I’ve put this one together, hopefully to help those riders new to minis, or new to bikes on the whole, with the idea that all the questions can be answered in one section, in one thread.
Basic necessary upgrades:
Generally price will normally denote quality… and generally chinas aren’t renowned for it. Having said that, every jap mxer I’ve had from new, has had some pretty crap standard items on them as well. Chains, suspension seals, levers, bars, sprockets and grips have all been immediate replacement items. There are several items on your standard china which can also be binned from new…
• Handlebars- usually crappy steel ones. Bite the bullet, get some pro-tapers. Genuine ones, or copies.. I’ve used both, still yet to bend either…
• http://www.miniriders.com.au/mini-tutorials/12201-how-change-your-handlebars.html
• Levers – Stock ones snap if you lean on them. Buy some ASV-copy bending levers. Look around on ebay, there are plenty of cheap ones available. If you cant stretch to ASV levers, drill a 5mm hole through the lever, roughly where you little finger goes around the lever, and using a file, grind/file a bit of a “V” above and below the hole you have just drilled. What this does is create a weak point in the lever, so if you fall off, it will snap off there, instead of snapping at the perch like they normally do.
• Chain – Turf the standard one. The chain will be crap, and stretch in no time. Be a man, (or an empowered woman…) buy a D.I.D. chain and be done with it. Minis don’t shake the earth powerwise, and a quality chain will probably outlast the bike.
• Tyres: Standard ones are often crap. Replace them with Kenda Millville’s or Carlsbad’s. They seem to be the ones to go for, and offer good grip and wear qualities. While your changing tyres, add a RIM LOCK and Heavy Duty tubes. The rim lock will stop the tyre spinning on the rim, and tearing the valve out. If i had a dollar for every mini i've seen going home early with a flat tyre and no rim lock... ha ha!
• Spark plug- Stock is crap. Go buy an NGK plug and be done with it.
• Fuel Filter – the plastic tanks on the minis aren’t renowned for being spotless.. buy a cheap in-line fuel filter, cut your fuel line half way between the fuel tap and the carby, and put the filter there. Pay attention to any arrows marked on the filter, as this will denote the direction of fuel flow.
That pretty much covers basic items that will require upgrading within the first couple of rides, or even BEFORE you go for your first squirt. Tie these upgrades in with the initial set-up, and you should have a happier day out on the track..
Performance upgrades Stage 1
These are more or less the first parts to upgrade if you want to go faster. They can all be found on either Ebay, or your local mini bike shop. You may actually have to get of you’re a$$es to find that shop though..
The below items are the cheapest way of making SMALL power gains, and can be done for under $70 if you do your searching on ebay..
• Air Filter – Measure the external throat diameter of you carby, and find yourself a “UNIFILTER”. Even nanna could figure out how to attach one. Buy, attach… simple.
• Quick turn throttle – These can be purchased in either ¼ turn or 1/8 turn versions. THESE WILL NOT MAKE YOUR MOTOR MORE POWERFUL… They will however allow your carby to go from closed to wide open much quicker…
• “Racing” CDI – These effect the timing curve of your ignition, and will generally allow a stronger spark, and a higher rev-ceiling. In 99% of cases, they are a straight plug and play item. The gains to be had aren’t massive, but they do help once you start doing further mods. They’ll also prevent the “it was fine last time I rode it, now it wont start” questions that are CDI caused or related.
• Gearing- Changing the gearing on your bike by going to a smaller countershaft sprocket is a cheap way to make your bike accelerate faster. It will be at the cost of top speed, and wont give you any more power, but it will be quicker from whoa to go. Going from a 17tooth front sprocket to a 15 is the equivalent of dropping between 6 and 9 teeth on the back sprocket. And lets be honest… when did you last wind your mini up to redline in top gear on the local track..?
I've found the easiest and quickest way to alter your gearing, is to buy a 37 tooth rear and leave it there. Then buy a 12, 14 and 17 tooth countershaft (front) sprocket. They take a couple of minutes to change, and give you a hell of a lot flexibility with your gearing.
Basically, the smaller the front sprocket, the better your acceleration will be, but at the expense of top speed.
The bigger the front sprocket, the better your top speed will be, but at the expense of acceleration.
Performance upgrades Stage 2
The following upgrades will net you some noticeable performance gains, and once again, search carefully on ebay, you’ll get out of it for under $250. Incorporate the below items with Stage 1 upgrades, and the gains will be rewarding.
• “Performance” carbies – Most pittys come standard with “Genuine” Mikuni “30mm” carbies. These carbies are about as genuine as the acting skill portrayed by the hot girly in the transformers movies… You can start by replacing them with something like a Molkt or an OKO carby. There are also Mikuni copy carbies that are just as good as the Molkt or OKO offerings, but are generally 26mm in throat diameter, with round-bore throats, as opposed to the standard oval-bores in your “Genuine Mikuni”. Occasionally you will be lucky, particularly with the Molkts, and the jetting they come with is pretty close. The OKO’s on the other hand, usually require a bit more tinkering, but offer great performance when tuned properly.
• http://www.miniriders.com.au/tech-talk/10183-mikuni-25mm-carbie-manual.html
• As a guide, if you have a 110 or 125 motor, a carby with a 22mm throat diameter will work best. 140’s and above work best with a 24 or 26mm throat diameter. (only on extreme engines, and if you have the tuning skills and patience, would I suggest a genuine 28mm carby)
• Exhausts- Mini bikes run four-strokes. Old-school design four strokes at that. Four strokes like to BREATHE.. A big bore exhaust, with a 33mm pipe diameter is a great place to start. The ones that step up from 33mm to 40mm are even better. Some of these, eg H-Bomb Carbon muffler pipes, have massive internal pipes in the muffler itself, breathe great, and offer a great, deep exhaust note, over the loud and crackly stock pipe. The big bore pipes are still loud, but the note isn’t as harsh. Shut your eyes, you’d swear someone was on a big-cc thumper somewhere. Where you source your pipe is up to you, and your conscience. Ha ha ha! Do Local business a favour, and buy locally.
• IRK or ORK- Inner or Outer rotor kits – These basically are replacement flywheels and rotors/stators, and allow your motor to build revs a lot quicker. Initially it was the IRK’s that gained the popularity, and can be had from ebay for as little as $30 nowadays. The Outer rotor kits are rapidly gaining favour as they fit a larger range of engines, and offer much more than the IRK’s in regards to having switchable ignition curves, while still offering a marked improvement in performance. The ORK still offers a reasonable amount of flywheel weight, which means better traction, and more torque. These are better suited to a broader range of riding styles than the IRK’s, as they are less prone to stalling, idle better and offer better grip on slippery ground. The IRK’s are still a great, cheap upgrade, especially when used in conjunction with a lightened oil slinger, which also helps “revvability”… They are however, better suited to more skilled riders who can swing off the throttle and keep the motor screaming.. And are also great for supermotard, where bottom end power and response isn’t quite so vital. I wouldn’t use an IRK if you’re planning on ramp jumping your mini…
• http://www.miniriders.com.au/mini-tutorials/13850-inner-rotor-oil-slinger-installation.html
Performance Upgrades Stage 3:
By now your motor should be a different animal to what it was in the beginning. “Stage 3” upgrades should turn it into quite the little monster, but are best carried out by a mechanic, or if you have the skills, go nuts. But then I guess if you had the skills and knowledge, you may not actually be reading this thread.. ha ha! A lot of the installations in this thread can be found in the “how-to tutorials” page… go have a looksee if it’s something you want to attempt yourself. Most can be done at home with the right tools
• Camshaft – Again these can be sourced either on ebay or mini bike shops. A couple of brands supply different cams that offer different amounts of lift and duration. They are a great way to increase power right the way through the rev range. Most however, do not come with an anti-kickback mechanism, and can be harder to start once installed. In some cases, depending on the lift of the cam, aftermarket cam-springs should also be installed to ensure your valves aren’t hitting the piston.
• http://www.miniriders.com.au/mini-t...10mm-14mm-sockets-n-ratchet-10mm-spanner.html
• Porting – By cleaning up the passageways in the inlet manifold, carby throats, exhaust manifolds and the head itself, again more power can be gained. There are tutorials on the best way to do this in the “how-to” section that are very useful. There is no hard and fast rule, so grab the dremel, read the how-to’s and have fun
• http://www.miniriders.com.au/tech-talk/6959-porting.html
Basic necessary upgrades:
Generally price will normally denote quality… and generally chinas aren’t renowned for it. Having said that, every jap mxer I’ve had from new, has had some pretty crap standard items on them as well. Chains, suspension seals, levers, bars, sprockets and grips have all been immediate replacement items. There are several items on your standard china which can also be binned from new…
• Handlebars- usually crappy steel ones. Bite the bullet, get some pro-tapers. Genuine ones, or copies.. I’ve used both, still yet to bend either…
• http://www.miniriders.com.au/mini-tutorials/12201-how-change-your-handlebars.html
• Levers – Stock ones snap if you lean on them. Buy some ASV-copy bending levers. Look around on ebay, there are plenty of cheap ones available. If you cant stretch to ASV levers, drill a 5mm hole through the lever, roughly where you little finger goes around the lever, and using a file, grind/file a bit of a “V” above and below the hole you have just drilled. What this does is create a weak point in the lever, so if you fall off, it will snap off there, instead of snapping at the perch like they normally do.
• Chain – Turf the standard one. The chain will be crap, and stretch in no time. Be a man, (or an empowered woman…) buy a D.I.D. chain and be done with it. Minis don’t shake the earth powerwise, and a quality chain will probably outlast the bike.
• Tyres: Standard ones are often crap. Replace them with Kenda Millville’s or Carlsbad’s. They seem to be the ones to go for, and offer good grip and wear qualities. While your changing tyres, add a RIM LOCK and Heavy Duty tubes. The rim lock will stop the tyre spinning on the rim, and tearing the valve out. If i had a dollar for every mini i've seen going home early with a flat tyre and no rim lock... ha ha!
• Spark plug- Stock is crap. Go buy an NGK plug and be done with it.
• Fuel Filter – the plastic tanks on the minis aren’t renowned for being spotless.. buy a cheap in-line fuel filter, cut your fuel line half way between the fuel tap and the carby, and put the filter there. Pay attention to any arrows marked on the filter, as this will denote the direction of fuel flow.
That pretty much covers basic items that will require upgrading within the first couple of rides, or even BEFORE you go for your first squirt. Tie these upgrades in with the initial set-up, and you should have a happier day out on the track..
Performance upgrades Stage 1
These are more or less the first parts to upgrade if you want to go faster. They can all be found on either Ebay, or your local mini bike shop. You may actually have to get of you’re a$$es to find that shop though..
The below items are the cheapest way of making SMALL power gains, and can be done for under $70 if you do your searching on ebay..
• Air Filter – Measure the external throat diameter of you carby, and find yourself a “UNIFILTER”. Even nanna could figure out how to attach one. Buy, attach… simple.
• Quick turn throttle – These can be purchased in either ¼ turn or 1/8 turn versions. THESE WILL NOT MAKE YOUR MOTOR MORE POWERFUL… They will however allow your carby to go from closed to wide open much quicker…
• “Racing” CDI – These effect the timing curve of your ignition, and will generally allow a stronger spark, and a higher rev-ceiling. In 99% of cases, they are a straight plug and play item. The gains to be had aren’t massive, but they do help once you start doing further mods. They’ll also prevent the “it was fine last time I rode it, now it wont start” questions that are CDI caused or related.
• Gearing- Changing the gearing on your bike by going to a smaller countershaft sprocket is a cheap way to make your bike accelerate faster. It will be at the cost of top speed, and wont give you any more power, but it will be quicker from whoa to go. Going from a 17tooth front sprocket to a 15 is the equivalent of dropping between 6 and 9 teeth on the back sprocket. And lets be honest… when did you last wind your mini up to redline in top gear on the local track..?
I've found the easiest and quickest way to alter your gearing, is to buy a 37 tooth rear and leave it there. Then buy a 12, 14 and 17 tooth countershaft (front) sprocket. They take a couple of minutes to change, and give you a hell of a lot flexibility with your gearing.
Basically, the smaller the front sprocket, the better your acceleration will be, but at the expense of top speed.
The bigger the front sprocket, the better your top speed will be, but at the expense of acceleration.
Performance upgrades Stage 2
The following upgrades will net you some noticeable performance gains, and once again, search carefully on ebay, you’ll get out of it for under $250. Incorporate the below items with Stage 1 upgrades, and the gains will be rewarding.
• “Performance” carbies – Most pittys come standard with “Genuine” Mikuni “30mm” carbies. These carbies are about as genuine as the acting skill portrayed by the hot girly in the transformers movies… You can start by replacing them with something like a Molkt or an OKO carby. There are also Mikuni copy carbies that are just as good as the Molkt or OKO offerings, but are generally 26mm in throat diameter, with round-bore throats, as opposed to the standard oval-bores in your “Genuine Mikuni”. Occasionally you will be lucky, particularly with the Molkts, and the jetting they come with is pretty close. The OKO’s on the other hand, usually require a bit more tinkering, but offer great performance when tuned properly.
• http://www.miniriders.com.au/tech-talk/10183-mikuni-25mm-carbie-manual.html
• As a guide, if you have a 110 or 125 motor, a carby with a 22mm throat diameter will work best. 140’s and above work best with a 24 or 26mm throat diameter. (only on extreme engines, and if you have the tuning skills and patience, would I suggest a genuine 28mm carby)
• Exhausts- Mini bikes run four-strokes. Old-school design four strokes at that. Four strokes like to BREATHE.. A big bore exhaust, with a 33mm pipe diameter is a great place to start. The ones that step up from 33mm to 40mm are even better. Some of these, eg H-Bomb Carbon muffler pipes, have massive internal pipes in the muffler itself, breathe great, and offer a great, deep exhaust note, over the loud and crackly stock pipe. The big bore pipes are still loud, but the note isn’t as harsh. Shut your eyes, you’d swear someone was on a big-cc thumper somewhere. Where you source your pipe is up to you, and your conscience. Ha ha ha! Do Local business a favour, and buy locally.
• IRK or ORK- Inner or Outer rotor kits – These basically are replacement flywheels and rotors/stators, and allow your motor to build revs a lot quicker. Initially it was the IRK’s that gained the popularity, and can be had from ebay for as little as $30 nowadays. The Outer rotor kits are rapidly gaining favour as they fit a larger range of engines, and offer much more than the IRK’s in regards to having switchable ignition curves, while still offering a marked improvement in performance. The ORK still offers a reasonable amount of flywheel weight, which means better traction, and more torque. These are better suited to a broader range of riding styles than the IRK’s, as they are less prone to stalling, idle better and offer better grip on slippery ground. The IRK’s are still a great, cheap upgrade, especially when used in conjunction with a lightened oil slinger, which also helps “revvability”… They are however, better suited to more skilled riders who can swing off the throttle and keep the motor screaming.. And are also great for supermotard, where bottom end power and response isn’t quite so vital. I wouldn’t use an IRK if you’re planning on ramp jumping your mini…
• http://www.miniriders.com.au/mini-tutorials/13850-inner-rotor-oil-slinger-installation.html
Performance Upgrades Stage 3:
By now your motor should be a different animal to what it was in the beginning. “Stage 3” upgrades should turn it into quite the little monster, but are best carried out by a mechanic, or if you have the skills, go nuts. But then I guess if you had the skills and knowledge, you may not actually be reading this thread.. ha ha! A lot of the installations in this thread can be found in the “how-to tutorials” page… go have a looksee if it’s something you want to attempt yourself. Most can be done at home with the right tools
• Camshaft – Again these can be sourced either on ebay or mini bike shops. A couple of brands supply different cams that offer different amounts of lift and duration. They are a great way to increase power right the way through the rev range. Most however, do not come with an anti-kickback mechanism, and can be harder to start once installed. In some cases, depending on the lift of the cam, aftermarket cam-springs should also be installed to ensure your valves aren’t hitting the piston.
• http://www.miniriders.com.au/mini-t...10mm-14mm-sockets-n-ratchet-10mm-spanner.html
• Porting – By cleaning up the passageways in the inlet manifold, carby throats, exhaust manifolds and the head itself, again more power can be gained. There are tutorials on the best way to do this in the “how-to” section that are very useful. There is no hard and fast rule, so grab the dremel, read the how-to’s and have fun
• http://www.miniriders.com.au/tech-talk/6959-porting.html
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