Yamaha XT 600 (start-up smoke) *video*
 

Hello. I have a Yamaha XT 600(DJ02) model. Recently i rebuild my engine:rebored, new valve seals, new ProX piston and rings,new .

In the morning,or after a few hours when i start-up i have for about 1minute a white/blue smoke and then after warm-up,disappear. Compression about 140+psi.

https://www.youtube.com/watch?v=Oa7wVmz0zMI

First i would check the plug and oil level, maybe overfill? New seals maybe damage on the valves or oil get past the rings when cold and seal up when hot. What exactly do you have on hot engine compression, 156 is the number you shuold have reach with all new.

Like I said on another thread, my 84 did just what your is doing and seemed to clear up when warm, however, on deceleration it would smoke and it consumed too much oil. Again 140 pounds compression on a new engine is very suspect. Was the cylinder honed to a good crosshatch pattern. This is very necessary to allow the rings to wear in, seat, break in, what ever you may call it.

Valve guide seals. Either new ones are the wrong spec? (some cheapo Chinese copy?) or installed incorrectly?

Could also be rings aren't yet fully seated or hone job not done well. New Piston and rings will take about 2000 miles to fully bed in and achieve max compression.
DO NOT use synthetic oil until fully broken in.

But semi-synthetic it's ok? (10w40)

in deceleration not smoke. no oil consumption,i mean not exaggerated (i have almoust 800 miles done,basically i'm in rode period)

Now i have 20w50 Cepsa,this week i will change with 10w40 Procycle. Some guys told me they have the same problem,it was bag choice of oil,after change it,everything was ok and the smoke disappear.

YES! Semi-Synthetic is fine for break in.

As mentioned earlier, make sure the bike isnt overfilled.

Oil level it's ok. Remains to change the oil these days with some 10w40 Semi-Synthetic.

most likely dirt in / bad check valve letting the cases fill with oil even after a few hours.
if anything else was suspect, there's no reason the engine would stop smoking after a while.

easy to check:
check your oil level after a long ride.
check again after an overnight, if level dropped considerably, then it's a bad check valve

Sidenote to the above... Oil expands when hot. I think in our bike with a good amount of oil, the difference could be 1-2dl in volume from very cold vs very hot. (I think i calculated the difference once, but cant recall the exact number)

Take notice of how much you drain :)

Smoke on startup but not when normal running is valve seals , oil seeps past and settles on the piston when it's sitting . I polish valve ends to keep from tearing new seals.

The rings are 95% fully seated within the first 15-20min running . I tested one new motor and it reach 90% of its final compression in 5min, then took another 10 minutes to get the rest . After the 30min mark it was done (208psi ). Never, ever, ever, use synthetic or semi synthetic(not as bad), they prevent seating .

JJ, what is your suggestions for breaking in a newly bored cylinder, new OEM piston and rings? I am a few days away from starting it.

I had noted it in another thread (and got bashed for itdoh) , just start it up letting it warm for a minute or 2 but be ready to ride it . take it through the first three gears no more than 2/3 throttle , hold for a bit then release the throttle and let the motor slow the bike down . Do that for the first 10-15 min ( reasonably high rpms, then use the motor to slow down). this forces the rings against the hatch marks in both acceleration and deccel). Change oil & filter . It's now mostly done but I don't run full rpms for 100 miles at least , always varying the throttle and will heat it up good for 10 min then shut down to cool till it's past the 1/2hr run time. No sustained high rpms for 250-500miles.(Change oil ?? or not , what ever a person wants here)

The one I tested throughout break-in for compression had been done in my garage using the rear brake for loading . Shutting down every couple minutes to check compression.

The above break in is pretty good but I would add that HEAT CYCLES are also very important in the first 200 miles of operation on a new motor or new parts.

Run bike as described above ... then park it 10 minutes, let cool.
Repeat, Repeat, Repeat ... you're done!

This is how both Honda and Suzuki have done it with 30 new press test bikes at
new model launch. A few heat cycles and straight onto the track where they spent the next two days at redline! :eek3: No problems.

What do you mean with "bad check valve" ?

Any info regarding the heat cycles? My bike never got hot after a rebore and new piston...At leats no heat was transferred to the oil to show an oil temperatre above normal...?

Oeh yeah, most new bikes are just about redlined on a dyno before they even leave the factory... So theres the ring seal and and heat cycle for ya :scooter:

Heat cycles just let new parts expand (heat) and contract (cool), allowing parts to scuff each other and speed break in due to expansion and contraction.

I figure if Suzuki, Honda and Triumph use this technique on new bikes then it should be OK for a new bike or newly rebuilt bike. I still follow break in procedures after doing heat cycles, like never running at steady RPM and never lugging the motor. I also like to snap off throttle and coast down. All this is good for a new engine, valve gear, rings, et al.

PS: you are right, OEM's do rev them to test them, check oil pressure. I've even heard they do this with ONLY assembly oil ... crankcase empty of oil.
But I didn't see this myself ... so can't verify. :scooter:

yo, lets not hijack this thread :)

study a bit your oil system from the manual. under the right side cover there is a check valve with a steel bal and spring that "should" prevent the tank draining oil to the motr when not working

open the right cover and youll see it

Aaa,and how i check if it's ok?

the ball should move freely, no dirt trapped between ball and seat, sealing o-ring might be squashed and old-change it . dismantle it all, good clean in solvent, remount with fresh o-ring, be careful not to let any sealant into the valve. the o-ring doesnt need sealant to seal ;)

but before you jump into this, do the very easy check i proposed you before the thread went into fresh-motor-run-in mode :)

Thank you!

I saw your video on a better screen now . It's your valves seals . The way it took a few seconds after starting to start smoking , got bad , then slowly tapered away , that's the seals . Rings would smoke right away , then get worse as it warms up and have some smoke the entire time it is running . Your's quits after a minute or so right?

Too much oil would simply smoke till the oil is gone or force it out somewhere and drip on the ground . The check valve has nothing to do with it other than making it harder to check oil , even then if the valve was shot the scavenge pump will keep the motor from filling and you check the oil level in the tank as soon as you shut it off rather than waiting a couple minutes.

JJ, seen the video too:) my bike smoked in similar fashion, fixed the check valve and problem was gone :clap: It could be seals like you are saying, but it MIGHT be the check valve too. checking the valve is so easy to do before tearing into the top end that it's really worth giving it a try before, don't you think? life taught me not to be so assertive about any on-line/remote diagnosis of engine problems, even with videos :)


dani, another super easy check you can do is drain the oil from the crankcase after an overnight stop and see measure how much drains down. tell us what you found :)

I'll bow out , all yours ><

BTW , why have him drain the oil when he can just check the tank level right after he just ran it , and then check it after sitting overnight and see how much of a difference ? Much less work ? , it'll have to be empty to cause it to possibly smoke ,though neither of mine did when the check valves were shot , but both took 3 days to drain the tank empty , unless he forgot to install the valve completely.

JJ, my bike did exactly what you described, after it was overfilled. It actually took a ride or two after overfilling it, before it startet to smoke.

As to the OP, the valve is around 10euro, so if you loose sleep over it, just change it. An easy way to check is to let the bike sit for a day or two, then loosen the oildrain-bolt in the frame. You actually dont need to take it completely out. If oil starts to seep, theres still oil in the frame, which means it isnt drained down into the engine, which again means the checkvalve is working. (or at least working to a point where all the frameoil, isnt drained into the motor in a day or two.)

If its bad, you should have a very hard time reading a correct oillevel when cold, but theese bikes seem like that even with the valve working.

Use a oilstick from a car, checking the pipe down to drain screw in frame.

tnxs JJ, actually that's exactly what i suggested in my very first reply :)

and agree with jens, they might as well drain oil slowly even with a good valve. i use both my supermoto and supermono XTs racers about once a month and I always have to drain the cases before a track session, ALL the oil usually drains down by then, it has become second nature by now.

OK! I will do that!

In manual says it's 1 l,it's that true?

At this point you might as well just drain everything out of the entire bike , take every bolt that holds oil (oil tank, frame bottom, motor drains everything, catch it all , measure it all . Tell us how much came out . Only way your issue can even begin to be resolved and be done with it.

I'll do that this week,now i'm not home. Thanks for everything!

crankcase oil: 800+ ml overnight

Is bad or not?

800ml is just about 1 quart , when I change my oils I get close to that , maybe a bit less out of all of mine . there is 1/2 to 2/3 quart in the engine anyways that the oil pump can't suck up . For it to smoke from too much oil you would have had to drain out the whole amount of oil in the bike, 1600-1800ml , IIRC on your model. It shows the check valve is leaking some, not very much though , and not your smoking issue , especially if it smokes like that after just sitting a few hours .

Now you can get into what needs to be fixed , unfortunately. You said there is no smoke once the motor is warmed up right ? Just on cold startup for a minute or 2 ?

agree with JJ, not that much to justify heavy smoking after a few hours.... it could be better of course... 800ml overnight, say 8 hours, means an empty oil tank after 2 days/48 hours, so worth fixing the valve in any case.

if you want to easily make sure thats its not an oil in the cases problem, drain the cases oil, close the plug and start the motor. if smoking problem remains, then as JJ said, problem is elsewhere.

Yes..now i have 1200miles done since the engine was rebuild. Maybe the rings are not yet break in?

The rings were done breaking in long ago.

Hei guys.I descover something weird. Today,i drained all oil from crankcase and surprise..no smoke.
I do the same thing tomorrow morning,but with oil in crankase..i'll be back with news.

Open the the front or rear cover for adjusting valves and check that you actually get oil up there when starting up, maybe take some time when you drained system. You can also fill some extra oil in the top end and check if you get smoke.

I turned it on now and,smoke. (with oil in crankase) So i have no ideea what's happened here..

It looks to me like you have found the problem. You drained the oil from the crankcase and no smoke, after sitting overnight it smoked since oil drained in the crankcase. However, since you only drained 800ml from the crankcase, that is not excessive.

Replacing the check valve is easily done by removing the clutch cover. Check the parts diagram under oil pump on Partzilla: OEM Motorcycle Parts, ATV Parts, Marine Parts to see the check valve and seat. items 22 and 23 on the 1986 XT600 USA model. They are all the same. Before tearing down, order the check ball and seat plus a clutch cover gasket. USE OEM gaskets.

You probably didn't have any/much oil getting to your topend after draining . The oil pump was emptied mostly so it'll take a bit to reprime. Like XTrock said take one valve check cover of and see if there is oil in there when it's running. You did make sure you now have the correct amount in there after draining 800ml out ?

news: i did a short ride,i left the bike aprox 1 hour,i drained the oil from crankase, this time aprox 1,200 litres. Start the engine,smoke! WTF? I'm desperate:(:(

I put back these 800 ml. So,in this morning i drained all the oil from crankase,800+ ml,start the engine,no smoke,i put back these 800 ml. At afternoon i did a short ride,i left the bike 1 hour,then i start it again,smoke...i let the bike for another 1H and then i drained again the oil..aporx 1200 ml..i start the engine without these 1200 ml and..smoke.

Its not like the system have 2,8l up in the tank all the time. Drain all the system, front plug and crank, then see how much oil you have. And remember to idle the engine before you kill it, then check if its full up in the tank, i said it before these systems can fool you any time about oil amount. I drain system, change filter and refill 2,8l and thats it, if you check system after filling 2,8l it seems like its not enough. Take a ride and check again its full when hot.

When i rebuild the engine,also i change the oring of cylinder(no 2). I bought one from local dealer,not OEM and I'm not sure if this fits ok there. Maybe it's something wrong here..



Yamaha Motorcycle Parts 1986 XT600SC CYLINDER Diagram

No dont worry about the O ring with smoke problem.

it's voodoo man...

It's your valve seal(s) . Actually common to have one damaged if not lubed or ends of stems not polished to get rid of any burr when sliding on new ones . They need to be slid on and seated very carefully.

what do you recommend?new valve seals?

dani, do the simple (and cheap) part first so you solve the oil drain issue. then with that solved you can see if you still have the problem before dropping the motor.

see here

Yamaha Motorcycle Parts 1986 XT600SC OIL PUMP Diagram

order parts 22,23,24, 10$ total and fit them. still have the problem? then as many tell you, it could likely be valve seals. but at least you solved another problem you have anyway to solve, 1.2L after a few hours = not good.
troubleshooting often works like this... solve one problem, then move to the next.

It doesnt tell us anything, only way to know is if he drain all and tell us how much in total. Then we need to know if the measure stick is on full when he drain crank, otherwise you never know where oil in the system are at the time. I always drain alot of oil from crank after bike is warmed up, still there is nothing wrong with the valve.

I just can't believe there is still some worry over that stupid check valve . WoW. This site is the worst I've ever attempted to help on !!!


FIX THE VALVE SEALS !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Please ????



Pretty please ??? with a cherry on top ???

But are new!! :))

Ya, unfortunately , doesn't always work out so good , they are really easy to rip or even nick .

Not yelling/ screaming at you .

This thread has become a notch in record...

Thanks guys for answers! bierbier

A more importan question for us to know, what mileage did engine have before rebuild and why did you deside to do this?

I have almoust 85000 miles and a terrible sound at cylinder. The cylinder was worn so i decided to do a rebuild,new quota.

So 136000km on the first rebuild? Its impressing, good engines!:thumbup1:

dont give up JJ, you will win at the end :)

turboguzzi you seem to know how much oil its suppose to be up in the tank, in the system and down in the crankcase, please inform us? When the oil valve is ok.

Hei guys,i found something new! Yesterday it was warmer than today (no smoke) and today at start-up smoke..it's voodoo like i saydoh

Can you do us all favour, ride the bike and let engine idle a minute, check oil level, if its maks drain crankcase and measure, then drain frame and measure. Let the drainplug stay open in crankcase, then you will see if its seeping down from frame trough the valve. Dont do this test before you have full level on the measure stick, just let it idle for longer time so oil is up there.

I did a test: i drained all the oil from engine and the tank. I put back 2L in tank..i waited until drained in the tank and then i put on this almoust 600ML until the edge of the tank..after almoust 1hour the oil which drained in the crankase was about 130-150ML..without to turn the engine on. So my question is..the oil valve is good or bad?

Haha are we back to the stupid valve againdoh Its hard to tell where the oil came from after only 1hour, did you drain cold or hot? So you had 2,6l oil coming out total?We still didnt get any answear about how much oil its in the crankcase when its full up in the tank..

As stated before, your new valve seals could have been damaged when installed, easily done. If this is the case then this will require you to remove the head and have the seals replaced again. As JJ stated, make sure the valve stems are carefully checked and burrs removed before new seals are installed to keep from tearing or damaging them.

The check valve is easily replaced, order the rubber piece and the ball plus order a new clutch cover gasket. Drain oil, remove clutch cover. Valve is in the crankcase at the bottom. Pull it out, clean the cavity behind it, install new ball and rubber piece. Make sure the spring behind the ball is there and clean.

This may not be the problem but now you will know it is in good shape.

I assume you know to check oil level after a warm up and short ride. This allows the oil to expand a bit and all excess oil in crankcase to be in the tank where you can get an accurate measurement. Measure right after engine shut off, bike vertical.

I feel like that some of the frustration shown in these posts that there is some translation error and you may not be understanding exactly what is being said here. Please ask for clarification if you are not understanding. :D

Steve

As I had said last week already, please drain ALL oil, every drop of oil from your motor, tank, everything. Put in 1.8l ONLY, and Please forget worrying about that valve, please???

Run it several times over several days to notice smoke.

I Repeat,
Completely ignore that valve right now and everything you've heard of it, and drain ALL oil and add back in 2.8L, NO more. Run it ! please?

Why do you want him to run bike 1l short of oil? I dont recomend you running the bike with only 1,8l oil! Dont waste anymore time on this, remove head and change the seals! If you remove head take picture inside.

Whatever the amount is , I was thinking it was 1.8L but maybe that's my KLX's . Good catch . I'm rather frustrated at these dragging on things I guess , it so simple to verify and move on .


BTW Danimalu , also very common for leaking seal(s) to not smoke every time . I have a KLX that only smokes every 2 or 3 times and when it does it's a cloud . That's a bad seal.

This engine have 2,8l with filter change, so 2,6l that he drained is normal without filterchange.

No wonder I go through so much oil in a year , I quit measuring and just keep dumping till full, plus a little. :innocent:

:oops2: :funmeteryes:

at hot! i forgot to measure from crankase.

OK,tommorow i'll do that! thanks!

So much to do:)) btw,yesterday,today was warm outside..and no smoke! Next step to do: i order some new valve seals.

anyway.thanks guys for your answers,really,thanks! I hope i can solve this..

Quote:
Originally Posted by jjrider View Post
As I had said last week already, please drain ALL oil, every drop of oil from your motor, tank, everything. Put in 1.8l ONLY, and Please forget worrying about that valve, please???

Run it several times over several days to notice smoke.

I Repeat,
Completely ignore that valve right now and everything you've heard of it, and drain ALL oil and add back in 1.8L, NO more. Run it ! please?
OK,tommorow i'll do that! thanks!


NO NO NO dont run the bike with 1,8 liter oil!!!!!!!!

YA ,Danimalu,

it would be 2.8L , I miss quoted the wrong bike amount .

OK! :)) bier Like i say,the weather is warming up,and until now i have no smoke..so something is there. If still smoke in future,next step..new valve seals.

Like i said in my first post, have you checked the spark plug? If you dont burn much oil, use the bike like it is and live with a little smoke..

I've been running my KLX for a while now with the bad seal , someday I'll fix it . You can change them without taking the head off . I have an attachment that hooks up to air compressor to pressurize the cylinder and hold the valves up , then with a finger style spring compressor take the retainers off and pop new seals in. Helps with no frame backbone right over the head.

spark plug is ok with no oil deposit.

If you just run it , make sure to watch the oil level carefully . Mine isn't a daily rider so it isn't as much of concern , but a daily driver can run low faster if not watched , depending how much it leaks. May never get any worse , may get horrible as the miles get put on.

I wouldnt do all the job with new seals for the little smoke you have when cold, when plug is ok just ride the bike and enjoy. Check oil level from time to time, i have a little smoke from my thunderace when cold, but its no problem with oil consumption. I would say most cars and bikes gives a little smoke when startup with choke..Try to smell the smoke, if there is no oil smell its ok, you are talking about cold weather so maybe only condensation in the exhaust. I had a car with crack in the top end, water in the cylinder and alot of white smoke all the time.

Checked the way smoke comes from my acer, its no smoke just when you start bike, but after a short time it comes and then after a short time its gone. So in my head thats condensation due to the hot air coming from engine, i dont know but seems logic to me. At night now we only have like 5Celsius, bike was hot last night.

Btw did you have someone ride behind you and check if there is any smoke when let engine brake down speed?Should be visible if you have bad seals.

It takes a couple of seconds for the bike to be hot enough to burn the oil. I remember than from back when I overfilled mine. My friend has an old TT600 and it does then same.

Enginebraking from cold, and /or from high rpm's should show smoke. Normal enginebrakeing (like from 3500rpm wont always show smoke on a hot bike.) But i've seen than happen with both bad piston/rings, and bad valveseals.

Its oil for sure. :)

You could do a leakdown test.

Ride it for the summer, keep an eye on the oil, and rebuild the bike when the weather turns bad.

Buy a endoscope camera for your PC and check if you can see oil inside after a day or two, turn engine slowly by hand when checking inside so all valves have been opening.

A person can just look down the intake and exhaust ports , the valve(s) will be wet/oily , ,puddled if valve is closed. That's how I confirm them .

I have no smoke from the XT in same temp, i see many people have issue with white smoke from the 4cylinder engines when cold. Hard to tell if its condensation problem in a big exhaust system or some oil, i always thought oil burning is giving a more blueish smoke. And specially if you rev it really high and let go you can see blue in the smoke, you see alot of old cars with that issue.

I have and have owned 10 or so different brands/models of bikes, plus multiples of most, and ride in every weather imaginable and haven't seen any condensation smoke from any of them. The Only weather/temp thing I've seen is cold and high humidity in the right light , seeing a light puff coming out in pulses but dissipate within 2 feet and never a cloud or something that can be easily seen. There's only so much water that can condense an internal surfaces and it takes a lot more than that to create a cloud behind a bike.

Ok, but why is there no blue in smoke and no smoke when you slow down on gears, no smell of burned oil in the smoke either.

Out tested now, its about 50sec with white smoke, when holding hand in front it get moisture on it. I have a hole in the endpipe buttom and water is dripping out, the pipe was inside all winter so its dry and no rain on it.

No! After the engine is warm ,and when i ride it. I have no smoke.

The engine was rebuild. New piston and rings,new valve seals. I have almoust 1300miles from rebuild.

Tomorrow i will open cylinder head and change the valve seals.

Ok good luck:thumbup1:

I am nervous about it. I do not know what to do..:( I hope to solve this problem of smoke.

Are you removing head or using compressed air so they can be replaced with head on engine? XT is easy job, the acer is 20valves so iam not doing it before i see the blue smoke behind.. I dont know if there is room for this tool with engine in bike?

http://www.ebay.com/itm/Universal-En...155519&vxp=mtr

Here is a video using rope metod

https://www.youtube.com/watch?v=B8WTTfkyW8g



And remember what JJ told you earlier:Actually common to have one damaged if not lubed or ends of stems not polished to get rid of any burr when sliding on new ones . They need to be slid on and seated very carefully.

With air:

https://www.youtube.com/watch?v=5ZNVKgD9ubA

No.I'm not doing myself this job. I have a mechanic that deals only with this kind of work

Hello again. It's bad,i mean bad bad. I opened the cylinder head and surprise one screw was torn and another screw worn and those two from rear was ok. I think this was the problem..in order new screws and tomorrow i restore the cylinder head threads. :rain: