|The easiest way to troubleshoot your scooter is by what kind of speeds you are seeing. This guide will focus on the Yamaha Vino, but it is easily applied to any other scooter, especially the Yamaha Zuma, and other bikes with similar motors (TNG, Vento, and others). All scenarios assume a stock scooter, but the same principles apply to modified or upgraded scooters.
Condition 1: Scooter is running a slower top speed than normal
Drive belt wear
Worn rollers or vee bushings
High mileage or high abuse/conditions motor
Condition 2: Scooter is hard to start
Spark plug is fouled
Scooter sat in the garage all winter
Condition 3: Scooter takes a long time to "catch" (clutch engagement)
Condition 4: Handling is less than desired (especially Vino)
Condition 5: My scooter is fine, but still isn't fast enough
Stage 2 Upgrade
- Condition 1: Scooter is running a slower top speed than normal. There are several reasons this could be happening. Here are some things to check:
- Tire pressure
This may seem simple, but is often overlooked, and will have a direct impact on the top speed you reach, especially when riding two-up. This can also have a detrimental effect on your wheel as the tire absorbs a lot of the small bumps. If your tire is low, that shock is transferred to your wheel, which can bend the lip or the entire wheel.
This will also have an effect on your fuel mileage. The less air in the tire, the more contact the tire has with the riding surface, and creates more friction, making the motor work harder to achieve the same performance.
Check your tire pressures often, especially at the change of seasons. Going from summer to winter will result in a decrease in tire pressure because cold air is more dense. I could go into why, but that is outside the scope of this guide. You can also upgrade your tires, which will improve your handling (more on that later) as well as increase your capacity to handle those small bumps that the tires deal with due to their increased size.
- Drive belt wear
As your drive belt wears, it decreases in width and efficiency. This causes a decrease in top speed because it is the belt that forces the rear pulleys apart (effectively changing the gear ratio) and if they are not getting pulled apart far enough, you will not see the highest "gear" possible. Picture a 5 speed car that will only go as high as 4th gear.
Inspect your drive belt. Make sure that it is the correct width (it will be printed on the belt, if it is worn off, your belt may need replacement). The normal width for a Vino belt is 30mm and Zuma is 28mm. If you have excessive rubber belt dust in your transmission cover, it may be best to just replace it. The belts are fairly inexpensive and are an integral part to running your scooter.
- Worn rollers or vee bushings
Another simple fix is to inspect your rollers and vee bushings. Baiscally remove them and check for flat spots. If there are noticeable flat spots, it is time for replacement. If the rollers are not allowed to "roll" freely, it will result in somewhat "jerky" acceleration, and top speed may be reduced. If there is excessive play between the variator ramp plate and the back pulley half, the vee bushings will need replacing.
You can replace the rollers and/or vee bushings. I would suggest doing both at the same time for convenience. Another route would be to replace the entire variator. Aftermarket variators, such as the Malossi or Athena units use a 16mm x 13mm roller as opposed to a 15mm x 12mm roller (stock size). That means there is a greater rolling diameter which allows easier operation of the variator. This will also result in a slight increase in top speed, but best results are reached with a pipe as well, as in the Stage 1 kit
- High mileage or high abuse/conditions motor
As your scooter starts to get high mileage (more than 5000) the piston rings will begin to lose their seal on the cylinder wall. This can also happen a lot earlier if is not used. This is a fact of life, and is eventually the demise of any well maintained internal combusiton engine, be it cars, motorcycles or scooters. This may also cause the scooter to be hard to start (low compression).
You can replace your cylinder with a new one from Yamaha or your manufacturer, but they are usually very expensive. More so than just upgrading it. If you have a completely stock scooter, you can run a 70cc cylinder kit without issue (make sure you do a spark plug read). The 70cc cylinder kit when used with an otherwise stock motor, will yeild more low-end power with a slight increase in top speed. The low-end power is significant and very useful for getting up to speed in a hurry, going up a hill, or riding two-up.
- Condition 2: Scooter is hard to start
- Spark plug is fouled
The spark plug on a two-stroke motor is a high wear item. They can wear out very fast if you don't have your carb setup just right, and can also wear out quickly under extreme conditions. When it is worn out, or fouled, the scooter will be hard to start and will sputter when starting. This can also cause the scooter to not start at all.
If your scooter is hard to start, before you kill your battery, take a minute and pull out your old spark plug. Now, the bad thing is that it is impossible to tell if your plug is fouled by just looking at it (unless it is extremely fouled, or has physical damage). The only real way is to replace the plug with a brand new one. The good news is that these are relatively inexpensive. If the problem is in fact the spark plug, your scooter should fire right up (unless it is flooded, then just be patient). If the scooter is still hard to start, there is another issue.
- Scooter sat in the garage all winter
If your scooter has sat in your garage all winter, and you didn't drain out the fuel before you parked it, don't worry, this situation can be remedied. What happens to fuel when it sits stagnant for an extended period of time is that it begins to seperate into a thick sludge and a nasty smelling liquid (yes those are the technical terms for it). Typically three or four months of sitting isn't enough time to make your whole tank of fuel go bad (unless you had very little left), but still drain it out and put in fresh fuel.
Drain the tank. The easiest way to do this is to pull the two hoses from the tank to the carb off the carb and suck on the vacuum switch tube until the fuel begins to flow out of the other hose. You can then just hold the vacuum hose shut with your finger and the fuel should continue to flow. The vacuum hose is typically the one that enters the carb horizontally, and the fuel line enters the carb vertically. You can also pull the hose going into the vacuum switch, but this is typically messier (at least you don't have to suck open the vacuum line). Note: no fuel should come out of the vacuum line.
The other worry is that the carb is full of the sludged fuel. This will happen in a short period of sitting, as little as a month or two. This is easily fixed as well. Once you have removed the airbox to gain access to the carb, there are two screws that hold on the bottom part of the carb (the bowl). Remove the bowl carefully as there are a few small parts inside. Inspect it and clean it out with brake parts cleaner, or carb cleaner. Also you will want to spray some cleaner up into the brass jets on the bottom of the carb that are visible once the bowl is removed. Be liberal with the cleaner you are using, you don't want to have to take everything apart again if you didn't get it clean enough. Be sure to re-install the airbox before you try starting your scooter as a stock bike does not run well without it.
- Contition 3: Scooter takes a long time to "catch"
- If your scooter takes a while to "catch" (engage the clutch) when first applying throttle, you may have a worn clutch or drive belt.
Inspect the drive belt and clutch. Refer to above section "Drive belt wear" for drive belt specifications. The clutch is only inspected after removing the clutch bell. There should be at least 1/16th to 1/8th of an inch of friction pad material on the clutch. If not, it is worn, replace it .
If you still have plenty of pad material and your belt is fine, you may be experiencing clutch fade. This is the case when the clutch gets too hot and begins to lose its effectiveness. This is especially the case in hot climates and when riding an upgraded scooter. If this is the case, you will not normally experience this symptom when the scooter is cold, but you will when warmed up and you have been riding in stop and go conditions for a little while. If this is the case, you will want to upgrade your clutch. An aftermarket clutch has friction material that has a higher resistance to clutch fade.
- Condition 4: Handling is less than desired (especially Vino)
- Typically scooters are fun and agile. The Vino can be that way too, it just needs a little help.
To make the Vino (2-stroke or 4-stroke) handle better the best bang for the buck is new tires. You will see better handling as well as better shock absorption. Aftermarket tires are a little bigger than the stock size, fit fine, and improve the ride by giving you more tire height and quality. They will also prevent you from having a bent wheel due to improper tire pressure, or simply not having enough tire height to overcome a bump or pothole. They are also great for riding two-up as they give you more ground clearance. Ever hit your pipe on the ground?
Another route is to upgrade your rear shock absorber. This is a simple process, and will also yield most of the results above. The big advantage to the new shock is more aggressive dampening which will prevent you from "bottoming out". They also increase the load capacity of the scooter allowing easier two-up riding.
Some things you can do are replace your worn tires, or go to a street tread pattern if you don't really ride off-road. A street tread will yield better fuel mileage and perhaps a touch more of top speed, due to reduced friction caused by the knobby tires.
- Condition 5: My scooter is fine, but still isn't fast enough
Well, we can help you there.
The Stage 1 kit is a great place to start. They are fairly easy to install and will get you around 50mph top speed, and increased acceleration.
The Stage 2 kit is also a great starting point if you are a little more serious. It will get you 55-60mph+ top speed and insane acceleration. Use our instructions for installing the Stage One along with the cylinder and carburetor installation instruction.