Topic: 78' 550K blowing white smoke, yet plugs look normal?

[rsvp9146]

 OK, so here's what I've done

 Got the carbs sorted out, cleaned all the jets out, soaked overnight in solvent. Floats set, idle mixture screws set, bench synched

 Engine came with a rebuilt head, valves have been addressed

 cam chain/tensioner checked out ok as well as chain.

 Reassembled it as is, only took a couple hours, valves adjusted.

  I fired it up and it started up with choke on, and it blows white smoke. 1, 3, 4 cylinders heat up evenly, 2 is cold and stays cold. Cuts out on quick throttle, idle at 1900 RPM. Choke off is the same condition

 The smoke looks like oil smoke, not water vapor. Continues with added throttle, no. 2 no smoke.

 I shut it down and see oil dripping off the bottom overflow fitting of carb no. 2  I imagine this is not a good thing.

 I pull the plugs and they all look pretty normal? No indication of oil burning, they all look tan, except for no. 2 which has no oil on it and looks new.

 All four leads have spark, plugs are new NGK

 So I'm off to the store to buy a compression tester, but in all likelyhood, I'm looking at rings here, right?

[Gordon]

Others may disagree, but I'd sort the carbs out, first.  Pull the float bowl drain plug on #2 carb to make sure it's getting gas.  The float could just be stuck closed.  If it is getting fuel, then chances are the idle circuit is still clogged. 
Then move on to checking the top end.

[TwoTired]

Since you've just assembled the engine, I'd do the compression check.  #2 won't fire if it has a bent valve not closing the combustion chamber for compression.  Carburation is irrelevant, in that case.

Oil smoke usually has a bluish tint.

 I shut it down and see oil dripping off the bottom overflow fitting of carb no. 2  I imagine this is not a good thing.

Oil from a carburetor? 
It there is no oil on #2 plug, indicating the cylinder isn't oily, where does the carb get a source of oil to leak?

[rsvp9146]

compression results

no. 1.  95
no. 2.  120
no  3.  92
no. 4.  90

guess it's time for new rings, huh?

[rsvp9146]

I would assume it isnbt a bent valve if no.2 has 120psi, right?

[tbone]

Try a couple of squirts of motor oil down each plug hole and re-test compression.

#2 having 120 it surely isn't a ring problem causing a dead cylinder.

Make sure you have spark on all 4 wire caps. Could be as simple as a burnt out plug cap.
Once spark is ruled out go back to carburetion. No fuel = No Fire.

Always rule out the cheap stuff first before tearing it all apart.

[TwoTired]

I would run an engine with those numbers for while to see if it will improve with use, particularly if the engine has been sitting for a while.  I would speculate that since #2 hasn't been firing, oil has sealed up the rings for extra compression.  It may balance out with the others after running for a while.  And, the others may improve as the rings settle into the lands after the long sit being idle.

If you can positively verify that the spark plug is indeed sparking across the electrodes, then it is time to focus on the #2 carb as not providing what the cylinder needs to fire.

Also, the chamber compression area is very small.  Low numbers may have more to do with the chamber volume added by the test aparatus rather than problems with the cylinder.  What you want to have is numbers within 10% across the bank, with a hot engine and all cylinders functioning.

It is unlikely you have bent valves with compression numbers you posted.
Just to verify, compression test should be done with a hot engine, throttle wide open, and the choke wide open too.

Cheers,

[rsvp9146]

OK, about two tablespoons of oil were added to each cylinder..

no. 1. 155
no, 2. 170
no. 3. 179
no. 4. 172

All plugs are firing, all plug caps and wires are good.

My old 911 used to have the same problem if it hadnt run in months. It would take a while for the rings to reseat.

So likely, something in no.2 carb is still blocked as well?

[tbone]

OK, about two tablespoons of oil were added to each cylinder..

no. 1. 155
no, 2. 170
no. 3. 179
no. 4. 172

All plugs are firing, all plug caps and wires are good.

My old 911 used to have the same problem if it hadnt run in months. It would take a while for the rings to reseat.

So likely, something in no.2 carb is still blocked as well?

If you've got compression and spark (in time) then fuel is all that is left.
Shut off your petcock and pull the bowl on #2. If it's full of gas then look for
a clogged carb. (slow jet, passages, etc.) If it's empty then look for a stuck
 or maladjusted float, blocked fill passage, etc.

[rsvp9146]

OK,

 but if I added oil and the cylinder compression increased, doesnt that mean my rings are shot?

[crazypj]

OK,

 but if I added oil and the cylinder compression increased, doesnt that mean my rings are shot?

Usually.
 If its smoking without oiling plugs its usually exhaust valve guide seals, oil doesnt get ino combustion chamber but burns in exhaust pipe
( sorry, didn't read all of thread)
PJ

[rsvp9146]

Valve seals and guides are new

[Hondell]

I'm with Gordon. Sounds like the idle circuit. I don't know 550's but take out the jet and see if a small dia. wire will pass thru it.
Rick

[rsvp9146]

carbs are now off the bike and dissasembled.

My more pressing concern is the rings. Anyone have an opinion

[rsvp9146]

so what do I do?

 run the bike for a while to see if it improves or do the rings?

[Cvillechopper]

Given the change in compression with the oil added, yes your rings are worn, but not beyond use.  It's a matter of what you want to do with her.  Are you interested in an overhaul.  Rings can be replaced with the engine in the frame but not having run the bike yet, are you sure nothing else will start leaking in a month of running and have you pulling the engine out for a re-build? 
Personally, I'd get her running on all 4 then see where she stands.  Once you decide to go for the rings, I recommend getting an overbore kit for a 500 (to 555) and having your cylinders bored to match.  Very little bore so your sleeves don't weaken and it's only about $100 for the kit (at least for me it was). 

I shut it down and see oil dripping off the bottom overflow fitting of carb no. 2  I imagine this is not a good thing.

Do you mean the tube that extends below the frame or actually from the bottom of the carb?

Good luck.  You'll love this bike once she running.

[rsvp9146]

I have a 550, not a 500. I dont want to bore the cyls. I just want the damn thing to run right.

where do I buy rings?

[ieism]

Make sure it's running on 4 cyl. properly first, Rule out the carb on the no. 2 cylinder. Then see if it keeps spitting smoke when the bike it  warmed up properly (not warm, but real hot).
95% of the times I have a problem with my 550 it's the carbs. How many miles are on this bike?

White smoke can just be watervapour that burns off, especially if the bike has been standing still for a while.  And if no. 2 cylinder is barely running and getting hot it won't get a change to heat up enough. If the smoke is blue rather than white you're probably looking at a more complicated issue (burning oil).

[rsvp9146]

the smoke is not water vapor. That I am sure of.

no. 2 cyl has nothing but cold air coming out of it.

the bike smoked when it was warmed up.

[Cvillechopper]

I read that you have a 550.  Getting the overbore kit for a 500 puts the pistons only slightly bigger than the 550s giving you just a bit larger bore than stock.  You can go for just rings and do a search or look in the FAQ section to find vendors.  Just wanting the "damn thing to run right", as you so eliquently put it, has different meanings to different people.  And you should at least have the cylinders honed if you do replace the rings or they won't last very long.

Looking at your previous posts I notice that you don't seem to have done the searching that would have answered many of your questions.  Impatience will have you replacing many more parts than necessary in the long run.  There are so many good people on here that have posted expert information of everything you've asked so far.  Use the search and I am sure you will find these answers as well as more information that will help make you experience owning an older machine much more enjoyable.  

Also, I feel this must be said as you may not have intended it, but you last post came across very snide and made it obvious that you weren't paying attention while reading the post I put on here in an attempt to help you out.  If that wasn't your intent, maybe take a breathe before writing a reply when you're frustrated.  If your intent was to be rude and dismissive, please don't expect much help from people in the future.  We all want these machines to work correctly, but you can't expect that to happen without proper, informed care and a willingness to do the research.

Good luck and ride safe.

James

[rsvp9146]

Not my intention to be snide. sorry if it came off that way. I have also used the search feature extensively. I was up at 1am this morning blowing out the carbs with cleaner and passing a guitar string through the jets..

 How do i go about honing the cylinder? stone or grape hone? how many passes? Where do I buy rings?

[Hondell]

Get it running right first. You poured oil into the cylinders and that will be burning off. The bike isn't overfilled with oil is it?? Find out what's happening with the wierd carb/oil leak before you go digging into the engine.
Rick

[rsvp9146]

SO I should sort out the carb, run the bike til hot and re-check compression?

keep in mind that the initial numbers were taken on a hot engine.

[TwoTired]

Get it running on all four first.  Drive it a hundred miles.  Check the compression and decide then.

I don't recommend simply new rings.  Pistons wear, including the rings lands, cylinders wear, and honing them removes even more metal.  You will have to measure the cylinders to see how close to the wear limits you are, as well as the pistons.

The engine has 9:1 compression, and each cylinder displaces 136 CC. This means the combustion chamber volume is about 15.11 cc.  1 tablespoon of oil is 14.75 cc.  You said you put two tablespoons of oil in the chamber.  This is enough to hydrolock the piston in the cylinder and blow a head gasket. It is also highly changing the compression ratio of the engine effectively making the combustion chamber smaller.   Some of this may be mitigated by the volume of the compression test apparatus which is unknown.
So, I don't think your wet conpression test is really valid and not really a clear indication that you need a ring job.

Fix the carbs, get all the parts comfy working together again and then do another comp test with maybe a teaspoon of oil, max, added to each chamber.

Cheers,

[rsvp9146]

Get it running on all four first.  Drive it a hundred miles.  Check the compression and decide then.

I don't recommend simply new rings.  Pistons wear, including the rings lands, cylinders wear, and honing them removes even more metal.  You will have to measure the cylinders to see how close to the wear limits you are, as well as the pistons.

The engine has 9:1 compression, and each cylinder displaces 136 CC. This means the combustion chamber volume is about 15.11 cc.  1 tablespoon of oil is 14.75 cc.  You said you put two tablespoons of oil in the chamber.  This is enough to hydrolock the piston in the cylinder and blow a head gasket. It is also highly changing the compression ratio of the engine effectively making the combustion chamber smaller.   Some of this may be mitigated by the volume of the compression test apparatus which is unknown.
So, I don't think your wet conpression test is really valid and not really a clear indication that you need a ring job.

Fix the carbs, get all the parts comfy working together again and then do another comp test with maybe a teaspoon of oil, max, added to each chamber.

Cheers,

Thank you for your advice.

 Should I switch to a 20/50 mix to help seat the rings/help with smoking? Or is this too much for the oil pump/journals etc..?

It's been damn hot here in Portland as well.