How Fast should it go?

[teltech2020]

My son and I are building a little minibike. It's an Azusa with 6 inch wheels and a 72 tooth sprocket. I have ordered a 6.5HP predator engine and a 12 tooth centrifugal clutch. My question is just how much speed can I expect out of this setup? I originally thought about buying a smaller engine because my boy is is still pretty young but then I decided that if I wanted to ride it some that the 6.5hp would be better suited for hauling my 185 lbs around.

 

[45t]

. Be careful if you let your kid ride it.

 

[INJUNTOM]

Sounds like you need 2 bikes before someone gets hurt...

 

[trinik7597]

my youngest son was about six when i got him his db30 with the 97cc stock motor on it went all of about 15mph top speed good for little guys to go slow at first :thumbsup:a 6.5 horse on the right bike can wheelie real easy with a hard twist on the throttle even with an adult on it :doah:

 

[rmm727]

Approx 25mph assuming 3600rpm and 12.5 diameter tire. 30mph @ 5000 rpm

 

[teltech2020]

If 40mph is top speed then I'm not too worried. He's 10 and we have 5 acre field of nice soft grass he can cruise around. I doubt he'll ever get her up to top speed in the grass anyway. Maybe I can rig up some sort of a throttle limiter if it looks like its to fast for him.

 

[buckeye]

It's the sudden acceleration that is a concern. :thumbsup:

And he WILL get into the throttle quick. No fear.:thumbsup:

 

[creia]

It's the sudden acceleration that is a concern. :thumbsup:

And he WILL get into the throttle quick. No fear.:thumbsup:

Buckeye's got it right.:thumbsup: WAY too much torque with that 6.5 Predator for a 10 year old, ESPECIALLY if this is his first minibike.:scared:
Michael

 

[jeep2003]

I think at ten he should be able to handle it if he has any prior motorbike experience. A set of forks with suspention does wonders for stability and control even on a well kept lawn. will help your boy keep a good grip on the bars that he will need :thumbsup:

 

[ratsrods]

Put a restrictor plate (Gasket) on it so you dont throw all the torque on it at once, it wont throw him off and you can still enjoy it too

 

[bikesandcars]

Predator's have throttle restrictors built into the throttle mechanism, if you are worried just turn in the screw a little

 

[toomanytoys]

Had the same setup on a little el tigre that thing would throw you on your butt before you even knew what was going on. You had to roll into the throttle real gently.

Even limiting the throttle will still allow the clutch to engage suddenly and throw him on his butt.

 

[KB2ROCKET]

basicly your setup will net a slow mini 25mph ish with lots of lowend torque it will be a wheelie machine hill climber

 

[David wulf]

This is JMHO he's 10 he will learn . My daughter was 7 when she got her first mini a PW 80 and on her second day she was jumping a little bump in the yard , she was wearing it out . Just watch him and teach him how to use the brakes . One more thing by the tine my girl was 10 she was on a 250 arctic cat and riding coal creek and royal blue , and out running most adults .

 

[Havasu Dave]

This is JMHO he's 10 he will learn . My daughter was 7 when she got her first mini a PW 80 and on her second day she was jumping a little bump in the yard , she was wearing it out . Just watch him and teach him how to use the brakes . One more thing by the tine my girl was 10 she was on a 250 arctic cat and riding coal creek and royal blue , and out running most adults .

:thumbsup: Agreed. All kids aren't created equal with regards to ability and comfort level on bikes. Got a PW 80 for my twin Grandsons. (9 y/o at the time) One could ride the wheels off of it, the other mostly crashed and wasn't real good at it.

 

[trinik7597]

basicly your setup will net a slow mini 25mph ish with lots of lowend torque it will be a wheelie machine hill climber

i have the same set up on my sons bike 6.5 predator 12 tooth clutch 72 tooth rear sprocket 6 to1 ratio you think top speed is 25 :shrug:

 

[KB2ROCKET]

i have the same set up on my sons bike 6.5 predator 12 tooth clutch 72 tooth rear sprocket 6 to1 ratio you think top speed is 25 :shrug:

well if you tell me the circumference of the rear tire or its diameter and the highest rpm your engine runs then I could figure out the mathmatical top end speed not accounting for wind resistance and friction loses and the weight of the machine and the operator .. not to mention that just because you put sprockets on a machine and math says you will top out at 80 mph dosent mean it will happen because the engine will need to have enough torque to do that amount of work the math doesent factor the engines ability .... so yes I just made a guess that it would top out at about 25 ish mph go grab a gps and check it out for your self and let us know:thumbsup:

 

[buckeye]

:hammer::laugh:

 

[KB2ROCKET]

In an atempt to be more helpful let me offer this . With your current setup if you could get your engine to spin 3200 rpms you would top out at 19 mph 3500 rpms 21 mph 4000 rpms 24 mph 5000 rpms 30 mph this is based on a 12 tooth driver and a 72 tooth driven and a 38 inch rear tire circumference that is somewhat typical and yes I did round the mph numbers to the nearest mph
I hope this helps

 

[george3]

25 mph in about 2 seconds.