Hill climbing!

GoldenMotor.com

Lotus

New Member
Aug 13, 2020
22
9
3
33
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 am chill as a cucumber if I can't go faster than 25mph max speed, as I know with these engines there are limitations and I'm after torque for climbing vs speed.

Base:

*26 inch Steel frame mountain bike with suspension on front fork (I can't machine a rear mount setup to use a Next bike suspension, etc. ATM)
*66 / 80 cc 2 stroke or 49-100cc 4 stroke kit (help me find an affordable kit, please)
*56-60 sprocket rear
*26 inch wheel/tires
*spring chain tensioner mounted to clutch side
*dual break lever
*possible head replacement if any oriented towards torque / climbing power > speed
*ngl bpr7hix spark plug

Help!
*Where to find affordable:
+4 stroke kit or 2 stroke?
+56-60 sprocket and adapter ($30 or less)
+Head built for low end torque and cooling for possible constant hills [unless sprocket takes care of that anyway] ($30 or less)
+What exhaust ($30 or less)

Contemplation station:

*PORTING FOR TORQUE LOW END TORQUE:
+Keep it simple with cleanup or try and round the exhaust and intake or widen exhaust? I'm afraid to raise or lower either.
+Aftermarket carb or just buy jets for the stock carb? (I'll cut extra junk out of/off the nt with a hot knife if the nt is recommended)
*lap the head only a tiny bit? (Sand paper/glass/600 grit)

I'm just looking to make a safe, comfortable, reliable (lol) toy. I will break it in with 44t sprocket not the 60t, by the way, then 60t or 56t is for after break in period when I use it for its purpose.

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

5-7HEAVEN

Well-Known Member
Aug 2, 2008
2,661
240
63
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
2,661
240
63
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
22
9
3
33
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
68
15
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
22
9
3
33
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
68
15
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
2,661
240
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
22
9
3
33
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
68
15
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
22
9
3
33
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
 

Lotus

New Member
Aug 13, 2020
22
9
3
33
I agree with the idea and benefits of a shift kit. I want a shift kit if I ever build a casual cruiser, however I think I ultimately have decided that I will opt out of shift kit for simplicity.

I plan to keep it at 5 to 20 mph max anyway, so the less hardware, the better for being out in the woods. I'm not real familiar with messing with bike gear shifters and repairing them, nor do I have spare parts.

I may actually opt for a 4 stroke kit, if people believe they have better pull/low end power for things like hill climbing.

I appreciate every single post so far, thank you and stay safe!
 

5-7HEAVEN

Well-Known Member
Aug 2, 2008
2,661
240
63
Or you could buy the largest rear wheel sprocket available for your bike.

If an 84-tooth sprocket fits, it'd give you 35.28:1 gearing.

FWIW, First gear on my shift kit was 46.36:1 and Second gear was 32.73:1.
 

Lotus

New Member
Aug 13, 2020
22
9
3
33
Or you could buy the largest rear wheel sprocket available for your bike.

If an 84-tooth sprocket fits, it'd give you 35.28:1 gearing.

FWIW, First gear on my shift kit was 46.36:1 and Second gear was 32.73:1.
I think I have settled on trying out a 56 tooth (+12 tooth than current) and seeing how it works. If it isn't slow enough @ idle speed, then I will try and judge from there before I go all the way to 84 hahahaha. I would absolutely love 84 for the low end/torque/crawl, but my guess is 7-10 mph max speed without vibrating to death? :D

This would be one of the better setups for what you want, better transmission. Just get a bigger rear sprocket.
https://www.gasbike.net/collections...al-edition-with-huasheng-49cc-4-stroke-engine .........Curt
this thing is a beast, i love it, but i'm trying to be a little bit of a penny pincher for this one. looking for some more affordable sets if possible~ but yeah, this thing looks GREAT.

UPDATE:
I have a 49cc from like 5 years ago that was stock - never once took it apart.
I had tried putting a different intake manifold on, but ruined the gasket. Then, taking the head off, that gasket was old and broke also / is dented and warped.

(first time attempt) I lapped the head and jug with 800 grit and then 1200 grit wet/dry sandpaper.
lightly sanded the intake and exhaust ports as well to get old gasket etc. off.

ordered a new gasket set for 9$ on ebay for 49cc (so hard to find 49cc, vs 66/80cc)
I plan to spray these with copper gasket sealer, sit for a day, then throw it all together.

I'll be curious to see if she runs any different with the lap, ngk 7hix, and new gaskets.

It was either knocking, 4 stroking, or detonating / dying when you were in the high end/near full throttle and coming back after a second or two. If I am able to get the gaskets/setup back together and sealed, then I will start with carb/clip adjustments and increase the intake length and more appropriate intake manifold opening. (found a great one on ebay for 10$ that has wide/squareish port/intake.
 
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5-7HEAVEN

Well-Known Member
Aug 2, 2008
2,661
240
63
My 46.36:1 gearing is like having a 110-tooth rear wheel sprocket!

An 84t would work well.

That'd be 35.28:1 gearing.

My Second gear on my shift kit was 32.73:1, like a 78t rear sprocket.

My First gear was the cat's meow!
 

Lotus

New Member
Aug 13, 2020
22
9
3
33
My 46.36:1 gearing is like having a 110-tooth rear wheel sprocket!

An 84t would work well.

That'd be 35.28:1 gearing.

My Second gear on my shift kit was 32.73:1, like a 78t rear sprocket.

My First gear was the cat's meow!
Yeah I would be all about it if I was doing a shift kit hahaha. That sounds pretty awesome/fun though I do admit.
 

Testname111

Active Member
May 20, 2021
331
167
43
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.


Not as true, check out my electrical system on my build its very reliable starts right up cold or hot


 

Sidewinder Jerry

Well-Known Member
Dec 19, 2011
1,996
928
113
61
Rockwood, TN
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 am chill as a cucumber if I can't go faster than 25mph max speed, as I know with these engines there are limitations and I'm after torque for climbing vs speed.

Base:

*26 inch Steel frame mountain bike with suspension on front fork (I can't machine a rear mount setup to use a Next bike suspension, etc. ATM)
*66 / 80 cc 2 stroke or 49-100cc 4 stroke kit (help me find an affordable kit, please)
*56-60 sprocket rear
*26 inch wheel/tires
*spring chain tensioner mounted to clutch side
*dual break lever
*possible head replacement if any oriented towards torque / climbing power > speed
*ngl bpr7hix spark plug

Help!
*Where to find affordable:
+4 stroke kit or 2 stroke?
+56-60 sprocket and adapter ($30 or less)
+Head built for low end torque and cooling for possible constant hills [unless sprocket takes care of that anyway] ($30 or less)
+What exhaust ($30 or less)

Contemplation station:

*PORTING FOR TORQUE LOW END TORQUE:
+Keep it simple with cleanup or try and round the exhaust and intake or widen exhaust? I'm afraid to raise or lower either.
+Aftermarket carb or just buy jets for the stock carb? (I'll cut extra junk out of/off the nt with a hot knife if the nt is recommended)
*lap the head only a tiny bit? (Sand paper/glass/600 grit)

I'm just looking to make a safe, comfortable, reliable (lol) toy. I will break it in with 44t sprocket not the 60t, by the way, then 60t or 56t is for after break in period when I use it for its purpose.

Thank all of you for your wisdom and call-outs. Feel free to call me an idiot and fix my bad ideas as needed, lol.
Let's start with first things first. Is the off roading for private property use only or deemed legal for hunting?