New engine

CrazyDan

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Is it geared to climb mountains? 20 mph is still a bit slow compared to most stock builds. I would understand if it's geared to offroad with inclines.
 


Bozeman55

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Oct 7, 2019
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Is it geared to climb mountains? 20 mph is still a bit slow compared to most stock builds. I would understand if it's geared to offroad with inclines.
No, no special gearing. Just the standard sprocket. I adjusted the carb today, revs much higher (sounds normal) but after it heats up it needs to cool again before it will rev high. Every time I ride it this gets better, today it held 20 mph without my pedal assist. Maybe it just needs more miles?
 

CrazyDan

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No, no special gearing. Just the standard sprocket. I adjusted the carb today, revs much higher (sounds normal) but after it heats up it needs to cool again before it will rev high. Every time I ride it this gets better, today it held 20 mph without my pedal assist. Maybe it just needs more miles?
Possibly. Have you checked your plug color? If the engine is overheating easily it might be running too lean.
If you have a dremel then cleaning the ports, matching the transfers and matching the exhaust port to the header are free upgrades. Make sure none of the gaskets are in the way of flow. If you really want to get into free mods (advanced stuff) then milling the head, adjusting squish, modding the transfers and opening/raising ports can give even more power.
I started this hobby with a 66cc 2 stroke with all stock parts, including the crappy exhaust, and nothing done internally that went 37 mph on stock gearing. 20 mph would piss me off... spandex superheroes would fly past me without a motor...
On another note: before you try to go fast make sure you can stop fast. A crash at 25 mph=crutches, a crash at 35 mph=wheelchair.
 
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Bozeman55

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Joined
Oct 7, 2019
Messages
17
Possibly. Have you checked your plug color? If the engine is overheating easily it might be running too lean.
If you have a dremel then cleaning the ports, matching the transfers and matching the exhaust port to the header are free upgrades. Make sure none of the gaskets are in the way of flow. If you really want to get into free mods (advanced stuff) then milling the head, adjusting squish, modding the transfers and opening/raising ports can give even more power.
I started this hobby with a 66cc 2 stroke with all stock parts, including the crappy exhaust, and nothing done internally that went 37 mph on stock gearing. 20 mph would piss me off... spandex superheroes would fly past me without a motor...
On another note: before you try to go fast make sure you can stop fast. A crash at 25 mph=crutches, a crash at 35 mph=wheelchair.
I haven't checked the plug, that'll be my first step tomorrow morning. Unfortunately no dremel, so that's out of the picture. Brakes work good, so stopping is ok. And Yeah, it is frustrating that I'm capped to 20. Dang, 37 seems so fast! I can't imagine my bike getting to that kind of speed
 

CrazyDan

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I just re-geared my 53cc 4 stroke today to do 46 mph instead of 50, 13.85:1 was a little too steep to race with, wasn't hitting top speed before I had to slow down for the turn on the longest stretch. Now I'm running a 15.11:1 reduction in 3rd gear, accelerates much faster without too much of a loss in the top end.
 

Bozeman55

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Oct 7, 2019
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I just re-geared my 53cc 4 stroke today to do 46 mph instead of 50, 13.85:1 was a little too steep to race with, wasn't hitting top speed before I had to slow down for the turn on the longest stretch. Now I'm running a 15.11:1 reduction in 3rd gear, accelerates much faster without too much of a loss in the top end.
So if your 53 can hit 40+ once my 80 is broken in should have no problem right? Also that's super cool that you race bikes, that'd be so fun to get into
 

CrazyDan

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Not really... if you leave it stock. It's kinda rare for someone with the 66/69cc 2 stroke to hit 40+ stock without at least mild porting. The 80cc is a lie, it's 65.928cc if a 38mm stroke and 69.398cc if it has a 40mm stroke. Idk why china advertises it as 80cc, and I don't know how american sellers advertise it as 80cc without lawsuits for the 80cc claim. 80cc is a huge lie.
 

Bozeman55

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Oct 7, 2019
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Not really... if you leave it stock. It's kinda rare for someone with the 66/69cc 2 stroke to hit 40+ stock without at least mild porting. The 80cc is a lie, it's 65.928cc if a 38mm stroke and 69.398cc if it has a 40mm stroke. Idk why china advertises it as 80cc, and I don't know how american sellers advertise it as 80cc without lawsuits for the 80cc claim. 80cc is a huge lie.
Huh that's weird, never knew. Wonder why they do that
 
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