Dodjy casting, any ideas how to fix it

Z

zwebx

New Member
Hey, this is my first time of opening this kit and i noticed this :
DSCF0071.JPG

sorry if the image comes up massive on this site.
any ideas on how to fix it? btw not my first time tinkering with an engine please do not consider that a bottleneck.auflg
 
Sandpaper, about 280 grit and a sheet of glass or another material that you know is flat.
Hold the head as flat as you can and run it across the sandpaper in a circular motion as if you're polishing a car. (wax on, wax off) Start slow and inspect the gasket surface often. You'll quickly see the high and low spots. Keep working until the gasket sealing surface is flat and uniform. I rotate the head in my hand after a few circles to keep from sanding an angle into it.

When you're satisfied with the cylinder head check the mating surface of the cylinder. Most of these little engines will benefit from dressing the head gasket surface for a flush fit.
Oh, and install a new head gasket and torque the nuts to about 150 inch pounds using a cross pattern (side to side)

Tom
 
yeah i know i should flatten the head out, but what i meant was that is around the sparkplug hole is where the terrible casting is
 
Other than alot of carbon buildup, I see nothing out of the ordinary with that head, even the carbon is ordinary if one uses an oil heavy mix.
What exactly are you seeing around the spark plug hole that I am not?
 
ooh, the chunk missing at the north side of the threads(relative to pic)? I'd check your cylinder walls... eep.

lapping the head/jug is a good idea, also raises compression a bit too.
 
Looks like your sparkplug could be longer, that's a lot of threads showing below the plug.
Longer plug increases compression ratio a little.

If the casting is kinda rough on that ridge around the plug hole, it is a good idea to file/sand it some to smooth out the sharp edges some.
 
I wouldn't worry about what you're concerned with near as much as the leaking head gasket. Those black marks radiating out from the gasket sealing surface is causing you more problems that a little rough casting in the combustion chamber. A few minutes with a Dremel and a stone will fix what I see in your photo but the head gasket is leaking. That allows a loss of compression (power).
Tom
 
My previous comments on the head appearing normal were taking into consideration the commonly poor quality that the HT engines are known for. While I agree that such a flaw would not be acceptable in a higher quality engine such as a Honda, Tanaka, Mitsubishi, ect. they are part of the game with HT's.
If you elect to use a longer reach spark plug be very sure that all the carbon has been removed from the threads in the head before installing the new plug. Also, absolutely all of the threads on the spark plug itself must be covered by the head to prevent carbon build up on them. If any carbon deposits are allowed to accumulate on the spark plug threads it will ruin the soft aluminum threads in the head when the spark plug is removed at a later date.
 
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2door said:
I wouldn't worry about what you're concerned with near as much as the leaking head gasket. Those black marks radiating out from the gasket sealing surface is causing you more problems that a little rough casting in the combustion chamber. A few minutes with a Dremel and a stone will fix what I see in your photo but the head gasket is leaking. That allows a loss of compression (power).
Tom
Click to expand...

im running gasket glue on all gaskets now...
And i checked the cylnder and seems to be decent but not perfect (hehee not after my crappy porting job) and the piston seemed to have a little bit of carbon below the rings.
I cant wait untill i recive my sbp expansion chamber and hardware kit with sounds dampeners.
 
also turn the head 90 degrees as your sanding every 10 strokes or so
use whats called wet/dry paper and lots of water
the water acts like a lube and washes away what you sand off making the
sand paper last longer
also do the cylinder where it meets the head as they are not perfect either

you may want to replace the head studs and nuts with a kit from www.sickbikeparts.com
 
that's a good sign, hows your jug wall look? (while the head was off and all), that chunk that came off didn't do any damage I hope...
 
It doesn't really look like a chunk came off, it looks like it wasn't there in the first place.
Shoddy quality control at the foundry.
 
killercanuck said:
that's a good sign, hows your jug wall look? (while the head was off and all), that chunk that came off didn't do any damage I hope...
Click to expand...

it has lines up it... not scratches though so i think its just how it was and the bit missing on my head was a bubble in the casting....
the cylinder looks worse off now after i ported it :P i really messed it up.
 
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