120 sportjet

[batboat11]

I have a 120xr sportjet. I have owned the boat for 3 years and has never ran right. both carbs have been rebuild, the head gasket, starter and exhaust manifold gasket replaced.

The problem seems to be the top two cylinders not firing corrctly, i have interchanged the clois and the problem did not follow the parts, i did a compression test and the top cylinder is 130 and the other 3 are 160. I pulled off the plastic air intake off of the carbs and ran it it gas is popping back out of the carbs, i disconnected the linkage connecting the carbs and the bottom carb revs the engine nicely but the top one makes it sputter. the adjustment screw on the top carb does absolutly nother and bottom one does change the pitch of the engine and will stall it out, when i remove the plugs the top two are soaked.

The stator is the red one and when i ohmed out the white green and green white i got about 724 ohms.

Ant help would be greatly apprecieated. thanks Mark

 

[aksor]

Re: 120 sportjet

Remove your intake and check your reed valves.

 

[Anders67]

Re: 120 sportjet

Yepp!. With askor here.



If thats ok.

They seems to popping back a little on closed throttle, that mine does too ( throttle-shutter/axel closed).


Otherwise if it?s not starts to run when spraying start-gas ore gasoline in carb. intake. pull both plugs, ground spark-plugs good, and check the spark so it?s ok and fat blue colored.

 

[batboat11]

Re: 120 sportjet

Remove your intake and check your reed valves.

thanks i pulled the top section andthey are creacked and two are broken, i have ordered a full set of Boyesen power reeds and gaskets, i should have them done this weekend, i thank you again for your help, I will let you know how they work, Mark

 

[Anders67]

Re: 120 sportjet

thanks i pulled the top section andthey are creacked and two are broken, i have ordered a full set of Boyesen power reeds and gaskets, i should have them done this weekend, i thank you again for your help, I will let you know how they work, Mark

I have Boysen on mine. They run great.

Have them on the snowmobile also. When you have pulled the carb. Clean them too.

 

[batboat11]

Re: 120 sportjet

thanks i did install everything and it took a bit to get it started, the carbs were rebuilt last year, i adjusted the carbs and it starts right up every time, now i need to find a cover for it that will last, thanks for all of your help, Mark.

 

[hypersniper]

Re: 120 sportjet

where did you get your boysen reeds and what was the cost? i dont think i boats allows competitive links so you can send me a pm if you have the time. dont wanna get anyone in trouble.
thanks

 

[Dave10KLakes]

Re: 120 sportjet

FYI...
I have '96 Sugar Sand Mirage SportJet 120xr
I had starting problems, especially when engine was warm. recently installed fuel pump rebuild kit. Diaphram was not so elastic and stretched out. Starts now a lot easier with much less cranking. So far to good.

I'm having troubles with ignition switch. First of all, it has three positions that seem to be undocumented. By the way, I am third owner and unfortunately do not have access to previous owners. Off is when key is at 12:00 position. Then when key is turned clock wise to 3:00 position, this is end of travel, and engine cranks if in neutral. Then when force is released on key, key travels and rests in 2:00 position. Turning the key left from the 2:00 position quickly will cause the ignition switch skip past 1:00 position and land back in 12:00. There is a detente at the 1:00 oclock position but it is easy to miss. For sake of discussion, 12:00 is off, 1:00 run, 2:00 choke, 3:00 start. This seems like a typical switch but the choke part is not documented and because I wasn't aware there was a detente at 1:00, I left boat in 2:00 position and had a miserable day on the water. Then by experimenting I eventually found the 1:00 position where I found that the boat ran alot better. It is so easy to try to switch from choke position to run position and skip right over run and end up in OFF. I wonder if it is an after market switch. To make matters even more confusing is that the after market depth finder, which comes in handy on a jet boat, only works in the CHOKE position. Power is removed from the depth finder in the RUN position.

I have no idea how this CHOKE is wired into the system. The throttle control itself has a manual choke. Owners manual states that SportJet system has automatic choke and that it is overridden by use of throttle control manual choke.

 

[batboat11]

Re: 120 sportjet

sorry mine has a fuel inrichment choke which i think works outomatically, the seloniod is located o the side of the top carb.

 

[Anders67]

Re: 120 sportjet

FYI...
I have '96 Sugar Sand Mirage SportJet 120xr
I had starting problems, especially when engine was warm. recently installed fuel pump rebuild kit. Diaphram was not so elastic and stretched out. Starts now a lot easier with much less cranking. So far to good.

I'm having troubles with ignition switch. First of all, it has three positions that seem to be undocumented. By the way, I am third owner and unfortunately do not have access to previous owners. Off is when key is at 12:00 position. Then when key is turned clock wise to 3:00 position, this is end of travel, and engine cranks if in neutral. Then when force is released on key, key travels and rests in 2:00 position. Turning the key left from the 2:00 position quickly will cause the ignition switch skip past 1:00 position and land back in 12:00. There is a detente at the 1:00 oclock position but it is easy to miss. For sake of discussion, 12:00 is off, 1:00 run, 2:00 choke, 3:00 start. This seems like a typical switch but the choke part is not documented and because I wasn't aware there was a detente at 1:00, I left boat in 2:00 position and had a miserable day on the water. Then by experimenting I eventually found the 1:00 position where I found that the boat ran alot better. It is so easy to try to switch from choke position to run position and skip right over run and end up in OFF. I wonder if it is an after market switch. To make matters even more confusing is that the after market depth finder, which comes in handy on a jet boat, only works in the CHOKE position. Power is removed from the depth finder in the RUN position.

I have no idea how this CHOKE is wired into the system. The throttle control itself has a manual choke. Owners manual states that SportJet system has automatic choke and that it is overridden by use of throttle control manual choke.

Hi.

Have the same boat and year.

Look on the right side of the top carb. Do you have a thing sitting there connected with fule hose from bowl of carb. And one hose going in to air intake + one more. And two yellow electric lines connected to it ?.

That shall be the auto-choke on this engine. You shall not need to put the ing.key in some position. The choke get it?s power from the stator/flywheel when the engine runs, like a dynamo ore generator.


It work very easy.

Engine off no power to the enritciner, if cold= choke, if just turned off engine hot and starts up again soon = no choke.

Engine running power to enritchiner if cold=coke, and shall close in 2-3 minutes ( you hear it on engine running better and better after a while= lean out ).



http://www.crowleymarine.com/mercury-outboard/parts/2010_60.cfm number 22

 

[aksor]

Re: 120 sportjet

Glad you got your boat running, I got Chris Carson reeds, My steel ones were fine but its piece of mind not having broken steel pieces in my cylinders.

I was out this aft tubing with the kids and I snapped my gate control cable, Had to tie the gate open with a rope to get back to the dock, it kept going in to neutral then reverse all by itself I almost submarined when it let go.

At first it acted like it was cavitating so I figured I sucked up some weeds so I jumped in and checked the intake (with motor off of course) then on my way back in the boat I noticed the gate moving freely.