Fri May 15, 2020 11:25 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 11:25 am linkquote
Be sure to check the timing with a strobe/degree wheel and with a 120 all will be fine.

Another relevent point is the squish. Needs to be around 1mm or less. If this is too big the piston (EGT) runs hotter.
Fri May 15, 2020 3:09 pm

bodgemaster
63 GL, 76 Super (x2), 74 Primavera (x2), 79 P200, 06 Fly 150
Joined: 26 Sep 2013
Posts: 6012
Location: So Cal
 
bodgemaster
63 GL, 76 Super (x2), 74 Primavera (x2), 79 P200, 06 Fly 150
Joined: 26 Sep 2013
Posts: 6012
Location: So Cal
Fri May 15, 2020 3:09 pm linkquote
I don't think the squish can be corrected to 1mm on these nicasil kits using a 57mm crank.
Fri May 15, 2020 3:22 pm

Enthusiast
'58 VBA '79CT90
Joined: 25 Dec 2019
Posts: 57
Location: Chico CA
 
Enthusiast
'58 VBA '79CT90
Joined: 25 Dec 2019
Posts: 57
Location: Chico CA
Fri May 15, 2020 3:22 pm linkquote
"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. "

Well, I bought a used VBA that came with a Pinasco Flytech and a 177cc kit. Instructions only for the ignition. My email inquiry to Pinasco got this reply,

"Dear Customer,
Our electronic ignition allows few errors, if fitted in a wrong way does not work and the Vespa works badly as well, so it is easy to found something wrong.
To find the best timing you must try to do the same you do with carburetion, you will find the best CDI timing driving or using a strobo light gun, in this case you should stay at 24° at 2500rpm.
Thank you for choosing our products.
Best regards,
Pinasco Staff"

Not a word about 18degrees anywhere

So this thread is of great interest to me with less than fifty miles on it since the rebuild and I don't want to follow SoCalGuy's example
Fri May 15, 2020 4:37 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
Fri May 15, 2020 4:37 pm linkquote
Grumpnut wrote:
"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. "

Well, I bought a used VBA that came with a Pinasco Flytech and a 177cc kit. Instructions only for the ignition. My email inquiry to Pinasco got this reply,

"Dear Customer,
Our electronic ignition allows few errors, if fitted in a wrong way does not work and the Vespa works badly as well, so it is easy to found something wrong.
To find the best timing you must try to do the same you do with carburetion, you will find the best CDI timing driving or using a strobo light gun, in this case you should stay at 24° at 2500rpm.
Thank you for choosing our products.
Best regards,
Pinasco Staff"

Not a word about 18degrees anywhere

So this thread is of great interest to me with less than fifty miles on it since the rebuild and I don't want to follow SoCalGuy's example
Grump- you're mixing up your Pinasco products. Flytech ignition isn't what we're talking about right here. That's a whole other thread with people complaining about shitty Pinasco instructions.

If you remember what the A and IT mean on a stator plate, you'll be able to read Pinasco Engrish and see they recommend IT or 18* ignition timing.



Fri May 15, 2020 5:53 pm

Enthusiast
'58 VBA '79CT90
Joined: 25 Dec 2019
Posts: 57
Location: Chico CA
 
Enthusiast
'58 VBA '79CT90
Joined: 25 Dec 2019
Posts: 57
Location: Chico CA
Fri May 15, 2020 5:53 pm linkquote
But we are talking timing. It is all confusing. And clearly Pinasco told me 24 degrees at 2500.
Fri May 15, 2020 7:20 pm

Ossessionato
1963 VBB2T
Joined: 07 Nov 2012
Posts: 2511

 
Ossessionato
1963 VBB2T
Joined: 07 Nov 2012
Posts: 2511

Fri May 15, 2020 7:20 pm linkquote
SoCalGuy I sure hope you get this sorted out.
Fri May 15, 2020 7:53 pm

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 7:53 pm linkquote
Gents - interesting discussion.
For a bunch of old guys - its remarkable how well we can run 1 conversation on three threads. Just like the kids do it.

Grumpnut:
1. Impressive screen name.
2. I read your Pinasco response differently.

I think what they were saying - in what ever the Italian version of Spanglish is: "we give you a targeta, but you have to adjust ita - like a carburatore. Every motor is differently - read the signs - make the changes - careful you don't blow it up. lots of hand gestures - ¯\_(ツ)_/¯

I'm not saying it was particularly helpful - but hey - its what we got.
For me - the interesting part of the discussion is - that plug reads are good - but piston reads can be the nuts.

Bad timing can be read on a piston, along with wash for lean and rich.
SoCal's plug was perfect - but the combustion timing was likely too retarded.
That's probably responsible for his head looking like it had never been used - cause basically - the combustion was happening at the wrong time and away from the head.

Chandlerman noted his own experience - one or two degrees can mean everything. The trick is - to be able to read the piston well enough to make the adjustments...
Fri May 15, 2020 9:46 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
Fri May 15, 2020 9:46 pm linkquote
CM explains it the way I read it. Each motor is different and has to be adjusted. Pinasco can't really say what the timing should be for your engine, as it depends on too many variables. Based on everything being as designed 18 but with all the manufacturing tolerances (especially with pinasco stuff lately) this is going to be variable. Compression, squish, head shape, fuel grade etc. all have a major effect on what the timing needs to be. We know from many years of blowing up 2 strokes, that for the best efficiency the timing should be as advanced as possible. About 1degree under detonation is the target. So for the more macho, increase until it pinks, then back it off until it stops, then 1 degree more.
Sat May 16, 2020 12:14 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)
Sat May 16, 2020 12:14 am linkquote
I timed my Pinasco 225 last weekend and I was amazed how far away it was from the factory marks. Same situation with my Super. I realise that SoCal would have used a strobe, but for anyone else who thought (like I did at first) that you can rely on those factory stator and case markings, here's your confirmation.

By the time I was at an accurate 19 degrees, the stator was almost on the 'A' mark (23 degrees). Therefore, had I just relied on the 'IT' mark for 18, I would really have been at ~15. Having read this thread, I'm going to advance it to 21, see if it pinks/pings under load, then work it back from there, 1 degree at a time.
Sat May 16, 2020 6:20 am

Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1320
Location: California
 
Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1320
Location: California
Sat May 16, 2020 6:20 am linkquote
charlieman22 wrote:
Gents - interesting discussion.
For a bunch of old guys - its remarkable how well we can run 1 conversation on three threads. Just like the kids do it.

Grumpnut:
1. Impressive screen name.
2. I read your Pinasco response differently.

I think what they were saying - in what ever the Italian version of Spanglish is: "we give you a targeta, but you have to adjust ita - like a carburatore. Every motor is differently - read the signs - make the changes - careful you don't blow it up. lots of hand gestures - ¯\_(ツ)_/¯

I'm not saying it was particularly helpful - but hey - its what we got.
For me - the interesting part of the discussion is - that plug reads are good - but piston reads can be the nuts.

Bad timing can be read on a piston, along with wash for lean and rich.
SoCal's plug was perfect - but the combustion timing was likely too retarded.
That's probably responsible for his head looking like it had never been used - cause basically - the combustion was happening at the wrong time and away from the head.

Chandlerman noted his own experience - one or two degrees can mean everything. The trick is - to be able to read the piston well enough to make the adjustments...
Hahaha so good Charlieman
Sat May 16, 2020 6:56 am

Hooked
Joined: 22 Jul 2018
Posts: 118

 
Hooked
Joined: 22 Jul 2018
Posts: 118

Sat May 16, 2020 6:56 am linkquote
swa45 wrote:
I timed my Pinasco 225 last weekend and I was amazed how far away it was from the factory marks. Same situation with my Super. I realise that SoCal would have used a strobe, but for anyone else who thought (like I did at first) that you can rely on those factory stator and case markings, here's your confirmation.

By the time I was at an accurate 19 degrees, the stator was almost on the 'A' mark (23 degrees). Therefore, had I just relied on the 'IT' mark for 18, I would really have been at ~15. Having read this thread, I'm going to advance it to 21, see if it pinks/pings under load, then work it back from there, 1 degree at a time.
Once you change the stroke, all the timing marks are thrown out the window. Even if the stroke stays the same and the rod length is changed moves the marks off.
Sat May 16, 2020 6:58 am

Hooked
Joined: 22 Jul 2018
Posts: 118

 
Hooked
Joined: 22 Jul 2018
Posts: 118

Sat May 16, 2020 6:58 am linkquote
What does the other side of the piston look like? Are there scoring marks aligned with the studs on that side of the motor? Take a pic of the underside of the piston. This can help show what the piston temp would have been based on deposits under the crown.

I think this looks more like lack of lubrication than tuning. Temp was fine for aluminum. Plug looks good. Not no lubrication but too little.
Sat May 16, 2020 7:23 am

bodgemaster
63 GL, 76 Super (x2), 74 Primavera (x2), 79 P200, 06 Fly 150
Joined: 26 Sep 2013
Posts: 6012
Location: So Cal
 
bodgemaster
63 GL, 76 Super (x2), 74 Primavera (x2), 79 P200, 06 Fly 150
Joined: 26 Sep 2013
Posts: 6012
Location: So Cal
Sat May 16, 2020 7:23 am linkquote
BlackT5 wrote:
What does the other side of the piston look like? Are there scoring marks aligned with the studs on that side of the motor? Take a pic of the underside of the piston. This can help show what the piston temp would have been based on deposits under the crown.

I think this looks more like lack of lubrication than tuning. Temp was fine for aluminum. Plug looks good. Not no lubrication but too little.
Here you go.

There's scoring on intake side but none at any of the corners. That would seem to rule out lack of lube.

Underside is virtually carbon free. Very little color at all.



Sat May 16, 2020 7:24 am

bodgemaster
63 GL, 76 Super (x2), 74 Primavera (x2), 79 P200, 06 Fly 150
Joined: 26 Sep 2013
Posts: 6012
Location: So Cal
 
bodgemaster
63 GL, 76 Super (x2), 74 Primavera (x2), 79 P200, 06 Fly 150
Joined: 26 Sep 2013
Posts: 6012
Location: So Cal
Sat May 16, 2020 7:24 am linkquote
Underside



Sat May 16, 2020 7:53 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
Sat May 16, 2020 7:53 am linkquote
BLT5 - your point's a good one.
That temp shoulda been fine for the cylinder.
But take a look at SoCal's piston.
The combustion black looks like a piece of pizza crust that fell in to the bottom of the oven and was forgotten. Way charcoaled.
Sticking with that - analogy - only half the pizza was getting cooked in the oven - the other half - in the exhaust port.

Look at how that black on top of the piston runs right off into what would be the exhaust port.
That's the give away that ignition was occurring at the bottom of the stroke - down by the exhaust port - rather than in the cylinder as the stroke came up to the top.
There should have been golden brown flares on top of the piston where the exhaust port was.

That combustion occurring with the exhaust port open exposed the rings to crazy high temps at the front of the piston facing the exhaust port - while leaving his head temp at a reasonable number.
Also explains why his head is pristine - cause the combustion heat was so far away from it.

Riffing on that a little - it looks like one of the transfer ports was in on the game too. See that weirdly placed bit of charcoal at the very tip of the piston? That looks weird to me.

If all that sounds smart - it is! But I can't take credit for it.
SoCal figured it out after Jack flagged timing.
If you look at the piston again now - you can really see how weird that burn pattern is - not for the wash at the inlets - but for how it goes right off in to the exhaust without interruption.



Sat May 16, 2020 8:02 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
Sat May 16, 2020 8:02 am linkquote
BlackT5 wrote:
Once you change the stroke, all the timing marks are thrown out the window. Even if the stroke stays the same and the rod length is changed moves the marks off.
There are 360 degrees in a circle, even without a Conrod. Nothing changes with degrees. If you do timing by mm to TDC, totally different.

Good effort CM. Think they are starting to understand. Timing too far retarded for the motor. Mixture too weak at high rpm. Next time out SoCal will have it all sorted.

Last edited by Jack221 on Sat May 16, 2020 8:05 am; edited 1 time in total
Sat May 16, 2020 8:04 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
Sat May 16, 2020 8:04 am linkquote
swa45 wrote:
I timed my Pinasco 225 last weekend and I was amazed how far away it was from the factory marks. Same situation with my Super. I realise that SoCal would have used a strobe, but for anyone else who thought (like I did at first) that you can rely on those factory stator and case markings, here's your confirmation.

By the time I was at an accurate 19 degrees, the stator was almost on the 'A' mark (23 degrees). Therefore, had I just relied on the 'IT' mark for 18, I would really have been at ~15. Having read this thread, I'm going to advance it to 21, see if it pinks/pings under load, then work it back from there, 1 degree at a time.
There a thread to continue progress on the 225?
Sat May 16, 2020 8:13 am

Hooked
Joined: 22 Jul 2018
Posts: 118

 
Hooked
Joined: 22 Jul 2018
Posts: 118

Sat May 16, 2020 8:13 am linkquote
Jack221 wrote:
BlackT5 wrote:
Once you change the stroke, all the timing marks are thrown out the window. Even if the stroke stays the same and the rod length is changed moves the marks off.
There are 360 degrees in a circle, even without a Conrod. Nothing changes with degrees. If you do timing by mm to TDC, totally different.

Good effort CM. Think they are starting to understand. Timing too far retarded for the motor. Mixture too weak at high rpm. Next time out SoCal will have it all sorted.
That is completely correct regarding degrees being degrees however I was speaking in regards to using the marks on the stator to time the ignition. Those are pointless once stroke and rod length is changed. The point is to get the stator timed to the point it will run then flash it with a strobe. A portion of the discussion was related to IT and A marks.

Edit to add more to this so my whole point comes across: if you had made your own marks on the flywheel and case using a degree wheel, for example 18 degrees, and removed that crank and change stroke or con rod length and put that crank back in, your still at 18 degrees, nothing changed. Is 18 degrees still the ideal ignition advance? Probably not but you wouldn't know till you ran tests with other advances. Now, if you swap that crank out for a stroked one your marks are going to be wrong until you measure them again for manufacturing tolorances. Blindly trusting timing marks get you in trouble.

This goes way deeper than that because changes in stroke and con rod change piston speed and dwell time which hugely effects the timing requirements.

Last edited by BlackT5 on Sat May 16, 2020 8:48 am; edited 1 time in total
Sat May 16, 2020 8:23 am

Hooked
Joined: 22 Jul 2018
Posts: 118

 
Hooked
Joined: 22 Jul 2018
Posts: 118

Sat May 16, 2020 8:23 am linkquote
charlieman22 wrote:
BLT5 - your point's a good one.
That temp shoulda been fine for the cylinder.
But take a look at SoCal's piston.
The combustion black looks like a piece of pizza crust that fell in to the bottom of the oven and was forgotten. Way charcoaled.
Sticking with that - analogy - only half the pizza was getting cooked in the oven - the other half - in the exhaust port.

Look at how that black on top of the piston runs right off into what would be the exhaust port.
That's the give away that ignition was occurring at the bottom of the stroke - down by the exhaust port - rather than in the cylinder as the stroke came up to the top.
There should have been golden brown flares on top of the piston where the exhaust port was.

That combustion occurring with the exhaust port open exposed the rings to crazy high temps at the front of the piston facing the exhaust port - while leaving his head temp at a reasonable number.
Also explains why his head is pristine - cause the combustion heat was so far away from it.

Riffing on that a little - it looks like one of the transfer ports was in on the game too. See that weirdly placed bit of charcoal at the very tip of the piston? That looks weird to me.

If all that sounds smart - it is! But I can't take credit for it.
SoCal figured it out after Jack flagged timing.
If you look at the piston again now - you can really see how weird that burn pattern is - not for the wash at the inlets - but for how it goes right off in to the exhaust without interruption.
It won't run with the timing so retarded that it ignites right before the exhaust port open.

Jack is correct with it being retarded timing. The dark spot under the crown shows deposits being placed due to high crown temperature. The piston top deposits are so bad because the crown temperature is so high from retarded timing that carbon is being deposited as the transfers open and wash out the exhaust. It would be very evident with an EGT gauge. Super high EGT with low CHT. The temperature that should be in the cylinder is being moved to the exhaust via retarded ignition.

The opposite is true if timing is to far advanced. Once detonation starts you see a drop in EGT but CHT skyrocket. Using both is ideal to dial in tuning so you can get a clear look at what is going on in the cylinder.
Sat May 16, 2020 8:30 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
Sat May 16, 2020 8:30 am linkquote
whodatschrome wrote:
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.
I do understand. I've owned 5 Water Buffaloes, 5 RD350/400s, a GT500 Titan, a Yamaha DT360, Suzuki TS100, and a Honda Aero 125, among others. Porting, expansion chambers, jetting, oiling, etc. Been there, done that. My point was, he might be asking too much from too little. For example, 12:1 AFR? The ideal, established for nearly 100 years and verified by multiple industry and government entities, for any IC engine, is 14.7:1 at sea level, Standard Day temp and humidity. 12:1 is lean, and will result in higher temps, which, judging from all the melting going on, is part of the problem. With such a small piston, he's just not getting the heat transfer out of the piston and to the cylinder walls fast enough. You're absolutely right about the pursuit of an idea at any cost-it's his dragon to slay, his money to spend, his time to use however he wants. I'm just saying maybe this particular engine, this particular quest for power AND reliability is not meant to be. I wish him well, and know that lots of experience is out there to guide his efforts.
Sat May 16, 2020 8:36 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
Sat May 16, 2020 8:36 am linkquote
Quote:
The temperature that should be in the cylinder is being moved to the exhaust via retarded ignition.
BLT5 - think we are mostly saying the same thing.
Super high temps in the exhaust port rather than the cylinder.
Ignition happening away from the point where the piston is at or near full compression.
Burn pattern running off the piston in to the exhaust is a tell tale sign.
Melted rings at front from facing super hot exhaust port is the result.
Retarded timing is the culprit.
Sat May 16, 2020 8:55 am

Hooked
Joined: 22 Jul 2018
Posts: 118

 
Hooked
Joined: 22 Jul 2018
Posts: 118

Sat May 16, 2020 8:55 am linkquote
charlieman22 wrote:
Quote:
The temperature that should be in the cylinder is being moved to the exhaust via retarded ignition.
BLT5 - think we are mostly saying the same thing.
Super high temps in the exhaust port rather than the cylinder.
Ignition happening away from the point where the piston is at or near full compression.
Burn pattern running off the piston in to the exhaust is a tell tale sign.
Melted rings at front from facing super hot exhaust port is the result.
Retarded timing is the culprit.
Yeah, 100%. I was elaborating on how timing moves combustion temperature around.

Edit: which was completely redundant because Jack already did on page 1 which I'm reading again because I have an idea.
Sat May 16, 2020 9:30 am

Hooked
Joined: 22 Jul 2018
Posts: 118

 
Hooked
Joined: 22 Jul 2018
Posts: 118

Sat May 16, 2020 9:30 am linkquote
SCG,

How are you setting your timing? Would you happen to be using an adjustable strobe and TDC marks?
Sat May 16, 2020 9:33 am

Hooked
Joined: 22 Jul 2018
Posts: 118

 
Hooked
Joined: 22 Jul 2018
Posts: 118

Sat May 16, 2020 9:33 am linkquote
25BIKEZ wrote:
whodatschrome wrote:
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.
I do understand. I've owned 5 Water Buffaloes, 5 RD350/400s, a GT500 Titan, a Yamaha DT360, Suzuki TS100, and a Honda Aero 125, among others. Porting, expansion chambers, jetting, oiling, etc. Been there, done that. My point was, he might be asking too much from too little. For example, 12:1 AFR? The ideal, established for nearly 100 years and verified by multiple industry and government entities, for any IC engine, is 14.7:1 at sea level, Standard Day temp and humidity. 12:1 is lean, and will result in higher temps, which, judging from all the melting going on, is part of the problem. With such a small piston, he's just not getting the heat transfer out of the piston and to the cylinder walls fast enough. You're absolutely right about the pursuit of an idea at any cost-it's his dragon to slay, his money to spend, his time to use however he wants. I'm just saying maybe this particular engine, this particular quest for power AND reliability is not meant to be. I wish him well, and know that lots of experience is out there to guide his efforts.
You got it backwards, the lower the number the richer and higher the number leaner.
Sat May 16, 2020 2:10 pm

bodgemaster
63 GL, 76 Super (x2), 74 Primavera (x2), 79 P200, 06 Fly 150
Joined: 26 Sep 2013
Posts: 6012
Location: So Cal
 
bodgemaster
63 GL, 76 Super (x2), 74 Primavera (x2), 79 P200, 06 Fly 150
Joined: 26 Sep 2013
Posts: 6012
Location: So Cal
Sat May 16, 2020 2:10 pm linkquote
BlackT5 wrote:
SCG,

How are you setting your timing? Would you happen to be using an adjustable strobe and TDC marks?
Non-adjustable strobe. TDC and timing marks were carefully measured and marked using degree wheel.
Sat May 16, 2020 3:19 pm

Hooked
Joined: 22 Jul 2018
Posts: 118

 
Hooked
Joined: 22 Jul 2018
Posts: 118

Sat May 16, 2020 3:19 pm linkquote
SoCalGuy wrote:
BlackT5 wrote:
SCG,

How are you setting your timing? Would you happen to be using an adjustable strobe and TDC marks?
Non-adjustable strobe. TDC and timing marks were carefully measured and marked using degree wheel.
That works. I asked because most people don't know adjustable strobes read half value when used on a two stroke. If you want 18 degrees you dial in 36. If you dialed 18 you end up 9. It's a real easy way to end up with way retarded ignition if you don't know.
Sat May 16, 2020 3:50 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
Sat May 16, 2020 3:50 pm linkquote
BlackT5 wrote:
SoCalGuy wrote:
BlackT5 wrote:
SCG,

How are you setting your timing? Would you happen to be using an adjustable strobe and TDC marks?
Non-adjustable strobe. TDC and timing marks were carefully measured and marked using degree wheel.
That works. I asked because most people don't know adjustable strobes read half value when used on a two stroke. If you want 18 degrees you dial in 36. If you dialed 18 you end up 9. It's a real easy way to end up with way retarded ignition if you don't know.
Do you have a reference for timing being off? That means mines at 12° retarding to 4°. I'm surprised it even runs, I've got to go look my light up and see if the instructions say anything. Nevermind, mine has a button for 2 or 4 cycle.



Sat May 16, 2020 4:54 pm

Hooked
Joined: 22 Jul 2018
Posts: 118

 
Hooked
Joined: 22 Jul 2018
Posts: 118

Sat May 16, 2020 4:54 pm linkquote
Super rad that one has a button to account for the difference.

Edit: I just looked up your model and I might want to buy one. Having a tach on there would come in pretty handy.
Sun May 17, 2020 5:41 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
Sun May 17, 2020 5:41 am linkquote
BlackT5 wrote:
25BIKEZ wrote:
whodatschrome wrote:
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.
I do understand. I've owned 5 Water Buffaloes, 5 RD350/400s, a GT500 Titan, a Yamaha DT360, Suzuki TS100, and a Honda Aero 125, among others. Porting, expansion chambers, jetting, oiling, etc. Been there, done that. My point was, he might be asking too much from too little. For example, 12:1 AFR? The ideal, established for nearly 100 years and verified by multiple industry and government entities, for any IC engine, is 14.7:1 at sea level, Standard Day temp and humidity. 12:1 is lean, and will result in higher temps, which, judging from all the melting going on, is part of the problem. With such a small piston, he's just not getting the heat transfer out of the piston and to the cylinder walls fast enough. You're absolutely right about the pursuit of an idea at any cost-it's his dragon to slay, his money to spend, his time to use however he wants. I'm just saying maybe this particular engine, this particular quest for power AND reliability is not meant to be. I wish him well, and know that lots of experience is out there to guide his efforts.
You got it backwards, the lower the number the richer and higher the number leaner.
Maybe THAT'S why my two strokes kept blowing up...!
Sun May 17, 2020 7:32 am

Ossessionato
1963 VBB2T
Joined: 07 Nov 2012
Posts: 2511

 
Ossessionato
1963 VBB2T
Joined: 07 Nov 2012
Posts: 2511

Sun May 17, 2020 7:32 am linkquote
Wow this has got to be the most interesting topic. Once I get my scooter fired up I hope it never effs up on me.
Sun May 17, 2020 8:49 am

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
Sun May 17, 2020 8:49 am linkquote
BlackT5 wrote:
Super rad that one has a button to account for the difference.

Edit: I just looked up your model and I might want to buy one. Having a tach on there would come in pretty handy.
When I was dialing in my Kytronix it allowed me to verify rpm and retard. Only having to get a good TDC mark is a bonus, I never new exactly what the letters were for exactly as I never used them for timing. I bought it originally to use on my 70cc BBK 2 stroke scooter to dial it in timing.

Measuring the exhaust temperature sounds like it could be interesting also.
Tue May 19, 2020 7:08 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
Tue May 19, 2020 7:08 am linkquote
I ordered an EGT Gauge this morning. Got an analog aircraft gauge, which I like the look of.

They make a dual EGT/CHT, too, but it's back-ordered, so I decided to just keep it separate for now.

Assuming I like it, I might swap the Koso CHT for a matching CHT, but there's also something to be said for the features like Max Temp on the digital gauge.


2" EGT

Sun May 24, 2020 6:34 am

bodgemaster
63 GL, 76 Super (x2), 74 Primavera (x2), 79 P200, 06 Fly 150
Joined: 26 Sep 2013
Posts: 6012
Location: So Cal
 
bodgemaster
63 GL, 76 Super (x2), 74 Primavera (x2), 79 P200, 06 Fly 150
Joined: 26 Sep 2013
Posts: 6012
Location: So Cal
Sun May 24, 2020 6:34 am linkquote
Update: cleaned up the cylinder, gave it a light hone, and installed a new piston, rings, pin and clips last night.

Reset timing from 18 to 20°.

Jack: Now before I take it out and melt it again, can you explain why you're recommending I put in a 120 air corrector? What exactly are the signs that it was running lean?



Sun May 24, 2020 8:20 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
Sun May 24, 2020 8:20 am linkquote
Nice. Back in business so soon. It won't happen again with better jetting and 20 degrees timing. Listen for detonation noises when at WOT and high rpm. Check the piston crown is running fully black right to the edge. There will be a bare golden spot in the full black crown near each main transfer, when the WOT jetting is all perfect.

Get the main jet to flood and work it down. Check the spark plug often. CHT at 300F for prolonged 4th gear WOT is the initial target.
Mon May 25, 2020 11:23 am

bodgemaster
63 GL, 76 Super (x2), 74 Primavera (x2), 79 P200, 06 Fly 150
Joined: 26 Sep 2013
Posts: 6012
Location: So Cal
 
bodgemaster
63 GL, 76 Super (x2), 74 Primavera (x2), 79 P200, 06 Fly 150
Joined: 26 Sep 2013
Posts: 6012
Location: So Cal
Mon May 25, 2020 11:23 am linkquote
Happy Memorial Day all!

Had some time earlier this a.m. before the grilling started, so tried some "Jack Jetting".

Again, this is a 20/20 carb with a bellmouth.

120AC / BE3 / 120 - temps under 300, but ran like crap, sputtery, no power up top. Clearly flooding.

120AC / BE3 / 118 - temps higher, still under 300, little cleaner. still sputters and lacks power up top.

Honestly I don't like the direction this is going. I sense trouble ahead. Convince me otherwise Jack.

Mon May 25, 2020 11:54 am

Hooked
Joined: 22 Jul 2018
Posts: 118

 
Hooked
Joined: 22 Jul 2018
Posts: 118

Mon May 25, 2020 11:54 am linkquote
Wait for Jack to respond but you are running a 20mm carb which flows a lot less which should have a much smaller jet.

Edit: but you have a bell mouth so I'm staying out of this.
Mon May 25, 2020 12:31 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
Mon May 25, 2020 12:31 pm linkquote
From here you have a few choices. As it is main jet will end up about 112. Do you have this jet. Do you have a BE4?

Other choice is AC140 and a BE5. Main jet will then be in the 120+ range. I would do it this way.
Mon May 25, 2020 1:56 pm

Ossessionato
1963 VBB2T
Joined: 07 Nov 2012
Posts: 2511

 
Ossessionato
1963 VBB2T
Joined: 07 Nov 2012
Posts: 2511

Mon May 25, 2020 1:56 pm linkquote
Oh the tension
Tue May 26, 2020 10:23 am

bodgemaster
63 GL, 76 Super (x2), 74 Primavera (x2), 79 P200, 06 Fly 150
Joined: 26 Sep 2013
Posts: 6012
Location: So Cal
 
bodgemaster
63 GL, 76 Super (x2), 74 Primavera (x2), 79 P200, 06 Fly 150
Joined: 26 Sep 2013
Posts: 6012
Location: So Cal
Tue May 26, 2020 10:23 am linkquote
Jack221 wrote:
From here you have a few choices. As it is main jet will end up about 112. Do you have this jet. Do you have a BE4?

Other choice is AC140 and a BE5. Main jet will then be in the 120+ range. I would do it this way.
All righty then ...

140AC / BE5 / 125 - now we're getting somewhere. Temps still under 300, cleaner up top and less sputtery. No sign of pinging. Better but still not making full power. I think a few points down and we can make a 140AC work.

Jack: What's the point of the BE5?

And to answer your question, yes I have a BE4.

Just for fun (and in the name of science) I ran the following:

160AC / BE3 / 135 - this is the same stack I was running when it seized, but with a 7 points fatter main. It ran a little hotter (due to the increased timing) and lacked power up top from the over-richness.

So ...

160AC / BE3 / 130 - dropping the main cleaned the top end up. The scoot ran like a demon. ~~ This is very close to the magic zone. ~~ I would happily run this combo on an extended trip. My only concern is temp, which is now higher due to the advanced timing.

If this is achievable with a 140AC I'll be satisfied. Ran out of garage time yesterday due to the Memorial Day festivities... I'll take it up again later this afternoon if work allows.
Tue May 26, 2020 11:39 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
Tue May 26, 2020 11:39 am linkquote
That's progress. Which is the AC140. With the smaller carb this will work better.

Looking for the main jet that runs WOT at 300F for several miles. Would expect 120 maybe 122. When done check the plug and piston. All black this time.

Once this is out the way it's onto atomiser/slide/pilot. Find the 300F jet first.
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