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1995 GTX 657x starting problems

csmelone

Member
Messages
25
Water Crafts
1998 gtx limited
(2) 1996 spx
New here to the forum but I have been working on seadoos for a few years. I recently picked up a 1995 gtx with a 657x. I have searched the forums but I couldn't find anything on this topic but here's the background to it: The guy before me bought it to make his project but didnt know what he was doing. He told me the previous owner started it and ran it in front of him. The issue was it was taking on water through the drive shaft. I guess this year and model doesn't have a carbon seal and boot but the guy replaced the seal on the drive shaft. I rebuilt the carbs, the kit came with multiple different springs for the pop off and there wasn't a perfect match to what was already in the carbs so I used the springs that were already in it(nothing wrong with them, carbs were clean to begin with). Put all new fuel lines in and took out the gear for the oil pump so it can run on premix, put premix in the tank and hooked up the oil lines the way they were before and put in new spark plugs. The ski will start but only when I hold it at wide open throttle but then dies after a second or two. When trying to start it, without touching the throttle, you can see the fuel moving into the carb, moving to the left one, and returning back to the tank. The plugs look wet with fuel after trying to start it. I ran a spark test and it shows both cylinders are working fine. I never touched the RV and either did the guy before me but when it fires up it almost sounds like its backfiring and sends some fuel and a lot of smoke out the carbs. Would a mouse house in the exhaust somewhere cause this? I can't seem to figure out whats wrong. Any help would be appreciated.
 

mikidymac

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Water Crafts
2003 GTI
2001 XP
1996 XP
1996 HX
1991 Superjet
2001 Superjet
Sounds like your needle and seat are leaking. Did you replace them and check for leak down?
 

csmelone

Member
Messages
25
Water Crafts
1998 gtx limited
(2) 1996 spx
Sounds like your needle and seat are leaking. Did you replace them and check for leak down?
Needle and seats are brand new. Don't have a leak down tester. Do you think its a bad head gasket/crank seals? I got it kinda firing before rebuilding the carbs but wouldn't really stay running. Not sure if that helps. Makes me think its carbs.
 

mikidymac

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Location
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Water Crafts
2003 GTI
2001 XP
1996 XP
1996 HX
1991 Superjet
2001 Superjet
It sounds like it’s flooding from leaking needles and seats. You have to check pop-off and leak down. It’s Easy and cheap to make a tester.

The flooding will cause the hard starting and backfire.
 

csmelone

Member
Messages
25
Water Crafts
1998 gtx limited
(2) 1996 spx
It sounds like it’s flooding from leaking needles and seats. You have to check pop-off and leak down. It’s Easy and cheap to make a tester.

The flooding will cause the hard starting and backfire.
I made a tester the other day and gave it a shot. The pop off was very low, around 10-12psi so I put different springs in and got the pressure to around 30-32 in each. It started to fire up more than before and sounded better than before but still wasn't enough to stay running. The seats aren't leaking. Still not sure what it could be. Any ideas?
 

noviceskier

Active Member
Messages
549
Location
Tennessee, Knoxville
Water Crafts
96 Seadoo HX
97 Seadoo GSX
95 Kawasaki 750 STS
96 Kawasaki 750 STS
I made a tester the other day and gave it a shot. The pop off was very low, around 10-12psi so I put different springs in and got the pressure to around 30-32 in each. It started to fire up more than before and sounded better than before but still wasn't enough to stay running. The seats aren't leaking. Still not sure what it could be. Any ideas?
Well if everything is set where it should be, wouldn't the idler screw be the next culprit?
 

gazzaskirepair

Active Member
Messages
646
Water Crafts
RXT. RXT IS SPEEDSTER 2006 REPAIR SEADOOS WEEKLY FOR CUSTOMERS
Are plugs fuel fouled or oil
If the engine hasn’t had crankshaft seals replaced in a long time it could be oil fouling
I had the same same ski would run great on trailer but under load on water would not rev
Put a new overhauled crank with with 4 new seals ran all day every day

how is the oil injection lines connected
You still need the oil tank system to lub center drive rotary valve shaft
 

csmelone

Member
Messages
25
Water Crafts
1998 gtx limited
(2) 1996 spx
I went through the carbs again, this time setting all the adjustment screws to stock. The low speed screws were previously at 2 and 1/2 turns out as opposed to stock that are 1 and 1/4. Now it doesn't seem to be getting fuel as the plugs are dry and you don't see fuel getting pulled into the carbs. I tested the seats and they hold pressure and the pop off is set properly. I am lost here. Not sure what to try next. The rebuild kit wasn't genuine Mikuni but was not a cheap kit either. I got it off of bay area power sports. I am hesitant to spend more money on a genuine kit if it is something else causing the issue. I'm not in the this ski for very much and would like to keep it that way.
 

mikidymac

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13,651
Location
California
Water Crafts
2003 GTI
2001 XP
1996 XP
1996 HX
1991 Superjet
2001 Superjet
There is no reason to move forward with this project if you are going to try and run the aftermarket carb kits.
The reason we keep beating the Genuine Mikuni slogan to death is because it is true and there is no way around it.
 

csmelone

Member
Messages
25
Water Crafts
1998 gtx limited
(2) 1996 spx
its been a while since ive worked on it but I put a genuine mikuni carb kit in it and it still wouldn't fire. Figured out the RV was way out of timing. Reset that and it runs great now on the trailer. Put it in the water today and started right up but anything past 1/4 throttle it just bogs and won't go. 1 or 2 times it took off pretty good and I got it to full throttle just fine but every other time it kept bogging. I took the plugs out and they looked pretty dry so I'm not getting enough fuel. The pop off is at 28ish in both. I finally got a compression tester thats accurate and both cylinders read 140. Is the pop off pressure too high or do I have another issue? Seadoosource says 19-35 psi for these carbs and I used the smallest spring the kit came with so I'm not sure if it is the pop off or not. The larger spring had them closer to 40psi.
 

csmelone

Member
Messages
25
Water Crafts
1998 gtx limited
(2) 1996 spx
this is probably going to sound stupid but due to being in a rush and just looking to test it real quick I didn't put the airbox on and I rode it without the seat on to check for leaks. Would this cause it to run like that?
 

mikidymac

Moderator
Staff member
Moderator
Messages
13,651
Location
California
Water Crafts
2003 GTI
2001 XP
1996 XP
1996 HX
1991 Superjet
2001 Superjet
Yes, but also using the springs in the kits is wrong and will give you a poor running ski.
You should be running a 95 gram spring I am pretty sure and those are not in the kits.
 

Mazachs

Member
Messages
38
Location
Levis, Quebec, Canada
Water Crafts
95 GTX657x
Does anyone already tried the kit from OSD?
This kit has Genuine Mikuni parts exept for needle, you have to check the option box to have the Genuine Mikuni:

I also have a 1995 GTX with 657x engine. I need to do a carb rebuilt and I want to find to best kit to do it. I leave in Canada, so i need to have the kit ship to Canada. Any suggest?
 

Seadoo Tuner

Member
Messages
124
Location
West Coast
Water Crafts
1996 Sea-Doo SPI
I also have a 1995 GTX with 657x engine. I need to do a carb rebuilt and I want to find to best kit to do it. I leave in Canada, so i need to have the kit ship to Canada. Any suggest?
I purchased some mikuni parts from one of their Canadian distributors last summer and they had some carb kits, not sure if they would have what you need but may be worth a try. Distributor is Trans Can Imports and they have locations in Edmonton and Richmond ( I dealt with the Richmond branch).
 

mikidymac

Moderator
Staff member
Moderator
Messages
13,651
Location
California
Water Crafts
2003 GTI
2001 XP
1996 XP
1996 HX
1991 Superjet
2001 Superjet
For carb kits I like OSD or Westside Powersports Seadoo.
For OEM parts I use Seadoo Warehouse or Pro Caliber out of Oregon.
For WSM or Hydroturf PWC Muscle
And for used parts Westside Powersports.
 

csmelone

Member
Messages
25
Water Crafts
1998 gtx limited
(2) 1996 spx
I put the 95 gram springs in and I'm still having the same issue. I only backed it into the water this time with it still on the trailer so I'm not sure how much this affects it. It ran a little better and I could finesse the throttle a bit to get it run wide open but it mostly just fell on its face whenever I gave it gas. I adjusted the high speed out 1/4 turn each but didn't make much difference. Pulled the plugs and they looked pretty dry. Not sure what to check or what needs to be adjusted
 

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