Custom/Hybrid Help with DASA 1200

Superjetjim

Superjetjim

X-
I'd go for a new one way valve and new needle/seats for what they cost first..

Also ha e you tried back the low end needle out by 1/4 turn - does that sort he flat spot?

Have you changed the plugs?

Jim
 
Breese08SJ

Breese08SJ

Location
New Jersey 732
I just had the same problem recently. With low pop off pressure ( yours around 20 ) Mine around 21-21.5 and a motor that vibrates a decent amount sometimes from stiff non-oem mounts can cause the needle to leak or dribble as you have described ultimately introducing an excessive rich condition. The engine wants to see atomized / vaporized fuel not raw puddles of gasoline. If possible check to see if the carbs are leaking by taking hood and flame arrestors off and riding it at idle. If they are you can increase the needle and seat pressure fairly easy ( just for diagnosis ) by stretching then with your fingers. If you are careful and stretch them 2-3 mm that should give you a 1-3 lbs increase in seat pressure and might help you diagnose if it is seat leaking causing your problems. Not sure how old your needles are but I would suggest replacing them if they are not new this season. Hope this helps you. Kenny
 
hink320

hink320

Location
sask, canada
Thanks for all the help, I got 'er fixed tonight!! I don't know if I missed it the first time or if it worked it's way through when I fired it up to test it yesterday, but I found some crap in the one carb's jet housing. Looks like silicone and it had the high jet plugged off. I water tested tonight and it ran great. When I had the carbs apart I stretched the springs out a bit and now I have a popoff pressure of 23 psi on both.
 
Superjetjim

Superjetjim

X-
hink320 said:
Thanks for all the help, I got 'er fixed tonight!! I don't know if I missed it the first time or if it worked it's way through when I fired it up to test it yesterday, but I found some crap in the one carb's jet housing. Looks like silicone and it had the high jet plugged off. I water tested tonight and it ran great. When I had the carbs apart I stretched the springs out a bit and now I have a popoff pressure of 23 psi on both.
Click to expand...

Great result! Glad your sorted :)
 
E

egbrig

Just for the record, stretching springs will work for a short duration but the springs will return to their original length and the gained "pop off" will be lost. The "pop off" will return at different times so each carb will wind up having different pressures fairly soon. Just something to be aware of.
 
KTM434

KTM434

Jamie FN Hickey
Location
Palm Coast FL
Just for future reference to anyone who has these issues, I've had the coupler loosen up on dual carb linkage causing the slave carb's butterfly to float around to any position it wanted (not usually closed) so it would spudder down low then come alive once the other carb was flowing a similar amount of air. Outside of the water when I blipped the throttle it would rev high and stay there on its own but not run away. The stop button would always kill the engine so it was obvious it wasn't running away. Tightened the coupler for the carb linkage with the carbs back in sync and everything was back to normal.
I've also had a broken reed that would rev fine out of water and give a good compression test but you could see fuel droplets spraying up out of the carb throat when revved. In the water it was like 1 cylinder dropped under heavy throttle... Feather the throttle and it would come to life slowly almost as if it was ignition related then it would rev nicely until you let off then gave WOT or heavy load again then it would drop a cylinder again. The signs of this were easily seen. I could see milky white and blue oil/water/fuel all around that carb from the blowback through the carb
 
DAG

DAG

Yes, my balls tickled from that landing
Location
Charlotte, NC
egbrig said:
Just for the record, stretching springs will work for a short duration but the springs will return to their original length and the gained "pop off" will be lost. The "pop off" will return at different times so each carb will wind up having different pressures fairly soon. Just something to be aware of.
Click to expand...
Whats the proper way to micro adjust psi so they are even within 1 psi? Buy a bag a springs and see which ones run high?
 
Philip Clemmons

Philip Clemmons

Owner, P&P Performance
Location
Richmond, Va
DAG said:
Whats the proper way to micro adjust psi so they are even within 1 psi? Buy a bag a springs and see which ones run high?
Click to expand...
I have tons of springs. They all test different. Finding the closest two is your best bet. Minor tweaks on the arm are ok, but you can only adjust small amounts.
 
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