300/440/550 Understanding a 550

S

Skatike27

Location
United States
So I know I just posted about getting parts for a 300 motor but over the weekend a running 550 came up for $100 bucks and I figured why not go bigger right away. So I took the carb rebuild kit i got for the 300 carb and put it in the 550, from my understanding it is the same. I transferred the 550 motor from the 550 hull to the 300 hull again because from my understanding the 300 pump with a 550 motor is more desirable. Got everything in and mounted up, cranked it over and kept cranking. Went inside double checked the needle positions, top left 15/16, middle right 1-1/8, bottom left 1-15/16. Tried again, full choke, crank-crank-crank nothing. Took off the spark arrestor, choked, then while choked, placed my hand over the opening of the carb, thing sputtered and then rev'd right up to what sounded like "im going to blow up mode" i quickly killed it. Tried to get it to fire off again after that, no choke, no hand choking, wouldnt pop. This motor is stock, has good compression, I can see fuel being pumped as I put on a clear-ish line, needles look brand new (i cleaned them), etc.

Im leaning towards and air leak but any other input would be nice. I also dont like the "module" that has two wires going to it and fuel going to it, it seems to me that anything with electricity and fuel going to it cant be good.

Thoughts, questions, concerns?
If anyones bored and in the area- Delavan, WI. P.M. me for an address.

Thanks again,
Tom.
 
two81's

two81's

Location
Baytown Tx
I would check the spark. After you crank it a few times,see how wet the plugs are. It could be flooded and might need to be cycled a few times with the plugs removed.

I would ohm the coil to check condition,could be weak.

I know there are a few threads or links on here on how to leak check a 2 stroke. That module you speak of is a rev limiter which can be removed if you prefere.
 
stagesrt4

stagesrt4

see ya out there
Site Supporter
Location
St Charles IL
that module is REV limiter...

if you remove it(which is ok) you will need to add a restrictor to the fuel line.


well if ski starts by pooring some fuel down carb throat but wont start on it own then its pointing to carb...

also check that you check valve is good on the fuel tank
 
S

Skatike27

Location
United States
two81's said:
I would check the spark. After you crank it a few times,see how wet the plugs are. It could be flooded and might need to be cycled a few times with the plugs removed.

I would ohm the coil to check condition,could be weak.

I know there are a few threads or links on here on how to leak check a 2 stroke. That module you speak of is a rev limiter which can be removed if you prefere.
Click to expand...


Any idea on the ohm specs? I have pulled the plugs, sometimes they are wet others dry, litterally hit or miss. I have looked at the spark with the plugs removed, seems to be quite blue or good spark.

stagesrt4 said:
that module is REV limiter...

if you remove it(which is ok) you will need to add a restrictor to the fuel line.


well if ski starts by pooring some fuel down carb throat but wont start on it own then its pointing to carb...

also check that you check valve is good on the fuel tank
Click to expand...


Ski will start with gas or starting fluid poured down the carb but will rev to very high rpms and stay there, never falls, sounds like its going to blow up.

Going to check that valve on the tank and make sure its not creating a vacuum.
 
Last edited:
stagesrt4

stagesrt4

see ya out there
Site Supporter
Location
St Charles IL
do not use starting fluid PLEASE!!

theres no oil/lubricant n you could hurt your motor



sounds like ski needs a set of crank seals or possibly base/head gasket.


i have base gaskets n maybe a head gasket if you need/want one
 
Last edited:
S

Skatike27

Location
United States
stagesrt4 said:
do not use starting fluid PLEASE!!

theres no oil/lubricant n you could hurt your motor



sounds like ski needs a set of crank seals or possibly base/head gasket.


i have base gaskets n maybe a head gasket if you need/want one
Click to expand...



A little starting fluid, not doing it everytime, I prefer gas and oil mixed accordingly in a oil bottle with a hole.

One thing I forgot to mention... the "spacer" between the intake manifold and carb
(made of black plastic) seems to chip easily as in it is brittle, im wondering now if it is cracked.

Im starting to see that these are as tempermental as the snowmobiles I own. I will report back with more later tonight or tomorrow.

Thanks for your input everyone.
Tom
 
stagesrt4

stagesrt4

see ya out there
Site Supporter
Location
St Charles IL
yes sleds n skis deal with all same issues...

no matter how new or expensive your ski is, youll still get the occasional issue
 
S

Skatike27

Location
United States
Alright bare with me, I have been sucking gas all day. Took the ski to the lake, didnt get to drive it. Tied it to the back of the truck, primed it with some gas and got it going after many attempts, got it into the high rpms and kept it there for the better part of 5 min. I then let it idle down, it idled for 30sec and died. (im assuming low jet plugged) If I had it between mid throttle and high throttle it would run good.

First off what is compression supposed to be and what is the minimum these things will run on and maximum. Need the average not the once in a million, "mine ran at 80psi" story.

Second, I took the line off the filter pod and ran it right up carb from the on/res selector and saw much better results, I then ran a line from the tank right to the carb and saw the best results.

Third, starting it out of water and gettting it to rev up= no problem. Putting it in water after having it running on land and holding it, it dies. Trying to start it right after it died, sputters, starts (barely) if I give it ANY throttle it will die, if I just let it sputter a bit it will die after about 10 secs. If I try and save it with the choke nothing will happen.

IMG_20130610_202520_389.jpgIMG_20130610_202530_636.jpg
Info-
Psi on both cylinders is 110.
Just put a rebuild in the carb
Check pictures of the carb make sure Im using the right thing.

Im not giving up. Tomorrow is another day. If anyone is in the Delavan, WI area and likes beer, come say hi. (PM me for an address)
 
Last edited:
naticen

naticen

Site Supporter
Location
wilmington, nc
I have rarely seen 135 on a piston port 550. They are always 120-125 on my gauge. I'd say even compression is most important and would guess you are alright, but low. Low compression definitely won't cause a runaway.

Sounds like several possible issues. Crank seals, gaskets, carb, fuel selector/lines... I just about always replace all gaskets and seals on any used motor I buy and then blow through all the fuel lines and make sure they are not leaking as well. I feel like 550's get such a bad rap because they are 20-30 year old motors and they all have these same problems.
 
S

Skatike27

Location
United States
stagesrt4 said:
300/300sx = 150psi stock

440 = 120-125psi

550 = 130-135psi

650/750/800 = 150-160psi

900/1100/1200 = 130-135psi
Click to expand...

naticen said:
I have rarely seen 135 on a piston port 550. They are always 120-125 on my gauge. I'd say even compression is most important and would guess you are alright, but low. Low compression definitely won't cause a runaway.

Sounds like several possible issues. Crank seals, gaskets, carb, fuel selector/lines... I just about always replace all gaskets and seals on any used motor I buy and then blow through all the fuel lines and make sure they are not leaking as well. I feel like 550's get such a bad rap because they are 20-30 year old motors and they all have these same problems.
Click to expand...




Thanks guys. I think im going to do the following, purchase a seal kit and replace everything. Going to replace all the fuel lines. Going to try and get the sbn 44 carb. Sounds like its the hot ticket to make thises skis easier to tune and keep them reliable.

Thanks again for the input all!
 
JETSKIBRATTTT

JETSKIBRATTTT

NO WATER, NO PROBLEM!!!!!
Location
COLDWATER, ONTARIO,CANADA
PWC TODAY HAS A THREAD CALLED THE 440/550 BIBLE
All your questions will be answered immediately
It is literally
The Bible to 550 survival
for the Newbie
Stick to gaskets
squish /with just a seal on these babies
will make your ski far from reliable
go aluminum base gasket with a micro fiche/copper style head gasket
best results
and reuseable
imo
J.bratttt
 
You must log in or register to reply here.
Top Bottom