Hill climbing!

Lotus

New Member
Aug 13, 2020
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Howdy,

Wasn't sure where to post this, as I'm new, but here we go!

I've been interested in making a fresh hill climber for hiking/mountain bike/dirt bike trails.

I do not care if I can't go faster than 25mph max speed, as I know with these little ladies there are limitations and I'm after torque climbing vs speed.

Base:

*Sturdy mountain bike with descent gears for very steep pedal assist/engine failure
*66 / 80 cc cheap Amazon base kit (links below)
*56-60 sprocket rear
*probably 26 inch wheel/tires

Ideas:

*port / partial polish / clean + cut crescent/window in piston
*sprocket adapter
*spring chain tensioner mounted to clutch side
*possible secondary/backup spring tensioner/guide near rear tire (a lot of bumps on trails)
*affordable Amazon carb/filter
*dual cable brake handle
*basic exhaust modification
*possible head/fin replacement if any oriented towards torque / climbing power vs speed w/ ability to keep cool and not too spendy

Help!
*Where to find affordable:
+56-60 sprocket and adaptor
+dual brake cable lever
+Head/fin

Contemplation station:

*PORTING FOR TORQUE LOW/MID
(I mostly understand how and why, but looking for advice on shaping/where to focus. Shorten bottom exhaust vs top and on intake or widen etc.) Otherwise I will just play clean-up and keep it simple.
*How do I modify exhaust for torque vs speed for "the cheap" without hurting the lady too much from the high rpm etc.? I'm hoping basic mods to stock exhaust may work for now, but may get aftermarket later.
*any good fin or head etc. that's affordable for heat reduction? My guess is going uphill constantly will make her quite warm.

Here are links to things I've considered:









I'm just looking to make a safe, comfortable, reliable (lol) toy. Already have a standard stock 44t bike, but rather than tear it apart, I'm looking to make a new one and upgrading it from the start to make it easier and have a comparison of the two. Will break in with 44t sprocket not the 60t, by the way. 60t or 56t is for after break in period when I use it for its purpose. If it rocks, I'll duplicate it and the wife and I will be adventuring in style.

I would love to get a jackshaft shift kit etc. for 150$, but trying to avoid that if possible (trying to keep it as affordable as possible)

Thank all of you for your wisdom and call-outs. Feel free to call me an idiot and fix my bad ideas as needed hahahaha.
 

5-7HEAVEN

Well-Known Member
Aug 2, 2008
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In my opinion, to climb steep hills, you need 3 things:

a VERY steep gear ratio and a freewheel.

A big gear to climb hills and over logs AT LOW RPMS.....

and a freewheel, so as not to over rev the engine while traveling at a faster speed.

ORRR.....install a shift kit with stiff low gears and shift to speeds of 35mph or faster.
 

5-7HEAVEN

Well-Known Member
Aug 2, 2008
2,505
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With a 60 tooth sprocket, you'd have 25.2:1 gear ratio.

With a shift kit, you get 50.58:1 in first gear.

That's like having a sprocket with 120 teeth in First gear!

When you ride home on asphalt, it'll be with 16.36:1, which is like a 39t sprocket.

And of course, everything's freewheeling.:)
 
Last edited:

Lotus

New Member
Aug 13, 2020
18
7
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29
With a 60 tooth sprocket, you'd have 25.2:1 gear ratio.

With a shift kit, you get 50.58:1 in first gear.

That's like having a sprocket with 120 teeth in First gear!

When you ride home on asphalt, it'll be with 16.36:1, which is like a 39t sprocket.

And of course, everything's freewheeling.:)
Yeah, truth be told the 150$ is incredibly worth it for a shift kit.
Would spend 20 on a sprocket, 20 on adapter, and 1 use bike - trails. (Then new rear tire too). For 100 bucks more could have something well rounded. Definitely an investment!

I have a difficult time deciding on a cheap 125cc pit bike or just going all put on a 2 stroke that I can ride anywhere at that point though.

Problem is I need to get/make 2x so wife and I can both go too while being budget friendly, as these can become scrap metal very easily hahaha.

Any tips on belts vs chains btw? I saw some belt drive kits and that seems appealing to me for some reason.

Tyvm for the ideas buddy! I really do appreciate it and am excited to hear more.
 

bonefish

Member
May 7, 2018
66
13
8
the MFG that makes the Kevlar Belt drive is Golden Eagle Bike Engines. I recommend staying away from that kit if you plan on climbing hills. Your best bet is making your own shifter bike. Both 5-7 and I have built them. They are ideal for hill/mountain climbing.
 

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Lotus

New Member
Aug 13, 2020
18
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the MFG that makes the Kevlar Belt drive is Golden Eagle Bike Engines. I recommend staying away from that kit if you plan on climbing hills. Your best bet is making your own shifter bike. Both 5-7 and I have built them. They are ideal for hill/mountain climbing.
Thank you for the tip and heads up!

Shifter bike aka 2 or 4 stroke with a shift kit on mtn bike?

I think for ease and simplicity of build, I may just 130$ shift kit, 130$ 80cc chinagirl (one of the above), and a 20$ right side chain tensioner
Vs
60$ sprocket and adapter + 2x 15$ spring tensioner for only 1 gear set.

Any tips, specifics, affordable recommendations are loved!
 

bonefish

Member
May 7, 2018
66
13
8
The problem is the 80cc china girls are notoriously unreliable. That is why we chose to go with a name brand(Japaneese pereferably) engines and mounted them to shift kits running the engine thru the bikes gears. There was a guy who made and sold kits called The Scooterguy, but I don't think he is no longer around. So make your own. A guy on here named Neat TImes made his own and it is not all that difficult with a few tools. Here is a link to how he did it. Follow the link all the way to the bottom of the threads to see. It is the Yellow Huffy bike.
 
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5-7HEAVEN

Well-Known Member
Aug 2, 2008
2,505
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63
The problem is the 80cc china girls are notoriously unreliable. That is why we chose to go with a name brand(Japaneese pereferably) engines and mounted them to shift kits running the engine thru the bikes gears. There was a guy who made and sold kits called The Scooterguy, but I don't think he is no longer around. So make your own. A guy on here named Neat TImes made his own and it is not all that difficult with a few tools. Here is a link to how he did it. Follow the link all the way to the bottom of the threads to see. It is the Yellow Huffy bike.
I have had Tanaka engines on shift kit.
Hella reliable.
My engines have been sitting for years. I know if I try, they'd all fire up to life with a few pulls.
 

Lotus

New Member
Aug 13, 2020
18
7
3
29
The problem is the 80cc china girls are notoriously unreliable. That is why we chose to go with a name brand(Japaneese pereferably) engines and mounted them to shift kits running the engine thru the bikes gears. There was a guy who made and sold kits called The Scooterguy, but I don't think he is no longer around. So make your own. A guy on here named Neat TImes made his own and it is not all that difficult with a few tools. Here is a link to how he did it. Follow the link all the way to the bottom of the threads to see. It is the Yellow Huffy bike.
Yeah shift kit is honestly the way id love to go! I saw a few for 120 to 150, which at first sounds spendy, but even if I toast a 150$ engine kit, the shift kit is universal and can be put on another bike. I hear its better on motor longevity and for the bike frame, just gotta be willing to drop the upfront coins.

Anything I should consider before a shift kit/red flags? I dont have the means/tools RN to build one myself sadly, so I'm limited to buying a motor kit and shift kit for around $300
I have had Tanaka engines on shift kit.
Hella reliable.
My engines have been sitting for years. I know if I try, they'd all fire up to life with a few pulls.
Ty for recommending the tanaka! So far ppl told me zeta/bgf are reliable too.

Any more info on with of your builds? Pics? Anything you did that you enjoyed/appreciated?

Ty guys, you rock!
 

bonefish

Member
May 7, 2018
66
13
8
Yeah shift kit is honestly the way id love to go! I saw a few for 120 to 150, which at first sounds spendy, but even if I toast a 150$ engine kit, the shift kit is universal and can be put on another bike. I hear its better on motor longevity and for the bike frame, just gotta be willing to drop the upfront coins.

Anything I should consider before a shift kit/red flags? I dont have the means/tools RN to build one myself sadly, so I'm limited to buying a motor kit and shift kit for around $300


Ty for recommending the tanaka! So far ppl told me zeta/bgf are reliable too.

Any more info on with of your builds? Pics? Anything you did that you enjoyed/appreciated?

Ty guys, you rock!
If you decide to get a China 80cc kit and a SBP shift kit, you will be able to notice the difference in craftsmanship. The metal/steel that comes from the USA that makes the SBP shift kit is stronger and harder and will outlast your China 80cc engine that is an inferior China metal/steel.

For a comparison, look at Craftsman tools. They used to be made in the USA and used to be made of the hard metal/steel and you had a hard time breaking one or stripping one out. Now they moved to China, Craftsman tools suck. They are made of the same inferior steel that the chinesse use and it is easy to break one or strip on out. Who cares if they have a lifetime gurantee, "all they sold you was a guaranteed P.O.S." My time is worth something, and I rather not spend it running to the store to replace tools that shouldn't have broken.
 

Lotus

New Member
Aug 13, 2020
18
7
3
29
If you decide to get a China 80cc kit and a SBP shift kit, you will be able to notice the difference in craftsmanship. The metal/steel that comes from the USA that makes the SBP shift kit is stronger and harder and will outlast your China 80cc engine that is an inferior China metal/steel.

For a comparison, look at Craftsman tools. They used to be made in the USA and used to be made of the hard metal/steel and you had a hard time breaking one or stripping one out. Now they moved to China, Craftsman tools suck. They are made of the same inferior steel that the chinesse use and it is easy to break one or strip on out. Who cares if they have a lifetime gurantee, "all they sold you was a guaranteed P.O.S." My time is worth something, and I rather not spend it running to the store to replace tools that shouldn't have broken.
Yeah I agree with you. I hope/plan on the shift kit outlawing the engine and I hope it does! I expect the engines to crap out :) but hope the craftsmanship lasts on the shift kit to be put in another bike/keep using with engine replacement.

I ended up finding a 100$ brand new 80cc China 2 stroke to play with on the ol craigslist hahahaha