My SBT motor won't start or run correctly....

[OrlandoPWC]

Short story, I recently purchased a 96 Wave Venture 1100 from a Yamaha dealer on ebay. The PWC had an SBT motor installed in it, which was purchased in late January of this year. It had 0 hours on it when I bought it, and I had to break it in with the SBT Break-In oil. I did everything correctly, and there were no problems. I now have 15 hours on the motor, have been running 87 octane with Yamalube at a 50:1 ratio (per the Yamaha tech's suggestion), and have noticed lately that it is going through plugs fairly quickly. In fact, in the 15 hours of usage, I have gone through 4 sets of NGK BR8HS's. I gapped them to .024 which is Yamaha spec. I recently did an oil block off on the motor, and am premixing the fuel, because I do not trust oil pumps.

The last few times I have taken the ski out, I have noticed that it has a harder time starting initially....this was not the case when I purchased the ski a couple months ago. Even with the choke on, and brand new plugs, it doesn't even sputter. The spark on the plugs is a strong blue/white. When I do put fuel in the top of the cylinders however, it fires right up....sputters a little, then kicks in....so it's almost like a fuel vaccuum issue.

Well, yesterday, I took it out to the lake, new plugs, primed the cylinders to fire, all was fine. Took it out for a lap around the lake, and as I was bringing it in, it was idleing pretty rough, and shut off a couple of times on me. I brought it in, pulled the plugs. 2 of them looked ok, and the 3rd was really black, and the electrode on the bottom of the plug looked to have been bent so that there was no gap.

I stuck another plug in there, gapped it correctly, and it runs really rough, like it's only on 2 cylinders. I pulled the new plug, to see if it was bent as well, but it was ok, and still at .024 on the gap.

Now, when I go out and try to fire it up, nothing happens, no sputtering, nothing. Choke is on, battery is full, and there is good spark. It seems to me like a carb problem, or fuel delivery issue. I pulled the fuel pump off, took it apart, it was debree free. Took off the carb plastic cover, didn't see any foreign objects on the outside.

I don't know what the problem is. I have scheduled a service date at my local Yamaha dealership (not the same I bought this from) for Thursday, but would like to diagnose this problem before that. I don't have a repair manual for this ski, haven't been able to find them locally. Is there anybody with suggestions. I can't imagine it being carb settings....they were set by a Yamaha tech only 15 hours ago (usage), and it has just recently suffered in performance. I'd hate to think it's this new motor....

[Technical Support]

It may be - when a plug gap is closed, it's from some sort of debris hitting it.

The first thign you need to do is take a compression check.

[OrlandoPWC]

Really bad news, I took a compression test of the motor. #1 cylinder is 108-110psi, #2 cylinder is a little ovber 30psi, and the #3 cylinder is around 28psi. You can even feel the difference when you put your finger over the spark plug hole....#1 cylinder blows your finger off, and #2 and #3 dont even move your finger.

Looks like this one is going back to SBT. Luckily I am fairly local, so will bring this POS to them in person. Totally unacceptable for a 15 hour old motor.

[Technical Support]

I can almost gaurantee you it's not something internal. Why was the motor replaced in the first place?

We will do a full rundown ont he block when it arrives, and be able to give you areas to investigate on your end if it's not something internal.

[OrlandoPWC]

I bought the ski off ebay back in February. I have no idea why the motor was replaced, probably because the old one was bad....

All I know, is I did everything correctly to break this in, from the beginning of its life. I have the warranty card that came with this motor, that has the serial # and the date of purchase, and it was installed by a Yamaha shop down in Sarasota back in Feb.

[OrlandoPWC]

Also, why would you almost guarantee its not an internal problem, if there is almost no compression in two of the cylinders?

[Technical Support]

I don't question your break-in procedures, only that the original cause for motor failure was not properly fixed.

Motors VERY rarely go from internal problems. The VAST majority of the time it's some external problem such as a carb problem, overheating, ignition timing, cracked manifolds, gad gasket surface, bad motor mount, loose bolt, etc.

The motor certainly has damage now, but it's most likely caused by something external. We will be able to tell exactly what type of damage it has when we get it torn down. From your description of events, I wouldn't be surprised to find detonation damage, pointing to a carb/fuel problem. Just speculation though, nothing will be known for sure until it can be inspected. Just call Julie Monday morning for an RGA number and we can get it swapped out with you, and let you know what to look for.

[ShowMePro1200]

What he means is there's an internal problem NOW, but the original source of the problem may have been external (such as carbs maybe?).

If you're in warranty it seems like it won't be a problem for them to replace (heck you even save the shipping cost!). But do let them diagnose the situation so as to prevent it from happening again.

[ShowMePro1200]

Agh, they beat me to the response! [img]tongue.gif[/img]

[OrlandoPWC]

I'm taking the ski over to my dads shop so we can take this motor out. I am going to try to get ahold of a manual so we know what we're doing. I am hoping to get this taken care of soon.

I'm going to call SBT on Monday, and ask exactly what we have to bring them. Since I was not the original purchaser of the motor, I do not know what came in the box, and what I have to return, so hopefully I get all this cleared up.

At least I am still fairly familiar with the break-in procedure, since I did it only 4 weeks ago, so I get to do that all over again.....but as long as this new one last longer, everything should be ok. Just for info, this is far from my first ski, I know preventative maintenance...I was the only one to operate this motor....so I have a hard time believing I had anything to do with the problem....it's fairly hard to conceive, since I have put very little hours on it, and have done nothing but put fuel/oil into it, that this is my fault....I can only predict that it was a problem that was present when the motor was new.

[Technical Support]

So far you are 100% correct.

As for pulling it, just read the Install/Remoaval guide in the tech section. The Venture 1100 is not a hard job, but will take about 8 hours start to finish for the complete swap, if it's your first time, assuming you go through the carbs too.

I took on a side job for a buddy a couple years ago. It was also a Venture 1100 coincidentally...and it's got to be one of the stragest stories I've ever heard and/or been involved with.

Short version was, I did a swap for him (SBT motor), knowing he had purcahsed the ski from a local dealer, who had put several engines in it already. They were confident that the causes for failure were found, and this next engine would be a keeper for the ski.

I installed the engine, broke it in for him and delivered. About 1 month later, after he had taken it out a few times, it had burned down a cylinder. Season had approaced and I couldn't do the swap again so I refered him to one of the very best shops in the nation. This guy took on the project as thouroughly as I did, and went through the whole ski. He had narrowed it down to an electrical issue, and long story short, found the iginition coils failing - one at a time.

It took all in all, 3 engines from the first dealer, one from me and one from the good dealer, to get it all working right again. Incidentally, the reason I didn't suspect the electricals was because I found clogged and mis-adjust carbs/pump, and fixed it during my install. My sucessfull break-in confirmed at the time, my repair was correct. The ignition components were failing at WOT during extended runs, which I didn't do during the first tank obviously.

As for what parts you need, we want the bottom braces, cases, crank, cylinders, head and cover, all assembled. Remove the carbs, intake manifold, exhaust and manifold, PTO coupler, flywheel cover, flywheel and starter.

[ April 10, 2004, 10:19 PM: Message edited by: Technical Support ]

[1fastski.com]

i had to say that its pretty crappy to say your going to drop off the POS then kinda put the company down and in the same post asking for a new motor and SBT being nice as they can be { goes to show what a good company they are . 99% of the time a bad motor will blow within the first tank of fuel, after that look else were for the problem . its easy to replace a blown motor , not many can find WHY it blew in the firstplace . worse yet for a company like SBT that offers a no foult warranty when a dealer installs there motor most wont care if they fix the problem . they know the customer will pay to have a new motor installed and poor SBT will foot the bill for the motor .

[Mpeavler1]

Yeah.....I was wondering if I was the only one who caught that post

MIke

[OrlandoPWC]

Originally posted by 1fastski.com:
i had to say that its pretty crappy to say your going to drop off the POS then kinda put the company down and in the same post asking for a new motor and SBT being nice as they can be { goes to show what a good company they are . 99% of the time a bad motor will blow within the first tank of fuel, after that look else were for the problem . its easy to replace a blown motor , not many can find WHY it blew in the firstplace . worse yet for a company like SBT that offers a no foult warranty when a dealer installs there motor most wont care if they fix the problem . they know the customer will pay to have a new motor installed and poor SBT will foot the bill for the motor .

....... Sorry that my post has such an impact on you, I was upset at the time, to find out that after paying big $$$ for a Yamaha tech to install this NEW motor before I picked it up, just went totally out the door.

Upon further inspection, the pistons have some holes in them, the exhaust ports are corroded with lots of yellowish hard film, the cylinder walls are burned, and the ports are chafed/knicked/bent. All this from a 15 hour, freshwater only, flushed everytime motor....hmmm

I really don't care, I am getting the new motor today, and plan to have this ski up for sale soon after....I break it in AGAIN.

[Technical Support]

If you do not fix the problem, you next new engine will be EXACTLY the same.