Author Topic: How to tell if your head has been decked to correct Squish  (Read 1570 times)

Offline bigbird337

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How to tell if your head has been decked to correct Squish
« on: February 18, 2019, 04:12:59 pm »
 I just came into an 87 lt500r. I have started to tear down the engine to replace the stock piston and the thrust washers. How can I tell if the head has been decked to fix the squish issue.

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Offline Q2W

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you'll need to do a squish test.  There's probably a thread around here that has pics to go with the explanation.

1.  Get some .062 solder. 
2.  Remove the head from the cylinder. 
3.  Roll the engine over so the piston is on the upward stroke just before TDC. 
4.  Cut a piece of solder and lay across the piston perpendicular to the intake and exhaust ports.  Make sure the solder is touching the cylinder walls on both sides. 
5.  Put the head back on the cylinder. 
6.  GENTLY roll the engine over TDC.  BE CAREFUL to not go too far so that the solder falls down to the crank.
7.  Remove the head and grab the solder.
8.  Mic the ends of the solder that are squished.  You want to be .045 to .060 -ish.  I like to be in the .05's.  Any adjustments need to be made at the base gasket.  Cometic sells gaskets at any thickness.  For example, if you're squish measures at .04, order a .015 or .02 gasket from cometic.  That will put you in the .05's -gaskets squish down a bit when you torque the cylinder studs.

Hope this helps

Offline RUn2it

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The dome should be shaped like the profile of WW1 helmets, not like the stock looking 13th century Mongol soup pot helmets, lol. If your pressed for time stick the solder through the plug hole to cyl wall and over the wrist pin, the end of the solder will leave a witness mark from the piston to cyl edge.   This way is usually done to check an engine already assembled and in use, Q2W is when you build it right the 1st time. Oh yeah, if you're worried about the solder going in the bottom end (follow Q2Wway exactly and it won't) and a Nervous Ned put a little dab of grease on the piston. Might as well o-ring the head (if you're doing it right the 1st time), I tried everything so I could ride what was left of dune season and I mean everything and coolant doesn't make power.


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