Speed vs Torque

ImpulseRocket89

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I am currently running a 40 tooth sprocket on the rear. Being a larger guy (280lbsish), I figured that might be the smallest sprocket I'd want to go on the rear.

As I am toying with my motor, it's obvious that I'm not going to push it much beyond her max speed at this point... which is 33.4mph. Sure... I bet I could hit 34mph... and I MIGHT be able to push it to 35mph, but that's all she's got..

I assume that if I went to a 36 tooth sprocket... I could add 10% to the top end speed... 37mphish... but at what cost to the low end? Am I going to see/feel a noticeable difference in torque going from a 40 to 36 tooth? To be honest... at this point, I think I'm there... I'm not sure if any gain going forward is going to be worth the cost/effort.

One thing this little hobby has gotten me involved in is looking for a tiny street-legal enduro to play around with. I've set my budget for $750... if I can pick up a project enduro for under $750 I'm gunna pull the trigger.

I was VERY close to picking up an old 1976 Honda 200 enduro the other day... it's just a little rich for what I have to play with right now at $1000...

EDIT: Now this is interesting... but maybe a little bit more than I wanna chew. This 1969 Suzuki is available about an hour from me for $400. Non-working but they do have all the parts.
For the first part of your question. With small engines you have to play a balancing act with the limited power that they have, and at some point you will reach a point where in the quest for more speed you exceed the engines ability to power you down the road. Keeping the engine in it's power curve at the speed you intend to cruise at is the real key.

Me being a 6'4 260lb man myself I often have to play this balancing act too. If you think all that motor can push you along at is 35mph, just 2mph faster than it currently goes, but the sacrifice would be both acceleration and the ability to climb hills... would it be worth it? I would rather go a bit slower up top to be able to maintain a higher average speed overall. I run a very powerful engine, the Phantom 85, and I had to run a 36 tooth sprocket on a 700C wheel, which is like a 32 tooth on a 26" wheel. If it wasn't for the low end and mid range power that the phantom makes, this sprocket setup would be way too much for my bike with me on it.


For the second part. I am an avid motorcycle person. I find, buy, and restore classic Japanese bikes in particular. One thing you should really consider with classic bikes is that they are REALLY hard to get parts for sometimes. You end up spending a lot of money on NOS parts that some guy has had in his shed for 30 years. It's not the more common parts that get you like gaskets and O-rings. It's the little bits and unique parts. It adds up very quickly.

I can show you my favorite resto-mod as an example. This was my 1975 Goldwing GL1000-K0.




Yes, there was a lot of money I put into it that I didn't need to - the lithium battery, upgraded Mosfet reg-rec, wiring, electronic ignition, custom paint work, Full high end LED lighting, etc. Even with that all aside, I spent $450 just to rebuild and restore the carbs, a few hundred on rebuilding the water and oil pump, timing belts, other misc gaskets, new clutch pack (were seized together from sitting), retoring the gas tank, rebuilding the brake system, and so on. I spent over 3 times what I paid for the bike just to get it to a safe rideable condition.

I could have taken that money, a couple grand, and bought a much better newer bike that needed a lot less work. I didn't because classic Goldwings hold a special place in my heart. It was a labor of love, but nowhere near practical
 

ImpulseRocket89

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That's a $100 bike

You can find those old Jap small 2 strokes from the early 70s running for $200

If ya got $1K to play with go buy a used 250cc Honda Rebel or a 250cc Yamaha Virago Star, Those bike will run forever
The market for old JDM bikes isn't like it used to be. Even that run down little 120 in the shape its in is a good deal anymore for a few hundred bucks. The days of $100 throw away bikes is long gone.

Never buy anything that doesn't run!!
Where is the fun in that? lol. I do it all the time, but admittedly... I am an experienced mechanic.
What? They're worth more than that in parts. I haven't seen a running one for less than 900 where I am.
Yeah, sadly it's hard to find a cheap and easy project bike to fix up anymore. Anything for less than $1000 is going to need a ton of work, or you managed to find somebody that doesn't know how bad the market is these days.
 

Chainlube

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The market for old JDM bikes isn't like it used to be. Even that run down little 120 in the shape its in is a good deal anymore for a few hundred bucks. The days of $100 throw away bikes is long gone.


Where is the fun in that? lol. I do it all the time, but admittedly... I am an experienced mechanic.

Yeah, sadly it's hard to find a cheap and easy project bike to fix up anymore. Anything for less than $1000 is going to need a ton of work, or you managed to find somebody that doesn't know how bad the market is these days.
That is so true, I bought a 50cc kids quad for 100 just for the motor. It was all busted up and the motor was seized, but in runs good now. As it turned out, when I went to order some parts the little bike is a 70cc. +++++
 

Wrench

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The market for old JDM bikes isn't like it used to be. Even that run down little 120 in the shape its in is a good deal anymore for a few hundred bucks. The days of $100 throw away bikes is long gone.
Here in SOCAL my friend was asking $200 each for a couple Yamaha 1972 125cc Enduro bikes
He ended up selling em both for $200 He almost couldn't even give em away.

Here in SOCAL the land of Big M/Cs and Dirt Bikes, Old small Jap Enduro bikes aren't very desirable

I guess the Value of Old Jap Small M/C is more about where ya live and how much demand there is for them
 

noah9988

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Here in SOCAL my friend was asking $200 each for a couple Yamaha 1972 125cc Enduro bikes
He ended up selling em both for $200 He almost couldn't even give em away.

Here in SOCAL the land of Big M/Cs and Dirt Bikes, Old small Jap Enduro bikes aren't very desirable

I guess the Value of Old Jap Small M/C is more about where ya live and how much demand there is for them
That's wild. A parts machine would probably be 200 where I am.
 

ImpulseRocket89

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Here in SOCAL my friend was asking $200 each for a couple Yamaha 1972 125cc Enduro bikes
He ended up selling em both for $200 He almost couldn't even give em away.

Here in SOCAL the land of Big M/Cs and Dirt Bikes, Old small Jap Enduro bikes aren't very desirable

I guess the Value of Old Jap Small M/C is more about where ya live and how much demand there is for them
Hell, I would have bought both of them for 200 a pop here. Region does play a big role for sure.
 

weefek

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Jealous of you guys. I've never been a huge bike person but I am beginning to understand the reasons people are drawn towards it. It's a feeling like no other. Once I get my license back I think I will shoot for something higher than a china special w/ a china special motor.... time will tell. Not having a valid license after 20+ years of having it really sucks.
 
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