TOPIC:

Hello kz headz I am putting together my first HP engine with a wise piston kist I manage to source 1260 78 mm. I sent the cylinder to have them bored and each piston was slightly different in sizes got them bored and honed to each piston what I need to know is the gap I have to leave in each ring.
could you guys give some light on this one.
This is a build that I am doing on 1976 KZ 900
Parts and mod:
1260 piston kit and rings
MTC billet clutch basket
MRE single stage clutch and cover and springs
MRE undercut gear box
windage tray and trap door in the sump
ported head with aftermarket spring font know with kind as came in the head
manual cam chain tensioner and mild camshaft not poem but no markings, came with shims over bucket so
APE studs, nuts and fiddler blocks.
new cometic bottom end gasket kit.
most of it I know but with the hem engines I use to have the cylinders bored and just fit the oem rings, on this build need to find out the gap.
thanks

Gap the rings per the piston/ring manufacturers specs.

If this helps.
Steve

So if I am getting this right and all this conventions I should do in 78 mm top ring at 3mm and second ring 4mm, I remember a friend of mine use to tell me he used a razor balde to gap his rings obviously he was not following this rules but his engines were good now between a razor blade and 3mm its a big difference.
would you guys confirm me if I am doing the right calculation.
aside from this thread: when I first bought this 1979 LTD came with the 1400 cc drag engine and you guys warned me that the engine was not going to last much due to the amount of heath and obviously whoever builded something like that had fun with it,so I listened and sourced a1978 A2 engine that was stored since 1978.
and the story of that engine goes like that a guy from NY bought himself a 1978 kz1000 A@ cherry red with golden lines and rode it very little(1000) said the guy that sold it to me. Then he fallen of the bike on the left side which is truth as the stator cover has a minor blemish. he got so scared that the bike sat in his house and he never got the courage to ride it again so he started to sell the bike in parts and the guy that sold it to me both it with a lot of other parts as he had a 1977 himself. he outed the engine on a basement and never had the need to use it, unfortunately humidity made its way trough the head and the valves stems got rusted along those 30 years.
I aquired the engine and opened ,2 exhaust valves where bended and the valves needed vaping , I replied the damaged valves and paper the whole head by hand and a drill bit with a plastic hose between the steam and the bit.I also did a mild porting more than porting the purpose was to get rid of the imperfections from castings and do polishing with adremel.
I took the cylinders out and the pistons where new but I did not want to take a chance so I did have the cylinders professionally honed and put gem Kawasaki rings, gaskets and steam valves seals. did the shims and left them all at 0.10 .the only not gem part I fitted was a manual tensioner.
I replaced the points with a dyna s ignition 3 and there is up and running the compression is 135 PSI in all 4 cylinders and I have only done like 200 miles on it its really smooth and quiet engine.
the tank cowl and side covers in the picture belong really to my 1979 KZ 900 build that will have the 1260 its only temporary while the original LTD set gets a paint job done.
now I have an original 1979 bike with 9600 original miles and a new engine and I could have never gotten here without you guys beware that this is a survival partially restored and modified I left the original patina of the engine and its not a concourse bike its just a bike that I love very much and made it to ride and be reliable I am pretty sure I will need more advice and the work will continue with this one the 900 and a j model I acquired as well in boxes. but you must know that your knowledge got me here
Thanks
Thanks

Sayonara wrote: So if I am getting this right and all this conventions I should do in 78 mm top ring at 3mm and second ring 4mm, I remember a friend of mine use to tell me he used a razor balde to gap his rings obviously he was not following this rules but his engines were good now between a razor blade and 3mm its a big difference.
Thanks
Thanks

No.
You have the decimal point out by a factor of 10.
For high performance street/strip its top ring 0.0045 thou per inch of bore and second ring 0.0055 thou per inch.
so for your 78mm ( 3.07086614 inch) bore it is -
Top ring = 0.01381" (0.35mm)
second ring = 0.1688" (0.42mm)
So 14 thou max on the top and 17 thou max on the second

one silly question oil ring are not to be gapped? should be left as they come?

CHECK TO BE SURE THEY'RE NOT TOO TIGHT

Sayonara wrote: one silly question oil ring are not to be gapped? should be left as they come?

Correct.
Oil rings are not gapped.