Ltd. Superjet won't make RPM's

Chris B · Joined: 18 Aug 2007 Posts: 4

My Ltd. superjet was feeling slow and sluggish, so I went and bought a
Tiny Tach to help with some tuning. Turns out I was right. The
highest RPM I could reach is 6130.

This spring, I replaced all seals and gaskets, new pistons and rings
(bored to 710 cc, 0.5 mm oversize), and new reeds.

I have the following setup: Factory dry pipe, Riva head (pump gas),
stock carbs, Solas X prop. The exhaust coupler is also new, along
with the o-ring that seals the pipe to the manifold.

Right now, I'm at a loss as to where to start looking for problems. I
reinstalled the head and pipe today, everything looks fine. Any ideas
or help would be appreciated.

Chris

Archived from group: rec>sport>jetski

momar · Joined: 18 Aug 2007 Posts: 13

usually the culprit is reeds , since you replaced the reeds the next culprit
is the cdi, and if you have water injection, water in a dry pipe can lower
the rpm's
"Chris B" wrote in message@posting.google.com...
> My Ltd. superjet was feeling slow and sluggish, so I went and bought a
> Tiny Tach to help with some tuning. Turns out I was right. The
> highest RPM I could reach is 6130.
>
> This spring, I replaced all seals and gaskets, new pistons and rings
> (bored to 710 cc, 0.5 mm oversize), and new reeds.
>
> I have the following setup: Factory dry pipe, Riva head (pump gas),
> stock carbs, Solas X prop. The exhaust coupler is also new, along
> with the o-ring that seals the pipe to the manifold.
>
> Right now, I'm at a loss as to where to start looking for problems. I
> reinstalled the head and pipe today, everything looks fine. Any ideas
> or help would be appreciated.
>
> Chris

Chris B · Joined: 18 Aug 2007 Posts: 4

Thanks for the ideas momar,

I checked the reeds anyway, they're ok. It's not a water injection
problem, I unplugged it and did a run just to check.

I just finished testing the CDI to the Yamaha service manual, all of
the resistances appear to be in tolerance, except for the
Black-BrownWhite combo (charger coil), which measures at about 9 ohms,
where the manual tolerance is 2-6. However, it's a cheap analog
tester that I'm using, so there's likely an error in the reading.

Where I did run into a problem is with the pulser coil
(RedWhite-Black). I am getting infinite resistance, where the manual
lists 12.6 - 15.4 ohms. To make sure I'm doing this right, I touch
the black lead to ground, the red lead to the RedWhite wire at the
electrical box, which leads to the flywheel.

Before I go out buying parts, is there anything else I should check,
or do you think this is the problem?

Chris

"momar" wrote in message news:...
> usually the culprit is reeds , since you replaced the reeds the next culprit
> is the cdi, and if you have water injection, water in a dry pipe can lower
> the rpm's
> "Chris B" wrote in message
> @posting.google.com...
> > My Ltd. superjet was feeling slow and sluggish, so I went and bought a
> > Tiny Tach to help with some tuning. Turns out I was right. The
> > highest RPM I could reach is 6130.
> >
> > This spring, I replaced all seals and gaskets, new pistons and rings
> > (bored to 710 cc, 0.5 mm oversize), and new reeds.
> >
> > I have the following setup: Factory dry pipe, Riva head (pump gas),
> > stock carbs, Solas X prop. The exhaust coupler is also new, along
> > with the o-ring that seals the pipe to the manifold.
> >
> > Right now, I'm at a loss as to where to start looking for problems. I
> > reinstalled the head and pipe today, everything looks fine. Any ideas
> > or help would be appreciated.
> >
> > Chris

Paco \"The Flyin' Finn\" · Joined: 18 Aug 2007 Posts: 3

Did you pressure test your pipe?

Nate
"Chris B" wrote in message@posting.google.com...
> Thanks for the ideas momar,
>
> I checked the reeds anyway, they're ok. It's not a water injection
> problem, I unplugged it and did a run just to check.
>
> I just finished testing the CDI to the Yamaha service manual, all of
> the resistances appear to be in tolerance, except for the
> Black-BrownWhite combo (charger coil), which measures at about 9 ohms,
> where the manual tolerance is 2-6. However, it's a cheap analog
> tester that I'm using, so there's likely an error in the reading.
>
> Where I did run into a problem is with the pulser coil
> (RedWhite-Black). I am getting infinite resistance, where the manual
> lists 12.6 - 15.4 ohms. To make sure I'm doing this right, I touch
> the black lead to ground, the red lead to the RedWhite wire at the
> electrical box, which leads to the flywheel.
>
> Before I go out buying parts, is there anything else I should check,
> or do you think this is the problem?
>
> Chris
>
>
>
>
>
>
>
> "momar" wrote in message
news:...
> > usually the culprit is reeds , since you replaced the reeds the next
culprit
> > is the cdi, and if you have water injection, water in a dry pipe can
lower
> > the rpm's
> > "Chris B" wrote in message
> > @posting.google.com...
> > > My Ltd. superjet was feeling slow and sluggish, so I went and bought a
> > > Tiny Tach to help with some tuning. Turns out I was right. The
> > > highest RPM I could reach is 6130.
> > >
> > > This spring, I replaced all seals and gaskets, new pistons and rings
> > > (bored to 710 cc, 0.5 mm oversize), and new reeds.
> > >
> > > I have the following setup: Factory dry pipe, Riva head (pump gas),
> > > stock carbs, Solas X prop. The exhaust coupler is also new, along
> > > with the o-ring that seals the pipe to the manifold.
> > >
> > > Right now, I'm at a loss as to where to start looking for problems. I
> > > reinstalled the head and pipe today, everything looks fine. Any ideas
> > > or help would be appreciated.
> > >
> > > Chris

Chris B · Joined: 18 Aug 2007 Posts: 4

I haven't checked the pipe, although now that you mention it, I am
hearing a 'resonance' sound. The last time that happened, turns out
the forward mount flange was cracked.

Back to the pressure test. I assume we're checking for an exhaust
leak into the water jacket. Would a leak test do the trick? I'm
thinking filling the exhaust chamber with water that has a dye in it,
and seeing what comes out the hoses. How would you cap off the ends
for a pressure test, and to what air pressure?

Chris

"Paco \"The Flyin' Finn\"" wrote in message news:...
> Did you pressure test your pipe?
>
> Nate
> "Chris B" wrote in message
> @posting.google.com...
> > Thanks for the ideas momar,
> >
> > I checked the reeds anyway, they're ok. It's not a water injection
> > problem, I unplugged it and did a run just to check.
> >
> > I just finished testing the CDI to the Yamaha service manual, all of
> > the resistances appear to be in tolerance, except for the
> > Black-BrownWhite combo (charger coil), which measures at about 9 ohms,
> > where the manual tolerance is 2-6. However, it's a cheap analog
> > tester that I'm using, so there's likely an error in the reading.
> >
> > Where I did run into a problem is with the pulser coil
> > (RedWhite-Black). I am getting infinite resistance, where the manual
> > lists 12.6 - 15.4 ohms. To make sure I'm doing this right, I touch
> > the black lead to ground, the red lead to the RedWhite wire at the
> > electrical box, which leads to the flywheel.
> >
> > Before I go out buying parts, is there anything else I should check,
> > or do you think this is the problem?
> >
> > Chris
> >
> >
> >
> >
> >
> >
> >
> > "momar" wrote in message
> news:...
> > > usually the culprit is reeds , since you replaced the reeds the next
> culprit
> > > is the cdi, and if you have water injection, water in a dry pipe can
> lower
> > > the rpm's
> > > "Chris B" wrote in message
> > > @posting.google.com...
> > > > My Ltd. superjet was feeling slow and sluggish, so I went and bought a
> > > > Tiny Tach to help with some tuning. Turns out I was right. The
> > > > highest RPM I could reach is 6130.
> > > >
> > > > This spring, I replaced all seals and gaskets, new pistons and rings
> > > > (bored to 710 cc, 0.5 mm oversize), and new reeds.
> > > >
> > > > I have the following setup: Factory dry pipe, Riva head (pump gas),
> > > > stock carbs, Solas X prop. The exhaust coupler is also new, along
> > > > with the o-ring that seals the pipe to the manifold.
> > > >
> > > > Right now, I'm at a loss as to where to start looking for problems. I
> > > > reinstalled the head and pipe today, everything looks fine. Any ideas
> > > > or help would be appreciated.
> > > >
> > > > Chris

momar · Joined: 18 Aug 2007 Posts: 13

no your checking for water from the water jacket leaking into the exhaust
chamber which would definatlley lower your r's seal all the holes and pump
twenty pounds in their and see if it goes down
"Chris B" wrote in message@posting.google.com...
> I haven't checked the pipe, although now that you mention it, I am
> hearing a 'resonance' sound. The last time that happened, turns out
> the forward mount flange was cracked.
>
> Back to the pressure test. I assume we're checking for an exhaust
> leak into the water jacket. Would a leak test do the trick? I'm
> thinking filling the exhaust chamber with water that has a dye in it,
> and seeing what comes out the hoses. How would you cap off the ends
> for a pressure test, and to what air pressure?
>
> Chris
>
>
> "Paco \"The Flyin' Finn\"" wrote in message
news:...
> > Did you pressure test your pipe?
> >
> > Nate
> > "Chris B" wrote in message
> > @posting.google.com...
> > > Thanks for the ideas momar,
> > >
> > > I checked the reeds anyway, they're ok. It's not a water injection
> > > problem, I unplugged it and did a run just to check.
> > >
> > > I just finished testing the CDI to the Yamaha service manual, all of
> > > the resistances appear to be in tolerance, except for the
> > > Black-BrownWhite combo (charger coil), which measures at about 9 ohms,
> > > where the manual tolerance is 2-6. However, it's a cheap analog
> > > tester that I'm using, so there's likely an error in the reading.
> > >
> > > Where I did run into a problem is with the pulser coil
> > > (RedWhite-Black). I am getting infinite resistance, where the manual
> > > lists 12.6 - 15.4 ohms. To make sure I'm doing this right, I touch
> > > the black lead to ground, the red lead to the RedWhite wire at the
> > > electrical box, which leads to the flywheel.
> > >
> > > Before I go out buying parts, is there anything else I should check,
> > > or do you think this is the problem?
> > >
> > > Chris
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > > "momar" wrote in message
> > news:...
> > > > usually the culprit is reeds , since you replaced the reeds the next
> > culprit
> > > > is the cdi, and if you have water injection, water in a dry pipe can
> > lower
> > > > the rpm's
> > > > "Chris B" wrote in message
> > > > @posting.google.com...
> > > > > My Ltd. superjet was feeling slow and sluggish, so I went and
bought a
> > > > > Tiny Tach to help with some tuning. Turns out I was right. The
> > > > > highest RPM I could reach is 6130.
> > > > >
> > > > > This spring, I replaced all seals and gaskets, new pistons and
rings
> > > > > (bored to 710 cc, 0.5 mm oversize), and new reeds.
> > > > >
> > > > > I have the following setup: Factory dry pipe, Riva head (pump
gas),
> > > > > stock carbs, Solas X prop. The exhaust coupler is also new, along
> > > > > with the o-ring that seals the pipe to the manifold.
> > > > >
> > > > > Right now, I'm at a loss as to where to start looking for
problems. I
> > > > > reinstalled the head and pipe today, everything looks fine. Any
ideas
> > > > > or help would be appreciated.
> > > > >
> > > > > Chris

Muskoka Motion · Joined: 18 Aug 2007 Posts: 1

Fill the water jacket with compressed air (20psi) then dunk the whole deal
in the pool when no one is looking. Or dunk it in a garbage can full of
water... look for bubbles coming from the chamber.
--
Scott Gillies
Muskoka Motion Limited
Boat and Snowmobile Rentals
(705) 789-0262
www.muskokamotion.com

"momar" wrote in message@corp.supernews.com...
> no your checking for water from the water jacket leaking into the exhaust
> chamber which would definatlley lower your r's seal all the holes and pump
> twenty pounds in their and see if it goes down
> "Chris B" wrote in message
> @posting.google.com...
> > I haven't checked the pipe, although now that you mention it, I am
> > hearing a 'resonance' sound. The last time that happened, turns out
> > the forward mount flange was cracked.
> >
> > Back to the pressure test. I assume we're checking for an exhaust
> > leak into the water jacket. Would a leak test do the trick? I'm
> > thinking filling the exhaust chamber with water that has a dye in it,
> > and seeing what comes out the hoses. How would you cap off the ends
> > for a pressure test, and to what air pressure?
> >
> > Chris
> >
> >
> > "Paco \"The Flyin' Finn\"" wrote in message
> news:...
> > > Did you pressure test your pipe?
> > >
> > > Nate
> > > "Chris B" wrote in message
> > > @posting.google.com...
> > > > Thanks for the ideas momar,
> > > >
> > > > I checked the reeds anyway, they're ok. It's not a water injection
> > > > problem, I unplugged it and did a run just to check.
> > > >
> > > > I just finished testing the CDI to the Yamaha service manual, all of
> > > > the resistances appear to be in tolerance, except for the
> > > > Black-BrownWhite combo (charger coil), which measures at about 9
ohms,
> > > > where the manual tolerance is 2-6. However, it's a cheap analog
> > > > tester that I'm using, so there's likely an error in the reading.
> > > >
> > > > Where I did run into a problem is with the pulser coil
> > > > (RedWhite-Black). I am getting infinite resistance, where the
manual
> > > > lists 12.6 - 15.4 ohms. To make sure I'm doing this right, I touch
> > > > the black lead to ground, the red lead to the RedWhite wire at the
> > > > electrical box, which leads to the flywheel.
> > > >
> > > > Before I go out buying parts, is there anything else I should check,
> > > > or do you think this is the problem?
> > > >
> > > > Chris
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > "momar" wrote in message
> > > news:...
> > > > > usually the culprit is reeds , since you replaced the reeds the
next
> > > culprit
> > > > > is the cdi, and if you have water injection, water in a dry pipe
can
> > > lower
> > > > > the rpm's
> > > > > "Chris B" wrote in message
> > > > > @posting.google.com...
> > > > > > My Ltd. superjet was feeling slow and sluggish, so I went and
> bought a
> > > > > > Tiny Tach to help with some tuning. Turns out I was right. The
> > > > > > highest RPM I could reach is 6130.
> > > > > >
> > > > > > This spring, I replaced all seals and gaskets, new pistons and
> rings
> > > > > > (bored to 710 cc, 0.5 mm oversize), and new reeds.
> > > > > >
> > > > > > I have the following setup: Factory dry pipe, Riva head (pump
> gas),
> > > > > > stock carbs, Solas X prop. The exhaust coupler is also new,
along
> > > > > > with the o-ring that seals the pipe to the manifold.
> > > > > >
> > > > > > Right now, I'm at a loss as to where to start looking for
> problems. I
> > > > > > reinstalled the head and pipe today, everything looks fine. Any
> ideas
> > > > > > or help would be appreciated.
> > > > > >
> > > > > > Chris
>
>

Thunderpimp · Joined: 18 Aug 2007 Posts: 2

i like the 'dump it in the pool' idea.

particularly a pool where exhaust pipe testing is fowned opon.

fight the power.

greg

Muskoka Motion wrote:
>
> Fill the water jacket with compressed air (20psi) then dunk the whole deal
> in the pool when no one is looking. Or dunk it in a garbage can full of
> water... look for bubbles coming from the chamber.
> --
> Scott Gillies
> Muskoka Motion Limited
> Boat and Snowmobile Rentals
> (705) 789-0262
> www.muskokamotion.com
>
> "momar" wrote in message
> @corp.supernews.com...
> > no your checking for water from the water jacket leaking into the exhaust
> > chamber which would definatlley lower your r's seal all the holes and pump
> > twenty pounds in their and see if it goes down
> > "Chris B" wrote in message
> > @posting.google.com...
> > > I haven't checked the pipe, although now that you mention it, I am
> > > hearing a 'resonance' sound. The last time that happened, turns out
> > > the forward mount flange was cracked.
> > >
> > > Back to the pressure test. I assume we're checking for an exhaust
> > > leak into the water jacket. Would a leak test do the trick? I'm
> > > thinking filling the exhaust chamber with water that has a dye in it,
> > > and seeing what comes out the hoses. How would you cap off the ends
> > > for a pressure test, and to what air pressure?
> > >
> > > Chris
> > >
> > >
> > > "Paco \"The Flyin' Finn\"" wrote in message
> > news:...
> > > > Did you pressure test your pipe?
> > > >
> > > > Nate
> > > > "Chris B" wrote in message
> > > > @posting.google.com...
> > > > > Thanks for the ideas momar,
> > > > >
> > > > > I checked the reeds anyway, they're ok. It's not a water injection
> > > > > problem, I unplugged it and did a run just to check.
> > > > >
> > > > > I just finished testing the CDI to the Yamaha service manual, all of
> > > > > the resistances appear to be in tolerance, except for the
> > > > > Black-BrownWhite combo (charger coil), which measures at about 9
> ohms,
> > > > > where the manual tolerance is 2-6. However, it's a cheap analog
> > > > > tester that I'm using, so there's likely an error in the reading.
> > > > >
> > > > > Where I did run into a problem is with the pulser coil
> > > > > (RedWhite-Black). I am getting infinite resistance, where the
> manual
> > > > > lists 12.6 - 15.4 ohms. To make sure I'm doing this right, I touch
> > > > > the black lead to ground, the red lead to the RedWhite wire at the
> > > > > electrical box, which leads to the flywheel.
> > > > >
> > > > > Before I go out buying parts, is there anything else I should check,
> > > > > or do you think this is the problem?
> > > > >
> > > > > Chris
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > > > > "momar" wrote in message
> > > > news:...
> > > > > > usually the culprit is reeds , since you replaced the reeds the
> next
> > > > culprit
> > > > > > is the cdi, and if you have water injection, water in a dry pipe
> can
> > > > lower
> > > > > > the rpm's
> > > > > > "Chris B" wrote in message
> > > > > > @posting.google.com...
> > > > > > > My Ltd. superjet was feeling slow and sluggish, so I went and
> > bought a
> > > > > > > Tiny Tach to help with some tuning. Turns out I was right. The
> > > > > > > highest RPM I could reach is 6130.
> > > > > > >
> > > > > > > This spring, I replaced all seals and gaskets, new pistons and
> > rings
> > > > > > > (bored to 710 cc, 0.5 mm oversize), and new reeds.
> > > > > > >
> > > > > > > I have the following setup: Factory dry pipe, Riva head (pump
> > gas),
> > > > > > > stock carbs, Solas X prop. The exhaust coupler is also new,
> along
> > > > > > > with the o-ring that seals the pipe to the manifold.
> > > > > > >
> > > > > > > Right now, I'm at a loss as to where to start looking for
> > problems. I
> > > > > > > reinstalled the head and pipe today, everything looks fine. Any
> > ideas
> > > > > > > or help would be appreciated.
> > > > > > >
> > > > > > > Chris
> >
> >

Chris B · Joined: 18 Aug 2007 Posts: 4

Ok, I've done the pressure test, in air, and in a tub of water. The
gage didn't move. Both times I let it sit for about 10 minutes. I
have it pressurized right now for a third time (20 min. so far), but I
don't think the pipe is cracked.

So, back to square one. This is what I've checked:
Pressure tested pipe - appears ok
Check for cracked reeds - they are fine
Check CDI to Yamaha service manual specs - it's fine
Checked for water in the collection bowl - it's empty

Could an air leak be causing a loss of performance? How about
something simple like trying new spark plugs? Perhaps I should try
new gaskets?

Another thing I noticed after idling to warm up the engine, and then
doing a couple of WOT runs, was that the cylinder was very hot. I
could only touch it for a couple of seconds. Also, the pipe was very
warm to the touch. Could I have damaged a piston and not know it?
What should I look for in that case?

I'm just throwing ideas into the air right now guys, this problem has
me stumped. With only four days until my next race, time isn't
something I have a lot of.

Thanks for the help so far,

Chris

"momar" wrote in message news:...
> no your checking for water from the water jacket leaking into the exhaust
> chamber which would definatlley lower your r's seal all the holes and pump
> twenty pounds in their and see if it goes down
> "Chris B" wrote in message
> @posting.google.com...
> > I haven't checked the pipe, although now that you mention it, I am
> > hearing a 'resonance' sound. The last time that happened, turns out
> > the forward mount flange was cracked.
> >
> > Back to the pressure test. I assume we're checking for an exhaust
> > leak into the water jacket. Would a leak test do the trick? I'm
> > thinking filling the exhaust chamber with water that has a dye in it,
> > and seeing what comes out the hoses. How would you cap off the ends
> > for a pressure test, and to what air pressure?
> >
> > Chris
> >
> >
> > "Paco \"The Flyin' Finn\"" wrote in message
> news:...
> > > Did you pressure test your pipe?
> > >
> > > Nate
> > > "Chris B" wrote in message
> > > @posting.google.com...
> > > > Thanks for the ideas momar,
> > > >
> > > > I checked the reeds anyway, they're ok. It's not a water injection
> > > > problem, I unplugged it and did a run just to check.
> > > >
> > > > I just finished testing the CDI to the Yamaha service manual, all of
> > > > the resistances appear to be in tolerance, except for the
> > > > Black-BrownWhite combo (charger coil), which measures at about 9 ohms,
> > > > where the manual tolerance is 2-6. However, it's a cheap analog
> > > > tester that I'm using, so there's likely an error in the reading.
> > > >
> > > > Where I did run into a problem is with the pulser coil
> > > > (RedWhite-Black). I am getting infinite resistance, where the manual
> > > > lists 12.6 - 15.4 ohms. To make sure I'm doing this right, I touch
> > > > the black lead to ground, the red lead to the RedWhite wire at the
> > > > electrical box, which leads to the flywheel.
> > > >
> > > > Before I go out buying parts, is there anything else I should check,
> > > > or do you think this is the problem?
> > > >
> > > > Chris
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > "momar" wrote in message
> news:...
> > > > > usually the culprit is reeds , since you replaced the reeds the next
> culprit
> > > > > is the cdi, and if you have water injection, water in a dry pipe can
> lower
> > > > > the rpm's
> > > > > "Chris B" wrote in message
> > > > > @posting.google.com...
> > > > > > My Ltd. superjet was feeling slow and sluggish, so I went and
> bought a
> > > > > > Tiny Tach to help with some tuning. Turns out I was right. The
> > > > > > highest RPM I could reach is 6130.
> > > > > >
> > > > > > This spring, I replaced all seals and gaskets, new pistons and
> rings
> > > > > > (bored to 710 cc, 0.5 mm oversize), and new reeds.
> > > > > >
> > > > > > I have the following setup: Factory dry pipe, Riva head (pump
> gas),
> > > > > > stock carbs, Solas X prop. The exhaust coupler is also new, along
> > > > > > with the o-ring that seals the pipe to the manifold.
> > > > > >
> > > > > > Right now, I'm at a loss as to where to start looking for
> problems. I
> > > > > > reinstalled the head and pipe today, everything looks fine. Any
> ideas
> > > > > > or help would be appreciated.
> > > > > >
> > > > > > Chris