engine smokes on start up

[frizzy]

ive just rebuilt my and restored my z1000j3, but on completion its smoking a lot on start up, enough to fill a double garage with thick smoke clouds which smell of oil. I had the head overhauled by an engineer who tunes old 70's and 80's superbikes, he put new valve guides in, new s/s valves and new valve seats and skimmed the head by 1mm. he checked the rings as about 4000 miles ago it went to .05 oversize. the gap on the rings were within the tolerances and he honed the bores. ive done about 80 miles on it since the rebuild and the compressions are 140 to 150, then if I put a couple of squirts of oil in the bores the compression goes to 165 to 180. has anyone got any ideas ?

[weaver]

Why did he hone the bores if it was recently rebored?Was it smoking before hand?You may now need new rings.

[1962royp]

I had this once on a Z1000 i bought with a fully built engine i took ot to bits and the bores were bored too big for the pistons.
I had to buy a new set of barrels check the bores with a gauge.

[zed1015]

Most likely the bores.
Shouldn't have honed them without fitting new rings.
Take it out for a hard 20 to 30 mile ride and see if that improves things.
They might bed in but you will be lucky now that you've already done a few miles on them.
Probably looking at another hone and new rings IF you can keep the piston/bore clearance acceptable.

[PAULJAC47]

Try cheapo oil in then run in ,up and down the gears dont keep at constant speed make the engine work,sounds like rings not bedding in.

[Pigford]

What about the valve guide seals - could be duff/damaged

[z1bman]

oil control spring overlapped or the ends have broken check the part of the rings that are coloured yellow & pink in this photo

[Mr Bump]

Plenty of chaps here with more expirience than me commenting on this, but thick oily smoke on startup sounds like valve guide seals to me, especially if it sorts it's life out once it's warmed up. If an exhaust guide seal is gone it will be very obvious as the oil that has run down the valve will cook off as the valve warms up and it will plume smoke out of an otherwise fairly happy engine.

A clue is white streaks in the exhaust header of the affected cylinder. Hopefully it will turn out that yr man has damaged a seal on installation (or forgotten it) rather than you needing a rebore.

Olly

[warren3200gt]

I assume you are running a 4 into 1? take off the rear half of the exhaust leaving just the down pipes in place. loosen of the downpipes and spread them out, re tighten them and start the engine. Are all 4 smoking or just 1?
If it's all four it's most likely new rings, if it's just one its more likely to be a valve seal.
At the very least if it's only one you've narrowed it down a bit. I had exactly the same on an engine I rebuilt and it was only smoking on one cylinder. I eventually tracked it down to one of the piston oil return holes being blocked.
And I thought I cleaned them all!

[frizzy]

thanks guys, were off for a long weekend this weekend so going to take it out for a couple of hundred miles so ill let youse know how I get on. thanks again frizzy

[Farmer]

Make the engine work hard, labour it and take it up to the red line, enjoy yourself.

[ZedHead]

Smoke on start up suggests valve stem seals are duff to me.

I agree with Paul that your rings wont have bedded in to the newly honed bores yet, which may account for the "red herring" compression readings. More so than the smoky starting.

[corky]

I,ve had same sort of problem. Bought a restored Z1 which was lovely to look at and a bit of smoke on start up which i put down to rebuilt motor with generous helping of oil. Motor allegedly built by ex works kawasaki mechanic. After running smoking got worse and rumbling from gearbox. Ended up stripping engine replacing clutch bush and bearing, rings on 3 pistons round the way, oil stem oil seals shot and no valve clearance. So much for expert. Honed bores new rings matched to bores and oil seals.Going back together on tuesday so hopefully cured !!

[RAYZ1]

rings wrong way up or 1st and 2nd ring swaped? will do this. happened to me on my z1b, top ring ring wrong way up, installed as per the 72 kawa base workshop manual, to find out the rings were changed later in design and to ignore the position of the rebate and fit with the stamped side up

the symptoms of my engine was poor performance, smoke most of the time (fill the garage type) , lower compression

flipped the rings over and hey presto perfect, once married into the honed bores after a hundred miles not a whiff of smoke, unless it sits over the winter and you get the startup puff, then clear

[Pigford]

flipped the rings over and hey presto perfect, once married into the honed bores after a hundred miles not a whiff of smoke, unless it sits over the winter and you get the startup puff, then clear

Usually more prominent when left on side stand - sit it up on centre stand may help .... valve guide seals (again)?