Smokin..........suggestions pls

[Reecy]

Hey up

Your learned suggestions would be appreciated

My Z1000 has been smoking for a while on the over run but is otherwise running great- it pulls cleanly from 900 revs right through to the redline- I don't think that compression is short it pulls so well- so rings aren't likely and it's doesn't smoke when accelerating

In an effort to stop it smoking, the valve guide oil seals have been changed but the problem persists

What else could be the cause?

Valve guides shagged?

Oil breather pipe work blocked?

Other ideas?

Thanks in advance

Reecy

[Pigford]

Could still be rings/oil rings, a brocken ring - or a scratch in one of the bores

[baz]

whip the exhaust off and try it again, this will show which pot (s) is giving the prob, then id'e do a compresion test

[z1bman]

whip the exhaust off and try it again, this will show which pot (s) is giving the prob, then id'e do a compresion test

+1 it is false economy to remove the head & not remove the cylinder to check the piston /rings & bore for the sake of an extra gasket & an hours labour

[ZedHead]

Do a compression or better still a leak down test. If this doesn't point to anything then go back to your valve seals/guides.

I would recommend Buzzard for any head work if it needs doing.

[Compo1955]

If an oil ring was faulty but the compression rings are ok, the compression would still be ok but that cylinder would smoke all the time.
Smoking on the over-run is usually caused by the inlet valve seal/stem being faulty.
When the throttle is closed from higher revs, a large vacuum is formed in the inlet tract and this pulls oil down the inlet stem.....

[Redbeard]

I thought this was about cigars or pipes, sorry.

[firyembers]

smoke on overrun I agree points to valve seals,guides,as suggested

That will be oil being sucked past the valve seal (s),the valve guide(s) to head fit or porus guides

You could do the seals again,they can be done without removing the head,a typical tool is this one

http://www.ebay.co.uk/itm/271069691844? ... 1423.l2649

Do a web search if you want to go that way,have seen it as low as £50 ish not on ePrey

Fill the cylinder combustion chamber with rope or similar and raise the piston to squeeze up to valves hence stopping them dropping unretrievably into the piston area.

Will be doing mine that way likely later this year when done working in August

this time just try this one,remove the spring from the seal and unscrew it,its a piece of coil spring wire,joined together then twist it past a couple more turns then screw it together,on the new seals you just fitted.

Practice on a larger seal if it not makes sense.

What in effect you are doing/achieving is making the spring tighter which tightens the rubber on the shaft,in this case the valve stem a couple more thou'.

Done that trick on many shafts weeping a little,learnt it from a guy donkeys older in one of the places I worked,when a groove worn in shaft.(Worked a treat for me)

Since you done seals anyways,next is rings,as telling if guides to head fit is causing the problem I suggest is more unlikely and difficult to pinpoint to..

Short cut could be borrow a known good head,still smoking more than likely to be a ring problem.

If on a tight budget reuse the head,rocker gasket as it's only a few miles and a leak there will be of no consequence for this exercise..

Or buy a base gasket and do the rings anyway,with a hone chucked in for good measure,if you decide a head off jobby.

Trouble then how is the cam chain and guides looking,the list can get longer...

Can do a hone yourself with the correct size/diameter purchased and an electric drill with variable speed on slowish(not at 9million rpm),you just need to glaze bust the shine to help new rings bed in and seal,aim for crosshatch scratch marks

Move drill in a fastish up down movement about 6-8 inches per 20 seconds at about 300 odd rpm

I just checked honing cylinders and this basically ok if a clean up,but if scratches past nail feel,then looking at an oversize rebore and pistons and rings.

Go here for self honing

http://www.dansmc.com/hone_cyl.htm

And likely your oil bother problem found

If you thinking oil breather blocked did you try removing it completely,an easy option to negate that thought.

Didn't the z1000 have cast iron guides as std have the idea they were porus to help lubrication from where I picked that one up from not remember,when you did the valve guides did you manage to view inspect valve stems,any scores there will affect seal,and could be a sign of a slight stem to guide seizure which will affect guide to head seal.

A compression and a leak down test may help guide better in the direction you need to go.
Make sure you paper and pen every detail to do each cylinder under same conditions

When you noticed the condition of smoking on overrun had you done any work on the engine within months 500 miles or so..

Changed oil to a different grade(thinner as believed to be better)

In the Uk with 20 degree normalish temps,20/50 is I believe good,as a 3-5 psi,high flow system,needs some viscosity to be pushed around.Thinner to be the same means a need for closer tolerances on the pump,since it's not changed (unless you changed tolerances) flow I suggest will be a lower flow and will escape easier to combustion chamber

That's neither to say likely a lot here will be using the new oils,semi or synthetic 10w somat or thinner with no difference,except costlier oil changes,although supposed to last tons of miles more..

Just some idea's to chuck atcha,i have similar bother but it's mostly all the time,runs 100 mile a pint,but since I rarely home to ride,no bother at moment.
Plus since it's a 1260 motor I think a reply said,yep it's an oil burner aswell..and I know the oil is pretty newish without having to regular change.

Excuse the long reply,i do trouble shooting and diagnostics as a living for the last 15yrs,mainly cnc stuff but anything in a steel structural factory including engines so able to offer many possible idea's.

Others here that has had a similar problem will likely be better suited to point you..but your choice and budget at end of day.

I generally aim my customers to cover all possibilities,regardless of cost,but then what I work on is a minimum of a $500/1000 per hour down time...another ball game agreed.

These are just my points of view,do your research,there is many members a lot of far more knowledgeable in this vein of view,plus tons via the web..
Read it all,

A piece of music digitised (sampled)will be more accurate sounding at 5,644,800 Hz than the same piece at 8,000 Hz

But it will never be true analogue like lp's etc,why the trend to go back to analogue music equipment.
And you CAN hear the difference..open your ears both of them...

[jimmock]

Smoke on over run, has GOT TO BE the guides or stem oil seals.

[Garn 1]

Reecy, could be glazed bore... Just need a hone!
A mate had a similar problem trying to trace the reason for smoken!
He found the bore was heavily glazed, he attributed it to his initial running in... too slow! Piston rings did not bed in.
Regardz.

[CAT3]

I'd suggest a rebore if the valve guides & seals have already been done.

[jimmock]

Guyz,

It is ONLY on over run.

This means only a guide or seal problem due to the vacuuming effect of closed carbs (on over run).

Bores / rings would be all the time and MUCH worse on hard acceleration.

[Garn 1]

Jimmock, You are probably correct regarding "Over-run" symptom.
I know my mate searched for ages, replacing the valve seals and checking guides for a second time.. Still smoked until he de-glazed the bores.

RegardZ.
I had a car like that once, every time I ran down a long steep incline, I would look into the rear-view mirror and hardly see a thing, except for smoke!

[PAULJAC47]

Yep valve seals,didnt use nasty copy ones by any chance? they fail real quick!!!