Asking for all 550 Gurus knowledge

550surf

550surf

I bought a ex race 550sx and double trailer 3 years ago. used the ski once, i ( i now know) a structural fb hull hole was in the hull so it filled and died. we poured the water out and went home and the ski wasnt used again.

around 2 months ago i decided to teach myself about engines, mainly the 550. after 2 months of working on it, alot of learning and back and forth i finally rode it today. OH THE SMILE. anyways i tried tuning it and got lost then got even more lost. used up my battery trying to start it, findig the correct mix. was just attempting the LS screw to find idle and 0-30% ( the first circut) but nothing.


what i would like is a default setting. for the setup.


Its a 550 ( maybe bored- has wisco pistions ) with a westcoast pipe and DUAL 38s both round body pumps. It has a lightened fly wheel, total loss ignition and ocean pro high compression head. I despressly need for both left and right carbs a number of "turns" from the base as a base/default setting for now and future. somthing like 2 or 2.5 i tried for low and 1.8 for high. its not what i want.
also, my understanding of what a "turn" is a 360 degree reveloution. not just a turn of the wrist. is this correct? about the "turn" is a full 360 rev.


also if u feel like taking a stab at this question go for it.
so after alot of wasted ignition on trying to find the idle point and even just start i think the engine may have been quite hot at some times. like u dont wana hold ur finger there really hot. so i pull plugs out and go to turn it over ( plugs out) i notice by covering the holes that the front cylinder is barely pushing my finger off while the rear is pumping even harder then normal, i have now, super low compression in the front cyclinder.

why is this?
how did this happen?
what is possilbly the problem? reed valves? pistion rings?


most importantly tho, i need a default carb setting for my race set up 550 ( was actually ex racers ski ).
it only has 2 screws. LS and HS. id like to be able to idle, never had that.

thanks so much guys,
super stoked i experienced a 550 hull today but also anoyed at this sudden low compression.


cheers

550surf
 
Big Kahuna

Big Kahuna

Administrator
Location
Tuscaloosa, AL
Start at 1 turn out on each LS and HS. Back ski in the water and crank up. adjust LS and Idle screw to where the ski cranks and idles smoothly. Then you will need to start riding it. See how it feels.
 
550surf

550surf

yeah i somehow fluked a rideable tune but it was quiet hot and i didnt want to do any damage so i decied to try adjusting but i got lost and the defauts i thought would work again now didnt.

I turned it back to 2 turns (360 degree reveloutions from base) on both LS and 1.8 turns Hs and was able to flush it
I stripped the ski down today as i have a new sterring cable to install. farkkkdd how hard getting the pole off is....

anyways,

you recon i cooked something in the cylinder? but why only that cylinder then ? dad said reed valves but idk?
what u recon?
 
Freestyla

Freestyla

Location
Gold Coast, Queensland,Australia
Hey mate, the manual settings for the 550 are Low: 1&1/8th out from a lightly seated position, and High: 5/8th out. You didn't say whether you were running water through the ski when you were trying to tune it, anytime you run your ski it has to have water circulating, never run it without water for longer than 15 seconds. It could be the reeds, but it could also be a head gasket. If you haven't already, rip the head off, check the gasket and when you put it back on, use a THIN coat of silicon gasket sealer or Threebond 1211, (be careful you don't block water cooling holes in the gasket and make sure it is put back on the right way, (it only goes on one way). If it isn't the gasket or the reeds, then the rings have gummed up (happened to me once before) and won't expand in the bore. Give all this a go and get back to us. Also if you don't know how long since the carbs have been rebuilt, get a kit from ebay from Winderosa and rebuild them, easy job just make sure you put stuff back in the order you took it off.. All the best mate, let us all know how you go. Matt
 
amitchell

amitchell

Location
Victoria BC
Get rid of the poop round bodies and get a single sbn44 you will be much better off. The round bodies are tough to get tuned in correctly especially on modified boats. They have no removable jetting.

Its possible that one cylinder was leaned way out due to crap carb. That would explain the heat and seizure.

Seriously don't waste your time with those carbs. get the single SBN44 and ride it.

The round bodies are also poor starters and idlers.
 
fastgtfairlane

fastgtfairlane

Location
Charlotte, NC
+1 on ditching the round bodies.. you could run the dual 38 sbns.. i run dual 38s too and could give some settings to start with.. the sbns have changeable jets which make tuning a breeze.. the fuel pumps also are much better as are the metering holes.. much more responsive which also helps with tuning.. finding a single sbn manifold for a reed engine is very expensive and hard to find.. the sbns will bolt right up
 
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