118cc lifan build

JerboaJohn

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Jul 29, 2018
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mbrebel! I know I was thinking on the side where'd I see a selection of sprockets and big ones,, good find Dan!
 


The_Aleman

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Back when I was trying to increase my engine-to-crank reduction, I figured on 9->76T on j/s out.

Since (Teeth * Pitch) ÷ Pi = sprocket diameter, that meant a 76T #4x(x) was over 12" in diameter.

I had to step down to #35 for my jackshaft output. A 76T #35 is about 9". Output is 9T either way.

There was no way I could fit a 12" sprocket on my pedal crank without hitting the whole motor :LOL:
 

CrazyDan

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Jul 9, 2016
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Back when I was trying to increase my engine-to-crank reduction, I figured on 9->76T on j/s out.

Since (Teeth * Pitch) ÷ Pi = sprocket diameter, that meant a 76T #4x(x) was over 12" in diameter.

I had to step down to #35 for my jackshaft output. A 76T #35 is about 9". Output is 9T either way.

There was no way I could fit a 12" sprocket on my pedal crank without hitting the whole motor :LOL:
Where did you find a #35 76t that fits the freewheel on the crank? This is the biggest one I found and am about to buy.

I guess 4 less teeth isn't that bad of a reduction loss. I'm going 20-100, 9-17, 13-72 for 52.308:1 to my crank. Then 48 crank output to 18 on my nexus 3 speed, putting me at 19.615:1 in second gear, which is when this hub spins 1:1 with the sprocket.
 

The_Aleman

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May 2, 2007
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I bought a custom blank from Azusa (they sell up to 104T #35) and sent it to my family's shop.
There it had 5 large circles laser cut out for lightness and the center circle enlarged to 2.125".
When it was sent back to me I beveled the sprocket sides and drilled the holes for freewheel.

that put me at 20->100, 11->18, 9->76, 48->15. My 18T is from Staton, I should have gone 19T.
T-belt -> HL710 -> #35 -> #415. I found full halflink chain is awesome for jackshaft input.
I had set my gearing up with an X-RD3(w) and later switched to an X-RD5(w) which made a 14.72:1 5th.
It's a little bit tall for my well-worn HS49 and unaero self, going to switch to a 16T on back wheel.
 

CrazyDan

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With my above mentioned setup, 1st gear is 26.755:1 which is funnily enough good for 26 mph. 3rd gear is 14.378:1 which will yank 48, want to hit it on flats tucked, something tells me 46 mph is my flat ground wall...till I make a fairing. This lifan build has potential to be much much faster. Just needs a cvt :p.
 

The_Aleman

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With my above mentioned setup, 1st gear is 26.755:1 which is funnily enough good for 26 mph.
Yeah, 9000 is fun to claim on these, but these engines don't have an oiling system worth a crap.

3rd gear is 14.378:1 which will yank 48, want to hit it on flats tucked, something tells me 46 mph is my flat ground wall...till I make a fairing.
Doubt you can do over 40 on a flat unless you have a tailwind. Even when mine was tip-top, my brother's cammed GXH50+Q-matic walked away from it over 30MPH and his never could do over 41, 42 on a windless flat. The shift kit robs top speed capability and increasing the engine-to-crank reduction also increases drivetrain load and therefore power loss. Also, under heavy load, these engines wear out their camshaft quick and suffer power loss over time.

This lifan build has potential to be much much faster. Just needs a cvt :p.
CVT, heh. Good luck with that one.
 

CrazyDan

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Yeah, 9000 is fun to claim on these, but these engines don't have an oiling system worth a crap.Doubt you can do over 40 on a flat unless you have a tailwind. Even when mine was tip-top, my brother's cammed GXH50+Q-matic walked away from it over 30MPH and his never could do over 41, 42 on a windless flat. The shift kit robs top speed capability and increasing the engine-to-crank reduction also increases drivetrain load and therefore power loss. Also, under heavy load, these engines wear out their camshaft quick and suffer power loss over time.
Gotta remember, I'm not running the 49 cc. The 53 cc has 25% more torque. I hit my wall at 46 mph, sorry for your lack of belief but w/e. Show up at the next race for proof, if you need it. Also, already replaced my cam, I know it wears fast.
 

Frogslayer

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Jan 20, 2019
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Gotta remember, I'm not running the 49 cc. The 53 cc has 25% more torque. I hit my wall at 46 mph, sorry for your lack of belief but w/e. Show up at the next race for proof, if you need it. Also, already replaced my cam, I know it wears fast.
Oooh he's calling you it bro! Lol JK 😋. 46mph is booking for a 53cc 4 stroke!
 

The_Aleman

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May 2, 2007
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Dan, I saw the first time you tried to claim the HS53 has 25% more torque than the HS49 previously and I'm very happy you have brought it up again. I find that amusing, same compression but with 8% increased displacement yields "25% more torque". You hit an imaginary wall on Gearcalc.exe

A stock HT66 has more power than any HS49/HS53. I smoked my brother's GXH50 with my old ported HT66.
This is all pretty simple stuff. Don't be sorry for me, be sorry for all the chinagirls you supposedly outpower :rolleyes:
 
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