1998 seadoo speedster 150

[AlG]

Hi

I recently bought a 98 seadoo speedster 150 from Tempe az. I live in Albuquerque nm. I tested the boat and It worked okay for the first 10 mins then it started to bog down. Now it wouldn't go faster than 15 mph. The left motor keeps dying when the throttle is all the way down and seems like the cable needs to either be adjusted or replaced. I checked compression and all cylinders are at 119. Is thip bad? A technician told me it's not bad but front what I'm reading it has to be 135 - 150. I'm really starting to get wortried because I spent alot of cash on it..I'm starting to feel I got ripped...

Any suggestions or help is appreciated.

 

[cdnjaguar]

Buy a compression tester and do your own compression test, then go from there. I was told 120psi by the shop and the guy said it was good. Bought a tester and got 145ish psi which is ok.

 

[AlG]

I bought a compressio tool and it tested at 119-120. Spoke to an R&S technician and he said that was a perfect compression. Is the 135-150 compression for Jetskis or for Boats? Because this guy's gotta be pulling my leg if thats the case..

 

[AlG]

In addition, i experienced some acceleration problems. when i have the throttle all the way up, it only accelerates to about 15-18 mph. any idea on what might be the issue that involves this???

 

[DSchmidt54]

what kind of RPMs are you getting when it does this ? Redlined? cause usually low compression will keep the motors from starting in the water entirely.

 

[speedster98]

I have the 98 speedster with twin 787s. Mine has 150 psi each cylinder in each engine and runs great, I am running rich on one engine though and will adjust that for next year. From what I have read on here once mine get down to 120 I must rebuild. Your engines need a rebuild. But before you go getting new engines you need to find the cause else it will happen again way too soon. Was it wear and tear or a lack of something causing the issue? With it bogging down that's a lean condition and that would cause extra engine wear and resulting low compression. Let the experts chime in on how to diagnose what lead to the demise of your engines. If they don't chime in soon try reposting with a descriptive title like "low compression cause? - 98 speedster". I've found that descriptive titles of the problem get a lot more help than generic titles like this thread.

*** On a final note: Don't ever, ever, ever buy a 2-stroke without getting a compression check!!!! **** I just was in the search for a ski and found one that looked and ran great on the trailer but had 90 psi. I completely saved myself from a BIG mistake with a simple compression check!

 

[AlG]

what kind of RPMs are you getting when it does this ? Redlined? cause usually low compression will keep the motors from starting in the water entirely.

from what i remember this is happening at 4500-5000 RPM. The Motor starts and actually, i tested it and i got 119-120 on all cylinder. I dont know if i did it right or what not. But what i did is i removed both spark plugs on one motor and i plugged the compression tool in. I cranked it and thats what i got. are you suppose to cover the other plug while testing one of them? is there a step im missing?

the port side motor also dies when throttle in on idle pos. there's a clicking that i hear but when i move the throttle up to almost halfway it stays on so i think its a cable adjustment or replacement..

 

[DSchmidt54]

Your supposed to only remove one plug at a time...... You'll need to retest

 

[robomatic12]

Incorrect, you do a compression test with all of the plugs removed and the throttle at WOT (wide open).

 

[cdnjaguar]

I there a difference doing the compression test at WOT or idle? Thought the throttle only influenced the carb, not the cylinder as well?

 

[speedster98]

There is. I get about 3psi difference when doing the test at wot. Others have gotten the same results. Its because of the fuel and oil lubricating the cylinders at wot. And yes do this test with both plugs out and spark plug wires on the grounding block.

 

[Guest_User]

I there a difference doing the compression test at WOT or idle? Thought the throttle only influenced the carb, not the cylinder as well?

Having the throttle wide open allows the cylinders to fill as much as it can to get a correct accurate reading.:cheers:

 

[cdnjaguar]

.......... Guess I know what I'm doing tmw lol

 

[AlG]

I have the 98 speedster with twin 787s. Mine has 150 psi each cylinder in each engine and runs great, I am running rich on one engine though and will adjust that for next year. From what I have read on here once mine get down to 120 I must rebuild. Your engines need a rebuild. But before you go getting new engines you need to find the cause else it will happen again way too soon. Was it wear and tear or a lack of something causing the issue? With it bogging down that's a lean condition and that would cause extra engine wear and resulting low compression. Let the experts chime in on how to diagnose what lead to the demise of your engines. If they don't chime in soon try reposting with a descriptive title like "low compression cause? - 98 speedster". I've found that descriptive titles of the problem get a lot more help than generic titles like this thread.

*** On a final note: Don't ever, ever, ever buy a 2-stroke without getting a compression check!!!! **** I just was in the search for a ski and found one that looked and ran great on the trailer but had 90 psi. I completely saved myself from a BIG mistake with a simple compression check!

Thanks for the awesome advice speedster98 and everyone who responded.

so I did the compression test again with the throttles open and i still only got 120-125 from all cylinders. so sounds like i need a rebuilt? what does the rebuilt on these motors need? i just got my Shop Manual for it maybe i can just do it myself...idk any advice is appreciated..

 

[DSchmidt54]

your looking at a "top end" rebuild, basically you'll be disassembling the head and removing the cylinders, having the cylinders bored to the next oversize and honed, then installing new pistons rings and gaskets. the hard part is determining what size pistons are in it , and if it has ever had a top end rebuild before. After the first oversize the rave valves need trimmed to accommodate larger pistons, on the plus side, you gain more power by doing all of this work because you are going with larger pistons. Now the pistons you choose also depict the power you gain from this, if you go with WSM graphite coated , you will see a very minimal gain in power, however if you splurge and go with WISECO pistons, you will see a significant bump in power. i don't recommend going with WISECO if your only doing one motor. its best to keep things even in the sport boats.

 

[speedster98]

Another option is going with a sbt top-end rebuild. The only downside I have heard to top-end rebuilds is the crank often needs replacing too. For me when it comes to that I'm planning on, and already saving for, a sbt full rebuilt motor swap with warranty. I am mechanically inclined but just find it easier to let the pros do it instead of having to buy a lot of specialty tools and spending lots of time. In the same breath I have to say I have done lots work myself on my boat and have found it very satisfying. I get the benefit of knowing I did it, how to do it, the specialty tools needed, and the ability to help others when they need the same work. With it now being near the off season, if you've got the time and funds, I would say go for it yourself. Worst case you put it back together and send it off to sbt for an exchange.

 

[AlG]

your looking at a "top end" rebuild, basically you'll be disassembling the head and removing the cylinders, having the cylinders bored to the next oversize and honed, then installing new pistons rings and gaskets. the hard part is determining what size pistons are in it , and if it has ever had a top end rebuild before. After the first oversize the rave valves need trimmed to accommodate larger pistons, on the plus side, you gain more power by doing all of this work because you are going with larger pistons. Now the pistons you choose also depict the power you gain from this, if you go with WSM graphite coated , you will see a very minimal gain in power, however if you splurge and go with WISECO pistons, you will see a significant bump in power. i don't recommend going with WISECO if your only doing one motor. its best to keep things even in the sport boats.

Is it necessary to Bore the cylinders?? i've been asking friends and technicians alike and what they tell me is that piston rings, seals, bearing repacked is all you need to do a top end rebuild.

 

[AlG]

Another option is going with a sbt top-end rebuild. The only downside I have heard to top-end rebuilds is the crank often needs replacing too. For me when it comes to that I'm planning on, and already saving for, a sbt full rebuilt motor swap with warranty. I am mechanically inclined but just find it easier to let the pros do it instead of having to buy a lot of specialty tools and spending lots of time. In the same breath I have to say I have done lots work myself on my boat and have found it very satisfying. I get the benefit of knowing I did it, how to do it, the specialty tools needed, and the ability to help others when they need the same work. With it now being near the off season, if you've got the time and funds, I would say go for it yourself. Worst case you put it back together and send it off to sbt for an exchange.

I think im leaning more on doing it myself because it's gonna cost me $1400.00+ to replace both motors..(should've gone with a single engine instead). also im hoping to save money that way. I'm not too familiar with these motors but i'm pretty good at figuring things out. all i need is a manual and the necessary tools and i can get it to work. May take me longer but like you said, knowing my boat will benefit me in the long run. any recommedations on where i can purchase the tools needed??

 

[speedster98]

Doc Honda and sbt are the 2 places I would look at first for the specialty tools. I also frequent harbor freight for some. Be sure to make use of this forum during your rebuild by posting descriptive titled threads. You will have frustration and fun doing the work yourself, but at the end you will know more than you ever thought possible about your boat and how well it was built. On a secondary note, I for one will never go with a single engine seadoo after owning this one. Yes it is double trouble but man it is amazing and a blast with twins!!! A couple of weeks ago I outran a 2012 wake jetski and 2 other newer models. Each one gained and gave respect for this bad little boat. You will love turning heads next summer with yours :cheers:

 

[AlG]

Doc Honda and sbt are the 2 places I would look at first for the specialty tools. I also frequent harbor freight for some. Be sure to make use of this forum during your rebuild by posting descriptive titled threads. You will have frustration and fun doing the work yourself, but at the end you will know more than you ever thought possible about your boat and how well it was built. On a secondary note, I for one will never go with a single engine seadoo after owning this one. Yes it is double trouble but man it is amazing and a blast with twins!!! A couple of weeks ago I outran a 2012 wake jetski and 2 other newer models. Each one gained and gave respect for this bad little boat. You will love turning heads next summer with yours :cheers:

Thanks for all advice and recommendations speedster! yes I will definitely use this forum for assistance and questions. im excited and a little apprehensive at the same time but i think it'll be a good experience.

couple more questions, when you say Crank needing replacement as well do you mean the crank shaft? also do the cylinders need to be bored on a Top end Rebuild?

 

[speedster98]

Yes, crank shaft and this will involve replacing the bearings and seals too. As far as the cylinders being bored it all depends on the type of rebuild you do. One type involves just replacing the worn out parts with new or re-manufactured ones. The other type of rebuild is boring the cylinders and using over-sized pistons. If you go with the boring option make sure it is done by someone who knows about the rave valves. They sometimes have to be bored too depending on how much the cylinders have to be bored to get a good surface. Sorry it took a few for my reply, its been a busy time in my personal life but things are all good now :thumbsup:

 

[DSchmidt54]

Yeah , you do need to bore the cylinders, i mean , you can measure them with to see if they are within factory tolerances, but usually there is scarring on the cylinder walls , so just replacing pistons wont get you enough compression. When you have a professional bore it, your having it bored to the exact tolerances of the oversize pistons, and increasing power somewhat, like i said, make sure you take it to someone who knows that the RAVE valves are going to need shaved to accomodate the oversize pistons

 

[speedster98]

After re-reading my reply I need to clarify the "replacing worn out parts" is referring to buying the top end rebuild kit from sbt.

 

[AlG]

Thanks for the reply guys. I've been reading on other forums that have the same issues as my boat and i thought about taking it to a dealer to have it diagnosed a and seems like most dealer dont know what it is they're doing..i don't know I'm starting to feel discourage and actually considering of just selling it. There's no descent technician out here in Albuquerque and it freaking sucks..