Cylinder head fitment

[1034am]

Hello. I'm planning to use a 2003 cylinder head on a 1989 motor.
Can anyone tell me if this will/won't work? All my research indicates main proportions are same, w/exception of tach cable.
Any help would be appreciated!

[The Buddha]

I'm guessing so. The 01-02 is identical to the 03 ? cos in US we don't got no 03.
Anyway electronic tach aside its identical head wise. As always do it and post back.
Cool.
Buddha.

[1034am]

Ok, so the '03 head seems to work perfectly w/the '89 valve train components.

But, I'm still having the exact same problem, white smoke out the the exhaust. Worse at higher rpms, less but still slightly visible at idle.

Ran compression test:
L side 130psi /143 w/oil squirted into cylinder
R side 122psi /137 w/oil squirt

Bike runs well & always starts right up.
Tried different weight oils with no luck (20w50)
& previously (last summer) new rings & base gasket. (Cylinders checked w/micrometer & were within spec)
About 13,000 mi on engine

The only thing I can think of is maybe the rings moved & gaps aren't in proper position. Rings are genuine Suzuki oem. Or maybe installed upside down?

What else would cause white smoke & low compression?  Is this just normal on these engines?
Any help is much appreciated.

[mr72]

That's rings. Did you hone the cylinders when putting in the rings?

[1034am]

No, i checked w/micrometer and they were in spec. I also figured with only 13,000 mi it was unlikely that the cylinder walls would be bad.
If I hone cylinders would the stock/oem rings still work, or would I have to get larger ones?

Also, any possibility of the cylinder body not sealing w/head gasket? I checked head for flatness but not cylinder body.

[mr72]

Someone here is a far more experienced engine mechanic than I am, hopefully they'll chime in. I hired someone to do my top end rebuild. But my understanding is fitting new rings always requires honing at least with a ball hone to break the glaze on the cylinder walls and allow the new rings to seat during break-in. My bet is this is what's causing your poor compression and oil burning. If it were me, I'd pull it back apart, do the ball hone and then fit another new set of rings, break it in.

As far as the flatness of the cylinder top, again I'm the wrong guy to ask. However I think that's the job of the head gasket to accommodate any minor irregularities in the mating surface. I guess it's possible for that part to warp but I would guess it's very unlikely just due to the shape of the part and physics involved. I think you'd have to crack it before you could get it to twist enough to warp.

[1034am]

But if it were the rings/cylindr walls wouldn't adding the oil (to cylinder) have created a more dramatic effect? More than just a bump if 5psi?

[qcbaker]

I'm not an expert by any means, but poor compression and visible smoke out the tailpipe sure sounds like piston rings to me...

[The Buddha]

If you didn't touch the cyl/piston set, you could be fine (aka just as bad as before the head swap).
The new head could be decked and valves checked and 3 angle refresh job cut - if that was your issue, which I don't believe it is.
However white smoke is gas, if you're getting that at startup, could you just be super rich ? Like where is float and what jetting
Cool.
Buddha.

[1034am]

So if I bring the cylinder body to the machine shop for honing, can I still use oem rings? Or do I need to size-up due to the machining?

[The Buddha]

So if I bring the cylinder body to the machine shop for honing, can I still use oem rings? Or do I need to size-up due to the machining?

OK from my earlier research, you get over .25 from original bore, you would need to get .5 over piston and rings. But a good bore with low miles and wear will not get to .25mm. I have a MZ that cracked a piston and was still in spec for the bore, I honed it and used wiseco and hand gapped the rings.
BTW you sure your problem is that ?
I cant imagine that causes white smoke @ start up, poor compression @ the rings will result in a bike that's anaemic @ high revs, but you need a good motor to compare it to from a seat of the pants perspective.
Cool.
Buddha.

[mr72]

Those 120-130psi comp numbers (dry) won't cause bad performance at high revs, but they will cause smoke. But that blue/white smoke would be more at higher vacuum (WOT, etc.) than on startup if the problem was rings.

Oil smoke only at startup is likely valve stem seals. But you can have oil leaking past rings that you only notice at startup until it's bad enough to begin showing while running. Combustion of the oil is more complete and it mixes more with ordinary exhaust at operating temp.

Truly "white" smoke is likely water in the gas or water in the crankcase getting into the cylinders. Oil smoke is a bluish.

I would think since you know you didn't break the glaze when putting in rings that this is the most likely cause of smoky engine and low compression. It's logical

[1034am]

Thanks for all the input.
Re: the rings, I did rub them w/steel wool to knock off any coatings or debris.It's possible they may be installed upside down, I remember the markings didn't exactly match shop manual, & I did get some conflicting advice. Gaps checked out as did the cylinder, but I'm no pro & its possible my micrometer is off a little.

Re: the smoke, when I say it's at start up, the choke is on & rpms are high. It's def oil burning.

I did the engine job last year for oil burn & hanging idle. Compression numbers were: L side 60/70psi & R side 105/130. The diff in psi with oil didn't lead me to rings, but maybe I was wrong.
The head was bought used (with new valve seals) so I figured it needed a valve job. When I saw a brand new head  I jumped at it. With the new head the compression is much better & no hanging idle (just oil burn)

Before I take it apart I want to make sure I'm checking everything that might be problematic.
So to be clear, if the cylinder walls need to be honed I will have to get larger pistons/rings? Or will existing pistons w/nee rings suffice?
Thx

[The Buddha]

The top ring doesn't have an upside down (I think its symmetric about the horizontal plane), but the middle ring definitely isn't symmetric. It will be bad to install it upside down.
However the oil ring - well its symmetric, but you should never never ever reuse that. Unless I guess you never got to it.
But installing the middle ring upside down - that should pretty much do it. Oil control will be worse than if it was installed correctly.
Cool.
Buddha.

[1034am]

Good info! I just found a brand new cylinder body, so hopefully w/a fresh set of gaskets & new rings I'll get this bike back to full potential. Thx!