Isolating vibration problem on a 701cc '94 Yamaha Wave Raide

TwoStar · Joined: 18 Aug 2007 Posts: 2

My Raider developed a vibration problem while out on the water on the
last run at the end of last season. Since I had been having overheating
and performance problems before that (and I was pretty sure the 12
year-old ski had never had any engine work) I decided to rebuild the
top end.

I replaced the pistons with WSP platinums and think I did a pretty
decent job overall. There were no significant problems other than some
fouling and the rings were shot. Once I got it back together it started
fairly easily (for an old 2-stroke PWC anyway). --By the way, after
opening up the cylinder head, I have vowed to be much more diligent
about flushing with fresh water in the future!

So now, of course, I still have the vibration problem. It's significant
enough that it kept me off the water and will still keep me from
launching.

I have the Clymer shop manual, which I have found to be very useful and
a bargain at twice the price. My next step is measuring the coupling
alignment and then taking a closer look at the drive train. My engine
mounts seem fine, although I don't know any reliable way of checking
them without taking them out. There is no sign that any shims are loose
or missing. And I am almost positive that there is nothing wrapped
around or stuck in the jet drive.

Assuming my coupling alignment is good and I can't find another
problem, I am considering something not addressed in the manual. In
order to rule out the engine as a source of the vibration, I'm thinking
of undoing the bolts, sliding the engine forward, and removing the
rubber coupling that fits between the engine and the drive shaft. Once
that's done, I'll bolt the engine back down and run it without turning
any part of the drive train. Seems to me that will split the problem
between the engine and the drive train and then I'll go from there.
This will also let me rotate the drive train while it's installed and
see if it's sticking or loose.

Anybody ever tried anything like this? Is this a dumb idea for some
reason I don't see?
Any other suggestions for how to find the problem?

Thanks in advance!

Archived from group: rec>sport>jetski

TwoStar · Joined: 18 Aug 2007 Posts: 2

> So now, of course, I still have the vibration problem. It's significant
> enough that it kept me off the water and will still keep me from
> launching.
>
> I have the Clymer shop manual, which I have found to be very useful and
> a bargain at twice the price. My next step is measuring the coupling
> alignment and then taking a closer look at the drive train. My engine
> mounts seem fine, although I don't know any reliable way of checking
> them without taking them out. There is no sign that any shims are loose
> or missing. And I am almost positive that there is nothing wrapped
> around or stuck in the jet drive.
>
> Assuming my coupling alignment is good and I can't find another
> problem, I am considering something not addressed in the manual. In
> order to rule out the engine as a source of the vibration, I'm thinking
> of undoing the bolts, sliding the engine forward, and removing the
> rubber coupling that fits between the engine and the drive shaft. Once
> that's done, I'll bolt the engine back down and run it without turning
> any part of the drive train. Seems to me that will split the problem
> between the engine and the drive train and then I'll go from there.
> This will also let me rotate the drive train while it's installed and
> see if it's sticking or loose.
>

Okay, so that wasn't my brightest idea. I put the shop manual down and
went and pulled the cover off my coupling. Of course, I CAN'T just take
the rubber coupler out and then run the engine because there would
stilll be metal-to-metal contact between the two halves of the coupler
housing. So strike the idea of running the eninge that way.

My engine mounts seem solidly attached and there are shims under each
of them that don't look like they've shifted. The coupling (including
the rubber) looks pretty good and solid. When rotating by hand, it
seems that there may be a very slight amount of misalignment although I
haven't measured it yet. That will be my next step, to align the engine
and run it again and see if it improves.

I'd sure like to rule out a crankshaft/crankcase problem. When I had
the cylinders off for my piston change-out, the connecting rods were in
good shape and had no wiggle to them. What are the chances the
crankcase is part of my vibration problem?

I'm not wild about the idea of turning the ski on it's side and taking
a whack at the jet pump, mostly because I'm doing all the work in the
parking lot of my apartment complex and don't have the means to support
the ski while I work. I'm thinking I have a bearing problem somewhere.

Any input at all would be appreciated.

Thanks!

robertg · Joined: 18 Aug 2007 Posts: 1

This group has lots of good old information but it is dead now. Try
pwctoday, maybe you will get help there. Did you check your pump
bearings? Do you ride in saly water? Maybe your impeller ring swelled
up and its rubbing.

On Jan 23, 4:45 pm, "TwoStar" wrote:
> > So now, of course, I still have the vibration problem. It's significant
> > enough that it kept me off the water and will still keep me from
> > launching.
>
> > I have the Clymer shop manual, which I have found to be very useful and
> > a bargain at twice the price. My next step is measuring the coupling
> > alignment and then taking a closer look at the drive train. My engine
> > mounts seem fine, although I don't know any reliable way of checking
> > them without taking them out. There is no sign that any shims are loose
> > or missing. And I am almost positive that there is nothing wrapped
> > around or stuck in the jet drive.
>
> > Assuming my coupling alignment is good and I can't find another
> > problem, I am considering something not addressed in the manual. In
> > order to rule out the engine as a source of the vibration, I'm thinking
> > of undoing the bolts, sliding the engine forward, and removing the
> > rubber coupling that fits between the engine and the drive shaft. Once
> > that's done, I'll bolt the engine back down and run it without turning
> > any part of the drive train. Seems to me that will split the problem
> > between the engine and the drive train and then I'll go from there.
> > This will also let me rotate the drive train while it's installed and
> > see if it's sticking or loose.Okay, so that wasn't my brightest idea. I put the shop manual down and
> went and pulled the cover off my coupling. Of course, I CAN'T just take
> the rubber coupler out and then run the engine because there would
> stilll be metal-to-metal contact between the two halves of the coupler
> housing. So strike the idea of running the eninge that way.
>
> My engine mounts seem solidly attached and there are shims under each
> of them that don't look like they've shifted. The coupling (including
> the rubber) looks pretty good and solid. When rotating by hand, it
> seems that there may be a very slight amount of misalignment although I
> haven't measured it yet. That will be my next step, to align the engine
> and run it again and see if it improves.
>
> I'd sure like to rule out a crankshaft/crankcase problem. When I had
> the cylinders off for my piston change-out, the connecting rods were in
> good shape and had no wiggle to them. What are the chances the
> crankcase is part of my vibration problem?
>
> I'm not wild about the idea of turning the ski on it's side and taking
> a whack at the jet pump, mostly because I'm doing all the work in the
> parking lot of my apartment complex and don't have the means to support
> the ski while I work. I'm thinking I have a bearing problem somewhere.
>
> Any input at all would be appreciated.
>
> Thanks!

Mr. HPT · Joined: 18 Aug 2007 Posts: 159

Take out jet pump and drive shaft.
Start the engine, if vibration persist you have twisted crank and
or damaged flywheel. If engine runs smoothly then
problem is at the jet pump or drive shaft.

GJG
HPT Sport USA
WWW.HPT-SPORT.COM

"TwoStar" wrote in message @51g2000cwl.googlegroups.com...
> My Raider developed a vibration problem while out on the water on the
> last run at the end of last season. Since I had been having overheating
> and performance problems before that (and I was pretty sure the 12
> year-old ski had never had any engine work) I decided to rebuild the
> top end.
>
> I replaced the pistons with WSP platinums and think I did a pretty
> decent job overall. There were no significant problems other than some
> fouling and the rings were shot. Once I got it back together it started
> fairly easily (for an old 2-stroke PWC anyway). --By the way, after
> opening up the cylinder head, I have vowed to be much more diligent
> about flushing with fresh water in the future!
>
> So now, of course, I still have the vibration problem. It's significant
> enough that it kept me off the water and will still keep me from
> launching.
>
> I have the Clymer shop manual, which I have found to be very useful and
> a bargain at twice the price. My next step is measuring the coupling
> alignment and then taking a closer look at the drive train. My engine
> mounts seem fine, although I don't know any reliable way of checking
> them without taking them out. There is no sign that any shims are loose
> or missing. And I am almost positive that there is nothing wrapped
> around or stuck in the jet drive.
>
> Assuming my coupling alignment is good and I can't find another
> problem, I am considering something not addressed in the manual. In
> order to rule out the engine as a source of the vibration, I'm thinking
> of undoing the bolts, sliding the engine forward, and removing the
> rubber coupling that fits between the engine and the drive shaft. Once
> that's done, I'll bolt the engine back down and run it without turning
> any part of the drive train. Seems to me that will split the problem
> between the engine and the drive train and then I'll go from there.
> This will also let me rotate the drive train while it's installed and
> see if it's sticking or loose.
>
> Anybody ever tried anything like this? Is this a dumb idea for some
> reason I don't see?
> Any other suggestions for how to find the problem?
>
> Thanks in advance!
>