Found this little trick on a go cart forum. I might be doing this to my spree next time I have it apart (probably over the winter), and Im gonna do it to my beater oil burner briggs I have on my go cart as soon as I get some sealant(engine is a piece of s***, im running it on gear lube till it blows).
Second, while you have DuraForce disassembled, it would be a good time to make a small but effective modification to increase compression ratio and therefore horsepower.
Eliminate head gasket and use a good high temperature flange sealant such as that pictured.
This will decrease space between head and cylinder block and will give a small boost to horsepower.
I took measurements first (using modeling clay) to make sure there were no clearance issues such as piston crown slamming into head especially around circumference of piston crown/cylinder head edge.
Anyway, sealant should be spread thinly (to one surface) and if done properly will ooze out a small amount (4th pic) once it is torqued to specification.
pics
I am not a mechanic, nor do I play one on TV. Actually my advice is probably worth slightly less than what you pay to view it.
thats all fine and good. But you need to know what you are doing.
you can shave like .20 off or something like that. But a head gasket is thicker then that (at least on the bike i was working on). If the head gasket is about as thick as the measurement that you can take off, Then go for it. But do some math first or you are going to be in deep s***.
"Its not what you ride, its that you ride"
1996--------Honda Elite S-
1991--------Tomos Targa-
And a Bunch of other bikes.
Im 99% sure a spree gasket is .020 (thickness of a matchbook cover), which is exactly how much you can safely shave off. No danger as long as you check clearances.
I am not a mechanic, nor do I play one on TV. Actually my advice is probably worth slightly less than what you pay to view it.
to mill the head, the metal shop teacher at my school had me use an extremely level table and some sand paper, moving the head across the paper in a figure 8 pattern. and a super accurate measurer. i was weary but it seemed to do the trick.
1986 Spree SE:
pulley mod
'85 head
SB50 intake, reeds, carb
UNI filter
44mm bbk
3x10 conti zipps
next:
taz gears, sa50 clutch w/ 2k springs
SPREEtown wrote:to mill the head, the metal shop teacher at my school had me use an extremely level table and some sand paper, moving the head across the paper in a figure 8 pattern. and a super accurate measurer. i was weary but it seemed to do the trick.
That will also work.
I am not a mechanic, nor do I play one on TV. Actually my advice is probably worth slightly less than what you pay to view it.
