85 xj700 white smoke out tail pipes. Accelerating rough.

Started running rough about 3 to 4000 rpms and takes a while to get up to speed. Rev it while in neutral and it puffs white smoke. Any ideas?

 

Sounds like it could be the head gasket starting to go. White smoke is usually burning oil. Check the plugs for oil fouling.

 

White smoke is never burning oil. Burning oil is blue (or black if you're burning a lot). White smoke is usually water vapor, water-contaminated fuel, or (rarely) a fuel mixture issue.


OP, we need more background info. Do you already have a thread for this bike?

 

You need to take another look at the smoke and or give it a sniff test. As K-moe said above, oil will only burn in a light blue to black smoke and you can tell it is oil by the smell. If it is water that some how got into the gas or other area, that would be white smoke. If you had a lot of water in the exhaust that too once it got hot would burn white and have no smell to it. Your bike is a air head so need to find out how much of this white smoke you have. Is it constant when if first starts and then gets lighter or is is always there.ect...

Let us know.

 

Right on guys. Thanks for all your input. I really appreciate it. I ve think in about it it I've put premium gas in it recently from a local gas station that doesn't get a lot of business and I'm going to try draining the bowls since I just hit the low fuel light and fill in her up to see what happens. My bet is that there was water in the tanks at the station. So I'm going to try that before anything. And. I know I left a really broad description and I like the fact that you guus told me more info would be needed. I ohmed out the coils and I have 3.2 ohms. I know that a lil abouve spec but I'm hoping the suspected bad gas fixes it. And I also have the carbs drilled out to 120. So there's that too. I'll get back to ya guys.

 

Why?

 

pods or velocity stacks in his avatar

 

Yeah, because of the pods and it gives much more power on the top end and throughout the rpm band. I was surprised to find out that this bike is just as quick my buddies Harley Dyna LowRider 1446cc. And it shocked the Hell outta him too. But I'm gonna drain the bowls n see what happens.

 

is that the only change you made to the carbs? what brand pods do you have?

 

NOT! White is water or anti-freeze. The bike in your pic is not a maximX.

 

Hate to break it to you, but with the airbox in place, and the stock jets, your bike is quicker than your buddies HD.

 

Correction--

Because of the pods you THINK it has more power on the top end because you're sucking in so much air that you get a teeny bit more boost at the expense of your engine running really lean-- just waiting to burn up. You'd be surprised to find out that you are actually just as SLOW as you're buddy's Harley right now.

With the correct airbox and correct jets, correct clearances, and correctly synced, you''ll leave him in the dust wondering where the heck you went.

 

J,
The above comments are from years of experience and trying all kinds of combinations on the XJ's. I hope you understand that they are Moderators and have thousands of posts on the forum, not just some lackey like me

Please take their advice for the longevity of your bike and you will really feel a difference. Bottom line, it is your bike and you can do what you want with it. Best of luck.

 

Right on guys. I really appreciate all of the extensive knowledge you guys have about these bikes and your advice.
When I picked the bike up it didn't have the airbox or filters at all for that matter. It was a project that someone gave up on. And to purchase the stock air box seemed like a little bit too much money than what I was willing to toss at it. The carbs were completely gunked up and the bike didn't run in over a year so the most economical choices was to get the pod filters. They are AMOX brand filters.
But to my dismay I now realize what the Hell the white smoke was. I was running low on gas and talkin about this with my buddy. He decided to toss a bottle of fuel cleaner in there hoping it would help but in turn it didn't help. It just made my bike smoke white clouds out the pipes. So anyways I drained the bowls and filled her up with gas from a reliable gas station. Still didn't make any sort of running quality difference. I put new coils on her too, seeing how they ohmed out above spec. And still no difference. Pulled the plugs and 1 and 2 look great but 3 is getting soaked in gas and slightly as well on 4. Changed out the plugs because I had another set as backups. And still no difference. Still getting wet on 3 and slightly on 4. To me it seems like the next step would be is to yank the valve cover n start checkin things out. Would you guys agree?

 

Carbs need to be refurbished.
IN THE CHURCH OF CLEAN
I know that you had the rack apart to change the fuel tansfer tube o-rings, and changed jets, but did you do all of the rest of the work?

Then do all of the other things.
The Information Overload Hour

And get an airbox.

 

was it seafoam carb cleaner and was it a full bottle

 

No it was about a half bottle of some chevron fuel system cleaner. But I see why you would think it was seafoam.
I ripped the carbs out tonight and checked the #3 carb out. Bottom end checked out ok but I was kinda shocked to find the needle was actually floating around all Willy nilly inside the plunger.
Basically the plastic cap screw that holds the spring against the needle completely loosened up. So I was just dumping way too much gas into that cylinder. So I put that lil bastard back into position and hooked everything back up and bingo. Problem solved. Bike is running amazing again.
And I found carb sizing recommendations for having pod filters and no mufflers according to chacals sermon. And it turns out I'm almost spot on with the main jet sizing. But anyways, big thanks to k-Moe and chacal for heading me down the right road and making the necessary info available.

 

Did you go bigger with the idle jets? From what to what? I did 40 up to 43 and I have a similar setup on a 650.

 

I agree, pods will make it SOUND faster, but even correctly jetted, with a performance exhaust......you MIGHT gain 5BHP, if you are lucky, at certain revs??

 

Just chiming in, I bought my bike with pods n a header, I'm a mechanic, and it never feels like it runs lean, I never set it up so I don't know, but bottom line is if you have to run it richer,(you should have to theoretically) it's pulling more air fuel and it makes more power.
I'll agree my bike is an asshole below 3000 rpm cause it essentially lacks vacuum, but on it it has a power band from 6000- 9000 rpm that's pretty gnarly, I'd guess 0-120kph (73mph) out of second in like 4 - 5 seconds, I've never driven a stock one to compare the powerband, but I'm sure it's equivalent or faster if it's on the pipe and jetted.
Plus, I love the noise
P.S. Never met a Harley I can't beat yet

 

By the way your probably right 5-10 or so hp, and only in the top end. 10% generally.

 

I don't post often, and not trying to cause a debate or the like, but could not help but chime in here. My 80 xj650 maxim came to me 3 years ago with 4.7K miles and OEM intake and exhaust fitments. Very good overall condition. After I completed all the necessary safety /maintenance/repairs in the first year and a half (full church baptism on the carbs too) I started to think about increased performance. My bike would easily pull redline in 1-2 gear. in 3rd, acceleration started to flatten out about 7K but it would hit redline. 4th, same but redline could not be reached unless going downhill. 5th, 7000 rpm was about it with a roll on. So I took a long long look at that tiny stock intake snorkel, the 4 32mm openings on the carbs - I thought - the soda straw size opening in that snorkel just can't adequately feed those 4 carb bores at wide open throttle, if the slides were really going all the way up....and it is a BIG carb for 163.25 cc's, even at 9500 rpm.
I bought this bike to enhance what I could and enjoy the improvements! and all my changes can be reverted to stock configuration if I choose. Nearly a purest at heart I am.
My recipe now- Stock air box is open top, K&N air filter installed securely, Carbs are - Fuel - new stock size needle jet/jet needle assemblies, 42 pilot, 118 main, stock 205 pilot air jet, main air jet drilled out to 3/64". MAC 4 into 1 exhaust header with baffled collector. This combination took quite awhile to develop. Lots of on again off again with carbs, etc.
I have been riding this configuration for over a year, from quick country block rides <75 miles, to 400+ mile weekends. Gets 45+ mpg average, cranks easily cold (a little choke required in the winter none in summer) Redline is no problem through all gears, but 5th does take a little longer. And there is no question on my bike the difference in power between 6-9k+ rpms is pronounced over stock set up. Not abusing her here either, still on the original stock clutch. 23K on the clock now. I sure do love that carb/exhaust sound when I roll on in 5th from 4K until, well ...... until I have to slow down. There really is a lot of untapped potential in that little motor.