Rider weight and engine power.

[Mando]

Alright so, does rider weight affect speed and power in a 2 stroke bike engine? Been wondering for a while. Im 335 lbs and everything is stock on my build except for what the guy who made it did to it. And the rear wheel i got for it, But no performance pipe and it has a stock carb. And at my weight its pulling me at 37mph on flat straights. 399 miles in with no problems. If weight does affect it then imagine then speed itd get pulling a 180lb-200lb person.

 

[Sidewinder Jerry]

Alright so, does rider weight affect speed and power in a 2 stroke bike engine? Been wondering for a while. Im 335 lbs and everything is stock on my build except for what the guy who made it did to it. And the rear wheel i got for it, But no performance pipe and it has a stock carb. And at my weight its pulling me at 37mph on flat straights. 399 miles in with no problems. If weight does affect it then imagine then speed itd get pulling a 180lb-200lb person.

So what rear sprocket are you using? What size tires are you using? What are you using to measure your speed?

For example: 26" tires using a 44t rear sprocket will produce a speed of 37 mph at 8630 rpm. Which is around the max rpm for an engine with slight mods done to it.

What all this means is if you're using a 44t on 26" tires, a much lighter person could use a 36t or maybe even a 32t sprocket. Thus getting a higher speed for the same amount of engine rpm on level ground.

Without changing the rear sprocket a lighter person isn't going to go any faster on an engine that's maxing out it's rpm. What will happen though is the lighter person will need less pedal assist to get up to the top speed. This'll result in the lighter person being able to accelerate much quicker than you can using your setup.

 

[darwin]

Weight always affects performance. Think of a Ford 1/2 ton p/u hauling a full load vs empty, huge diff.

 

[GW's Motorized]

Have you ever heard that fancy term in racing. It goes somthing like "weight reduction." I'd guess weight affects performance if the guys on the track are trying to get rid of it

 

[Whitewill1412]

Less weight = faster acceleration. You will get to top speed faster, but still max out at the same top speed. I think I am just repeating the same thing that was already said.

 

[Mando]

So what rear sprocket are you using? What size tires are you using? What are you using to measure your speed?

For example: 26" tires using a 44t rear sprocket will produce a speed of 37 mph at 8630 rpm. Which is around the max rpm for an engine with slight mods done to it.

What all this means is if you're using a 44t on 26" tires, a much lighter person could use a 36t or maybe even a 32t sprocket. Thus getting a higher speed for the same amount of engine rpm on level ground.

Without changing the rear sprocket a lighter person isn't going to go any faster on an engine that's maxing out it's rpm. What will happen though is the lighter person will need less pedal assist to get up to the top speed. This'll result in the lighter person being able to accelerate much quicker than you can using your setup.

Im using a 32 tooth. And i get up to speed fairly quick. Tires are 26x2.125

 

[Mando]

Less weight = faster acceleration. You will get to top speed faster, but still max out at the same top speed. I think I am just repeating the same thing that was already said.

Ah okay. Ik on electric bikes and scooters that isnt the case, have an electric scooter too and top out at 13 but my brother half my size hits 19. So i wasnt sure if they same applied to these engines

 

[Al Regresar]

God bless you for getting on a bike. Most people assume that being overweight is just bad habits or lack of will (some of it is) when this condition can be much more complex (medical, genetic, psychological, dietary). At any rate, keep going! Also, what engine kit do you have (solid performance)?

 

[Mando]

God bless you for getting on a bike. Most people assume that being overweight is just bad habits or lack of will (some of it is) when this condition can be much more complex (medical, genetic, dietary). At any rate, keep going! Also, what engine kit do you

To be fair ive just been a lazy person most of my life, been trying to change that though. But i appreciate it. And yea the guy who built it said its a yd100 with a high compression head. With a 50mm piston. Said he drilled smoothed and polished a bunch of stuff

 

[Sidewinder Jerry]

Im using a 32 tooth. And i get up to speed fairly quick. Tires are 26x2.125

That means your engine is turning 6276 rpm to do 37 mph on 26" tires using a 32t sprocket. Around 6000-ish is the max these engines do with no mods.

I weigh 250 lbs and my bike weighs 100 lbs; it's also a shifter bike. If at full throttle I'm doing 7000 rpm shifting to a higher gear won't make me go any faster. My speed will remain the same but the increased workload will cause the engine's rpm level to drop.

You can try putting a lighter person on the bike and see if they go any faster on level ground. If they do go faster, it means your extra weight and high gearing is putting a significant workload increase on the engine.

If they don't go any faster on level ground it means your engine is at it's max rpm until performance mods are done to increase horsepower and rpm.