i know i shouldnt

S

stewpedassle

New Member
i always find my self lost in the oment trying to go as fast as i can, i guess my ? is what the longest safe time to run hs 142f at topspeed dont wanna lose another.wee.
 
That depends on what RPM you're turning. If you don't know what RPM you're turning, post this information:

What gearbox, how many teeth on output, how many teeth on rear sprocket, what size tire

Generally speaking, your engine should easily handle a constant 6-7.5K.
 
Well that's a 14.55:1 ratio there, and with 29" tires you get roughly:

~4500 @ 27
~5250 @ 31
~6000 @ 35.5
~7000 @ 41.5

Your gear ratio is pretty tall, so you're pretty much lugging the engine when below 4000. A HS142F makes max torque at 4500RPM.

5252 has the distinction of being where the horsepower and torque are equal. You're not even coming close to where the engine makes maximum hp (7K).
And you probably won't either, unless you're drafting someone, going downhill, and/or have a mean tailwind :D

IMHO, for best results, 16:1 is about tallest gear one should run with a HS. If you had a 44T, that would give you 16:1.
 
stewpedassle said:
i always find my self lost in the oment trying to go as fast as i can, i guess my ? is what the longest safe time to run hs 142f at topspeed dont wanna lose another
Click to expand...
You are over geared so much that you have no chance of over revving
your motor.

At the hausheng's redline of 7800 rpm your speed would be 46.3 mph.

You would still be safe, get faster acceleration and top speed if you
geared it to go about 40 mph

48 tooth = 38.6 mph
44 tooth = 42 mph
 
Keep in mind, if you go to the 48 tooth and sacrifice a few mph top speed, you will make much better use of the low end torque without having to pedal as hard.
 
stewpedassle said:
i appreciate all the input, guess ill be lokking for 44 tooth
Click to expand...
If you weigh 240 a 48 tooth would be better as you will get better performance.

You don't need a tach, just don't go faster than 38 mph if you can even go that fast.
Actually the HS motor can be safely revved to 9,000 rpm not that I am recommending that you do it.

The ones I have seen break their connecting rod have been abused at 10,000 rpm
for an extended distance.

Usually a 4G with a 5:1 gearbox and 11 to 50 teeth 26" wheels.

7800 rpm with the above gearing is only 27 mph!!!!

9800 rpm with the above gearing is only 34 mph!!!!

10,000 rpm with the above gearing is only 34.7 mph!!!!

The HS motor will rev that high ......Kaabooom!
 
Yeah, you'd definitely be better off with a 48T than 44T, IMHO. That gives you a 17.45:1 ratio, and with your 29" wheels, it'll be plenty tall enough for cruising.

I've often said 16:1 is just about perfect for HS 49CC, and I always meant 26" wheels. A 48T on your 29er would be equivalent to ~15.64:1 on 26".

Edit: my current cruise ratio is 17.67:1 on 26" and it cruises very nice at 20-29 :D
 
i just remembered i do have 100t pulley for tranny what kind of ratio would that give me guys run the math magic give me some good news lol
 
If you have a 5:1 4G, that does change things.

2000RPM = 9.5MPH
4500 = 21.4
6000 = 28.5
7000 = 33.2
8000 = 38

That gearing is fine, but expect to pedal under 20MPH
 
more teeth = more torque, less teeth = more speed. There are some questions you should be asking yourself in terms of gearing, all of which assume your motor is capable:

Do you have a top speed in mind? (Most laws state 20mph/35kph max)
--Yes: Choose a gearing that will max out at your chosen top speed (or at an RPM you're comfortable with), this will give you max torque with a guarantee of your speed.
--No: Read on, then, going as fast as possible requires either guesswork, or alot of physics calculations (and requires you know exactly how much power your engine makes at any RPM)

Do you want to have to pedal to get going?
--No: Go with a lower gear ratio, I'm unsure of what the HS produces at low RPM, but I know a china girl will get going (albeit struggle a bit) with a 44T, feathering the clutch for about 3 seconds
--I dont care: Read on

Do you care about milage? (That is, the difference between 80mpg and 100mpg)
--Yes: Choose a higher gear ratio, this will lower your cruising speed RPM, if you cruise at redline all the time, it's going to eat your gas, this is where the tradeoff happens with the previous question
--No: Then... well... you know you want a low ratio, what are you waiting for?
 
You must log in or register to reply here.
Back
Top