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Re: DD50 corsa
Posted: Thu Jul 12, 2012 9:16 pm
by Downsouthdio
Thats crazy high comp.. You may end up with 3 gaskets. I have 2 to get mine at 125
Re: DD50 corsa
Posted: Fri Jul 13, 2012 12:59 am
by veedubh20
well, I dont have trouble using polini gasket base and oring head gasket.
I dont play on compression ratio gaskets.

Re: DD50 corsa
Posted: Fri Jul 13, 2012 7:33 am
by Downsouthdio
Well i dont wana fry my engine either , i can pull more power out of it
Re: DD50 corsa
Posted: Fri Jul 13, 2012 10:31 pm
by kauaianman
added head gasket again. compression now 120-125.
motor still running hot.
I have since put hondabon with the base gasket to ensure no leaks.
I'm starting to think it's the cylinder.....
like i said the piston sits a good 1mm below the exhaust port on the bottom stroke. maybe when the exhaust port is all the way open the 1mm bottom lip is causing bad airflow out of the exhaust.
this is the first cylinder that i put in that sits below the exhaust port.. they are all usually dead flush with the bottom of the exhaust port.
I seem to have tried everything with this block. don't know what to do next.
going back to stock carb and mani. soon. just to try
Re: DD50 corsa
Posted: Fri Jul 13, 2012 10:36 pm
by kauaianman
kingkamehameha wrote: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
only did very minor port work and only on upper portion of boost port. i just soaked some rags with oil stuffed them in the crank area, flipped the block upsidedown, and used a small file and very frequently wiped out all the filings as much as possible.
Corsa boost port not much bigger than stock so not much to clear.
Re: DD50 corsa
Posted: Sat Jul 14, 2012 12:22 am
by tru72
kauaianman wrote:kingkamehameha wrote: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
only did very minor port work and only on upper portion of boost port. i just soaked some rags with oil stuffed them in the crank area, flipped the block upsidedown, and used a small file and very frequently wiped out all the filings as much as possible.
Corsa boost port not much bigger than stock so not much to clear.
thats not porting ...
boost port helps in cooling the motor as well...
Re: DD50 corsa
Posted: Sat Jul 14, 2012 12:57 am
by kingkamehameha
Boost port needs to go straight down thats why the case needs to be separated an crank taken out. I doubt your getting hot because of that. You need to do a correct pressure test on your motor and then get back to us
Re: DD50 corsa
Posted: Sat Jul 14, 2012 1:43 am
by kauaianman
thanks for the advise.
i usually cutr the boost port straight down. i was lazy and just wanted to clean up the top a little.
still working on making a pressure tester.
i dont think an intake leak is causing the heat because wheni soak the intake (the entire intake) with carb cleaner i get no change in idle at all.
i would think a manifold leak big enough to run the bike lean would be found with some carb cleaner.
and the weird thing is the plug shows no signs of running lean.
Re: DD50 corsa
Posted: Sat Jul 14, 2012 1:45 am
by kauaianman
the other day that minor leak on the boost port was bothering me so i pulled the head and put hondabon on with the aluminum base gasket.
sopme pics
Re: DD50 corsa
Posted: Sat Jul 14, 2012 1:47 am
by kauaianman
made sure hondabon was even all around.
Re: DD50 corsa
Posted: Sat Jul 14, 2012 1:50 am
by kauaianman
after putting the hondabon i used only original corsa O-ring head gasket and got 150psi compression

- 2012-07-12_16-58-41_423.jpg (28.35 KiB) Viewed 6562 times
tried it out and ran hot so i pulled the head again and used a regular size head gasket with the corsa O-ring and compression came down to 120.

- 2012-07-12_17-08-30_80.jpg (26.79 KiB) Viewed 6562 times
still running hot.
no leaks comming from base of cylinder at all.
Re: DD50 corsa
Posted: Sat Jul 14, 2012 1:55 am
by kauaianman
tru72 wrote:kauaianman wrote:kingkamehameha wrote: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
only did very minor port work and only on upper portion of boost port. i just soaked some rags with oil stuffed them in the crank area, flipped the block upsidedown, and used a small file and very frequently wiped out all the filings as much as possible.
Corsa boost port not much bigger than stock so not much to clear.
thats not porting ...
boost port helps in cooling the motor as well...
yeah i kno.... sad for me to call that porting at all... more like minor clean up. i though maybe it would help a little.
my friend running same setup with no porting at all on hisd dd50 block and bike run good. 250-270 degrees cruzing under 35mph. all bolt on no adjusting/tweaking anything.
Re: DD50 corsa
Posted: Sat Jul 14, 2012 2:10 am
by veedubh20
what oil did you use and gas?
Re: DD50 corsa
Posted: Sat Jul 14, 2012 8:08 am
by Downsouthdio
Check your shrouds, make sure they are snapped together, you running the plug that came with the corsa?
Re: DD50 corsa
Posted: Sat Jul 14, 2012 3:27 pm
by kauaianman
using shell V-power gas. redline oil. premix 3.5oz per gal.
all cooling/engine shrouds are good and tight. i use NGK B8hs plug.
pulled the manifold last night and found leak at base of manifold.
tested base of manifold and it doesn't sit perfectly flush with the block. I gotta find a belt sander and try to get the CT back as flat as possible so there is good contact between the manifold and the block.
any good ways to do this?
i cant imagine that i have the only CT manifold with this casting issue.