XJ starting problems solved but smokes

[tab1324]

I had some starting problems because of an oversized choke hole previously but have since solved that problem by installing new floatbowls tonight. Also intalled the EMGO pod filters.

I had also had issues with exhaust smoking. Now that I have this set up is it possible that exhaust smoking is due to my idle mixture settings. I did play with them a bit before removing the carbs the last time.

Smokes from both sides and the plugs look dark (but dry). 2 plugs are black except for the electrode and "gap wire" which are dark gray. The others are pretty well black.

Is this most likely related to fuel mixture?

My oil level is staying the same so I don't THINK it's oil....

Tom B.

[graybird78]

sure sounds like to much fuel. float levels ok.idle mixture screws all adjusted similiar. pod filters have been known to cause overly rich fuel mixture. do a search on pod filters should be some good threads on it.

[ratbyk]

Smoke

Blue smoke=oil.
Black smoke=excess fuel.
White smoke=water. If a liquid cooled motor.
Ken/Sooke

[tab1324]

understanding carbs

I don't have a real good understanding of how carbs work except that they meter fuel and air into the combustion chamber. The parts that throw me are what circuit of the carb is being used when?

In the XJ I'm assuming the only tool I have is to set the idle mixture properly. After that (at higher revs) the main and pilot jet do the work - right?

So, as I'm tryign to figure out what the smoking is, I've screwed the idle mix screws in so they're all about 2 1/4 turns out. At 3 1/2 turns it was smoking severely and the plugs were fouling badly. Now it smokes a little and it appears that it is white smoke, not blue and definately not black. I know - white smoke - water.. But it ain't liquid cooled... I'm friggin going nuts here..

I even had my wife come out in the garage and check the smoke color for me.... It's white. It smells rich and the plugs are sooty so it has to be gas right.. Even new oil would burn dark right? To exagerate the smoke I held a rag up to the exhaust so that the smoke was more concentrated. White..... Smelled rich....

I took a short ride to get on the throttle a bit and see what happened. It was boggy off of idle but then came alive as normal after about 1500 rpm in 1st gear. I usually idle around 1100.

Seems to idle smoothly, although when I blip the throttle and the revs come down, they dive below idle speed and then slowly come back up.

Man I just want to get this thing right... It's rideable, but I want reliable - not just rideable. Planning to take some long trips this summer.

Thanks for any suggestions....

Tom B.

[ratbyk]

smoke

If your float levels are correct then I would start turning the idle mixture screws down a 1/4 turn at a time on all carbs. Keep doing it until it revs freely without the bog.
Should plan on purchasing a colortune tool if you want to make the idle/low speed circuit perfect. Or find one you can borrow. Best to get the colortune owner to come over and demonstrate on your bike. Tee Hee
Also plan on purchasing the bank of 4 vacuum gages and/or borrow. This is to get the synchronization right on. Again get the tool owner to come over and demonstrate on your bike.
Ken/Sooke

[tab1324]

float levels and smoke

Ken,

Thanks for the comments on float height but could you elaborate a little? I'm not a technical guy just a wrencher.

Last year when I had "triple cleaned" the carbs I believe I set the floats at 25 mm (about 1") above the carb body (the recess the gasket sits in) This is from memory so I'm not completely positive on the measurement.. It's an 82 XJ with pods and stock exhaust - so I'm not sure what the measurement should be. I haven't rejetted yet - I wanted to make one change at a time... And so far it seems that it's still rich.

What affect does float height have on different rpm ranges or loadings? After my short ride tonight at 2 1/2 turns out on the mixture screws, I rechecked the plugs and they were a bit sooty but getting brown instead of black, so I think I'm moving in the right direction.

The other thing you mentioned is the synch job... I never did one except the old bread tie method last year. It ran pretty smooth all year last year, it only has been a problem since I started putzing around with things again this year. Could not starting with a synch job be throwing all the other adjustments way out of whack??

Thanks again!

Tom B.

[ratbyk]

Smoke

Getting brown instead of black is a GOOD thing.
25mm is right on for float height. I have found that different sets of carbs, different bikes, different riders may need to have the float height adjusted a little (just a little). Up or down dependent on plug read. Yours are still a little rich BUT!
Don't touch float heights yet. Simply try and turn down the idle mixture screws a 1/4 turn a t a time and road test. Keep going a 1/4 turn step at a time. The bog you are experiencing is likely due to a slightly over rich mixture. You are close, very close. Keep reading the plugs. You may find as you get even closer that 1 or 2 carbs are right on (the plugs) but others a still slightly rich. The ones right on-don't touch anymore.
You are getting very close. Keep your patience. Just little steps, road test, check plugs, adjust a bit more.
At this point I would think long and hard about going back into the carbs. I don't think it is necessary.
Ken/Sooke

[pggg]

Tab, if you're still getting sooty plugs above 1500 revs then tweaking the idle screws wont have any real effect and you'll need to attack the the intermediate circuit. (1500 - 4200revs approx). Carry a plugwrench and check the plugs on the roadside after a 7000 rev cruise. Empty roads are helpful! I'm picking the plugs will look clean. Do a 4000 rev cruise for a few miles then check again. If sooty again you'll know its a rich intermediate circuit. Maybe the slide needles are set one notch too rich? Dunno if your particular model has adjustable needles though. Rich float levels might also be the cause. Not all XS carbs have the same float level specs - my manual claims the later carbs have a 23mm setting. Also a compression test would be useful.

[tab1324]

latest in the saga

Ken - you were right.... I seem to be getting close. So, tonight I turned the mixture in another 1/4 turn and I seem to be getting less smoke although still a little bit. Took a look at plugs after a few minute idle and they were brownish gray - seems right. So I took her for a ride... When I get on the throttle in the low rpm range, say 1000-3500 it's a bit boggy but still pulls. But then after 3500 the power really comes in.

This is probably beyond the mixture screws I suspect but I don't know where to turn from here. Someone mentioned the intermediate circuit but does that seem rich or lean? To me the bog means rich. I usually cruise and shift in the 4000-5000 rpm range and it runs pretty sweet there. So after a 15 minute ride trying to keep the revs up I came to rest in my driveway and checked the plugs. Brownish gray on 1 & 2 and gray to light gray on 3 & 4. Will fatten up 3 & 4 tomorrow and try again. But I don't think this will solve the intermediate problem.

I don't believe the slides are adjustable in the XJ either. I know everyone says that rejetting is necessary with pods but I haven't rejetted and the symptoms seem to be saying rich instead of lean. I believe I have the stock jets in - don't recall. Does it sound like larger pilots might be in order or is this more of a float setting thing?

Haven't tried a long run at 7000 rpm yet - usually don't push it that hard.. cept when I feel like having a little fun. Myabe will try this tomorrow and report after road checking the plugs. If I knew how to post photos I'd take photos of the plugs at each phase for you guys to take a looksee.

Tom B.

[ratbyk]

Tom, XS's are meant to rev. Being a bit weak on power below 3000RPM is normal. This is not a V twin. There is not much torque below 3000. I aways down shift anytime my revs drop below 3000. I try and cruise in the 4000-5000 range. If speed limits/traffic interfier with those revs then drop a gear or two. Let the sucker rev a bit and run free. It will last longer reving freely at 4000 then lugging or laboring below 3000.
Ken/Sooke

[ratbyk]

Tom, thinking back the torque and HP curves cross at about 3700.
I would not be going for WOT below that. Crank it on a bit below 3700 but feed it in gently but steadily below 3700. After 3700 go to WOT. Grin a lot. Take it for a good run operating above 4000 the whole time. Then check your plugs.
Ken/Sooke

[TopCatGr58]

Hey Tom,

Ratbyk is right and I totally agree with the rpm range to run in. I'm amazed at how many people want to lug the XS11's engine at the 3K range.....ugh!!! I also ride at 3.5 to 4K and above, with no problem taking it to 7-8 when I want to get going quickly. I actually like 4th gear much better than 5th, and unlike many folks that think it needs a 6th gear, in 5th gear at 60+mph, I'm doing just over 4K which is like Ken said, right at the beginning of the best power/torque range of this engine. So.....let it run, and don't worry about a sluggish response in high gear below 4k!!

I'll bet in 1st gear once you get it rolling, if you let it slow to 2.5K rpm, and then crack the throttle to WOT, you won't experience any lag..... will probably be flying on the back wheel for a while!
T.C.

[tab1324]

to tweak or not to tweak....

Rode last night for little after making another small idle mixture adjustment. I haven't been able to get out and do a high rpm run and check the plugs but it's still a bit boggy in the lower rpm range. I agree, mostly I'm not running there but it should have pretty smooth transitions from low all the way to high right.

If I tweak at this point, what should be tweaked first? Float height? Jets? I'm still running the stock jets. I did roll it all the way up to about 7000 yesterday but ran out of road (this was in a 40 mph zone). It seemed to loose a little pull after about 5500-6000. Not a ton but it was noticable. No noticable change in engine noise though.

Tom B.

[ratbyk]

At this point can't suggest any or what until you have made a good run and done a plug check. At that point it should be obvious to you whether to leave it alone, richen up a bit, lean out a bit. Quit worrying about being a bit boggy (?) at low RPM. Get away from running at low RPM. Let the sucker rev. The only time to be below 3700 is as you decelerate to a stop.
Ken/Sooke

[Ken Talbot]

Aww, c'mon now, Ken, there is one other time to be below 3700. That's when you're still in first getting up enough revs to make it worthwhile going to second...