DD50 corsa

[kingkamehameha]

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.

You need to get a sanding block. Carb cleaner is a very poor way to find leaks. Most small leaks wont affect idle too much. Build a pressure tester

[kauaianman]

pressure tester built.

can't seem to seal exhaust good enough to keep pressure. made metal plate with 2 holes and used exhaust gasket underneath to seal up sxhaust side.

so far exhaust is the only area i see leaking.

any tips for sealing exhaust?

gonna buy big paper gasket tomorrow and try that...

gotta pull mag/stator again to check crank seal but gotta figure out how to seal exhaust first.

[Madman]

pressure tester built.

can't seem to seal exhaust good enough to keep pressure. made metal plate with 2 holes and used exhaust gasket underneath to seal up sxhaust side.

so far exhaust is the only area i see leaking.

any tips for sealing exhaust?

gonna buy big paper gasket tomorrow and try that...

gotta pull mag/stator again to check crank seal but gotta figure out how to seal exhaust first.

Big thick paper gaskets, I used two layers it worked fine!

[Red Eft Performance]

I have good success with these just go to your hardware store and find correct size for your exhaust port.

[bakaracer]

a boat drain plug works good too

[kauaianman]

cannot find the right boat drain plug.

tried madman method but still leak.

i put high temp RTV with exhaust gasket and metal plate. going to let it cure and see if better tomorrow.



On the other hand I also tested my ministroke 50mm and found manifold leaks. i decided that i am doing to Hondabon EVERYTHING but i can decide if i should run hondabon and paper gaskets on the manifold or just the hondabon without the paper gaskets.

area i'm talking about is where the reeds sit. i already put hondabon and paper gasket at the base where it connects to the block.

was going to use High temp RTV but i using CT chrome and the hondabon looks better.

what you guys think? hondabon + paper gasket or just straight hondabon?

[kauaianman]

got some drain plugs and worked for selaing exhaust.

pressure tested 8psi. holds pressure.

put hondabon on everything (all manifold mating surfaces and base gasket of cylinder)

switched to CT chrome.

28oko
52pilot (but highest idle at 2 1/2 turns out) i run it at 1 1/2 turns.
138 main.

around the block 3miles. crusing at 35 max varying RPM. still hitting 370 degrees by the time i circle the block?????????

bike runs good no bog or misfire just smooth riding. never tried WOT but smooth response to 1/2 throttle from cruising speed 30mph.

don''t know what else to do/test.

need more advise

[dv/dt]

how high is your compression?

[kingkamehameha]

Where is your needle clip at and also how deep are the crank seals set

[tru72]

Wat gears are you runniing in that .. 7.0/6.8?

[kauaianman]

compression 130

crank seals set in stock position (big flush, smal 4mm in)

needle position 2nd to the richest (1 down from center)

52 pilot.

28oko.

[kauaianman]

running 7.9 gears.

(stock SYM primary)

[tru72]

lol try a bigger pilot.. unported blocks can handle up to 55. Since your "porting" is only to a S block size, its still considered stock to me. did you really tune the carb? You told me that you build many motors and this is the first time you have this problem. You know that just because one motor has the same parts doesn't mean its the same jetting. You need to tune the carb , starting with the pilot, then the main, then the clip if necessary. I knew it wasnt a air leak, air leaks usually have high or hovering idle also if it did leak your plug wouldn't be a nice color. Again jst cause the plug is that certain color doesnt mean its tuned correctly..

[kauaianman]

lol try a bigger pilot.. unported blocks can handle up to 55. Since your "porting" is only to a S block size, its still considered stock to me. did you really tune the carb? You told me that you build many motors and this is the first time you have this problem. You know that just because one motor has the same parts doesn't mean its the same jetting. You need to tune the carb , starting with the pilot, then the main, then the clip if necessary. I knew it wasnt a air leak, air leaks usually have high or hovering idle also if it did leak your plug wouldn't be a nice color. Again jst cause the plug is that certain color doesnt mean its tuned correctly..

thanks tru.

i guess i "try" to build motors... first couple (72cc) that i did went good. (had to adjust carb a few times to find the sweet spot but never had overheat problems that i could not find the issue to) but now i feel like IDK what the * im doing.

the motor that i am currently working on "this build thread" is a STOCK BLOCK (no porting) DD50 with that "cleaned up" upper side of the boost port. Polini Corsa.

as far as carb tuning I think I'm taking the correct steps to determine the correct jetting.

on all pervious builds I start with the pilot jet. basically start with a guess (usually 52 for 28oko and 45 for 24oko) and go up or down from there depending on what the temps do on the test run. test runs usually around the block 3 miles at or below 30mph on speedo varying throttle position but mainly staying between close to 1/8 throttle to test pilot and needle circut.

if its running hot i try to up the pilot. if bike starts to run crappy i put the pilot back down to where it was and adjust needle setting to richer.

i try not to tune main jet until break in is over and can go WOT. but for break in as long throttle resposne is good and temps arent going up i usually run (142 main for 28oko and 135 main for 24oko)

going to try the 24oko today.

i know that these motors run better/cooler when port matched to the cylinder and intake ports are also opened up, but i know (or at least i seen) people with stock dd50 block unported running corsa with 28oko and bike runs fine. definitely not nearly as fast as a ported and fully tuned corsa and block but no overheat problems and 60mph no problem.

only recently stated trying to get more serious about building quality reliable motors (was always a hobby of mine but never really took it serious enough to get really good). always appreciate the help and input of you guys that been doing it for a living and have tried and tested many different setups and parts.

thanks again for the input and i will definitely try the 55 pilot for the 28oko before i switch to the 24.

will post results later tonight

[kingkamehameha]

Did you pressure test with the temp gauge on the head to make sure thats not leaking? When you did the pressure test how long did you leave it for