Why do 951's Seize?
Rob Munach
understanding is that the stock air box allows water to enter the engine
easily. There has to be plenty of race boats out there using very poorly
splash protected flame arrestors and I don't hear about them siezing
from water ingestion Is there something inherent in the design of the
motor that causes these problems?
--
Rob Munach
Larry KN4IM
wrote:
>So how come the 951 is so suseptible to siezure from water injection?
>--
>Rob Munach
Simple. Some IDIOT put the air intake down in the bottom of the bilge
where the BILGE PUMP SHOULDA BEEN!
Now it needs a snorkle!
Larry
Bill O'Neal
I have many customers and aquintences from the lakes that have had top end
jobs done by their dealers. In almost every single case it was attributted
to "water injestion".
Here are some of the "real" reasons, that the dealerships either missed or
just did not comment on.
1. pinched oil lines
2. bad oil injector pump.
3. stripped oil injector drive
4. out of round clyinder bores
5. faulty MPEM
6. faulty oil injector cables
7.broken bellcrank on oil injector
8. Other reasons that do not come to mind this morning.
It is my belief that for some reason or another, most repairs are getting
lumped into the "water injestion" catagory. Maybe because SD pays for that
repair without question ?
We run our racing boats very hard with R&D or Prok flame arresstors. These
motors occasionally take in huge amounts of water, but rarely sieze because
of it, if ever. The pistons sometimes have water related damage to the
skirts, much like almost every watercraft piston shows upon inspection when
taken apart.
Maybe because we advance the oil injector about 1/8th inch and we also add a
few (8oz.) of oil to each tank of fuel, we have less problems ? I also run a
very good special blend of racing snythetic oil made by Neo oil Company of
Long Beach, Ca. It is expensive at $45 a gallon retail. But, I would rather
run my oil that replace my pistons :)
Bill O'Neal
WCM
--
Bill @ E-MAIL: Water...@worldnet.att.net
Rob Munach wrote in message <37A969...@pobox.com>...
Andy Whittle
As I understand it, about the only ways to stick a motor is to run out / run
short of oil or to overheat the motor in some way that gets the piston
clearance too tight from expansion or soft from heat. Any one of these will
melt the motor down. Heat can come from too much from the combustion like
detonation, from cheep fuel or from lack of cooling. That being said....
Group K has an article that talks about a lean condition around 5000 or 6000
that is inherent in the 951 motor. They also explain, in another article,
about how a restrictive filter can help cover for a lean condition by
helping the carb to cover the lean spot. Sea-doo apparently tried to kill
two problems with one cure. Restrict the water and the air and wile they
were at it they increased the fuel. All of these things will richen the
midrange and kill speed.
If I had one of these motors I would go to carbs that were known for good
signals like a set of Novi's of about 45 mm. Next I would throw the stock
oil injection as far as I could in a deep water floatation test. Go to
about 34:1 pre-mix at first and work up to about 40:1 on the oil using
Maxima Super M or Mercury marine oil #92-813743a2 designed for the 2 Liter
race motors. This is NOT the stuff at the dealer but hlsm can get it for
about $130 for 5 gal. Last I would play with water roughing to cool the
head and cylinders first then the pipe. You must think out the water
injection as you will greatly change the water pressures at the nozzles and
can melt your exhaust system by accidentally shutting the water down. And
pray a lot, but the guys with the stock motors have to pray a lot.
This is all why I run a 785 superstock motor in a 97xp.
Good luck!
Andy
jetski junkies
>
> So how come the 951 is so suseptible to siezure from water injection? My
> understanding is that the stock air box allows water to enter the engine
> easily. There has to be plenty of race boats out there using very poorly
> splash protected flame arrestors and I don't hear about them siezing
> from water ingestion Is there something inherent in the design of the
> motor that causes these problems?
> --
> Rob Munach
Anytime you suck water into the motor, it wipes the oil off things. No
oil and it will sqeak!
My theory......The exhaust leaks water at the head pipe/chamber joint.
It's directly over the carbs. Only happening at full speed or close.
Alot of water will stop the motor immediately. A little water will just
tear things up slowly without any real notice.
Pistons sqeak so hard in a cyl. that puts out that much HP, and rods
break and pistons completely blow apart.
Perry
H Krause
Sounds like a terrific design.
--
Harry Krause
- - - - - - - - - - - -
It would never work. I'm Aquarius and you're ridiculous.
X*2, XPL, & SJ Fan (Dennis Copfer)
>So how come the 951 is so suseptible to siezure from water injection? My
>understanding is that the stock air box allows water to enter the engine
>easily. There has to be plenty of race boats out there using very poorly
>splash protected flame arrestors and I don't hear about them siezing
>from water ingestion Is there something inherent in the design of the
>motor that causes these problems?
>--
>Rob Munach
I suspect much damage has ocurred due to a few different things,
especially for newbie riders:
- XPL rolls from side to side easily, so it's possible water is
coming from the exhaust back into the cylinder when being boarded by
larger riders
- Some people have had water leaking from the exhaust manifold
- Siphon tubes in the pump have come off allowing water into the hull
(and racers use duckbill drains)
- The trays leaked and allowed a lot of water into the hulls, (can be
fixed at rest, but the hood/hull flexes while riding......and racers
usually tape the hood which deflects water)
- The XPL is REALLY easy to sub at slow speed...add rollers or a turn
and you have to plan to keep the bow up
dc
Freestyle Forever!
Bill O'Neal
I disagree with your statement about high output motors siezing and then
breaking rods. We have seen the siezures and the broken rods. IMO, the two
are unrelated (at least in the ones I've seen).
The rods usually snap off right below the wrist pin bearing on the small
end. The pistons do not show signs of siezure. The damn rods just break in
half. This is not common, but it does happen. Maybe the manufacture should
magnaflux each rod before assembly ?
Bill O'Neal
WCM
--
Bill @ E-MAIL: Water...@worldnet.att.net
jetski junkies wrote in message <7oc4rj$1...@dfw-ixnews11.ix.netcom.com>...
>Rob Munach wrote:
>>
>> So how come the 951 is so suseptible to siezure from water injection? My
>> understanding is that the stock air box allows water to enter the engine
>> easily. There has to be plenty of race boats out there using very poorly
>> splash protected flame arrestors and I don't hear about them siezing
>> from water ingestion Is there something inherent in the design of the
>> motor that causes these problems?
>> --
>> Rob Munach
>
>
>
KDA
the 951 than for any other twin 2-stroke engine in world history (i.e., it
is the largest two cylinder 2-stroke ever made). When you get water in it,
the water turns to vapor, increasing engine pressure, which causes a variety
of problems that other PWC engines with more but smaller displacement
cylinders (i.e., triples) do not have.
There obviously are benefits to SD's approach, but there also are
negatives. All other PWC manufacturers looked at the trade-offs and went to
triples years ago while SD continued upsizing its twin motors to stay in the
horespower hunt and because they thought they were being smart and unique--
kind'a like a SAAB with a two stroke motor and an oil stain running down the
side of the care from the filler cap was real smart and unique way back in
the 60s.
:)
Jettski
about?
KDA wrote:
> When you get water in it,
> the water turns to vapor, increasing engine pressure, which causes a variety
> of problems that other PWC engines with more but smaller displacement
> cylinders (i.e., triples) do not have.
>
So I guess you worked at all the other manufacturers? Once again, what are the
tradeoff you're speaking of? "Continued upsizing its twin motors"??? They made
1 ONE bigger motor. And guess what, it's probably the third best selling motor
of all pwc engines, behind S-D's 785 and Yamaha's 701. Doesn't sound too bad to
me.
> All other PWC manufacturers looked at the trade-offs and went to
> triples years ago while SD continued upsizing its twin motors to stay in the
> horespower hunt and because they thought they were being smart and unique--
Darin
Rob Munach
> >understanding is that the stock air box allows water to enter the engine
> >easily. There has to be plenty of race boats out there using very poorly
> >splash protected flame arrestors and I don't hear about them siezing
> >from water ingestion Is there something inherent in the design of the
> >motor that causes these problems?
> >--
> >Rob Munach
Thanks for the info.
--
Rob Munach, PE
Excel Engineering
Carrboro, NC
Robert Cross
and it shouldn't to stand-up freestylers either. I get water in my motor all
the time after doing subs and fountains and all the motor does is run rough
like it is really rich for a few seconds and then everything is fine. Same
thing happens after sinking one too. If you get too much water in one you
wind up with bent rods but the pistons still look great. I dont know about
everybody else but I have never siezed one from water ingestion(and I have
siezed a few) Robert
MR-HPT
Have a good day you nasty old would be tuner.
GJG
Bill O'Neal wrote:
MR-HPT
hidden problems regarding this power plant. Harry has not yet reached high
degree of understanding metallurgy and design characteristics of the scavenging
system. I advise you as well to invest time in study this engine be for bluntly
suggesting after market products which will do more harm then good to this
finicky power plant. One thing is certain this engine has driven many would be
tuners in to loony house who attempted to modify it using data provided by slick
sales man. No advice is better then bed advice. It is best to R&D your own
machine be fore posting such critical data. I'm hoping that you are not one of
the G K mart pressure gage students. Are You?
George HPT Sport USA
http://www.hpt-sport.com
MR-HPT
near 300 pounds. His 98 XPL never "digested" any water. Machine runs strong
going on second season with out engine problem. How do you explain that?
GJG
X*2, XPL, & SJ Fan (Dennis Copfer) wrote:
> Rob Munach <XLE...@pobox.com> wrote:
>
> >So how come the 951 is so suseptible to siezure from water injection? My
> >understanding is that the stock air box allows water to enter the engine
> >easily. There has to be plenty of race boats out there using very poorly
> >splash protected flame arrestors and I don't hear about them siezing
> >from water ingestion Is there something inherent in the design of the
> >motor that causes these problems?
> >--
> >Rob Munach
>
MR-HPT
offering even bigger bore displacement? Bill you dirty old man how can you sleep
knights?
GJG
KDA wrote:
> Cylinder displacement relative to seals (head & rings) is greater for
> the 951 than for any other twin 2-stroke engine in world history (i.e., it
> is the largest two cylinder 2-stroke ever made). When you get water in it,
> the water turns to vapor, increasing engine pressure, which causes a variety
> of problems that other PWC engines with more but smaller displacement
> cylinders (i.e., triples) do not have.
> There obviously are benefits to SD's approach, but there also are
> negatives. All other PWC manufacturers looked at the trade-offs and went to
> triples years ago while SD continued upsizing its twin motors to stay in the
> horespower hunt and because they thought they were being smart and unique--
> kind'a like a SAAB with a two stroke motor and an oil stain running down the
> side of the care from the filler cap was real smart and unique way back in
> the 60s.
> :)
>
MR-HPT
Must 951 stick ruds throe cases and cylinders yet piston top looks like brand
new. How do you explain disintegrated pistons below wrist pin with out any
damage to piston top. Back to drawing board my man. This one is beyond simple
minded would be tuners of your caliber. If you think I'm insulting your
personality you are wrong. I'm waging war on erroneous information. Get smart
attend HPT tuning school, it pays big dividends.
George HPT Sport USA
jetski junkies wrote:
> Rob Munach wrote:
> >
> > So how come the 951 is so suseptible to siezure from water injection? My
> > understanding is that the stock air box allows water to enter the engine
> > easily. There has to be plenty of race boats out there using very poorly
> > splash protected flame arrestors and I don't hear about them siezing
> > from water ingestion Is there something inherent in the design of the
> > motor that causes these problems?
> > --
> > Rob Munach
>
MR-HPT
stay together even if one of the cylinder was to be employed as water pump. You
getting smart on your old age Billy boy. I'm impressed. Sent this one to Harry
at G K mart as well.
Perhaps after two years of arguing with me he to will admit that I was right
from the very beginning.
Bill O'Neal wrote:
> Perry,
> I disagree with your statement about high output motors siezing and then
> breaking rods. We have seen the siezures and the broken rods. IMO, the two
> are unrelated (at least in the ones I've seen).
>
> The rods usually snap off right below the wrist pin bearing on the small
> end. The pistons do not show signs of siezure. The damn rods just break in
> half. This is not common, but it does happen. Maybe the manufacture should
> magnaflux each rod before assembly ?
>
> Bill O'Neal
> WCM
>
> --
> Bill @ E-MAIL: Water...@worldnet.att.net
> jetski junkies wrote in message <7oc4rj$1...@dfw-ixnews11.ix.netcom.com>...
Seadooracr
ingestion is the problem.
Seadoo needs to find another machine shop a new forging house for the rods
they need to spend more time checking the stack up of tolerances. I have
one motor that I raced all season and it was one of the fastest Xpl's in the
BP series and is has not failed yet other than a rave boot popping off. I
have another boat that stuck right away then it spun a balancer bearing
than lost a rod. Seadoo than replaced it with a brand new short block and at
4 hours the rod broke ruining everthing they replaced it again
Why would one motor run forever and the next keep destroying itself they are
both set up Identicle.
Evertime it lost a rod other than the piston skirt being broke the pistons
looked like new.
Quality thats the problem.
Kevin
ps
I also know a shop that would make the parts for them if they where to ask.
Craig Stripling
dealership. On these particular ones, they all had a certain companies exhaust
jetting kit installed. The pistons were a pretty shade of blue!!! Our GTXL
did in fact take on lots of water due to a pump failure and even with the
"fix", there was water still standing in the airbox. On my GSXL, I can't say
it was water that caused the scarring because to my knowledge, it has never
been wet inside other than the normal amounts that finds its way in there. Who
knows, maybe it came from when I had the stock pipe jetted.
Craig Stripling
<http://members.aol.com/gsxl/seadoo.html>
J 5 5 2000
Why does the piston blow apart from the wrist pin down and the top of the
pistons look good? I dont see it as being a water problem! Glad we are at the
end of the 951 era. I'm scared to do anything inside of a 951 and ride WOT for
long periods of time. It's like a time bomb! And most of the aftermarket
parts for the 951 are worthless.
Give me a 785 anyday or something better than a 951....
James Styles
John
magnafluxed?
FOR D 9ers
951's...just look at the classifieds.... a few trips to the dealers and the 951
owners want out. Just look at the posts of people selling their 951 pipes.
must be going stock to sell theirs too. JOE96XP
SnowXr
>?
why did the chicken cross the road?
lol
Kurt
MAC
times pie. Smaller displacement multiple cylinder engines will always
take more abuse than a fewer cylindered engines of the same displacement
unless they're detuned. The 951 isn't a detuned motor-- can't be
because even with big slugs, the engine displacement is smaller than the
triples it's made to run with-- but, people like'm because they are not
detuned-- they're race motors. However, they will break sooner or later
just like all race engines. Even when 951s run as long as could be
expected, they're not expected to have a long life-- that's not what
they're engineered for. They're engineered to keep up with bigger
triples no matter what the cost in repairs and sacrifice in longevity.
:)
Jettski wrote:
>
> Where is your proof to back up this *statement*? What problems are you talking
> about?
>
> KDA wrote:
>
> > When you get water in it,
> > the water turns to vapor, increasing engine pressure, which causes a variety
> > of problems that other PWC engines with more but smaller displacement
> > cylinders (i.e., triples) do not have.
> >
>
> So I guess you worked at all the other manufacturers? Once again, what are the
> tradeoff you're speaking of? "Continued upsizing its twin motors"??? They made
> 1 ONE bigger motor. And guess what, it's probably the third best selling motor
> of all pwc engines, behind S-D's 785 and Yamaha's 701. Doesn't sound too bad to
> me.
>
> > All other PWC manufacturers looked at the trade-offs and went to
> > triples years ago while SD continued upsizing its twin motors to stay in the
> > horespower hunt and because they thought they were being smart and unique--
>
> Darin
greg/erin
MAC wrote:
> As the radius increases, the volume increases by a square of the radius
> times pie.
brilliant. (pi)
> Smaller displacement multiple cylinder engines will always
> take more abuse than a fewer cylindered engines of the same displacement
> unless they're detuned.
why? dont make a statement such as this when you got me all hot and bothered by the
breathtaking geometry lesson, and not pull through with a thorough explanation!
> The 951 isn't a detuned motor-- can't be
> because even with big slugs, the engine displacement is smaller than the
> triples it's made to run with-- but, people like'm because they are not
> detuned-- they're race motors.
ooh yeah, gimme a finicky motor with less room to improve, thats what i want...
> However, they will break sooner or later
> just like all race engines.
just like ALL engines
> Even when 951s run as long as could be
> expected, they're not expected to have a long life-- that's not what
> they're engineered for.
for the most part that can be said about all recreational 2strokeys, its all about the
bang per displacement/weight.....
> They're engineered to keep up with bigger
> triples no matter what the cost in repairs and sacrifice in longevity.
yous still didnt answer the question.......
greg
Bill O'Neal
I have yet to ever see aluminum rods in any watercraft motor. They are
forged steel.
Bill O'Neal
WCM
--
Bill @ E-MAIL: Water...@worldnet.att.net
John wrote in message <37AA5EEC...@redconnect.net>...
X*2, XPL, & SJ Fan (Dennis Copfer)
<200 pounders have difficulty boarding.....and I didn't say every
large person would cause the problem.
dc
MR-HPT <hpts...@apex.net> wrote:
>DC what do you consider to be LARGE RIDER? One of my friend is about 6 + and
>near 300 pounds. His 98 XPL never "digested" any water. Machine runs strong
>going on second season with out engine problem. How do you explain that?
>GJG
>
>X*2, XPL, & SJ Fan (Dennis Copfer) wrote:
>
>> Rob Munach <XLE...@pobox.com> wrote:
>>
>> >So how come the 951 is so suseptible to siezure from water injection? My
>> >understanding is that the stock air box allows water to enter the engine
>> >easily. There has to be plenty of race boats out there using very poorly
>> >splash protected flame arrestors and I don't hear about them siezing
>> >from water ingestion Is there something inherent in the design of the
>> >motor that causes these problems?
>> >--
>> >Rob Munach
>>
X*2, XPL, & SJ Fan (Dennis Copfer)
the 98 Limiteds? And some posts about the link to quality in this
newsgroup?
Bubba
I agree 100%... Many 951's went because of little quality control stuff.
Pinched oil lines.... I could go on and on, but I won't Waste your time.
A good dealer should have inspected all of these things before delivery. The
sad fact is many don't.. they just program in the lanyard, adjust the idle
and throw a little gas and oil in.
Many Ski's and people would have been saved many problems.. if the dealer
would have done a thorough inspection before delivery.
Doo would have not got hammered on the back-end of warranty work also....
Quality control was one of the big problems IMHO.
Bubba
X*2, XPL, & SJ Fan (Dennis Copfer) wrote in message
<46D4829D51BE369F.FC285615...@lp.airnews.net>...
JCF957
first let me say that it is not really "Water Igestion" that is the problem.
It is that the engine is not tollerant to water ingestion. It is inevitable
that every engine that runs on the water is going to have water go through
it from time to time no matter how carefull you are. So, the two main
reasons I feel the 951 is intollerant to water ingestion are:
1) Tight piston clearances with sometimes tapered bores.
2) Oil injection set up from factory with minimal lubrication.
I cannot comment on the 951's that are going down with broken rods as I did
not know of these nor have I seen one of these failures. I have a hard time
correlating this type of failure to water ingestion, it sounds more like a
quality control problem to me. Most of the broken 951's I saw were very
similar to mine with the piston and cylinder wall scoring.
This is JMO, I could be wrong! :)
--
James France (JCF957)
JFr...@execpc.com
'97.5 GSXL w/Rossier Stage I Kit
'97 GSX Stock for now
Bill O'Neal wrote in message <7oc3vt$3r5$1...@bgtnsc01.worldnet.att.net>...
>Bill O'Neal
>WCM
>
>--
>Bill @ E-MAIL: Water...@worldnet.att.net
>Rob Munach wrote in message <37A969...@pobox.com>...
H Krause
You skipped a few monthly payments?
JCF957
I'm sorry Harry but if this was meant for me it went clear over my head. I
don't get the question. :)
--
Jim France (JCF957)
JFr...@execpc.com
'97.5 GSXL w/Rossier Stage I Kit
'97 GSX Stock for now
H Krause wrote in message <37AC5719...@erols.com>...
MR-HPT
the box XPL. Talking quality. Second to non.
GJG
MR-HPT
little later.
Agreed 100%.
GJG
Bubba
happen and does are 2 different things ;-)
bubba
MR-HPT wrote in message <37AF61FB...@apex.net>...