it look enough to let the rings wear in properly, this might just stop on its own if that is the case.

[kliff]

Billowing smoke, after a high speed run, sounds like either a galled cylinder, or broken rings.

Ring end gap should have been .009" MINIMUM, otherwise, when the heat and expand, they can close the gap, and break themselves.

A machine shop honed the cylinder... what grit stones, what final piston to wall clearance, less than .002", possible over heat on new engine, cylinder gall

Over.005", already at the beginnings of a wear replacement.

Coarse hone, makes the cylinder wall work like a file on piston amd rings, wearing them on an exponential curve. Fish hone with nothing coarser than 320 on these, I prefer a 600, almost polished, but seating the rings is a biatch, and I won't recommend it.

[numbski]

I'm not going to know the answer to how it was honed, but it's looking pretty clear that I need to tear this down again, and I'm not going to do that without professional help. I know I can get it apart, but once I get it apart, other than saying "yup, it's broken", I won't be sure of how to proceed.

[Rebel]

Sorry that your are having such problems. If you find that it indeed is a broken ring or galled cylinder, you might just want to put the original 150cc piston and cylinder back on, other wise you are going to be replacing the big bore kit at most or rings at least.

[kliff]

I wish we weren't so far apart, I'd love to get into that engine to see just what is going on...

[Rebel]

We got to know somebody in St Louis that can help you out.

[numbski]

Well, there's Fenton Powersports/Midwest Pocket Bikes that's helping me right now. He had me pull my redneck-oil-catch (ie, diet pepsi can) and just leave the breather hose draining to the ground and try riding it for a while. His theory is that I had the hose down in the bottom of the can, breathing hot air into the pool of oil, and making smoke. Just a theory. The engine *is* loud though. He kept commenting on the knocking, like maybe the rings are bad.

Now, since I put a high-compression piston on it, I have a spare set of rings. If he's wrong and it starts smoking after I get a chance to ride it (it's been raining here), then the next step is to open it up and get a look at the inside. I'm not sure I know what a "galled cylinder" is. The cylinder is visibly burned or warped?


EDIT:
Nevermind, looked it up for myself.

Galling, according to ASTM standard G40 (2006), is: “a form of surface damage arising between sliding solids, distinguished by microscopic, usually localized, roughening and creation of protrusions (i.e., lumps) above the original surface”. In other words galling is material transfer from one metallic surface to another caused by movement and plastic deformation.

So in other words, bumps on the cylinder wall and piston because the engine got hot enough from friction to transfer material.

END EDIT

However - if all is well after this, it just means I need to pony up the $20 or so for a proper catch can with breather. That I can deal with. It's just that I'd been using the soda can for a good long while before the big bore, so I'm skeptical.

[numbski]

Oh, almost forgot!

I asked him to run a compression check while I was at his shop the other night - 210 psi! Again, no mechanic here, but if the rings were blowing by, wouldn't there be a loss of compression too?

[numbski]

I've been busy making one of these this evening:

www.srtforums.com/forums/f75/how-oil-catch-can-pcv-leak-stop-valve-418507/

Pics:

www.flickr.com/photos/numbski/archives/date-posted/2009/10/30/

Now the obvious question that I should have been asking when I was buying these pieces was - where did I expect the "out" line to go? I bought a check valve, elbow, and nipple - I didn't need any of them, did I? LOL



I'm not so bright sometimes. Most of the time, really. Seems as though for their application, they tie the other end back into the vacuum lines.

[Rebel]

That will make a great oil catcher, just remember to drain it every once in a while. The filter it has, now that looks like something that might get plugged by oil to me.

[kliff]

Oct 30, 2009 16:08:25 GMT -5 numbski said:

Oh, almost forgot!

I asked him to run a compression check while I was at his shop the other night - 210 psi! Again, no mechanic here, but if the rings were blowing by, wouldn't there be a loss of compression too?

Amazing....now I'm stumped. Yet the shop owner keeps mentioning a rattle in the engine too.

Then I must have mis-read too. I thought we had billowing smoke coming from the exhaust, but it's the breather... that sounds more like blow-by, on a set of rings that haven't seated in yet. Continue with the break in, just no more banzai passes for a while.

The compressed air, oil & water / air separator... interesting idea. Certainly thinking outside the box, definitely has merit.... think I'll run down to HF and buy a couple and experiment myself.

The shop owner being concerned about the rattle has me puzzled though. Before tearing into the engine, just check the valve clearance, maybe an adjuster loosenned up, and take a quick look, with magnifying glass for a broken spring....at this stage, and with what your saying....I'd suspect an internal spring....look close, those can be the hardest to spot.
Some cams, A-12 for example, are just plain noisey, due to the ramp angles. Some folks try to adjust it out, by decreasing the lash adjustment, but all they are doing is shooting themselves in the foot.... don't do that .004"in/.005"ex, works just fine.
dammit, i'd like to see, hear, and feel that engine.....just too limitted by keyboard input.

[numbski]

Well, I didn't get your message about "no more banzai runs" (oops). Put my new nifty oil catch on, took it on the interstate - got about 2 miles, and the oil catch was full and it was overflowing through the check valve and spraying where the other nipple was pointed - in this case, right at my muffler. Again, oops.

So I towed it in, and I swear we just had this conversation about the rings not being seated quite right. What has him worried right now is that at a normal idle, he pulled the breather off and just put his hand in front of it and was getting oil on his hand.

So he's tearing it down tonight. I left him an extra set of rings. He's also concerned that there might be a hairline crack in the cylinder wall - but he just wants to see inside before jumping to conclusions.