How and When to Upgrade
At KNM, we love doing videos showing you how to do repairs and upgrades.
However, if you’re new to these machines and modding, before you browse through our “how to videos”, it’s a good idea to bone up on a few basics before tackling any upgrade.
We’ve listed our “Top 20” Q&A’s that we get here at KNM about upgrades. There's some real good info here so browse through them all!
Enjoy, and we hope you find something that helps!
If you have a question that is not listed here, feel free to email us and we may add it to the list!
20 KNM's FAQ’s
What is a “Mod” and when should I do it?
A “Mod” for our purposes will usually mean, “a modification you do to something on your ride to improve performance” however, we think the best thing to work on first with a new machine (Or even if it’s just new to “you”), would be your electrical connections and rubber hoses. Trust us; these are predominantly weak links in these Chinese imports. It’s cheap to correct and will save you a ton of headaches later by inspecting and/or replacing them now.
Make sure all electrical connections are tight and the wires aren’t loose inside (Use a dab of super glue or silicone to hold wires securely in the plastic connectors) and replace your vacuum and fuel lines with a quality hose. The rubber used in these Chinese imports is a low grade and will degrade and crack over a short period of time. Coil wires, intake manifolds & fuel/vacuum lines are notorious for this cracking and can affect performance at the least and can even be a safety hazard. Your machine needs to be running its best before you start any mods.
What will mods do for me?
At KNM, we concentrate on specific areas when looking for more performance without needing a lot of mechanical know-how or funds. (Or even with mechanical know-how & funds for that matter). These are:
CVT Upgrades- work mostly on your bottom end by raising rpms higher before you start to move (takeoff speed.)
“Redneck intake” upgrades are more for your top end performance by improving your fuel and air intake ratios. (more fuel and air means more combustion and more power).
Commonly associated with doing Redneck upgrades, are upgrades to your
Spark. These upgrades commonly include your Coil, Spark plug and CDI. When you improve your fuel and air flows, you should also improve the spark that lights it all up and the CDI and coil that controls it!
“Improved Spark” covers all aspects of performance from idle to top speed.
Of course, there are crossovers in all 3 areas but the performance curves lean more towards how we have them grouped here in most cases.
I just bought a brand new machine and I want to mod it!
We know how hard it is to keep your hands off a new machine and modding it but, Not yet!!! You’ll need to put some miles on your stock ride first. Each machine will show most of its “personality” by the time the motor is broken in. You’ll want to be sure your motor is fully broken in and all characteristics show themselves before attempting to mod anything. (a couple hundred miles or more) You should also wait until your warranty period is up. Many warranties are void once you modify anything so make sure everything is “as it should be” before considering voiding a warranty and doing an upgrade. Also keep in mind, your top speeds will most likely increase a little as well by your 2nd or 3rd oil change all on its own, (if you have a brand new motor and it’s broken in properly).
In order to upgrade the right parts at the right time, ride it for a while then figure out what you like about your ride and what you would like to improve while you break in the motor. Once it’s broken in, you’ll know the area/s you want to improve better.
Next, learn about all the type parts that can get you the improvements you want then start slow and work your way up.
Rushing into upgrades can be a big waste of money for you if you’ve done it in the wrong order or by not doing your research first so take it slow and plan ahead. If you have a wonderful dealer like us, you can always discuss it with them until you feel comfortable with a plan of action however, Simply put:
Be sure everything is running and working properly before upgrading anything .
Should I get a whole kit or buy one part at a time?
You can just buy a bunch of parts and throw them into your ride all at once and get some great performance increases and be “one and done” as we say, IF, you know what you’re doing and what is going to provide the best performance for your particular ride, terrain, weight, other mods etc.
The only way to really get it “perfect” the first time for you is to either be an incredibly lucky person or have someone else near you with the same model machine, built the same year and month, same approximate body weight, same mods and most importantly,
similar ideas of what “performance” means.
Most upgrade kits are not an exact science from a MFG/Dealer stand point because of all the variables possible out there so although a “Kit” can give you peace of mind that everything was designed to “work together”, and it is nice to have everything right there, don’t assume it will always work straight out of the box the way you want. You may need to tweak most any “multi-part” Kit out there to your liking to some extent.
In most cases, do one part at a time and even if you did get a whole kit at once. Get one part/area dialed in first, then move on to the next.
What should I do first?
As we mentioned earlier, there are 3 “general areas” you can play with in your own garage for better performance without messing with internal motor parts or spending a ton of money, while still keeping a reasonable reliability factor.
In our opinion, this is a good order to follow but your particular needs may suggest starting in another area first.
The CVT (Your transmission, consisting of the Variator, Roller weights, Torque spring, Clutch arm springs and the Clutch itself). Mods here will mostly add a quicker start off the line, quicker from stopped to your top speed, better climbing ability and could even net you a couple more mph on your top end depending on which or how many of these you install.
The next is upgrading your,
Carburetor and Intake (Redneck intake upgrades). Mods here will not only add to your low end power some but you’ll get improvements all through your power band and lastly,
Your Spark type upgrades consisting of your CDI, Coil & Spark plug.
Spark upgrades will improve your starting, especially in cold weather, add more voltage to the spark plug to get better combustion and helps burn the larger fuel and air mixture from Redneck upgrades. In the case of a CDI, it can allow the extra rpm’s you’re now getting with new mods, to be used.
Spark and Redneck upgrades are commonly done together, which can be just a little harder to “Dial in” due to more parts being involved.
This is why we suggest your easiest first upgrade is in your CVT as a roller/variator change.
We suggest starting with ONE of these areas first and stick with it until you get the best results you can, before moving on to the next area.
Modding your CVT
If you start your modding in the CVT area, there are several choices of parts to upgrade.
You can simply lighten up your roller weights in your stock variator to get a little quicker off the line. (In the “old days”, we drilled out some of the middle of the roller to lighten them up!)
2-3 grams lighter is all you need to notice an improvement.
You can install a Performance Variator which will add just a bit more quickness and in some cases, you’ll get a little more top end and at the least, you’ll have more options when tuning.
You can also install stiffer springs (Main torque spring and clutch arm springs) which also raise your starting rpm’s and adds to your low end torque.
You can install a Performance Clutch, which can improve not only your takeoff but also some top end and better hill climbing, or you can do any combination of any of these.
Where to start is up to you and what you want to spend but all will get you a little more quickness off the line and possibly more top end depending on what you do.
What does my variator do?
The variator is your front pulley that your drive belt rides in (The one on the left as you look at your CVT). It is attached to your crank shaft and is where the power to the transmission starts from. How quickly the 2 halves of this pulley open and close together determine your RPM’s at takeoff. You can adjust how slowly or quickly this happens by going up or down in weight with your roller weights.
Going UP in roller weights, speeds up the transition from idle to top speed (Like starting in 2nd gear. You’ll be slower off the line but get to top speed a little quicker) and
going DOWN in weights, slows down this process and keeps you in a higher rpm range longer at take off. (Like popping the clutch or power braking in 1st gear, you’re raising your rpm’s more before moving)
Is a Performance variator worth it?
Just replacing your stock roller weights for some slightly lighter ones in your stock variator will increase your take off speed but you will also have to drop further in weight than what you would need to in a performance variator and the more you drop in weight the more you rob from your top end.
*With all performance variators on the market right now , the ramps are simply angled steeper. This causes your rollers to need a little more rpm’s to move them up the ramps without having to drop any weight. This gets you more rpms at start off.
Dropping say, 3 grams from your stock weight in a “Performance variator” will net you better torque with half as much “top end trade off” as you would get from just using your stock variator with lighter rollers because of the steeper ramp angles doing the work of what a lighter weight alone would get you.
*For something really unique in variators, check out KNM’s, in house designed,
Dual Ramp Variator for the 150cc, our DR2. It gets you a great take off with No drop off in top end. It simply does what no other variator out there can do! (OK, end of commercial!)
If you have no idea where to start with your weights, a good way to jump in, if your looking for a little more pep when you first hit the gas, would be to drop 3 grams from what you had stock and see if you like it. Go up or down accordingly from there. Dropping further than 8-10 grams or raising more than 2 grams over all (with everything else stock) is uncommon. The closer you get to 8 grams lighter, your RPM’s will start to raise too high (in most machines) and going more than 2-3 grams heavier won’t get you any more top end but it will slow down your take off a good bit.
What are Roller weights?
Most Variators have 6 or more small roller weights (they look like tiny “old school” roller skate wheels) that roll up and down angled ramps via centrifugal force. They are listed in mm’s by height, width then weight in grams (i.e.: 18h X 14w x 10g or 23x18x23g etc).
As the weights reach the top of their ramps via centrifugal force, this closes the 2 pulley halves together and forces your belt towards the outer edge of the pulley and into your top speed.
You can simply replace your rollers with lighter weight ones in your stock variator for more torque. It will increase your RPM’s before you start moving by increasing the amount of force (rpm’s) it takes to move the rollers up the ramps. This lengthens the time it takes for the variator halves to close and put you into top speed.
When your belt is down low into your front pulley, you get higher rpms. As your belt rides towards the outer edge, your top speed increases.
Keeping that belt down low in the front pulley longer, improves your takeoff and climbing ability because you’re staying in a higher rpm longer.
Don’t go too far though. We don’t suggest dropping any more than 5-8 grams from stock without changing some other things, in most cases. Any more and it will raise your rpms too high for most peoples liking plus kill your top end dramatically.
Lowering your weights about 2-3 grams from your stock weight for low end torque,
is about as far as you can go before you start trading some top end for it.
However, if you are willing to trade a couple mph off your top end for that low end grunt you can drop around 5 grams or more. For every gram lowered past 2-3g from stock, you will lose about 1 to 1-1/2mph off top end. (This is not exact in every machine but is a good rule of thumb)
Note: If you don’t have a scale handy to weigh your roller weights, like mom’s food scale (just don’t let her catch you!), you can always take one down to the Post office and have them weight it for you!
What are Sliders (or “D”) weights
Although a bit more expensive than roller weights, you now have the option of replacing your rollers with “D” weights or sliders instead. A “Slider weight works a little differently than a roller. They have flat sides on them that cause them to “slide” up the ramps instead of roll. Simply put, a Slider weight will get you about 1-1/2 grams more low end for the same weight in roller because it takes more force (rpm’s) to move them up the ramps because they’re not rolling, they’re sliding.
Example: If you liked the drop to 10 gram rollers in your scooter or buggy, an 11 to 12gram slider will get you about the same low end torque, with a little more top end back.
Or, you could stay with a 10gram weight in a slider and get even more, low end torque and keep your top end about the same.
Note: Despite what others may tell you, you really can’t get more Top end over what you have stock just from changing a variator weight but you can lessen the impact of the “top end trade off” by using a slider weight instead. We suggest finding your “perfect weight” in rollers then getting the same weight in a slider. (you could even drop an additional gram and get a little more without any sacrifice)
“I have an off road buggy” or “I have a Scooter”, How much different are the two when choosing an upgrade and should I go in a different order?
The rules are the same and most of the parts will be the same. The GY6 150 motor in most scooters are also the same motors they put in these off road buggies. (150cc Buggies actually use the unused kick start gear as a muffler bracket!) Same with the CN and CF250 models. These motors are interchangeable between most scooters and buggies therefore, so are their parts!
From what we’ve seen from riders all over the world, your geographical area will help determine what you do.
If you’re riding an off road buggy on tight ATV trails on the East coast or short track racing, many are more willing to trade a few MPH off the top end for that hole shot and get the back end a little loose for better cornering. Going over 35mph isn’t top priority for that kind of riding for most folks so why not trade 4-5mph for some loose gravel doughnuts!
If you’re a buggy rider in the open areas out in the West and Mid West, top end is more of a priority. In desert terrain (or southern Fla), sand riding is a torque and clutch killer. It’s a good idea to spend a couple extra bucks on a good clutch here due to the extra stress involved and the longevity of your pad surfaces. A “Racing clutch” may not be the best choice here.
Scooter riders need all the top end we can get no matter where you ride and getting up to top speed quickly helps keep cars off your rear fender so dropping weights here is a more precise venture! You can do it but you won’t have as much room to play with as the buggy folks do if weights are all you do.
For Scooters, a slightly lighter slider/roller (2-3grams tops), combined with a 1500 main torque spring is the way to go when starting out. It’s about the same in a buggy. Only drop 2-3 grams and install a 1500rpm main spring and get a little better take off without any loss in top end.
To get a really nice hole shot and keep top end, we can then go with a better clutch and/or, redneck upgrades in conjunction with a roller upgrade or in extreme torque upgrade needs, a big bore kit and/or racing head as well.
As long as you’re realistic on your expectations, most people are happy with just CVT and Redneck upgrades without doing any major motor work like that. This is why we suggest starting off slow and work your way up. You may find your “happy spot” before spending extra money on unnecessary parts. At the very least, it won’t hurt anything to improve these areas first.
If you’ve done everything you can here and still want more, then you can move up to the motor upgrades like a cool BB kit or 4 valve head!
What does my clutch assby do?
Your clutch is attached to your REAR PULLEY. Power from the front pulley (variator) is transferred to the rear pulley and clutch by the drive belt.
At idle, your belt starts out LOW in the FRONT pulley (Variator) and HIGH on the REAR pulley (Clutch assby). When it is like this, you’re in take off mode then, once it goes down inside that rear pulley, you are in top speed mode.
Slowing down your drive belts transition from the rear to the front pulley is what we’re doing to get more torque. We’re not “adding” anything, just trading one for the other.
The rear pulley starts out with most of the belt. For torque, we want the rear pulley to keep the belt a bit longer. We accomplish this with a stiffer Main Spring (Torque Spring). A stiffer main spring causes the two pulley halves need more rpms to open them thus causing your belt to transition to the front pulley slower, keeping you in a higher rpm (Lower gear) range.
Open the rear pulley faster and the belt gets to the outer edge of the front pulley (variator) quicker to reach your top speeds but you’ll be slower on take off.
There are essentially the 3 parts to tinker with in the rear pulley assby that all work together to accomplish a quicker take off or quicker to top end.
The Clutch and bell housing, (Transfers power to your wheel)
The Clutch arm springs (in charge of when your clutch engages) and your
Main spring. (Torque Spring) In charge of how quickly your rear pulley opens and closes.)
Your clutch and Bell housing
Your clutch is what transfers the power that is sent from your rear pulley, into your rear wheel.
The clutch spins along with the rear pulley. The outer bell housing turns only with your axle/wheel. When the clutch arms are forced out by the centrifugal force of the rear pulley spinning, they make contact with the inside of the bell, transferring that power from the pulley, to the clutch and then on to the rear wheel.
The important parts to know about your clutch are your Pad surfaces and the Arm springs.
Pad surfaces that come with your clutch, are what they are. You can really only inspect them for excessive wear but, if your pads still have plenty of wear left on them, you can change your stock arm springs for stiffer ones for more low end torque. A stiffer set of arm springs will cause your clutch to engage at a higher rpm resulting in more low end torque. 1500rpm is our most popular for both scooter and buggies. (Most stock clutches come with 1000rpm springs)
What makes a Performance clutch, “Performance?”
For performance clutches, there are several choices to look at. Most will get you a higher take off rpm and better grabbing power over a stock one via one of several ways.
Some have longer/thicker pads, some even have weights or extra springs to tune it with.
Some clutch kits come with a bell housing and some do not and all vary in price from fairly cheap to “What, are you out of your mind?
Be sure to do your research on what models fit your particular machine and what they will do for you. There may not be a need to spend $300 on a clutch when a $200 one could do what you are looking for. Even a $60 clutch can be a big improvement over stock in many instances!
Browsing Web Forums are a good way to get “an idea” of what you can expect from each model but remember, your results may vary.
Clutch Arm Springs?
(The 3 small Springs that hold the clutch arms in place until it reaches the springs designated rpm’s then the arms shift out and grab the outer bell housing to make your wheel turn)
Changing these out for stiffer ones is similar to what you get when you lower your roller weights in your variator. A higher rpm before you start to move.
Most stock arm springs hold back the clutch arms until you reach around 1000rpms.
By going with a stiffer 1500rpm clutch spring set, you’ll raise the rpms needed to engage the clutch by about 500rpm’s. This results in a quicker takeoff. (Like popping the clutch in a manual transmission car). These springs are a little tricky to replace as they are tight but a little ingenuity and a brake spring tool makes short work of it.
If you lowered your roller weights which would also raise your rpms’, you can also tune that to your clutch springs. 1500 clutch springs are standard when upgrading your rollers but is not necessary to do both.
Main Spring? (Torque Spring)
In charge of how quickly your rear pulley opens and closes.)
Your Torque spring sits between your clutch and the pulley and is what adds force to your pulley opening and closing. Changing this timing, changes how quickly you get up to top speed and back down again. Typically replaced to improve quickness and cornering speed. A stock torque spring is usually around 1000rpm’s. Most folks will bump up to the 1500 main spring.
What are “Redneck intake upgrades?
Redneck upgrades are modifications to your air intake and your fuel mixture. (They originally got the name because we commonly used household items and tools to make the mods.).
These upgrades are favorites for most on their first venture into modding. The reason for this is, it’s cheap, pretty easy to install and the fact that most of these machines are slow off the line and take a mile or more to get to top speed, helps make this decision easier.
It’s also popular because these type upgrades involve parts that wear out and will eventually need to be replaced anyways such as the paper filters so many of these machines come with.
These mods are done by either modifying your stock air box and Carb or replacing them with performance ones.
The cheapest way is to open up your stock air box more, and replace the main jet in your stock carb for a larger one to match the extra air you’re getting.
You can drill hole/s in your stock air box and insert either a “press-in” UNI/K&N filter or place some filter mesh over the new holes to keep debris out. (or most just remove the air box completely and install a Uni fiter).
When you add more air into your carb, you need to add more fuel and this is done by changing your main jet in the bottom your carburetor for a larger one. (Or lowering the clip on the needle in slide carbs). (“Old School” was to drill out your main jet larger!)
More Air, More Fuel, more power!
Do I need a bigger carb?
Depends on what else you plan on doing. Simply replacing your stock jets and adding an open type air filter, can get more out of your stock carb on the cheap. Going with a larger carb can get you even more HP and better performance but there is a point where it is over kill. We find that most 150’s without any major motor work really can’t use over a 30mm carburetor (Most come standard with either a 24 or 26mm). A 250cc in that same category can benefit from a 32mm carburetor but not much larger (Stock is usually around 28mm).
What does a Performance CDI do?
Honestly, it’s a bit complicated but simply put, it is in charge of how much voltage is put out to your spark plug and how it’s timed. One of the most understood performance parts, in our opinion, is the CDI. It’s electrical and a lot of folks have little idea of how one works (we fit somewhere in that category as well). However, you don’t need to know how it works really just, what does it do and when would you need one?
A CDI does not generate more rpm’s.
A “no rev limit” or 9000rpm CDI does little good if you aren’t capable of generating more RPMS in the first place. It allows a motor that is already generating more rpm’s, to use them. A Stock CDI will limit the amount of rpm’s your motor can do and is a good thing to leave alone when you are stock. Unless it is broken, it is doing exactly what it needs to do for you.
A lot of folks think that an Adjustable CDI is like a “Speed dial”, it is not. Any adjustment a CDI may have is only for the timing of your spark and rarely needs to be messed with more than a fraction of a turn at best.
A Performance CDI is best used after installing a larger carb or rejetting your stock one and adding a fresh air intake or when doing engine mods like a larger cam, head etc. This will get you more spark for better combustion and some even adjust the spark timing at higher rpm’s to prevent engine knocking and over revving. A “stock machine” doesn’t need any of this to run good. It definitely helps in all facets of your ride but you won’t see its true potential without other mods being done first or in conjunction with.
When would I need to replace my Coil wire for a performance one?
The coil wire is one of those items that if you’re in there, replace it. If you install a performance CDI, or if you see cracks in the rubber or are experiencing a weak spark, replace it.
Stock coil wires degrade quickly and cause all sorts of issues. If in doubt on the age or reliability of it, replace it with a quality one. You can replace it with a standard coil wire but when the H.O. ones are under $50 in most cases, replace it with one of these and be done with it.
High output (H.O.) performance coils are made with better materials and offer less electrical resistance than standard coil wires. A better spark means better starting and better combustion. Always a good thing!
This is similar to the CDI in the case of “Need”.
Without any other mods such as larger intakes, carbs, heads, pistons etc, an exhaust upgrade usually provides minimal performance increases and may even hurt your bottom end. It may “sound cooler” but in reality, you probably won’t get out of it what you expect. Add in the fact that most performance exhaust kits will set you back a good bit, we suggest saving that for after you do some other things first to get the most out of your purchase when you do.
These motors are designed to run best with a certain amount of back pressure. Open up the exhaust too much without creating more combustion on the other end and it’s a waste of money.
Air in, Air out. Ying and Yang.
When you’re ready to make the plunge into a shiny new exhaust, a few well placed holes in the internal baffles on your stock exhaust may add some pep and if it doesn’t or if you mess it up, you were going to buy another one anyways. This way, you may get a chance to save a few bucks or even get another mod done instead with the money you saved!
