1996 KAWI STS - Starts but dies

[Purple Rocket]

I have a 1996 Kawi STS (JT750-B2) with my second SBT motor in it. The first motor died due to "foreign debris" according to the warranty sheet that came with the second motor. Got the first motor in mid April '05, the second at the end of June '05 - just in time for the 4th!

I had rebuilt the Keihen CDK2 carbs this past April when I installed my first motor, so when the second motor arrived (with a new external gasket kit too BTW), I did not do anything to them other then just make sure they were physically clean and re-installed them on the new motor.

Now just to cover the bases here, after the first rebuild, my STS ran beautifully. Low speed, High Speed, idle, you name it. No problems there.

After the second rebuild, it started great, idled great for about 30-seconds. I did not rev it up. I then ran it on the hose at my house for about 8 to 10 minutes - no problem. All seemed well.

I put it into the water on Friday, and it started up great, ran great for about 2 minutes, then starting dying. At first, I could re-start it using the choke, but it would die almost immediately after I turned it off. If I started it, and tried to give it gas, it would die. Then it got the the point where it just would not start unless I sprayed starting fluid into it - which I don't like to do and only did about 3 times just to see if it would run at all. Now, it will only run if I pour gas/oil directly into the carbs, and only as long as it takes to burn it off and then it dies. It does start easily, sounds good, and seems to run nice until the gas burns out. BTW, I also tried switching to RESERVE to see if that made any diff - nope. I also changed the plugs twice - just to make sure - no help.

What is going on? Could it be that the two filters inside my tank alre already clogged? After the first rebuild, since I had the engine out, I cleaned the tank and filters at that time. The filters were actually rattling around in the tank, so I cleaned and re-installed them. I have only run about 3 1/2 tanks of gas since then. Of course, this is with extra oil added to the gas (following break-in procedures) since I am using an oil pump (brand new and bled before using).
Anyone? Rebuild the carbs again? What am I missing here?

[Technical Support]

Re: 1996 KAWI STS - Starts but dies

Well you have definitely pinpointed your problem down to the fuel system. just because the carbs were done a few months ago doesn't mean they aren't in need of it now. I would get two more kits and go throught he whole system this time. You may have water in your tank, you may have trash in the system and clogged filters...

[Purple Rocket]

Re: 1996 KAWI STS - Starts but dies

I'll give that a go. 2 more carb kit sets are cheaper then having someone "look at it" and tell me the same thing. Is is normal for newly rebuilt carbs to need to be re-done so soon?

Let me go ahead and ask this too. Apparently, the filters at the ends of the intakes in the fuel tank are/have been a problem on numerous PWC systems I have read about in other posts. Apparently, they were a problem on my PWC at some time in the past, because they were knocked off and floating around in the tank. Are they really necessary? I mean, I ran my PWC for almost 4 years before I even found out that the filters were not there - and never had a problem in that area. I guess it is because I try to make sure and use good quality oil and gas in my ride.

Now of course, I understand that it only takes one large glob of gunk to clog the whole works, and the filter will certainly prevent this, but if the filters clog that easily, then I don't need that much hassle.

[Purple Rocket]

Re: 1996 KAWI STS - Starts but dies

:emoticonn Well, I finally had the time (and money) to find out what was going on. To make a long story short, I screwed up - big time. :o Fortunately, other then lost pride and lost time riding my rocket, it doesn't appear that it is going to cost me more $$$. Yea! Now no one likes to admit their own F3's (read as fat-fingered F### ups), but if what I did helps anybody out there - then great! If more folks will own up and admit these on the forums, they would end up being even more helpful then they already are.

OK, enough soap boxing! I crossed the water exhaust manifold water pump pressure indicator spit valve line with the Keihen CDK II excess fuel return to tank line. How did @#$@# did I do that!? Stupidity, lack of double-checking, and working too late into the night (3am) to have my ride ready to go. I was pumping my excess fuel out the water spit valve, and water from the exhaust manifold into my fuel tank. Once the water level reached the point where it was being sucked into the pickups (remember folks, water sinks in a gas/oil mix) - deadsville! Which also explains why I could get it to go when I dumped gas/oil directly into the carbs.

So, I cleaned out and dried the tank (without removing it I might add - very clever method given to me by my Dad BTW). Cleaned out the lines (air hose).
Took off and cleaned the carbs (no I did not rebuild them - I may later on, but we will see), replaced the filter, and whammo - the engire fired right up and purred like a kitten.

Final test is this weekend. We shall see how it all goes. Wish me luck!

Lesson learned (ie the moral of the story)? Double-check, double-check, and then have someone knowledgeable double-check you before you fire it up. Also, forget putting in all nighters - more likely then not, you are too tired to ride all day the next day anyway after working like a dog getting it ready, and god forbid you screwed something up.......

[Technical Support]

Re: 1996 KAWI STS - Starts but dies

Thanks for posting back!

[Purple Rocket]

Re: 1996 KAWI STS - Starts but dies

Tested it this weekend. Looks like I am going to have to do something with the carbs anyway. Let me break it down.

1) Cranks and idles - no problem. I let it warm up before I did squat.
2) Giving the goose for the initial hole-shot, bogs and dies almost immediately.
3) If I turn the choke full on, and give it some gas easylike, it starts to rev up and come up to begin planing out, but I have to quickly turn off the choke to get the revs to go past a certain point or it will bog and die again. If I get the revs to come up and then give a quick off/on/off of the choke, the engine to "jump" out of the hole and go. I may have to do it two or three times to get it going.
4) Once I get it going, if I want to run flat out - which I really do not want to do right now as I am still breaking it in - I can leave the choke off and give it full throttle and it will go fine. I just cannot let up the throttle any at all or it will bog - ie all the way, or dead in the water. This is just not doable of course - break in or not.
5) If I want to run between 4-6K variable revs, I can put the choke on about 1/2 and run it all I want - no problems, I just have to constantly man the choke as it will not stay on by itself. Doing this, I ran almost a full tank of gas.

The motor itself is running fine - compression check at the end of the day was showing ~~ 125 for both cylinders, and I did not foul out the first set of plugs even though I had extra oil in the tank.

Happy to resolve problem A! :), on to problem B! :emoticonn My dad and I are wondering if we put a low pressure inline electric fuel pump (2.5 - 4psi max) after the on/reserve switch and before the fuel filter if it would work to resolve what appears to be a running lean problem - and make it easy to start, etc without flooding the carbs, running super rich, etc. Anyone have any ideas/opinions about this? Anyone ever done this? We actually have the pump already, but we don't want to do anything to blow this motor up - again.......