787 with new carbs will crank /run for about 30 secs but as soon as I feed it fuel it dies

[chriscornatzer]

Hi,
to all that has posted before and helped me thru their posts.
your post has saved me many an hour of guess work and testing.
Now let me catch me you up on my current troubles.
I have a 96 GSX w/787 that has been going thru a on going restoration.
I was running good with :
new fuel lines
carb rebuild
145ish compression
new starter
rehab the INFO CENTER
Start button
VTS button
anyway your getting the picture now im sure.
It ran as good as it did when we put it in the water the first time.
It still needed new paint and epoxy on the bottom so brought it in and flipped it over to start that project and as my luck would have it I had to go out of town for work for about 11 months.
I get back and complete the bottom and get it up right and it seams as this is where my troubles start.
I get it all back together and get it ready to do a stand test and the shaft breaks to the prop.
Ok I replace that and it is working fine.
As I was running it on the trailer it was running fine or so it seemed.
Get it to the lake and its like it was running on one cylinder.
Get it home and check for pinched fuel lines and break down the carbs to look thru them but seen nothing really wrong but knowing that I would be replacing them soon because they did look iffy in a over all condition.
got a set of new MIKUNI carbs from jetski parts with acc pump.
But now I can only get it to crank/run for about 30sec. and when I try to give it gas it kills it.
Yes I set the low speed screws at 1 1/2 turns out.
I have not had it running long enough to tell what the idle speed is yet.
Now I told the story about the shaft to see if that could have snapped the flywheel key and it give this action I am experiencing now. I will say for the 30sec. it dose run it sounds like its in great shape. its only backfired a couple of times while trying to get it running not like as if it were out of timing.
Any thoughts or help would be greatly appreciated.

 

[FL-Rider]

Maybe the spark plugs fouled from sitting in oil when upside down? 2 strokes can hold a little residual oil in the crankcases after shut down.
Maybe run some tests on the fuel supply to make sure no air leaks or restrictions on the suction side?

 

[chriscornatzer]

Thanks FL,
I do have new plugs in.
Not sure about how to go about testing the lines and at what pressure would be correct to test at.
Is their a procedure in the manual?
I have a hard copy and have thoroughly went thru it but don't remember a test for fuel lines and not wanting to add to my troubles with over pressure or telling myself a lie with under pressure.

 

[FL-Rider]

One way to test would be to disconnect the fuel supply line from the carb and splice in a short clear polyurethane line. If you get steady bubbles then you likely have a leak allowing air in. If your engine won't run to do the test, put a longer clear line into a gas can and get a siphon going. If you can't start a siphon or you see bubbles, then likely you have an air leak.

 

[POPPS]

I usually block off the return lines, block off the pulse fitting so water doesn’t get in there, take an air hose to the fuel inlet, and put the carb in a clean white pail ( if you don’t have the mikuni popoff gauge) you will easily see any leaks,,,same for the rear carb.

 

[chriscornatzer]

thanks guys for all the feed back but wound up buying new carbs and got it back together and spun a bearing within 5 min of starting it up. so who has a great reputation for reman motors

 

[mikidymac]

Nobody has a great reputation, rebuild it yourself.

 

[Lothsahn]

Nobody has a great reputation, rebuild it yourself.

Isn't SBT "good"? As in, you'll get what you pay for, which is a professionally reman engine with a quick turnaround that's using parts that are "just good enough" and should last if you don't hot-rod it at all? But not nearly as bulletproof as OEM?

I've got a couple years on my SBT and have been pretty happy with it...

 

[mikidymac]

Isn't SBT "good"? As in, you'll get what you pay for, which is a professionally reman engine with a quick turnaround that's using parts that are "just good enough" and should last if you don't hot-rod it at all? But not nearly as bulletproof as OEM?

I've got a couple years on my SBT and have been pretty happy with it...

Every ski in my area with a SBT has blown up in short order. So personally my answer is no, SBT is not good enough from what I have personally seen. There are two blown up SBT 787 RFI engines across the street from my driveway I see every day.

 

[WhiskeyD]

Isn't SBT "good"? As in, you'll get what you pay for, which is a professionally reman engine with a quick turnaround that's using parts that are "just good enough" and should last if you don't hot-rod it at all? But not nearly as bulletproof as OEM?

I've got a couple years on my SBT and have been pretty happy with it...

A friend bought a SBT 787 this summer and it showed up with one RAVE housing missing a huge chunk. Broke off the cap mounting points so it was not useable. They just painted right over it and sent it out. Then tried to fight him for shipping both ways!