Scooter supe ups

:help: :help: :help: :help: I am wondering if any one out there can help me… I have recently bought a yamaha majesty and I want to give it a bit more grunt… the top speed is fine but I am looking for more torque off the line… it’s stock in the engine/exhaust department and I am wondering what I can do about it… do the bigger exhausts help with torque? are there kits one can buy to redo the engine? bore it out? shorten the piston rod? etc… I go to a great bike shop on Keelung (Jilong)/ ba de in Taipei but since I am new here and am learning the language I can’t just ask them… can you help me? :help: :help: :help:

Read down, man. This has been asked before. Notice the thread has been locked. Apparently scooter mods are illegal (they can’t all be, can they?). The last thread on this topic was locked. Seems strange that scooter mods would be illegal. We’re talking about vehicles with engines that only make lawnmowers envious. Countdown to flounder? 5, 4, 3, 2, …

ya… i did look into it but i didn’t find anything about the majesty
specifically… any thoughts???

Well, if they’re suddenly going to allow this discussion to stand, I do have some ideas. Maybe, I’ll include a little disclaimer/warning like they put on cigarette packages first: "[color=darkred]of course we both know you don’t intend to ride your new high horsepower ride on public roads in Taiwan, because that would be illegal :wink: [/color] The easiest way to get extra “oomph,” especially down low, is an over sized piston. Ths will make an immediate difference in giddyup. It’s also relatively simple to explain with little Chinese. You should be able to clue in your mechanic with a diagram or something. It will cost a few thou for the bore job and the new piston.

[quote=“TS”]Maybe, I’ll include a little disclaimer/warning like they put on cigarette packages first: "[color=darkred]of course we both know you don’t intend to ride your new high horsepower ride on public roads in Taiwan, because that would be illegal[/color][/quote]Including such a disclaimer is a very good idea. I am sorry for any seeming inconsistency and will clarify the policy in the near future.

Anyway, I have heard that the easiest cheapest way of getting a scooter to accelerate faster ON PRIVATE ROADS is to change the roller bearings for lighter ones.

Hey, no prob Joe. I understand the need to keeps things legal here. I’m more surprised by the legalities surrounding scooter mods–considering how many scooter punks have them done–than the moderating of this forum. It’s actually enlightening to find out that these mods are technically illegal, so I’m pleased you let us all know this.

Would changing the roller bearings affect the top speed on his bike? He says he’s happy with the top speed on his bike. I take that to mean he doesn’t want it to change either way. I’m not too familiar with the inner workings of these gearless, continuously variable, pully operated trannies (if I can call them that). Would changing these roller bearings lower the theoretical top speed of the bike in the same way changing a sprocket on a conventional bike in order to get snappier acceleration would?

[quote=“TS”]Would changing these roller bearings lower the theoretical top speed of the bike in the same way changing a sprocket on a conventional bike in order to get snappier acceleration would?[/quote]I believe so. But not necessarily by much.

[quote=“joesax”][quote=“TS”]Would changing these roller bearings lower the theoretical top speed of the bike in the same way changing a sprocket on a conventional bike in order to get snappier acceleration would?[/quote]I believe so. But not necessarily by much.[/quote]No Joe, they don’t. The pullies stay stock, just the roller weights and pulley spring are changed. Simply put, it moves the whole torque/speed curve up the rev range.

I hear getting new drive belts and springs would increase torque. Polini and Malossi make some good products specfically for scooters (for race use, not sure if they are road legal mods). Here are some links to these products. … t=%B7j%B4M

hey guys thanks for the help… much appreciated :slight_smile: if someone were interested in getting the work done could any mechanic do it? well, maybe not any mechanic but one of the bigger shops?
and any thoughts on why this would be illegal when there are monster 1300cc superbikes zipping around now? it doesn’t seem to make any sense??? :loco:
if someone were to wanting a bigger piston does it have to be specific to the model? i’ve also heard about a shorter rod which gives the piston a longer throw ie more cc’s and a plus is that it doesn’t affect the integrity of the block??? discuss…

Modding the transmission is not illegal. Overboring/stroking into another license or tax bracket is illegal, and so is running with mods that put pollution (emissions or noise) out of the limits in place when the vehicle was produced.

Fitting a shorter connecting rod does not change displacement at all. Two ways to do that; increase bore, stroke, or both. A stroker crank will require either a shorter rod or a different piston to avoid the piston smacking into the head. Yes, an overbore piston will be specific to the model because the diameter is only one of many critical dimensions.
A great many engines are somewhat modular in design. Same basic engine, comes in different capacities like 125cc and 150cc. It’s often very simple to fit the 150cc components like the crank assembly, piston and cylinder into your 125. There may be differences in supporting hardware like the carburettor and ignition module that require their replacement in addition. Quality and longevity will be like the original as long as everything matches and your mechanic is competant. Aftermarket hop-up parts vary wildly in quality and the average wrench cannot do any more than hammer and bolt them into your engine. Without proper adjustment to fuelling or other parameters reliability may be compromised severely.
It’s almost always a better idea to upgrade to a quicker bike than to seriously modify what you have, unless you have deep pockets and are modding for the hell of it.

Buddahian, I had a Majesty which I progressively modified over a long period of time. Basically, whenever the bike needed a new part, I would ask around to see if there was an alternative that would improve its performance. One of the shops I went to was along Kanding St, in the Wan Hua district. It’s associated with the Majesty Club, and the guys in there are very friendly & helpful, although definitely of the “dodgy” variety (i.e. they’re all brothers, if you know what I mean…). There’s often a row of suped-up Majesties parked out the front.

The 1st time I went there was actually for oil. Out of interest, I asked if there was anything I could do to make the bike run a little faster (let’s be realistic, I’m 100kg, and even with my petite girlfriend on the back, that Majesty rode around like a big blue slug). So I asked about replacement parts & modifications. The laoban made a quick phone call and about 2 minutes later, I heard a rumbling sound outside the store: about 5 or 6 beautiful Majesties and Apex’s came roaring around the corner, parking at the store. I had a good look at the bikes and a chat with some of the owners, and their advice really helped me to decide what modifications were feasible.

Let me preface this by saying that for some of those guys, their bikes were their pride & joy. Some had spent over $200,000 on modifications. For me, however, it was more of a hobby, and the modifications were basically replacement parts that helped the bike to run faster or to give it a little more torque.

If you were really keen, you could replace the engine with an imported Majesty engine (cost: about $50-60k).

I eventually replaced the bike’s piston with a larger Majesty piston (probably imported). I believe there are a few different sizes to choose from; however, I wouldn’t necessarily recommend this option because it changes the dynamics of the engine and in my opinion, makes it far more susceptible to overheating (and damaging the precious parts that you’ve just installed).

Another thing I did was replace the fuel injection, which helped slightly. There’s a range to choose from, and the performance that they can offer depends on what’s been done to the engine.

When my exhaust went, I replaced it with a racing exhaust, which added maybe an extra 10-20% torque (subjectively). However, although they look good, I don’t think a new exhaust will do much to improve the bike’s performance unless you’ve already upgraded the piston.

Perhaps the best thing I did was add a racing flywheel. It cost about $1000-1500, and gave a lot more zip to the bike… These things are a lot of fun, but they tend to wear out very easily since the bike’s revving at a much higher rate.

For the next year I did quite a bit of touring (around the mountains north of Taipei and even down to Kending), during which time I tended to ride pretty fast. I once took a wrong turn near Keelung and landed on the freeway. Thinking it would be a good idea to get off asap, I cruised along the freeway overtaking cars along the way). Anyway, during that year, I replaced about 3 or 4 worn-out flywheels. One day, after a long, demanding ride, my clutch eventually overheated and melted, and so I opted to go for the standard Majesty assembly in order to reduce the bike’s maintenance costs.

To sum up, I suggest you work out how much you can afford to spend on modifications, and then determine the safety (e.g. if the bike’s running faster then think about how well the existing braking system will work) and of course, the legality of what you’re doing. The smaller bikes lend themselves towards mods, simply because they’re so popular and the parts are readily available. Also find yourself a good mechanic, and learn some Chinese so you can communicate what you want. It might actually work out cheaper to sell your Majesty and buy a bigger bike.

Sorry for the long post, and apologies in advance if my motorbike terminology is a bit off. Cheers!

Well, I had lighter roller bearings and a tighter spring put into my tranny on a Guangyang 125 at a cost of $600 for each change, $1200 together.
The mechanic (in Donghu) chose 8-gram rollers, replacing an original weight of 14 grams. According to him, this mod is legal even on the street, unlike boring out your cylinder.

The bike, which already had enough power and a high enough top speed for me (I don’t really ride that fast or race or anything) feels higher-strung, more ready to accelerate quickly, but also feels like it’s racing all the time as if you’d left a car in each gear too long. I’m not sure there’s really any better acceleration from a standstill or at lower speeds, but in the 40-60kph range, it feels like there’s more quick oomph. On the other hand, cruising at top speed (which of course you only want to do on a safe private track), the engine is revving too high for my tastes. And gone is the nice, throaty growl of the engine at low to mid speed.
I guess I like the old sound better, and feeling of the old bike, especially at higher speeds. But I also like the quickly available oomph in the mid range, in case it’s needed to get out of an unsafe situation.

It does not feel more powerful. It feels higher-strung. Clearly, it’s just a shift in the torque curve.

Was it worth it?

I’d say if you like high-strung, whining Formula ONe sounds and sudden bursts of juice in the 40-60 range for quick passing, go for it. If you like a nice baritone growl, and a smoother, more relaxed kind of power, don’t do it. If you like high speeds on a private track, I probably wouldn’t do it either, as you’re likely to do damage in the long run from revving too high all the time. But I’m no expert.

Me, I’m keeping the old parts, and if these bearings wear out at some point, I’ll probably put the old ones back in.

They have many engine “kits” for the Majesty. If you go to a mechanic and tell him to give you a bigger piston…he’ll do just that. He’ll give you a plain cheap Taiwan piston. But if you buy a kit…these are kits that have been tested and proven to give more horses. And since the Majesty has been around for so long…there are probably some good kits out there…they would run anywhere from 10k-20k I’m guessing.

Yeah, my mechanic suggested a bigger piston to get any real boost in hp, and he showed me a ceramic kit, about 10K; sounded like he might come down to 7. He had replacement exhausts and other stuff too. I don’t pretend to understand how an exhaust would boost power. But my 125 is just street-legal transportation, and it has enough power anyway. If I were 20 years younger and had a private racetrack nearby I probably woulda gone for it.