idle trouble, smoke and water

alright! my situation
valves are good
brand new air and fuel jets
broke the carbs completely down and cleaned the sh*t out of them.
diaphragms are all good, no broken rings, passed the clunk test
changed all the throttle seals and fuel rail o-rings, no leaks at all
fuel levels in the bowls are good, wet and dry tested.
bench synced them using 1/4 pieces of business cards
I'm using an auxiliary hanging fuel source instead of the tank

I just put the carbs back on the bike and at first the idle was superrrrr high, backed the idle screw down and got it to idle. a couple things:

1. when i pulled the throttle lever it would hang and come down super slow?

2. Something was dripping from the exhaust, is condensation normal? It definitely wasn't fuel or oil

3. I had to stop testing it because it was smoking out my garage. i never remember it smoking that much when it was running. What could cause this?
(im in jersey city so testing it outside would really p*ss off my neighbors!)

any help would be awesome!

 

1. Possible vacuum leak or fuel/air ratio is off. Make sure your throttle cable isnt sticking.

2. When fuel is combusted 100% it forms H2O and CO2. Carbon monoxide and greenhouse gases only come from incomplete combustion.

3. Is the smoke black or white? Black smoke means its fuel from running rich, white(can be blueish) smoke means its oil being burned

 

Incomplete combustion is the norm in real-world conditions. There is no method by which complete combustion of gasoline can occur in an internal combustion engine. So....

Dripping water from a cold exhaust is normal, but should disappear once the engine is up to temp.

Don't run the engine in a confined space unless you can vent the exhaust completely.

A hanging idle can be symptomatic of an overly rich condition, which jibes with the extra emissions that you're seeing.

 

the dude doesn't abide!

the smoke is white. it comes out for a little after the bike is off too. Thought it could be steam from the water, guessing thats not the case?

 

Let's back up a step. Which model XJ do you have?

 

followed all the steps to put my bike in my signature but it still hasn't shown up, sorry...

its an 86 xj700. i have carbs from an 85 xj700 on it. i got all the stuff from chacal to convert them

 

have you done a color tune on it? are the enrichment valves closing completely? I concur with the rich mixture diagnosis. did you check the float levels after installing them?

CN

 

I have an 85 xj700 and it does the same thing until it is warmed up as far as the smoke and water dripping (condensation in hollow mufflers). Your hanging idle could be a result of not being vacuum synced yet (I know mine was). Just some ideas

 

haven't done a color tune yet
there no cables on it right now so the enrichment valves are completely closed
i checked the levels and they're all good

when you say "oil is being burned" how and why would it be getting into the cylinder?

 

Burning oil could either be piston rings, valve guides & seals, etc. Chances are if your engine still has GREAT compression & still screams long, then it could be valve guides.

Not super familiar with XJ engines, but that's usually what causes it.

 

Or (less likely) a failed head gasket can also cause oil burning. I think we need to go back to basics on this, when you say "valves are good" have you personally checked & set them? what numbers do you have for them?

I notice you said you have no cables, does the engine start right up from cold or do you need to prop the enrichment open a touch? When the engine is warm, how does it respond to slowly cracking the enrichment open a tiny amount?

Providing the clearances are correct for your 700 model, warm the engine up for 5mins or so (with the garage doors open) then pull all the plugs out, disconnect the TCI box & hold the throttle wide open to do a dry compression test to start with & then a "wet" test (no more than 1-2 TEAspoons of light engine oil in each cylinder.) Come back with the figures & we'll have a better idea...

Also, if possible a video of the smoke and to show the exact rev symptoms might be useful.

 

If the engine was not smoking before the carb rebuild, then I would water condensation or cleaning residue left in the carbs. My initial high idle was caused by a bad cable hook-up, and another time by a high idle screw setting. It's interesting that you have an 86 XJ700 and put 85 carbs on, and I have an 85 XJ700 that had 86 carbs--which I have recently replaced with 85 carbs. Now I have a set of really clean 86 carbs as a spare.

 

You have to do more than bench sync them too like somebody said, you can build a monometer easy out of two bottles, some liquid (I use ATF, red is easy to see) and 3 or 4 feet of hose. Due to the design of these carbs, if one carburetor is pulling harder, its vacuum slide will open up causing the idle to hang.

I also concur with the compression checking. You might wanna piston ring soak on the motor depending on your results, sometimes it can free up dirty rings. Just pour an ounce of Marvel Mystery Oil or Seafoam into each cylinder and slowly turn the motor over by hand a couple times, then let it sit for a few hours. Repeat this a few times, but make sure not to dilute the oil in your crankcase too much.

Are you sure the rubber intake boots arent leaking?

 

these are the valves:

Ex. In.
1. .17 .14
2. .19 .12
3. .20 .14
4. .19. .14

the engine starts right up with no cables from a cold start. which it never did before.
im gonna take it out saturday and let it runs awhile and video the smoke so i can post it.

tabaka how much you want for those carbs?!

 

i will also run the compression test after its warmed up to see what i get.

thanks for sticking with this guys!

 

It sounds like it's running rich for some reason then, that needs to be addressed. Combined with the initial high idle (and now hanging/slow return), provided your wet-set/clunk test are definitely all good then I'd suggest the enrichment circuit is at fault somehow, if all the plungers are seated & not hung up on their "forks" at all then I'd want to go back into the carbs, ensure the plungers are seating fully & their tips/seats are not damaged.

By the way, while I'm thinking of the enrichment circuit did you check/clean out the jets that are hidden in the float bowls? Not likely here but they are commonly blocked & very hard to clean without damaging/enlarging them in the process)

Also, how many turns out (from lightly seated, never screw them down hard as the tips get damaged) are your pilot screws & did you fit new O-rings to them?

 

Hadn't planned to get rid of them because I have a spare 85 XJ700 engine. Might be willing to swap them for the 85 carbs. You mentioned that you got the parts to "convert" them to work on the 86 you have. Didn't know any converting was required.

 

ok, so i took the carbs back off and bench synced them again. also checked the fuel levels again, they were all at exactly 3mm. replaced the petcock vacuum hose from #2, turns out that thing was shot.
I had her running for 10 minutes and it was idling nice and it wasn't hanging after i pulled the throttle anymore, i was pretty excited about that!
Had to turn it off though because it was smoking like the dickens.
Shut her down and ran a compression test. tic unplugged, all the sparks out and held her wide open with a full battery. Results:
1: 62
2: 64
3: 60
4: 63

Then i tried with some oil
1: 90
2: 93
3: 92
4: 92

any ideas about the smoke? does smoke have anything to do with the compression?
the smoke is whitefish and smells like burning plastic/rubber/crap, if that makes sense.... Also i looked at the oil through the glass and it got pretty dark.

thanks guys

 

XjN,

Although low those numbers are too close to suggest bad rings. Remove the air box lid and filter air and re-do the compression test. Let us know.

Gary

 

ok, i won't be back to the bike until next teusday so ill definitely try that then.
when you say that the "numbers are too close to suggest bad rings" I'm assuming thats because its unlikely that all the rings would go at the same time?
just trying to soak up as much knowledge as possible, would love too return the favor one day! thanks for all the help