Honda Spree and Elite 50 Forums

another build.

specs:

SYM DD50 block Ported
polini corsa Ported
Ctblack manifold Ported
Taida ministroke crank
7.9 gearing
Kelli Pulley
SEF Ramp
Kelli Heavy Clutch
28OKO carb.
BMF V8 exhaust
ZX transmission


heres the beginning:

all dirty 8K miles!


lots of oil and sludge

cleaning everything up

remove motor and everything else







tiny stock intake windows.


lots of humps to take out

split case and breathe in those little aluminum flakes for a few hours!



before


after


before


after


before


after






before


after

You should probably cut your gasket to match the block and the cylinder to the block, not just block matching to gasket, there's a huge air flow stop in the corners. Picture the air flowing. Minarelli corsas are worse matched.

1man8scoots wrote:You should probably cut your gasket to match the block and the cylinder to the block, not just block matching to gasket, there's a huge air flow stop in the corners. Picture the air flowing. Minarelli corsas are worse matched.

yup the SYM block is smaller the the AF16 so i match gasket to cylinder and then open case for flow even to cylinder. Cylinder openings are bigger than the stock block openings. AF16 transfer ports are wider/bigger stock than SYM.

i guess i could have opened up the transfer ports bigger on the corsa then match block for the bigger corsa.

i usually degree everything before cutting a custom gasket to set port timings correct for the ministroke crank.



after i find the correct base gasket thickness to get the transfer ports to the correct timing i want, i port the exhaust port to finish off the port timing correction.

i usually shoot for

ex-185*-190*
trans - 130*-135*
bst - 125*- 130*

in this case a 1mm base gasket got my boost and transfer timings right in the zone and i had to open up the exhaust port about 1mm to get that timing correct.



custom cut base gasket matched to cylinder then matched to case







final numbers came out to be

ex- 187*
tns- 135*
bst - 128*

should be OK with 32* of blowdown should give good powerband.

any other suggestions?

cleaned up cylinder. didn't need much just knife edge transfer openings, chamfer all ports inside cylinder, open exhaust port to accomplish desired 187* of exhaust timing with 1mm base gasket.







after porting and setting up for the correct timing i add whatever head gaskets are needed to get the compression to 120 for street riding.

CT black was next. great manifold but ugly casting inside from the factory








all cleaned up






also need to clean up mating surfaces so no air leaks

AWESOME!

How's the build going?

legit work!

I'm interested to know how it's going also. According to my test timing engine and corsas on hand the timing you're looking for wouldn't be done with a simple 1mm base and 1mm up porting of the exhaust. The extra .8mm you added with the fiber gasket and longer stroke you would be over 190 on ex port and blow down wouldn't be near 32. Also with the numbers you're saying you have, you have 27 degrees of blow down. That's not a guess, that is simple math.

Simple formula for would be engine and cylinder porters of the world....
Take your exhaust port timing, subtract your transfers, take that number and divide it by 2. There's your blow down. Simple truth.

porting work looks siickkkk dude