quench/squish follow up from gdfp blog post

[rumble]

Have just taken hold of a z160 and have noticed that there is 4.7mm from top of piston to bore. From reading the blog it looks like this is something i should be worried about.
If i remove the base gasket is this enough? What is the easiest way to then measure piston to valve clearance?

 

[ringo]

I've heard of using playdoe rolling the engine over and then removing the head and checking how thin the playdoe was under the valves!!

 

[The_GDFP]

Rumble, are you certain the cylinder was held down well? Piston was at TDC? Even a few sockets and washers and spinning the nuts on with a mild bit of torque helps. 4.7mm is a mile, and not what I've seen in the Zongers. Is it a stock 60x55 155cc version? Base gasket is only half a mm.

Oh, and thanks for reading my post I hoped some of you would. lol

 

[rumble]

Apologys guys, jumped the gun again, a little bit of internet knowledge gets me in trouble. i was measuring the bore stain, thought that was the top of the piston, it was the top of the ring.
So can i improve anything by putting a silicone gasket on the bottom?
Or best of just putting it all back together as it was.

 

[The_GDFP]

lol. Measure actual distance first. Zongers are usually pretty good, stock. YX's almost always get the base gasket tossed for Yamabond 4. Silicone sucks.

 

[sean01]

yeah iv found all zongers get the death rattle when removing the base gasket... yx's on the other hand can handle it..

bolt down the barrel and use a micrometer gauge to find the true piston to deck height, verniers just dont cut it for accuracy.. make sure you leave 0.5mm clearance for piston to head tho (which is usually spot on stock on a zonger), these china engines like stretching conrods... and piston will tilt slightly in a bore when running..

compression can be had in a number of ways..

and yep blue tack or plasticine is best used for checking piston to valve clearance..
can also wind the valve adjusters down 1mm or so more on full lift and do a engine roll over by hand to see if all is good, but the other method is better..

and lol Terry.. after 15 or so years people still look at me sideways when i ask for yamabond or honda bond at a parts shop.. in aus its better known as 3 bond

 

[The_GDFP]

Haa. Yeah, Three Bond 1194 is what's on the bench, right now. 10 minutes to the Yamaha shop, or get the 3B in the mail from the distributor. Yamabond 4 is a little more viscous, and I prefer that, but not leaving the house is worth it, and I don't have to drool on new bikes. A pack of Dollar Store brushes keeps the mess less.

You let out the valve adjuster trick I use it, especially when changing cam timing on an assembled engine. Half a mm per turn gives a good indicator. S35's tighten up the clearance quick when shifting them around. The Motion Pro adjuster is great for that. I have marks scribed on my adjuster knob for that.