Weight concerns

[Greggl4321]

I'm a little torn between models guys. I hear the lil Duc may have 3 engine bolts, additionally it looks like it conforms to the shape of the legs. I heard in a "why choose boom Vader" YouTube video that the lil Duc also vibrates less than the boom Vader. Lastly, weight concerns-- I hear power might be a problem because of my weight or not. I'm 280lbs, how fast do you expect me to go? It's also still a mystery to me how overloading an engine slows it down, the explosions inside the chamber aren't slowed, and that piston is sure going to move right?

[Greggl4321]

Ultimately what I'm wondering is about speed.


Different sprocket or stock -- what if I go larger tires?


(Does the fender need to be adjusted?)

[wheelbender6]

For a big fella, I think it is better to buy a used bike with more engine displacement, like a 200 or 250 cc bike. I'm afraid a nice 125 will not go as fast as you need to go (even if you choose the TNT with the 4 valve head)

[franque]

I think you could reasonably expect up to 50 mph if the engine is properly broken in and tuned right with a 125.

Any more is expecting something outside of the design of the machine.

Overloading an engine slows it down because there is a limited amount of thrust that the engine produces, for example, let's say 10 ft-lbs at 7k rpm.

Assuming zero loss in the driveline, we could say that hypothetically, between the three reductions in engine speed from the primary, transmission, and then the sprockets (just making numbers up to give you an idea) that at the rear wheel, the driveline is now producing 600 ft-lbs at 300 rpm of usable rear wheel power, let's say that RPM is good for 30 mph.

If the object weighs 600 lbs, (lets also assume zero wind resistance right now) it theoretically has no problem maintaining 30 mph, once it gets there, as there is sufficient thrust.

If the object weighed 1200 lbs, it wouldn't be able to go 30 mph, it would be limited to 15 mph, because to move that weight with the available power, you would have to gear it down to where it would now move 1200 ft-lbs at 125 rpm.

If you want to go twice as fast, you don't just need twice as much power, but 4 times as much, due to wind resistance, as wind resistance's power quadruples for every doubling of speed, which is especially a factor at speeds above 40-50mph.

You could probably theoretically go 90mph, even at your weight, with that motor, but you'd need nearly a million gears to shift between, good aerodynamics, and ideal conditions.

To wit, I'd shop for a Chinese 250 if I was your size.

[Greggl4321]

They don't make them, I plan on reducing my weight and
Doing the mikuni carb
Perhaps a sprocket too
Looking to go 55mph? Not even sure, does anyone know of a website that tells you the speed limits?

[scoot newb]

They don't make them, I plan on reducing my weight and
Doing the mikuni carb
Perhaps a sprocket too
Looking to go 55mph? Not even sure, does anyone know of a website that tells you the speed limits?

Looking for 55? You could maybe do that with an exhaust tuned carb and 16/32 gear ratio or 17/34 if it was not windy out and you had it pinned wide open on a flat surface. The vibration would be insane and with that gear ratio the stock motor even with the carb isn't powerful enough to max out the RPM.

Maybe if you ran that bitch lean. :) DON'T

These bikes are fun and practical for around town 30 - 45 but otherwise they suck. You will be happier with a bigger bike in the long run.

Or dude, if you're are dead set on a clone, order a 190 kit along with the clone and install it. That will get you around much better.

Good luck

P.S. They do make 250 Chinese bikes. I think someone already pointed out the Hawk there is also an Apollo brand enduro bike the Db 36. It is $1800.

[Greggl4321]

16/32. / 17/34


Front : rear?

What is it stock?


Why not just change the front?


Im pretty deadset on a 125cc, I want to run it as close to stock as possible, avoiding major repairs and costs/liability


What would be the ideal sprocket combination between the two of them?


I'm just looking to reach 55 tops

Carb/exhaust not enough to get me there alone?

Which exhaust?

[scoot newb]

The ideal sprocket combination is a personal choice. Stock is most likely 16/34.

Kepspeed exhaust something for DAX or Monkey that mounts on the bottom.

Something like... https://www.motorkit.com/en/exhaust-onder/10843-kepspeed-down-carbon-exhaust-for-honda-dax-monkey-chaly-and-skyteam.html?search_query=kepspeed+exhaust&results=47

[Greggl4321]

And why again just not change the front sprocket?

I read somewhere that changing the front sprocket by 1 is like changing it by 2 in the rear

[franque]

If you're talking about 55 as the maximum achievable speed, with the right phase of the moon, wind direction, temperature, and slope of hill, then a 125 will work. If you're talking about cruising speed, well, when I was 100 lbs lighter than you currently are, I was having trouble doing that on a Grom. It would just be easier to get a Hawk/TBR7/Brozz. I'm not sure that I understand the fixation with a Grom replica.

[Greggl4321]

17:33 ?

[scoot newb]

17:33 ?

Close. 17 / 34 would give you a better top speed but the motor isn't able to max out. Some people do better with 16/34.

You never answered any questions about your wrenching experience or whether someone you know will do the work. It's ... I mean really if you are new to it, it is going to cause some problems. Ask me how I know.

Oh I see what you are asking now. 17/33 . 33 rear sprocket. Here is a chart. https://imgur.com/lNewmFh.jpg

[scoot newb]

If you're talking about 55 as the maximum achievable speed, with the right phase of the moon, wind direction, temperature, and slope of hill, then a 125 will work. If you're talking about cruising speed, well, when I was 100 lbs lighter than you currently are, I was having trouble doing that on a Grom. It would just be easier to get a Hawk/TBR7/Brozz. I'm not sure that I understand the fixation with a Grom replica.

He just wants to hear the answer he is looking for. At this point I am only responding for entertainment purposes. Bottom line, these are huge shit boxes until you put time and money into them. A 7 HP motor is not going to be a good fit.

[Greggl4321]

I have some wrenching experience, it's kind of hard to quantify, I wasn't timing it...

I have no tools, but tools are cheap


It's arbitrary to the questions that I have asked.



So 17/33 might be better than 17/34?


--Why do you want to know? It's conflating the issue... There is no requirement of a certain level of wrenching experience. Besides, everyone starts somewhere.

[Greggl4321]

Unfortunately for me I do not know how to interpret the chart.

I think I have gathered enough information now to make an informed decision. I'll search around for information on the ideal sprocket -- or likely just go with 17:34,. -- whatever is simplest, maybe I'll leave it stock actually.


Thank you everyone for your time and cooperation.

[JerryHawk250]

Gregg, The best thing to do is get the bike first. No one sprocket combo will work for everyone. A lot comes into play. Run it stock, tune it and let it break in first. You can decide on what sprocket you will need after that.

[scoot newb]

I have some wrenching experience, it's kind of hard to quantify, I wasn't timing it...

I have no tools, but tools are cheap


It's arbitrary to the questions that I have asked.



So 17/33 might be better than 17/34?


--Why do you want to know? It's conflating the issue... There is no requirement of a certain level of wrenching experience. Besides, everyone starts somewhere.


The answers for the questions you've asked have been on this site all along. If you're still unable to connect of the dots on why a 7hp Grom clone may not be the best bike for you or why questions about tools or wrenching experience aren't important I'm just gonna assume you're waiting to hear the answer you want.

[Greggl4321]

What are you saying B?

I'm open to other sources of info because I heard the bike will work