YFZ Central banner
1 - 20 of 56 Posts

·
Registered
Joined
·
46 Posts
Discussion Starter · #1 ·
ok i had a post on here yfz 480 build and its finally done.


now i have had about 5 hours on the motor. problem is grey/blue smoke out the exhaust.


1. its been 3 days since i rode last didnt notice any oil when i was out jsut fired it up today and let it idle 30 seconds or so then gave it a little braaaap of throttle a few times and each time a significant amount of blue smoke came out. (almost as if oil was leaking into cylinder as it sat for 3 day). now not smoke out your block but a decent amount that made me think something not right.

when idling no smoke what so ever.
fire up in like 2 turn overs of the starter. so very quickly.....
dont even need to choke it.
once warm i dont notice the smoke........im assuming its the valve seals???? maybe the piston rings havent seated yet???

i added maybe .3 litres of oil after 2 rides being around 3 hours total. 1.85 litres is what it holds. i added about .3 or less.


just want a few opinions id liek to get it fixed asap.


side note i just had new valves installed, ported n polished, new springs, seals, retainers ect......might take head back for warranty........or new seals??
 

·
Registered
Joined
·
4,737 Posts
All the YFZ's i've had or seen over the years have blown smoke like you are describing while they are warming up.

Another thing to consider is that if you can start it cold without choke, your to rich on the pilot and that will create a little black/grey smoke as well.

Edit: what piston did you use and what was the ring end gap?
 

·
Registered
Joined
·
46 Posts
Discussion Starter · #3 ·
its a cp 12.5/1 piston not sure on gap..........didnt set a gap it was all brand new. that may be the issue.


im not sure its supposed to smoke when revving.............it doesnt smoke when idling.


the choke is needed on most starts. think the pilot is ok........and it would create this problem i dont think......




any more opinions???
 

·
Registered
Joined
·
4,737 Posts
QUOTE (Yfz480Rider @ Feb 11 2009, 05:17 PM) index.php?act=findpost&pid=745409
fire up in like 2 turn overs of the starter. so very quickly.....
dont even need to choke it.[/b]

QUOTE (Yfz480Rider @ Feb 11 2009, 06:39 PM) index.php?act=findpost&pid=745451
the choke is needed on most starts. think the pilot is ok........and it would create this problem i dont think......[/b]
which is it?

does it stop smoking once its warmed up? if it does you have nothing to worry about.
 

·
Registered
Joined
·
46 Posts
Discussion Starter · #5 ·
yea choke sometime sorry if this confused yoou. just wanted to explain it starts very well no troubles.



idles perfect. just noticed while its warming up or has been sitting for 3-4 days seems like first few throttle braaaaps smoke. as it warms up there is less and less smoke.


i just had the head redone new seals,valves,springs,retainers. talking to a few others they believe its leaking oil through a unsealed vavle while parked then i fire it up and burn the leaked oil. once warm the seals swell therefore no more smoke.......


looks like a tear down again. im gonna replace piston rings anyways since im there. eliminate 2 problems at once hopefully.
 

·
Registered
Joined
·
4,737 Posts
QUOTE (Yfz480Rider @ Feb 11 2009, 08:42 PM) index.php?act=findpost&pid=745542
yea choke sometime sorry if this confused yoou. just wanted to explain it starts very well no troubles.



idles perfect. just noticed while its warming up or has been sitting for 3-4 days seems like first few throttle braaaaps smoke. as it warms up there is less and less smoke.


i just had the head redone new seals,valves,springs,retainers. talking to a few others they believe its leaking oil through a unsealed vavle while parked then i fire it up and burn the leaked oil. once warm the seals swell therefore no more smoke.......


looks like a tear down again. im gonna replace piston rings anyways since im there. eliminate 2 problems at once hopefully.[/b]
What you have been told makes sense and could very well be the case, but its a common occurrence in YFZ's to do this while they are warming up.

If it was a leaky stem seal, it should smoke while idling as well.

Before you rip it apart, have a look at the valve stems and guides through the ports to see if there is any oil film that has collected. If there isnt enough to see, there isnt enough to make smoke and thats not your problem.

On another train of thought, what oil did you run for the first startup?
 

·
Registered
Joined
·
46 Posts
Discussion Starter · #7 ·
ok i rebuilt late last summer jsut motor for 1 last ride since we get winter here in canada. i used 20w, 50 i believe. did a startup and quick ride then changed it. replaced with the same oil. the last 2 rides have been when the weather is warm here down the frozen creek and sand trails. kinda fun padles in snow. its been 10w/30. which i have in right now. only has 5 hours max on motor. 3 oil changes. 1 because winter and 1 was after 2 rides. just thought clean oil would help. its all been regular yamalube right from the dealership. no synthentics here. not yet anyways.


when u say look down ports u mean take cams out and push them open by hand?? or take entire head off?? before getting it resealed??
 

·
Registered
Joined
·
4,737 Posts
no, have a look in the intake and exhaust ports with the motor assembled. take the carb and header off to see down the ports, you can see the guides and stems just fine with a little extra light.
 

·
Registered
Joined
·
46 Posts
Discussion Starter · #9 ·
alright someone also mentioned make sure the valve clearances are all correct. would this in anyways burn oil if they were off spec?? the dealership said they set the clearances while they had it but to check again after breakin to confirm they are correct.

i just think its 2 much smoke to be a regular yfz thing. even if its cold. i mean its coming from a heated garage and had 2 big puffs of smoke then less and less as it got warmer.
 

·
Registered
Joined
·
4,737 Posts
QUOTE (Yfz480Rider @ Feb 11 2009, 09:10 PM) index.php?act=findpost&pid=745563
alright someone also mentioned make sure the valve clearances are all correct. would this in anyways burn oil if they were off spec?? the dealership said they set the clearances while they had it but to check again after breakin to confirm they are correct.

i just think its 2 much smoke to be a regular yfz thing. even if its cold. i mean its coming from a heated garage and had 2 big puffs of smoke then less and less as it got warmer.[/b]
is there any way you could post a vid of it?

the dealership is just playing it safe by telling you to check the clearances, its a good idea to check them after the first run anyway. If they are out of spec, they wont cause an oil burning issue.

do you have a bored out stock cylinder? was it bored/coated to the size of the piston that is in there now?
 

·
Registered
Joined
·
46 Posts
Discussion Starter · #11 ·
nope brand new cylinder from nmotion, with a new cp piston 12.5/1.


and yah i assumed they were playing a guessing game. im going there tomorrow to show them. was talking to terse and came up with the same thing either valve leaking onto cylinder. it makes sense because it gets less and less as it gets warmer. if it were psiton rings wouldnt it be consistant???? or getting worse???



as for video its 2 late to go rev it lol. pretty loud. i can toss a video tomorrow. here a picture though lol doesnt help but atleast i can show it off.



 

·
Registered
Joined
·
4,737 Posts
nice pics lol.

It doesnt have the symptoms of being rings. it would continue to burn oil once it was warm.

If its valve stem seals you will see an oil film on the valve stems where they come out of the guides.
 

·
Registered
Joined
·
46 Posts
Discussion Starter · #13 ·
yah i guess ill have to go talk them tomorrow explain what i feel is the problem see if they will stand by there work.......get the head reseated and sealed. on there dime.
 

·
Registered
Joined
·
46 Posts
Discussion Starter · #14 ·
ok taking it to the shop see what they decide is wrong........or not wrong......


ill post a video or a link so u all can see the problem........
 

·
Premium Member
Joined
·
12,069 Posts
I also want to ask what the temps are? If it is really cold the seals... be it water pump or valve guides will shrink some, and if left for a few days would eventually leak "some", and until warmed up by riding/ running the motor for the seals to expand will cause what you have described.
 

·
Registered
Joined
·
46 Posts
Discussion Starter · #17 ·
no it doesnt smoke crazy, doesnt smoke when idling, only when i give it a flick of the throttle. and seems to get less and less as the engine warms up. havent taken it for a ride to get the temp up enough.

now this is first time its happened......that being said i rode it sunday parked it in heated garage. wanted to fire it up midway through the week always do keep everything fresh.........


let it idle in -4 degrees celcius for 30 secs or so maybe more wasnt timing.........

gave it a couple of flicks of throttle and first 2 were a decent amount of blue smoke.

then next 2 less blue more grey.
then less and less ect. didnt run it long becuase i came on here all paranoid that something is wrong and here we are now.

i think u may be right terse the combo of weather, and rubber seals (atleast im hoping) . only reason i dont think its piston rings (im not an expert by any means) is from what i have read the blowthrough from rings wouldnt die down would stay somewhat constant.


its even colder today -16 degrees celcius today.
 

·
Registered
Joined
·
1,210 Posts
mine is doing the same thing, i just rebuilt the motor to reseal the cases, i reused the piston, cylinder and rings, they all had 5 hours on them, at idle is fine and when you rev it i get a puff of smoke, when its warm it stops, i have not rode it yet
its very cold her, minus numbers with lots of snow and ice, im going to remove the carb and header to see if it leaking down there
sam
 

·
Registered
Joined
·
46 Posts
Discussion Starter · #19 ·
THANKS FOR ALL YOUR GUYS HELP...... I FIGURED OUT EXACTLY WHAT IT IS TODAY. I TOOK ONE OF THE GUYS POSTS ADVICE TOOK OFF CARB, EXHAUST HEADER AND CHECKED INSIDE THE HEAD.



INTAKE ALL 3 WERE CLEAN AND LOOKING GOOD.


EXHAUST BOTH LEAKING HORRIBLY.



CALLED DEALERSHIP AND SAID THATS ALMOST IMPOSSIBLE.........why do all the shops that make a mistake try and blame other mods on your bike??? they were 100% certain it was piston rings. well i proved them wrong thanks to TERSE AND YFZ 450 #69.



the service guy said hes gotta talk to the "boss" they dont think they will cover it. im waiting for a call back will keep all of u posted.
 

·
Registered
Joined
·
4,737 Posts
if they assembled the head, the right thing to do would be to cover it.

did you get the old valve stem seals back from them? demand to see them, if they cant produce them, accuse them of not replacing them in the first place.

the squeaky wheel gets the oil....
 
1 - 20 of 56 Posts
Top