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Discussion Starter · #1 ·
Hey everyone!

I picked up a 2003 Yamaha Vino 50cc (2-stroke) that had a bad top end as a project. Installed a brand new 70cc big bore kit and spark plug. It has a performance exhaust on it with the stock air box. It runs very lean for cold starting, meaning I have a to stuff a rag in the airbox inlet hole to get it started until warmed up. I rebuilt and sonic cleaned the the carb with new stock jets hoping it would help, it didn't. Then I drilled out the old stock 46 pilot to about 60-64, still can't start from cold without the rag. If I go any larger on the main jet as well then it has no power and can barely go walking speed, but with stock main it's fine at about 3 turns out of the pilot screw.

Wondering if anyone has figured out the jetting for a 70cc big bore with performance exhaust and stock airbox that allows cold starts. Note: after I start it and warm it up it'll start immediately, it's just cold starts that require restricting airflow to richen the mixture.
 

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Hey everyone!

I picked up a 2003 Yamaha Vino 50cc (2-stroke) that had a bad top end as a project. Installed a brand new 70cc big bore kit and spark plug. It has a performance exhaust on it with the stock air box. It runs very lean for cold starting, meaning I have a to stuff a rag in the airbox inlet hole to get it started until warmed up. I rebuilt and sonic cleaned the the carb with new stock jets hoping it would help, it didn't. Then I drilled out the old stock 46 pilot to about 60-64, still can't start from cold without the rag. If I go any larger on the main jet as well then it has no power and can barely go walking speed, but with stock main it's fine at about 3 turns out of the pilot screw.

Wondering if anyone has figured out the jetting for a 70cc big bore with performance exhaust and stock airbox that allows cold starts. Note: after I start it and warm it up it'll start immediately, it's just cold starts that require restricting airflow to richen the mixture.
Curious, this thing has no choke? Why?? It is normal to need more fuel when cold.

If it runs good on the top end I would not mess with the main. Maybe just go a little bit bigger on the pilot.
 

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Discussion Starter · #3 ·
The first gen Vino 2 strokes use an automatic choke system. I've already drilled out the stock pilot from stock 46 to around 60-64, which is why I'm asking to see if anyone who's done the 70cc big bore kit has jetting already figured out.

Also I forgot to mention I'm at sea level elevation (Long Beach, CA).
 

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The first gen Vino 2 strokes use an automatic choke system. I've already drilled out the stock pilot from stock 46 to around 60-64, which is why I'm asking to see if anyone who's done the 70cc big bore kit has jetting already figured out.

Also I forgot to mention I'm at sea level elevation (Long Beach, CA).
Are you sure the auto choke is working? It doesn't sound like it.
 

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Discussion Starter · #5 ·
Hard to tell, tried bench testing it, then tried to test it plugged into the bike. Either way it didn't seem to do anything. However, I can get it started by kickstarting it and having it at WOT, so that's interesting. I still am looking for other peoples jetting input that have 70cc kits installed. Power doesn't come in until about 25mph (no tach, so no idea what RPM that is), and it's max speed is only 35mph currently. I should be seeing closer to 50-55mph top speed with the 70cc kit.
 

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Hard to tell, tried bench testing it, then tried to test it plugged into the bike. Either way it didn't seem to do anything. However, I can get it started by kickstarting it and having it at WOT, so that's interesting. I still am looking for other peoples jetting input that have 70cc kits installed. Power doesn't come in until about 25mph (no tach, so no idea what RPM that is), and it's max speed is only 35mph currently. I should be seeing closer to 50-55mph top speed with the 70cc kit.
Yes it would be nice if someone chimed in about the jet sizes, but this forum is like a ghost town so it's not likely to happen.
 

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I should be seeing closer to 50-55mph top speed with the 70cc kit.
NOPE

So, late posting, but I own one, among other 2 stroke scooters. Better late then never? Here I go posting anyways.

ANYWAY

The 2 stroke Vino is my favorite, and is very special. The engine has a lot of modifications made to it by Yamaha that make it different/better to any other scooter they stuck a Minarelli Horizontal engine into. Its engine is better, and more sporty, then the 2 stroke zuma that was out at the same time! BUT I DIGRESS Lets address the issues.

First- it will never go 55mph with just a 70cc kit. The Vino 2t, even with the restrictor ring in the CVT removed, won't go any faster then around 40mph. The stock gearing, at 6000 RPM, runs out at around 35-ish mph. You can over-rev the engine to hit 42mph. The stock crank and bearings are good up to around 9k, redline 10k. To hit 50-55 on the stock top gear ratio, would require 13k+ RPM. You'd require a longer final drive/reduction ratio gear set to go any fast. Good news! Malossi makes a set! The Malossi part number is 67 7324. With it, 55mph is around 8000RPM on the stock variator and belt.

But meh jetting!
The jetting!

The Vino stock intake/carb setup is extremely weird. The air box is extremely restrictive, at both the snorkel and carb intake ,on purpose, and the carb is jetted to match that airflow. IE the pilot jet is a huge #46, and the main jet a tiny #64. The difference in airflow between idle and WOT on it, with the airbox restrictions in place, is so small that the #46 pilot jet is doing a lot of the main jets work.
To put this into perspective, a typical restricted minarelli horizontal jog setup, that just restricts the carb intake and not the snorkel, would be a 35 pilot jet, and a 75/78 main jet. A de-restricted intake runs closer to a 88 main jet on the stock bore.
WHY DOES ALL THIS MATTER- the idle is actually extremely rich. So you saying that yours is lean, means there's something wrong elsewhere.
The jetting on my vino with a 70/80cc bore installed, and a different air box, tops out at 108 before it starts bogging with a 112. However my idle is still too rich, even at a 98 main jet. Which is what brought me here, looking for the threading/type of idle jet the carb uses. However jetting varies with where you live, how your engine is setup, and if your engine has any leaks.

But wait, there's more

The Vino has so many small kinks to it, among restriction after restriction after restriction. Lets go through them all.
The air intake box is restricted doubly. The exhaust has a limiter in the header that needs cut out. The CVT, the torque driver spring in-particular, is prone to overheating above the stock 6k RPM. The CVT has a restrictor ring. The CVT has a under-sized belt (788 instead of a 792). The CVT cover acts a restrictor, and any larger belts/pulley setups will have their belts rub against it acting as a brake, while also overheating it further. The stock variator has a larger-then-normal collar/sleeve that prevents it from down-shifting fully, and forces it to start at a lower RPM then the shift RPM its been weighted for. The exhaust port on the stock cylinder is not "port matched" to the exhaust.

The Vino also has a different intake bolt pattern, different reed cage angle, different (better) case porting, and different reeds then any other minarelli horizontal Jog engine. The stock carb is also the largest you can fit without modifying/cutting away at the seat to fit a more standard designed one. The CVT cover bolt pattern is slightly different too. As in all the bolt holes are shifted a few mm off where a typical jog engine would have their's- making the use of a non-restricted and/or vented cover, impossible without modification. The crank seals are metal-reinforced unlike the Yamaha Jogs pure rubber seals. The stock CDI does not have a rev limitter from what I can tell, and if it does, it's above the 9k I've run it up to. It uses a vacum shutoff valve for the fuel line, and has no fuel pump. The fuel filter is inside the line where it connects to the fuel tank.


As you can tell, modifying it is a adventure. It's no Areox sadly, which the US never got, but Europe never got the 2 stroke vino either. Best we got were 90's liquid cooled Aprilias and Kymco liquid cooled Super 9's with jog engines. The Vino is way prettier though, and the JDM lights make it even better if you can get them.
 

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NOPE

So, late posting, but I own one, among other 2 stroke scooters. Better late then never? Here I go posting anyways.

ANYWAY

The 2 stroke Vino is my favorite, and is very special. The engine has a lot of modifications made to it by Yamaha that make it different/better to any other scooter they stuck a Minarelli Horizontal engine into. Its engine is better, and more sporty, then the 2 stroke zuma that was out at the same time! BUT I DIGRESS Lets address the issues.

First- it will never go 55mph with just a 70cc kit. The Vino 2t, even with the restrictor ring in the CVT removed, won't go any faster then around 40mph. The stock gearing, at 6000 RPM, runs out at around 35-ish mph. You can over-rev the engine to hit 42mph. The stock crank and bearings are good up to around 9k, redline 10k. To hit 50-55 on the stock top gear ratio, would require 13k+ RPM. You'd require a longer final drive/reduction ratio gear set to go any fast. Good news! Malossi makes a set! The Malossi part number is 67 7324. With it, 55mph is around 8000RPM on the stock variator and belt.

But meh jetting!
The jetting!

The Vino stock intake/carb setup is extremely weird. The air box is extremely restrictive, at both the snorkel and carb intake ,on purpose, and the carb is jetted to match that airflow. IE the pilot jet is a huge #46, and the main jet a tiny #64. The difference in airflow between idle and WOT on it, with the airbox restrictions in place, is so small that the #46 pilot jet is doing a lot of the main jets work.
To put this into perspective, a typical restricted minarelli horizontal jog setup, that just restricts the carb intake and not the snorkel, would be a 35 pilot jet, and a 75/78 main jet. A de-restricted intake runs closer to a 88 main jet on the stock bore.
WHY DOES ALL THIS MATTER- the idle is actually extremely rich. So you saying that yours is lean, means there's something wrong elsewhere.
The jetting on my vino with a 70/80cc bore installed, and a different air box, tops out at 108 before it starts bogging with a 112. However my idle is still too rich, even at a 98 main jet. Which is what brought me here, looking for the threading/type of idle jet the carb uses. However jetting varies with where you live, how your engine is setup, and if your engine has any leaks.

But wait, there's more

The Vino has so many small kinks to it, among restriction after restriction after restriction. Lets go through them all.
The air intake box is restricted doubly. The exhaust has a limiter in the header that needs cut out. The CVT, the torque driver spring in-particular, is prone to overheating above the stock 6k RPM. The CVT has a restrictor ring. The CVT has a under-sized belt (788 instead of a 792). The CVT cover acts a restrictor, and any larger belts/pulley setups will have their belts rub against it acting as a brake, while also overheating it further. The stock variator has a larger-then-normal collar/sleeve that prevents it from down-shifting fully, and forces it to start at a lower RPM then the shift RPM its been weighted for. The exhaust port on the stock cylinder is not "port matched" to the exhaust.

The Vino also has a different intake bolt pattern, different reed cage angle, different (better) case porting, and different reeds then any other minarelli horizontal Jog engine. The stock carb is also the largest you can fit without modifying/cutting away at the seat to fit a more standard designed one. The CVT cover bolt pattern is slightly different too. As in all the bolt holes are shifted a few mm off where a typical jog engine would have their's- making the use of a non-restricted and/or vented cover, impossible without modification. The crank seals are metal-reinforced unlike the Yamaha Jogs pure rubber seals. The stock CDI does not have a rev limitter from what I can tell, and if it does, it's above the 9k I've run it up to. It uses a vacum shutoff valve for the fuel line, and has no fuel pump. The fuel filter is inside the line where it connects to the fuel tank.


As you can tell, modifying it is a adventure. It's no Areox sadly, which the US never got, but Europe never got the 2 stroke vino either. Best we got were 90's liquid cooled Aprilias and Kymco liquid cooled Super 9's with jog engines. The Vino is way prettier though, and the JDM lights make it even better if you can get them.


incorrect on the speed. I have a 2005 Vino with a Polini 70cc top end. No gearing changes. All restrictions removed and a Polini sport pipe. Top speed is 56mph so far. My idle is way lean too. Just haven't gotten around to dealing with that bike as I got a 58 Vespa I'm working on now.
 
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