yamaha RS100T

[smurfyot]

hi guys,

its great to be part of this website, I have been working on my RS100T bike for a while, I did a couple of modifications like having a tune pipe, fitted with a carburetor from a RXT 135 (dont know how much mm it has), and i am planning on putting in a boost bottle if it will really help to boost up some speed, For now, sprocket combinations are 14 front:39 rear, taking consideration that my bike is heavier than it should be, let say about 60kg-65kg w/o the driver? i think, .. any suggestions pls? kinda new at this stuffs

[90GTVert]

I don't really know anything about the RS100 specifically. I can tell you the boost bottle probably won't give you any real performance gains. Their best use seems to be keeping the throttle response a bit more crisp in more conditions. Around here, temps and humidity make pretty big swings at times and it seems like I need to fiddle with the carb more without a boost bottle in place. Not a bad thing to have, but if you're just looking for more power/speed it's not your best bet.

I really don't know what gearing is ideal for you. Best thing I can tell you is to evaluate what it does now and how you'd like that to change and adjust accordingly. You are probably already aware of what gearing changes, but here's something I wrote about gearing on 4T midbikes years ago that may be helpful if you aren't sure what does what. Again remember the gearing setups there are for a different bike, just good for general info.

"There are two sprockets that drive your bike. The front (counter) sprocket and the rear sprocket. The number of teeth on each of these sprockets determines a gear ratio. For example, say your bike has a 14 tooth front sprocket, and a 28 tooth rear sprocket. Divide the rear sprocket by the front sprocket to see a numerical gear ratio. 28 divided by 14 equals 2. Your gear ratio is 2.00:1.

O.K., now you're thinking, that's nice, but what does it mean." If you have a gear ratio of 2.00:1, that tells you the counter sprocket must rotate 2 times to rotate the rear sprocket 1 time. The more your front sprocket rotates to rotate the rear sprocket 1 turn, the more take-off power you will have. This comes with a price though. Let's say when your engine is at it's maximum RPM, it can turn the counter sprocket at 1,000 RPM (Revolutions Per Minute). If it takes 2 revolutions of the counter sprocket to rotate the rear sprocket 1 time, it is only acheiving 500 RPM. Now, if you had a gear ratio of 1.00:1, the rear sprocket would be turning at 1000RPM.

Alright, so I can turn the tire at different speeds with different gears, so what? Let's say your tire will travel 10 inches every time it rotates. If you turn that tire at 500RPM, in one minute, it will revolve 500 times, and travel 5,000 inches. If you use the other gear ratio, and turn the tire at 1,000 RPM, it will travel 10,000 inches. The farther it travels in one minute, the faster it is going.

Hopefully you are not completely confused right now. If you are, there is still hope. Here it is in simple terms. The higher the gear ratio is, the more take-off power you will have, and less top speed. The lower the gear ratio is, the less take-off power, but the greater the top speed. More teeth up front
will lead to more top end oriented gearing. Less teeth up front is better for take-off power. More teeth in the rear will increase take-off. Less teeth in the rear with increase top end potential.

Here are some gear ratios you can achieve on your X18, and what sprockets will get you there. You have many options that will allow you to fine tune your bike to your needs.

3.17:1 - 12T front, 38T rear
2.71:1 - 14T front, 38T rear (stock setup on many X18s)
2.53:1 - 15T front, 38T rear
2.38:1 - 16T front, 38T rear
2.33:1 - 12T front, 28T rear
2.24:1 - 17T front, 38T rear
2.11:1 - 18T front, 38T rear
2.00:1 - 14T front, 28T rear
1.87:1 - 15T front, 28T rear
1.83:1 - 12T front, 22T rear
1.75:1 - 16T front, 28T rear
1.65:1 - 17T front, 28T rear
1.57:1 - 14T front, 22T rear
1.56:1 - 18T front, 28T rear
1.47:1 - 15T front, 22T rear
1.38:1 - 16T front, 22T rear
1.29:1 - 17T front, 22T rear
1.22:1 - 18T front, 22T rear

You should have a basic understanding of gear ratios by now. There are other important factors to consider before you run out and buy some sprockets. Gear ratios will give you an idea of what speed you are potentially capable of. The key word being potential. Your engine must have enough power to effectively use those gears, or you won't reach your full potential.

Here's an example, that may help you understand. A friend put a 14/22 setup on his 110cc manual X18, with a gutted muffler, hotter plug, and carb tuning. It reached 63mph (the bike in the video you see everywhere). At 63mph, the engine was not able to rev to its full potential with a 140 pound rider. I tried 14/22 (1.57:1) gearing on my 110cc semi-auto X12, with some minor mods. My bike topped out right around 52mph at a low RPM in 4th gear. I weigh 280 pounds. Obviously, my X12 did not have the power to pull a 280 pound rider to the gearings full potential. Even with a 140 pound rider on a little more powerful bike, the gearings full potential was not seen.

As the example illustrates, it is important to choose a gear ratio suitable to your bike and your needs. From other posts, gearing around 2.00:1 is an excellent choice for stock or nearly stock X18s and light to average weight riders (100-175 pounds). Of course, if you are a heavy rider like me, you may want to consider a numerically higher gear ratio. At 280 pounds, I would be better off with something like a 2.33:1 or 2.38:1 gearing. If your bike is more powerful, you may be able to go numerically lower and see good results. Try doing a search and looking at other peoples gearing/weight/mods/speeds to get more information on what gearing may work well for your needs.

I would also take ease of installation and cost into consideration when choosing sprockets. For example, if you decide you want 2.00:1 gearing, you would need a 28T rear sprocket and your stock 14T front. If you moved up to 2.11:1 gearing with an 18T front and stock 38T rear, you wouldn't see much difference. Changing front sprockets tends to be cheaper and easier than swapping rear sprockets. Some more extreme sprocket changes also require adding or removing chain links. If price and difficulty are not issues to
you, get whatever gearing you feel is the best. If you want to save time or money, you may want to search for information about similar gear ratios that may be cheaper or less difficult to install.""

[aeroxbud]

from most of the tests i have read and people i know boost bottles dont really work as they were originally designed to work with rotery disc valves and people now use reed petals a lot of people seem to fit them for show but as they are cheap give them a go i dont think there are many performance parts for you bike at least over here