DD50 corsa

[kauaianman]

going to document my biuld.

SYM DD50 motor w/ Polini Corsa

stock intake ports

somewhat matched upper half of boost port to corsa boost port (i turned block upsidedown and used a small file)

[kauaianman]

test fit everything

making sure gaskets don't interfere with eachother.

very tight fit with CT black and polini corsa. once gaskets looked good i tightened the base of the CT black (10ft lb.)

also the stock head bolts wouldn't fit in the corsa head?? 2nd time this happend to me. had to switch to stud kit.

[kauaianman]

test fitting cylinder for clearance (making sure it's not sitting on the layover gaket of the CT black.

actually had to dremel clearance for good fit.

even with dremel very tight fit.

[kauaianman]

cleaned all gasket surface and gasket and installed piston and cylinder.

the corsa piston seems to be (actually is by about 1/2mm eyeball/feel) below the exhaust port at BDC.

[kauaianman]

Installed Head and tightened 5 > 8 > 10ft lb.

cleaned off mating surfaces of CT black and put all new gaskets. also tightened CT black to 10 ft lb.

also putting on a new 28 oko starting jets 52 pilot 140 main needle 2nd to the richest position.

[kauaianman]

put motor back on the bike and did compression test.

165ps1 with stock corsa gaskets.

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i added 1mm head gasket and lowered compression to 125

2012-07-10_21-13-17_401.jpg (27.79 KiB) Viewed 10237 times

[kauaianman]

so at the end we have

DD50 block
polini corsa (new)
7.9 gears (new)
28oko 52pilot 140 main (new)
CT black manifold (new)
V8typhoon exhaust (used)

for trans

stock DD50 (ZX)
kelli pulley
SEF 2 ramp
7.5G weights
1500RPM center spring
stock clutch w polini yellow shoe springs.

everything installed and torqued to spec.

[kauaianman]

first test run

went 3/4 mile at 30mph max speed while varying throttle position

hit temps of 320 degrees.

took shrouds off and found little traces of fluid on base gasket near boost port area.

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there is also a little puddle of gas sitting inside the sleeve of the manifold where the carb sits (always there when i take off the carb).

2012-07-11_16-08-39_237.jpg (21.71 KiB) Viewed 10235 times

going to re tighten head bolts and see if that stops the leak. would such a small base gasket leak cause that much heat in under 1 mile?

[veedubh20]

did you remove paper old gasket on boost port area? need to clean good!

or the stud bolt on bolt tread end ( head bolt) not flush in down

[kauaianman]

did you remove paper old gasket on boost port area? need to clean good!

or the stud bolt on bolt tread end ( head bolt) not flush in down

yes i clean everything really good. no paper gasket left behind at all. even wiped all oils off base gasket and base gasket area before mating cylinder to block.

[kauaianman]

rode around for 4 miles then lost compression (dropped to 115 bike wouldn't go when i open the throttle)

took off head everything looks new no soft sieze no lines at all inside cylinder

i removed the 1mm head gasket and reinstalled with just corsa O-ring gasket

compression now 155.

same temps.

tomorrow will try a new PG long copy exhaust and see if that makes difference.

getting late so i just trying to clean everything up and test tomorrow.

just want to be able to break in at 30-35mph and not worry about overheating during break in.

[Downsouthdio]

That "o ring" needs to be on no matter what.. And the bolts that hold the cylinder down you need to clean real good to slide thru.. You want your compression around 120

[Downsouthdio]

Compression test again with throttle open.. Kick start start not electric.. I still real high add metal head gasket..remember that "o ring" needs to be on at all times

[kauaianman]

Compression test again with throttle open.. Kick start start not electric.. I still real high add metal head gasket..remember that "o ring" needs to be on at all times

yup got the O-ring on. and i also use the O-ring when i add extra head gasket.

WOT compression is 160. goes back down to 155 when i close throttle.

all compression test done with kick starter never electric.

[kingkamehameha]

Crank needs to be taken out anytime that you do port work. If your compression is at 155 you will blow a hole in your piston with the pump gas