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@gummy8879 avatar
UTC

Enthusiast
2009 Stella, 2001 Honda Helix
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Posts: 85
Location: Memphis, TN
 
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@gummy8879 avatar
2009 Stella, 2001 Honda Helix
Joined: UTC
Posts: 85
Location: Memphis, TN
UTC quote
I removed the autolube on my stella, and ordered the case hole plug available on scootermercato. Unfortunately it seems like the plug is too big for the LML cases. I can fit the plug inside the reed block but I'm not sure if that's the intended location.

Any ideas? Originally I just left the driveshaft in (I removed the pinion gear that turns it) but right now I am diagnosing a loud metallic knocking/tapping noise at lower RPM.

I can supply some pictures when I get home if anyone is hazy on what the LML/stella setup looks like.
@orwell84 avatar
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Ossessionato
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Location: northern New York
 
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UTC quote
Someone will come along who knows the answer for sure, but if the plug fits in the reed block, it should be sufficient to block off the hole.
@mjrally avatar
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73 & 74 Rally, 76 ET3, 80 P200, 06 PX150, 59 Ser 2, 65 Silver Special, 90 V5N 50, 2015 HD Road Glide Special
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@mjrally avatar
73 & 74 Rally, 76 ET3, 80 P200, 06 PX150, 59 Ser 2, 65 Silver Special, 90 V5N 50, 2015 HD Road Glide Special
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UTC quote
If the pinion gear is removed and it's just the oil pump shaft in there, you shouldn't be getting any noises as nothing is turning. Is it a constant sound or does it change with revs?

The clutch side half of the engine cases shouldn't be under any pressure so technically anything can work to plug that side. Maybe some oil resistance silicone in the shaft?

Don't toss those gears as they're pretty expensive to replace $200+
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UTC

Enthusiast
2009 Stella, 2001 Honda Helix
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Location: Memphis, TN
UTC quote
MJRally wrote:
I was thinking that the shaft could be bouncing up and down from the crank's vibration. It changes with revs but the noise kinda goes away once you rev the engine up. It comes back as it lowers back near idle. I will post a video once I get home. The sound almost sounds like very bad piston slap but I don't know how that could be the case if it didn't do that before I tore the engine down, and I am using the same top end.
@mjrally avatar
UTC

Veni, Vidi, Posti
73 & 74 Rally, 76 ET3, 80 P200, 06 PX150, 59 Ser 2, 65 Silver Special, 90 V5N 50, 2015 HD Road Glide Special
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Location: Oceanside, CA
 
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@mjrally avatar
73 & 74 Rally, 76 ET3, 80 P200, 06 PX150, 59 Ser 2, 65 Silver Special, 90 V5N 50, 2015 HD Road Glide Special
Joined: UTC
Posts: 5136
Location: Oceanside, CA
UTC quote
Yea definitely could be piston slap. High mileage top end?

Did you leave both parts of the pump shaft in there? The longer shaft through the cases and the short piece through the reed block? If you have the short piece installed, I can't see how anything could bounce.
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@gummy8879 avatar
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Enthusiast
2009 Stella, 2001 Honda Helix
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Posts: 85
Location: Memphis, TN
 
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@gummy8879 avatar
2009 Stella, 2001 Honda Helix
Joined: UTC
Posts: 85
Location: Memphis, TN
UTC quote
MJRally wrote:
Yea definitely could be piston slap. High mileage top end?

Did you leave both parts of the pump shaft in there? The longer shaft through the cases and the short piece through the reed block? If you have the short piece installed, I can't see how anything could bounce.
It is a VMC Super G cast iron with ~1800 miles on it. It has never seized and I believe the CHT has never been above 370F; almost always stays below 330. I am confused because it did not have piston slap before I tore the engine down and I don't know how it could have been introduced by anything I did. I replaced the LML stock crank with a 57mm Mazzu economy crank, replaced all gaskets+bearings+seals with Piaggio quality or better, and swapped to a 23/64 malossi primary. I also replaced the clutch pads and springs, swapped to a GGR hot reed, and removed the autolube as mentioned.

I left both parts of the shaft in originally but it has been making this noise ever since I first started it back up after closing the case. I removed the short piece thinking that might be the source of the noise but it didn't change anything.

2 videos of idle:
https://www.youtube.com/watch?v=R0M7xSC0EP8
https://www.youtube.com/watch?v=_CQfXbIW7L0
@mjrally avatar
UTC

Veni, Vidi, Posti
73 & 74 Rally, 76 ET3, 80 P200, 06 PX150, 59 Ser 2, 65 Silver Special, 90 V5N 50, 2015 HD Road Glide Special
Joined: UTC
Posts: 5136
Location: Oceanside, CA
 
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@mjrally avatar
73 & 74 Rally, 76 ET3, 80 P200, 06 PX150, 59 Ser 2, 65 Silver Special, 90 V5N 50, 2015 HD Road Glide Special
Joined: UTC
Posts: 5136
Location: Oceanside, CA
UTC quote
Yea sounds like piston rattle. Here's a video I took a few years ago.

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UTC

Enthusiast
2009 Stella, 2001 Honda Helix
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Location: Memphis, TN
 
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@gummy8879 avatar
2009 Stella, 2001 Honda Helix
Joined: UTC
Posts: 85
Location: Memphis, TN
UTC quote
MJRally wrote:
Yup just installed the plug and the noise is still there. I found this thread on another forum, the video sounds just like mine. I'm still struggling to see how piston slap could have suddenly been introduced after running fine up until the rebuild.
https://vespa.proboards.com/thread/5709/noise-crank


Actually I just remembered that I did go one size thinner on the base gasket, but the squish is still ~1.2mm (spec is 1.0 +-0.1 and this is the thinnest one I have).

Could I have somehow installed the rings incorrectly when putting the top end back on? I lined up the opening with the pins on the piston before sliding the cylinder on, and I made sure they didn't jump out. Are they one-way-up or something?
@mjrally avatar
UTC

Veni, Vidi, Posti
73 & 74 Rally, 76 ET3, 80 P200, 06 PX150, 59 Ser 2, 65 Silver Special, 90 V5N 50, 2015 HD Road Glide Special
Joined: UTC
Posts: 5136
Location: Oceanside, CA
 
Veni, Vidi, Posti
@mjrally avatar
73 & 74 Rally, 76 ET3, 80 P200, 06 PX150, 59 Ser 2, 65 Silver Special, 90 V5N 50, 2015 HD Road Glide Special
Joined: UTC
Posts: 5136
Location: Oceanside, CA
UTC quote
If youre curious, pull the head and push down on the piston crown while moving the flywheel up towards you. See if you can find any play between the two. That would indicate a crank bearing problem. The last time I worked on one of those, the rattle sounded a lot louder than the piston slap and didnt go away with revs. Did you use the same little end bearing on the wrist pin? Replace that little end bearing?

The piston slap is the bottom of the piston whacking the cylinder walls. Sadly nothing by the rings or base gasket. The tolerances are tight .004", and it doesnt take much more to start to rattle.
OP
@gummy8879 avatar
UTC

Enthusiast
2009 Stella, 2001 Honda Helix
Joined: UTC
Posts: 85
Location: Memphis, TN
 
Enthusiast
@gummy8879 avatar
2009 Stella, 2001 Honda Helix
Joined: UTC
Posts: 85
Location: Memphis, TN
UTC quote
MJRally wrote:
You might be onto something. I replaced the crank but I remember using the same needle bearing because of a FMP video saying the Mazzu design is worse, but I guess I forgot that I'm not reusing a Piaggio one anyway since it's a LML.

I will do your test after dinner, but I might just swap bearings anyway since it's not that much more work. Fingers crossed!
@orwell84 avatar
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Location: northern New York
 
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@orwell84 avatar
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Posts: 3197
Location: northern New York
UTC quote
Mine went to bits on my Stella. Good thing to rule out.
OP
@gummy8879 avatar
UTC

Enthusiast
2009 Stella, 2001 Honda Helix
Joined: UTC
Posts: 85
Location: Memphis, TN
 
Enthusiast
@gummy8879 avatar
2009 Stella, 2001 Honda Helix
Joined: UTC
Posts: 85
Location: Memphis, TN
UTC quote
Just put it back together with the Mazzu needle bearing and it did not fix the noise. Made no difference. I have made a new thread dedicated to solving this issue.
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