Jackshaft questions
- Thread starter alxx01
- Start date
I'd keep the jackshaft. If you want it to act like a straight chain. All you have to do is keep the input and output sprocket on the jackshaft a 1:1 ratio as your clutch sprocket. Example if it is a 10 tooth sprocket on your clutch. Then both input and output sprockets on the jackshaft should be 10 tooth. But the beauty of a jackshaft is you can play with the ratios to get awesome torque multiplication if needed. Along with more flexibility of chain alignment and shorter chain lengths.
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Yes, since the sprockets would be the same ratio from clutch to output of the jackshaft it will be the same as is the jackshaft wasn't there. Essentially for top speed you want as close as possible yet functional to a 1:1 ratio from output to rear sprocket on the wheel. Now that being said if you get did exactly a 1:1 for a final drive ratio. There won't be enough torque to get the bike moving with a rider and it would take a long time to get up to speed. You have to look for a happy medium ratio.
It is hard to tell without all the factors ex: bike weight, rider weight, engine rpm, tire size. All can effect top speed. You will most likely have to use a calculator to get you in the range you have in mind then try it out in the physical world. Keep in mind mini bikes are not really meant for high speed and to achieve it safely. The right engine mods, brake upgrades, speed rated tires, and safety gear should be used. I don't know how fast you are wanting go, but it can get pretty costly to get a mini bike up over about 50-55 mph.
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You mean too low ratio. The closer the two numbers are to each other, the lower the ratio. Some people are confused by low ratios being referred to as high gearing and high ratios being referred to as low gearing. Using ratios mentioned above, 5:1 is a lower ratio than 6:1, 12:1 is a (much) higher ratio than 6:1. Maybe acquire a basic understanding of numerical ratios before advising others...
Count the teeth on your clutch. Count the teeth on the sprocket where that chain connects. Divide the big number by the small number. Write down the answer. Now, count the teeth on the other end of the jackshaft. Count the teeth on your wheel. Divide the big number by the small number. Write down the answer. Now, MULYIPLY THOSE TWO ANSWERS. That will be your gear ratio. As long as you have the same size sprockets on your jackshaft, you have basically the same ratio as straight chain from clutch to wheel.
If you wanted to, you could put a smaller sprocket on the engine side of the jackshaft and a larger one on the wheel side of the jackshaft, making it actually FASTER than straight chain. Your acceleration would be terrible, but your top speed, if you ever get there, would be terrifying.
So, tell me, why are you looking into minibikes, and not motorcycles? They have multiple gear ratios and they go faster.
If you wanted to, you could put a smaller sprocket on the engine side of the jackshaft and a larger one on the wheel side of the jackshaft, making it actually FASTER than straight chain. Your acceleration would be terrible, but your top speed, if you ever get there, would be terrifying.
So, tell me, why are you looking into minibikes, and not motorcycles? They have multiple gear ratios and they go faster.
Another thing is that a sprocket change may not be easy. You may get a bike with a metric jackshaft. 5/8 bore sprockets with a 3/16" key way are not going to fit on a 16mm jackshaft that has a 5mm key. If you find a place that sells sprockets with a 16mm bore let me know. I don't think anyone does.
Exact thing can happen when getting China clone torque converter. You could receive one with either 5/8" or 16mm jackshaft. Sprocket changes are easier with the 5/8" jackshaft.
Exact thing can happen when getting China clone torque converter. You could receive one with either 5/8" or 16mm jackshaft. Sprocket changes are easier with the 5/8" jackshaft.
I am into motorcycles too actually I just haven’t been able to get my license, I don’t want to go crazy fast on this bike, only around 40-45 top speed. My gear ratio is gonna be 5:1 compared to 10:1. I did a speed run yesterday and I hit 30 on the 10:1 ratio. I bypassed the governor and the new ratio is 5:1. Any ideas about how fast i’ll be going now?
if you bypassed the governor and didn't do any internal work or install a billet flywheel, you are building a dangerous bike.
How tall are your tires, and what is your tire pressure?
WITH THE GOVERNOR CONNECTED, going from 10:1, to 5:1 would theoretically cut your acceleration in HALF and double your speed.
Why did you bypass the governor?
My guess, without knowing tire height and pressure, you may never hit 35.
How tall are your tires, and what is your tire pressure?
WITH THE GOVERNOR CONNECTED, going from 10:1, to 5:1 would theoretically cut your acceleration in HALF and double your speed.
Why did you bypass the governor?
My guess, without knowing tire height and pressure, you may never hit 35.