Thu May 14, 2020 4:23 am

bodgemaster
63 GL, 76 Super (x2), 74 Primavera (x2), 79 P200, 06 Fly 150
Joined: 26 Sep 2013
Posts: 6010
Location: So Cal
 
bodgemaster
63 GL, 76 Super (x2), 74 Primavera (x2), 79 P200, 06 Fly 150
Joined: 26 Sep 2013
Posts: 6010
Location: So Cal
Thu May 14, 2020 4:23 am linkquote
~ 1000 miles on brand effing new Pinasco aluminum 177.

This is getting tiresome and expensive ...



Thu May 14, 2020 4:42 am

Ossessionato
1963 VBB2T
Joined: 07 Nov 2012
Posts: 2511

 
Ossessionato
1963 VBB2T
Joined: 07 Nov 2012
Posts: 2511

Thu May 14, 2020 4:42 am linkquote
Wow what happened?
Thu May 14, 2020 5:03 am

Ossessionato
76 Sprint V, 63 GL, 62 VBB, 05 Stella
Joined: 16 Jun 2011
Posts: 3481
Location: Nashville
 
Ossessionato
76 Sprint V, 63 GL, 62 VBB, 05 Stella
Joined: 16 Jun 2011
Posts: 3481
Location: Nashville
Thu May 14, 2020 5:03 am linkquote
That'll buff right out...

Seriously, though, that looks really effing bad. Did it seize coming off a high speed run? The ol' "Let off the throttle and it just...dies...?"

I feel like that's how I usually manage to make pistons look like that.
Thu May 14, 2020 5:10 am

El Presidente Del Topo Chico
VNB VSC VBC VSX
Joined: 28 May 2008
Posts: 5114
Location: Hustletown, TX
 
El Presidente Del Topo Chico
VNB VSC VBC VSX
Joined: 28 May 2008
Posts: 5114
Location: Hustletown, TX
Thu May 14, 2020 5:10 am linkquote
Damn.

That's not inspiring. How many is that now?
Thu May 14, 2020 6:39 am

bodgemaster
63 GL, 76 Super (x2), 74 Primavera (x2), 79 P200, 06 Fly 150
Joined: 26 Sep 2013
Posts: 6010
Location: So Cal
 
bodgemaster
63 GL, 76 Super (x2), 74 Primavera (x2), 79 P200, 06 Fly 150
Joined: 26 Sep 2013
Posts: 6010
Location: So Cal
Thu May 14, 2020 6:39 am linkquote
chandlerman wrote:
That'll buff right out...

Seriously, though, that looks really effing bad. Did it seize coming off a high speed run? The ol' "Let off the throttle and it just...dies...?"

I feel like that's how I usually manage to make pistons look like that.
Pretty much.

That's three cooked 3 pistons in <2000 miles.

What in the bloody hell?
Thu May 14, 2020 6:54 am

Ossessionato
76 Sprint V, 63 GL, 62 VBB, 05 Stella
Joined: 16 Jun 2011
Posts: 3481
Location: Nashville
 
Ossessionato
76 Sprint V, 63 GL, 62 VBB, 05 Stella
Joined: 16 Jun 2011
Posts: 3481
Location: Nashville
Thu May 14, 2020 6:54 am linkquote
what's your ignition timing set to? probably a couple degrees too advanced. That's all it took for me to kill a couple pistons.
Thu May 14, 2020 7:55 am

Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1319
Location: California
 
Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1319
Location: California
Thu May 14, 2020 7:55 am linkquote
darn it So Cal my condolences. Hate to see that happen to anyone.

Couple of questions why is the piston so clean see no carbon or anything on it did you clean it off already? Also the piston looks so smooth don't see those horizontal machine lines is it my bad eyes?
Thu May 14, 2020 8:03 am

Hooked
79p200e 66smallstate 85pk50xl 84p125ets 63GL
Joined: 24 Nov 2016
Posts: 280
Location: Flatness, TX
 
Hooked
79p200e 66smallstate 85pk50xl 84p125ets 63GL
Joined: 24 Nov 2016
Posts: 280
Location: Flatness, TX
Thu May 14, 2020 8:03 am linkquote
Nooooooo! Say it isn't so!

Dang it; SUX is not a strong enough word. Sorry to hear.
Hope this wasn't the resqmod... That engine is brand new.
In any case less than ~1000 clicks is new on any engine...
Thu May 14, 2020 9:28 am

Ossessionato
62 VBB1T Round Tail W/ leaner sidecar
Joined: 26 Jan 2019
Posts: 2358
Location: california
 
Ossessionato
62 VBB1T Round Tail W/ leaner sidecar
Joined: 26 Jan 2019
Posts: 2358
Location: california
Thu May 14, 2020 9:28 am linkquote
Quote:
That's all it took for me to kill a couple pistons.
CM - what was the failure mode on the ones you killed?
Pinging disintegration around the top perimeter of piston?
Hole in the center under plug?
Seize on sides?

Is there a type of failure that occurs with timing related meltdowns in your experience?
Thu May 14, 2020 9:54 am

Ossessionato
1963 VBB2T
Joined: 07 Nov 2012
Posts: 2511

 
Ossessionato
1963 VBB2T
Joined: 07 Nov 2012
Posts: 2511

Thu May 14, 2020 9:54 am linkquote
charlieman22 wrote:
Quote:
That's all it took for me to kill a couple pistons.
CM - what was the failure mode on the ones you killed?
Pinging disintegration around the top perimeter of piston?
Hole in the center under plug?
Seize on sides?

Is there a type of failure that occurs with timing related meltdowns in your experience?
Normally from detonation I would say hole in the top.
Thu May 14, 2020 9:59 am

Ossessionato
76 Sprint V, 63 GL, 62 VBB, 05 Stella
Joined: 16 Jun 2011
Posts: 3481
Location: Nashville
 
Ossessionato
76 Sprint V, 63 GL, 62 VBB, 05 Stella
Joined: 16 Jun 2011
Posts: 3481
Location: Nashville
Thu May 14, 2020 9:59 am linkquote
I forgot to ask earlier...s it just the piston, or is the Nicasil on the cylinder trashed, too?

And you probably already know, but you can clean any smeared aluminum off the cylinder with muriatic acid (thanks to Ginch for that tip).
Thu May 14, 2020 11:04 am

Addicted
2006 GT200L "Lone Star"-Sold, 2006 Yamaha Majesty YP400(Sold)
Joined: 15 Jan 2019
Posts: 679
Location: Texas
 
Addicted
2006 GT200L "Lone Star"-Sold, 2006 Yamaha Majesty YP400(Sold)
Joined: 15 Jan 2019
Posts: 679
Location: Texas
Thu May 14, 2020 11:04 am linkquote
Three melted pistons is your engine trying to tell you something.

Maybe you're pushing the envelope just a bit too much?

Reliable, fast, cheap-pick any two.
Thu May 14, 2020 11:20 am

bodgemaster
63 GL, 76 Super (x2), 74 Primavera (x2), 79 P200, 06 Fly 150
Joined: 26 Sep 2013
Posts: 6010
Location: So Cal
 
bodgemaster
63 GL, 76 Super (x2), 74 Primavera (x2), 79 P200, 06 Fly 150
Joined: 26 Sep 2013
Posts: 6010
Location: So Cal
Thu May 14, 2020 11:20 am linkquote
Chandler: Timing is 18°, as specified by Pinasco. This is the formerly trusty yellow Super... 20/20 carb, bell mouth, 55/160, 160/BE3/128, BGM BB Touring, autolube.

Was maybe 70 miles into a long ride. Pulling a long, gentle uphill prob between 3/4 - WOT, 60+ mph. Engine just fizzled, like it was outta gas.

At first thought it was the clutch ... removed the cover and the nut was loose, clutch was just spinning on crank. Tightened it up, went to kick it ... piston wouldn't budge. Then found this.

hibbert: Piston is indeed clean, and weird burn pattern. Cylinder is clean too. Head is pristine, literally looks unused (see pics).

Have no idea what's going on.

poidog: No, not the GL, thankfully. But hesitant to even run it now. Totally second guessing my skills and feeling a bit cursed.





Thu May 14, 2020 11:22 am

bodgemaster
63 GL, 76 Super (x2), 74 Primavera (x2), 79 P200, 06 Fly 150
Joined: 26 Sep 2013
Posts: 6010
Location: So Cal
 
bodgemaster
63 GL, 76 Super (x2), 74 Primavera (x2), 79 P200, 06 Fly 150
Joined: 26 Sep 2013
Posts: 6010
Location: So Cal
Thu May 14, 2020 11:22 am linkquote
Head ...



Thu May 14, 2020 11:22 am

bodgemaster
63 GL, 76 Super (x2), 74 Primavera (x2), 79 P200, 06 Fly 150
Joined: 26 Sep 2013
Posts: 6010
Location: So Cal
 
bodgemaster
63 GL, 76 Super (x2), 74 Primavera (x2), 79 P200, 06 Fly 150
Joined: 26 Sep 2013
Posts: 6010
Location: So Cal
Thu May 14, 2020 11:22 am linkquote
Plug ...



Thu May 14, 2020 11:24 am

bodgemaster
63 GL, 76 Super (x2), 74 Primavera (x2), 79 P200, 06 Fly 150
Joined: 26 Sep 2013
Posts: 6010
Location: So Cal
 
bodgemaster
63 GL, 76 Super (x2), 74 Primavera (x2), 79 P200, 06 Fly 150
Joined: 26 Sep 2013
Posts: 6010
Location: So Cal
Thu May 14, 2020 11:24 am linkquote
Hot as it got ...



Thu May 14, 2020 12:00 pm

Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: 14 Jun 2017
Posts: 2867
Location: London UK
 
Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: 14 Jun 2017
Posts: 2867
Location: London UK
Thu May 14, 2020 12:00 pm linkquote
Unfortunate. Too weak by the looks of it. Piston crown should be fully black to the edge when jetted correctly. Timing more than likely not exactly measured at 18 degrees but lower. Low timing gives low CHT but high EGT (where the seize marks are).

Cylinder will clean up. It will live again. Chuck more money at it.
Thu May 14, 2020 12:57 pm

Molto Verboso
2007 Stella 225
Joined: 02 Nov 2019
Posts: 1781
Location: Rochester, Minnesota
 
Molto Verboso
2007 Stella 225
Joined: 02 Nov 2019
Posts: 1781
Location: Rochester, Minnesota
Thu May 14, 2020 12:57 pm linkquote
SoCalGuy wrote:
Chandler: Timing is 18°, as specified by Pinasco. This is the formerly trusty yellow Super... 20/20 carb, bell mouth, 55/160, 160/BE3/128, BGM BB Touring, autolube.

Was maybe 70 miles into a long ride. Pulling a long, gentle uphill prob between 3/4 - WOT, 60+ mph. Engine just fizzled, like it was outta gas.

At first thought it was the clutch ... removed the cover and the nut was loose, clutch was just spinning on crank. Tightened it up, went to kick it ... piston wouldn't budge. Then found this.

hibbert: Piston is indeed clean, and weird burn pattern. Cylinder is clean too. Head is pristine, literally looks unused (see pics).

Have no idea what's going on.

poidog: No, not the GL, thankfully. But hesitant to even run it now. Totally second guessing my skills and feeling a bit cursed.

I have a DR177 that I have tuned with an AFR meter and head temperature meter, I'm at about 1000 feet, aiming for around a 12.6 AFR little leaner in a few places, low 13's. Would have thought you would be running a richer main jet than my DR. Does the 55/160 run that much richer than a 45/160?

Timing is 24° with a Kytronix retarding retarding to 18°, 20/20 carb, bell mouth, 45/160, 160/BE3/130 (SIP), carburetor hole drilled out to 2.0 mm, SITO +, autolube. My temperature gauge gets to around 310°F on a hill pulling a grade in 4th, lugs down a bit with the 22 tooth gear. My carburetor slide is also flat no cutouts underneath and the oblong hole that would feed air to the slide is blocked off.

How hot was your motor getting? What brand of jet is it? Interesting that our jetting is close to the same. I did raise the DR cylinder a bit 1.0 mm to increase timing and reduced the squish to 1.0 mm by zero decking the head.

I was thinking I would need to go to a 132 or 134 with the PM Tuning chambered pipe.
Thu May 14, 2020 1:22 pm

Member
Vespa P125X, Stella 2T
Joined: 15 Jul 2019
Posts: 39
Location: Pocatello ID
 
Member
Vespa P125X, Stella 2T
Joined: 15 Jul 2019
Posts: 39
Location: Pocatello ID
Thu May 14, 2020 1:22 pm linkquote
I have also gone through multiple pistons in a similar manor and found that the oilier was not working correctly. Have you tried just running premix?
Thu May 14, 2020 1:32 pm

Ossessionato
76 Sprint V, 63 GL, 62 VBB, 05 Stella
Joined: 16 Jun 2011
Posts: 3481
Location: Nashville
 
Ossessionato
76 Sprint V, 63 GL, 62 VBB, 05 Stella
Joined: 16 Jun 2011
Posts: 3481
Location: Nashville
Thu May 14, 2020 1:32 pm linkquote
TromboneBob wrote:
I have also gone through multiple pistons in a similar manor and found that the oilier was not working correctly. Have you tried just running premix?
I can torch a piston like that running pre-mix, too. I think it's a combination of a couple degrees too advanced on the timing and a couple points too lean on the main.
Thu May 14, 2020 2:16 pm

bodgemaster
63 GL, 76 Super (x2), 74 Primavera (x2), 79 P200, 06 Fly 150
Joined: 26 Sep 2013
Posts: 6010
Location: So Cal
 
bodgemaster
63 GL, 76 Super (x2), 74 Primavera (x2), 79 P200, 06 Fly 150
Joined: 26 Sep 2013
Posts: 6010
Location: So Cal
Thu May 14, 2020 2:16 pm linkquote
Christopher: A 55/160 is quite a bit richer than a 45/160. The A/F ratio is almost 20% lower.

I believe the jets are BGM, but don't remember for sure. I can check.

The engine temp never got above 304°F (see pic of gauge above).

And at the time we were somewhere between 3000-3500 feet elevation and going up, which means the whole set up would've been running richer than normal.

TromboneBob: I'm fairly certain the autolube is working, but not ruling anything out. I've done every test I know how to do on the auto lube. Oil moves through it. Piston had a coating of oil when I pulled it. There was oil in the small end bearing and on the crank. I have not tried running premix in this scoot.

Chandler & Jack: So which is it? Timing too advanced or not advanced enough? Doesn't look to me like there's any detonation. I'm willing to admit it may not be exactly 18°. It could be 18.5 or 17.5. Is that 1 degree really going to make the piston melt?

Also how do you explain the plug color? It looks damn near perfect to me. Plug was brand new when I left the driveway two hours earlier.

Does the burn pattern on the piston definitely indicate a lean condition?
Thu May 14, 2020 4:52 pm

Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1319
Location: California
 
Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1319
Location: California
Thu May 14, 2020 4:52 pm linkquote
Why was the clutch spinning on crank? Key ok?
Thu May 14, 2020 5:15 pm

Ossessionato
Joined: 26 Oct 2015
Posts: 3005

 
Ossessionato
Joined: 26 Oct 2015
Posts: 3005

Thu May 14, 2020 5:15 pm linkquote
25BIKEZ wrote:
Three melted pistons is your engine trying to tell you something.

Maybe you're pushing the envelope just a bit too much?

Reliable, fast, cheap-pick any two.
You are correct that the engine it trying to say something. 2T engine speak a different a little bit different language though. And those three words are very true in the 4 stroke world in any type of vehicle. With air cooled 2T bikes there are more variables involved than that. Most all of us here are more than willing to be eating Ramen noodles 3x a day to be able to throw our hard earned time and money on expensive scooter parts instead! Socalguy isn't cheaping out for sure. He just needs to figure out the cause.
Thu May 14, 2020 5:19 pm

bodgemaster
63 GL, 76 Super (x2), 74 Primavera (x2), 79 P200, 06 Fly 150
Joined: 26 Sep 2013
Posts: 6010
Location: So Cal
 
bodgemaster
63 GL, 76 Super (x2), 74 Primavera (x2), 79 P200, 06 Fly 150
Joined: 26 Sep 2013
Posts: 6010
Location: So Cal
Thu May 14, 2020 5:19 pm linkquote
hibbert: I don't know why the clutch nut was loose. Yes, the key was sheared. The clutch was spinning on the crank because the nut was loose and the key was sheared. Why is a mystery.

It's possible the key sheared and the clutch nut came loose when it seized (thus saving me from an ugly high speed lockup).

It's also possible the clutch nut came loose, causing the autolube spacer/cog to disengage, causing the engine to seize from lack of oil.

Thoughts?
Thu May 14, 2020 5:23 pm

Ossessionato
79 P200E (Ruby), 62 Allstate (B-62), 2008 Stella (Olive)
Joined: 11 Jan 2006
Posts: 2261
Location: Florence, OR
 
Ossessionato
79 P200E (Ruby), 62 Allstate (B-62), 2008 Stella (Olive)
Joined: 11 Jan 2006
Posts: 2261
Location: Florence, OR
Thu May 14, 2020 5:23 pm linkquote
Oh Man - so sorry SCG. I'll be following closely to see when you solve the mystery. You got this....
Thu May 14, 2020 9:09 pm

Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: 14 Jun 2017
Posts: 2867
Location: London UK
 
Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: 14 Jun 2017
Posts: 2867
Location: London UK
Thu May 14, 2020 9:09 pm linkquote
SoCalGuy wrote:
Is that 1 degree really going to make the piston melt?

Does the burn pattern on the piston definitely indicate a lean condition?
Yes. I've said this a few times but I'll try to make it clearer. When you turn the timing down to reduce the CHT the heat doesn't disappear, it moves, to the exhaust, the EGT. The head is designed to dissipate heat, the exhaust port is not. Your jetting is too weak at high rpm. Timing is too low, measure it exactly.

And yes. Lean where it seized. Rich at low rpm and lean at the top.

Change the AC to 120 and timing precisely at 18 (I would set at 19) and it will all work out fine. Probably go faster too.
Thu May 14, 2020 9:39 pm

Ossessionato
73 & 74 Rally, 76 ET3, 80 P200, 06 PX150, 61 Ser 2, 65 Silver Special, 86 & 96 Elite 80s, 2015 HD Road Glide Special, 2011 Ural Tourist
Joined: 18 Jan 2012
Posts: 4022
Location: Oceanside, CA
 
Ossessionato
73 & 74 Rally, 76 ET3, 80 P200, 06 PX150, 61 Ser 2, 65 Silver Special, 86 & 96 Elite 80s, 2015 HD Road Glide Special, 2011 Ural Tourist
Joined: 18 Jan 2012
Posts: 4022
Location: Oceanside, CA
Thu May 14, 2020 9:39 pm linkquote
128 with a bell mouth is super lean. I'd lean 125 without it. Probably 140 with the bell mouth.
Thu May 14, 2020 10:35 pm

Ossessionato
Joined: 26 Oct 2015
Posts: 3005

 
Ossessionato
Joined: 26 Oct 2015
Posts: 3005

Thu May 14, 2020 10:35 pm linkquote
We should all chip in and buy Jack a plane ticket and bring him to the US. Once here, then ship him around the country to have him personally jet in all of our scoots! Then again if we did that, we wouldn't have threads here that were multiple pages long.
Fri May 15, 2020 1:05 am

Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: 14 Jun 2017
Posts: 2867
Location: London UK
 
Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: 14 Jun 2017
Posts: 2867
Location: London UK
Fri May 15, 2020 1:05 am linkquote
If I did it all who would learn anything.
Fri May 15, 2020 1:24 am

Molto Verboso
One or two fun scoots....nothing too precious
Joined: 17 Jul 2013
Posts: 1723
Location: UK (South East)
 
Molto Verboso
One or two fun scoots....nothing too precious
Joined: 17 Jul 2013
Posts: 1723
Location: UK (South East)
Fri May 15, 2020 1:24 am linkquote
And you'd be quarantined for 14 days when you return to the UK
Fri May 15, 2020 2:05 am

Hooked
PX 187, 2005
Joined: 17 Mar 2010
Posts: 105
Location: London
 
Hooked
PX 187, 2005
Joined: 17 Mar 2010
Posts: 105
Location: London
Fri May 15, 2020 2:05 am linkquote
Have all the seizes been with the 20/20 carb?
Fri May 15, 2020 5:50 am

bodgemaster
63 GL, 76 Super (x2), 74 Primavera (x2), 79 P200, 06 Fly 150
Joined: 26 Sep 2013
Posts: 6010
Location: So Cal
 
bodgemaster
63 GL, 76 Super (x2), 74 Primavera (x2), 79 P200, 06 Fly 150
Joined: 26 Sep 2013
Posts: 6010
Location: So Cal
Fri May 15, 2020 5:50 am linkquote
MJRally wrote:
128 with a bell mouth is super lean. I'd lean 125 without it. Probably 140 with the bell mouth.
Started with a 140 main when I got the bellmouth. It barely ran past 1/2 throttle. Worked progressively down through the 130's. 128 is about as fat as can be. It wasn't just a random choice. Good thinking though.
Rooney wrote:
Have all the seizes been with the 20/20 carb?
No, just last two. Seized before that with a 24/24 + 118MJ (no bellmouth).

For reference, a Polini 177 bolted on to my other Soop (identical 3-port Veloce engine) 20/20 carb, no bell ... and a 112 main. It's been up and down the California coast, thousands and thousands of miles, not quite as fast but solid as a rock.

IDK. I think maybe I'm gonna ditch the bell mouth altogether.

Jack: That burn pattern is just wrong. I like your theory. I can see it being the result of timing being too far retarded. To paraphrase Forrest Gump, I may not be a smart man but I know how to time an engine. In fact I checked it just before the trip. I'm willing to bet it's dead on 18°. I'll reset it to 19°.

What I don't understand is how anyone would possibly know NOT to follow Pinasco's express instructions about setting the timing to 18°. That is the one thing they are absolutely clear about.



Fri May 15, 2020 6:11 am

Ossessionato
62 VBB1T Round Tail W/ leaner sidecar
Joined: 26 Jan 2019
Posts: 2358
Location: california
 
Ossessionato
62 VBB1T Round Tail W/ leaner sidecar
Joined: 26 Jan 2019
Posts: 2358
Location: california
Fri May 15, 2020 6:11 am linkquote
I place a vote (not that I have a vote, or if I did have a vote, that it would count) for trying the Jack Stack with the 120AC/BE3/___ and bell mouth. If you can jet in the bottom - you're all set as the top, as it doesn't wanna lean out at WOT as much - at least in my experience.

Seems like with 160AC you otherwise get in to this loop:
Quote:
Started with a 140 main when I got the bellmouth. It barely ran past 1/2 throttle. Worked progressively down through the 130's. 128 is about as fat as can be.
Fri May 15, 2020 6:15 am

Ossessionato
1963 VBB2T
Joined: 07 Nov 2012
Posts: 2511

 
Ossessionato
1963 VBB2T
Joined: 07 Nov 2012
Posts: 2511

Fri May 15, 2020 6:15 am linkquote
Jack221 wrote:
If I did it all who would learn anything.
Uh me
Fri May 15, 2020 6:54 am

Ossessionato
1979 P150X, 1983 P200E, 1988 T5, 1995 PX200E, 2011 Yamaha Fazer 600 S2
Joined: 02 Aug 2015
Posts: 2374
Location: Veria, Greece
 
Ossessionato
1979 P150X, 1983 P200E, 1988 T5, 1995 PX200E, 2011 Yamaha Fazer 600 S2
Joined: 02 Aug 2015
Posts: 2374
Location: Veria, Greece
Fri May 15, 2020 6:54 am linkquote
Just a thought. I know 4 people here that seized their P/PXs (a 150, a 177 and two 200s) with BGM boxes. All properly jetted...

Never liked them to be honest...
Fri May 15, 2020 7:18 am

bodgemaster
63 GL, 76 Super (x2), 74 Primavera (x2), 79 P200, 06 Fly 150
Joined: 26 Sep 2013
Posts: 6010
Location: So Cal
 
bodgemaster
63 GL, 76 Super (x2), 74 Primavera (x2), 79 P200, 06 Fly 150
Joined: 26 Sep 2013
Posts: 6010
Location: So Cal
Fri May 15, 2020 7:18 am linkquote
There's an interesting twist. Any specific ideas how the BB might be contributing to the piston failures? It has a distinctly different (fatter) low- to mid-range than the SIP Road 2.0, which is the only other pipe I've directly compared it to.
Fri May 15, 2020 7:31 am

Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: 14 Jun 2017
Posts: 2867
Location: London UK
 
Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: 14 Jun 2017
Posts: 2867
Location: London UK
Fri May 15, 2020 7:31 am linkquote
Nothing I say is theory.

If you showed me that piston crown a week ago I would have said it will seize on a long journey. It's too weak. Must be black to the edge or it's going to blow.

Wouldn't read too much into the BB . The better an exhaust is the better your jetting needs to be.
Fri May 15, 2020 10:21 am

bodgemaster
63 GL, 76 Super (x2), 74 Primavera (x2), 79 P200, 06 Fly 150
Joined: 26 Sep 2013
Posts: 6010
Location: So Cal
 
bodgemaster
63 GL, 76 Super (x2), 74 Primavera (x2), 79 P200, 06 Fly 150
Joined: 26 Sep 2013
Posts: 6010
Location: So Cal
Fri May 15, 2020 10:21 am linkquote
I like your confidence, Jack. We're gonna find out. New piston, rings and clips have been ordered and are on their way.

The way I see it, the burn pattern shows that LOTS of fuel is washing in over the piston from each of the three ports.

It's definitely not detonating. There aren't any signs of early ignition.

The plug is exactly what I'd want it to look like.

I suppose too retarded ignition could account for the sparkly clean head.

Would also account for the exhaust port is getting red hot and dragging the rings. And the relatively cool head temp when it seized.

Makes sense that advancing the ignition a degree would cause combustion to occur earlier and up closer to the head.

I'm willing to give it go.

Thanks all.

Stand by ...

Last edited by SoCalGuy on Fri May 15, 2020 8:53 pm; edited 2 times in total
Fri May 15, 2020 10:32 am

Ossessionato
'15 GTS300, '86 PX125EFL, '66 VBB, '04 Ninja 250
Joined: 04 Apr 2013
Posts: 4788
Location: San Diego, CA
 
Ossessionato
'15 GTS300, '86 PX125EFL, '66 VBB, '04 Ninja 250
Joined: 04 Apr 2013
Posts: 4788
Location: San Diego, CA
Fri May 15, 2020 10:32 am linkquote
that's a bummer. I hear you on the frustration - but sounds like you are getting some good advice. good luck with it - are you going to stick with the same kit?
Fri May 15, 2020 10:44 am

bodgemaster
63 GL, 76 Super (x2), 74 Primavera (x2), 79 P200, 06 Fly 150
Joined: 26 Sep 2013
Posts: 6010
Location: So Cal
 
bodgemaster
63 GL, 76 Super (x2), 74 Primavera (x2), 79 P200, 06 Fly 150
Joined: 26 Sep 2013
Posts: 6010
Location: So Cal
Fri May 15, 2020 10:44 am linkquote
Thanks John, yeah sticking with the Pinasco for now. It's got a nice smooth power band and runs cool... when it's not eating pistons.

I added a tooth to the clutch so cruises nicely at speed. Trying to dial it in as the road trip bike.
  DoubleGood Vespa T-Shirts  

All Content Copyright 2005-2021 by Modern Vespa. All Rights Reserved.

Modern Vespa is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to amazon.com.

Shop on Amazon Smile with Modern Vespa

[ Time: 0.0586s ][ Queries: 28 (0.0274s) ][ Debug on ][ 201 ][ Thing Two ]