Only getting 30mph tops

Lorenzo Guevara

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Apr 28, 2019
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After break in with stock motor ,Happy with that .But is that normal for stock 2 stroke motor with no up grades.
 
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indian22

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Dec 31, 2014
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Lorenzo answering speed questions isn't easy there are variable factors involved. "break in" means different things to people. Many think an engine is broken in after two or three tanks of fuel. I don't though I have had a couple that started to run "free" after two tanks, but most of my kit motors started to really free up after several more tank refills. If you are running a 44 tooth final sprocket with a kit engine and weigh over 180 lbs. I'd say 30 mph is pretty decent for a stock motor, & running 26" diameter tires, that's pretty fresh. Most of mine really started running well after the first 7 or 8 hundred miles...let's say 35 or 40 hours of run time at varying speeds, not wide open throttle.

I like to break in motors running standard oil in a heavy ratio mix & switch to ash free semi-synthetic or full synthetic at a lighter ratio fuel mix from then on.

Welcome to the forum. Have fun and ride smart.

Rick C.
 
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curtisfox

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I agree with Indian22, but also where you ride and tires, if you have mountain bike tires they will slow you down a lot also..........Curt
 
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indian22

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Right Curt sea level and a cool, moist day is faster than half a mile high, low humidity and hotter than heck! Tire pressure and tire style like you said, also makes a noticeable speed difference.

Rick C.
 

Lorenzo Guevara

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Apr 28, 2019
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Thanks for the info.much appreciated. Im not into it for the speed ,I injoy just cursing down canal banks and bike paths by the river.At 63 don't need a spill.
I also injoyed building them. I built a few recumbents from donor bikes ,but this is much more rewarding .thanks again.
20190512_124803.jpg
 

indian22

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Great looking bike Lorenzo & one that states cruiser not racer. There are a lot of us older guys on the forum that are starting to acknowledge our maturity. but occasionally still feel a need for a bit of speed, lol.

I really like the recumbents, but find getting down & up from them somewhat of a strain...might be the age.

Rick C.
 
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javy mcdees

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Jul 30, 2018
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30 mph and it is stock. yea thats it and it runs crappy above half throttle. I started out using 100:1 breaking it in but the plated cylinders are so bad it do not matter what you do. Breaking in is for iron cylinder engines not plated anyway. to this day my bike has never smoked out the tailpipe.
amsoil-100-1.jpg.JPG
 
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indian22

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I've only built a dozen or so of these Chinese kit motors and I'm still learning stuff. Not only linear motion, but also rotating & lateral forces are involved during break in. While it's true that Inexpensive 2 cycle kit motors aren't machined to high standards; it's also a fact that experienced engine builders get great engine life and power using the kit jugs. One of my mildly modified motors (maybe 5 hp?) has close to 700 hours of varied riding on it and the original jug is still working fine. I changed the rings & wrist pin bushing out when I machined, added a port to, the jug and cut a piston window for reed valve induction about a year ago and the cylinder walls were fine at that point.

All this said I'd prefer a 10 hp Honda, quality engine, priced at $100. or less, but there ain't no free cake included with this meal! The main motivating force that has driven this motor biking craze, from the beginning, was the availability of the China girl kits at cheap pricing that justified building one bike just to try it out & get it out of our system. Many bikes latter some of us are still at it and I'm constantly impressed with the varied bike builds presented on this forum by novice assemblers, advanced builders, to the pros...great stuff!

Now with 4 cycle builds quite common and e-bikes galore the future of motor biking looks quite bright indeed, but it's all been done on the back of the China girl & a lot of great bikes are still going to use the little 2 stroke for power & the entry level pricing...add a few hundred dollars and some hours of sweat equity & these (now expensive) imports can really purr. The made in U.S.A. two cycle, billet cases will open the door to much engine innovation, if they prove to be precision machined.

As to "poor performance over half throttle" my motors have and will spin to 13,000 rpm with an open KTM expansion pipe and jetting, but will also run street strong with just the kit muffler & pipe in place. I'd add that my motor probably wouldn't hold together for many runs up to 13K however, redlining at 11,000 rpm's seems more reasonable & I'd not think not much if any additional power is being generated past that point anyway. I run a 48 t final cog & 26" rubber with this engine on a Grubee frame. Two of my other China girls that are often ridden, aren't internally modified (for power increases) but they run nicely through their power band with stock CDI kit ignition timing, neither of them have required any top end rebuilds or other internal work either.

Norm I've seen your 2 cycle builds for years & know from the comments posted by those who have ridden with you over the years; that they flat crank! I'm sure you've built and sold more China girls than any of us. You being a vendor and a really experienced builder; I'd be especially interested to hear more of your input as well as that of others on this topic.

Sure a great pastime, Rick C.
 
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Jimmy Bloodmaker

Active Member
Nov 24, 2018
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midwest
After break in with stock motor ,Happy with that .But it that normal for stock 2 stroke motor no up grades.
30mph is nice for a stock motor. if it's pulling hard, switch to a smaller rear sprocket for more speed. torque and the right sprocket equals speed with a single speed bike. i personally run a 32 tooth on a 24" rim for my main bike. i can get to around 37-38 mph before i fear the reaper. usually keep her at about 25 though. at 25 she is so quiet the wind is louder, just sipping gas. i can get around 120-140 mpg at 25 mph. i have a .92 gallon tank, usually empties at around the 120 mile mark. you want to keep your rpms low if you want a long lived bike. the lower rpm's also attract less attention.
 

Jimmy Bloodmaker

Active Member
Nov 24, 2018
176
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28
midwest
I've only built a dozen or so of these Chinese kit motors and I'm still learning stuff. Not only linear motion, but also rotating & lateral forces are involved during break in. While it's true that Inexpensive 2 cycle kit motors aren't machined to high standards; it's also a fact that experienced engine builders get great engine life and power using the kit jugs. One of my mildly modified motors (maybe 5 hp?) has close to 700 hours of varied riding on it and the original jug is still working fine. I changed the rings & wrist pin bushing out when I machined, added a port to, the jug and cut a piston window for reed valve induction about a year ago and the cylinder walls were fine at that point.

All this said I'd prefer a 10 hp Honda, quality engine, priced at $100. or less, but there ain't no free cake included with this meal! The main motivating force that has driven this motor biking craze, from the beginning, was the availability of the China girl kits at cheap pricing that justified building one bike just to try it out & get it out of our system. Many bikes latter some of us are still at it and I'm constantly impressed with the varied bike builds presented on this forum by novice assemblers, advanced builders, to the pros...great stuff!

Now with 4 cycle builds quite common and e-bikes galore the future of motor biking looks quite bright indeed, but it's all been done on the back of the China girl & a lot of great bikes are still going to use the little 2 stroke for power & the entry level pricing...add a few hundred dollars and some hours of sweat equity & these (now expensive) imports can really purr. The made in U.S.A. two cycle, billet cases will open the door to much engine innovation, if they prove to be precision machined.

As to "poor performance over half throttle" my motors have and will spin to 13,000 rpm with an open KTM expansion pipe and jetting, but will also run street strong with just the kit muffler & pipe in place. I'd add that my motor probably wouldn't hold together for many runs up to 13K however, redlining at 11,000 rpm's seems more reasonable & I'd not think not much if any additional power is being generated past that point anyway. I run a 48 t final cog & 26" rubber with this engine on a Grubee frame. Two of my other China girls that are often ridden, aren't internally modified (for power increases) but they run nicely through their power band with stock CDI kit ignition timing, neither of them have required any top end rebuilds or other internal work either.

Norm I've seen your 2 cycle builds for years & know from the comments posted by those who have ridden with you over the years; that they flat crank! I'm sure you've built and sold more China girls than any of us. You being a vendor and a really experienced builder; I'd be especially interested to hear more of your input as well as that of others on this topic.

Sure a great pastime, Rick C.
teach a kid how to motorhead, and you'll never worry about them being a " crackhead". engine parts cost to much to afford drugs and building engines. it's one or the other. lol
 
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Jimmy Bloodmaker

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Nov 24, 2018
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Thanks for the info.much appreciated. Im not into it for the speed ,I injoy just cursing down canal banks and bike paths by the river.At 63 don't need a spill.
I also injoyed building them. I built a few recumbents from donor bikes ,but this is much more rewarding .thanks again. View attachment 100960
if your drops outs allow it, get rid of tht kit tensioner and go with a engine case mounted spring loaded one. they mount on top of the clutch cover. i got 3 mph gain on my first bike by removing it and going with the spring loaded one. i never realized how much friction they put on the drive chain. blew my mind how awesome my first bike felt after removing it. i'd say it was the part tht got me addicted to these bikes. they are like $10 bucks on ebay or amazon. removing it on my first bike gave me way better mileage too. i'll never go back to the kit tensioner if i don't have to use it. nice bike, by the way. simple and sexy.
 
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Citi-sporter

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Jun 16, 2014
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And here I am thinking doing above 20 mph on my 48cc engined bike was pretty impressive with just 150 miles on the engine so far. Frankly pushing any bicycle above 30 seems a bit asking for a bad accident. I happily cruise at 18 mph with mine, The engine is relaxed, I get better fuel mileage, the engine sounds unstrained even, ever so slightly 4 stroking.
 
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javy mcdees

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Jul 30, 2018
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And here I am thinking doing above 20 mph on my 48cc engined bike was pretty impressive with just 150 miles on the engine so far. Frankly pushing any bicycle above 30 seems a bit asking for a bad accident. I happily cruise at 18 mph with mine, The engine is relaxed, I get better fuel mileage, the engine sounds unstrained even, ever so slightly 4 stroking.
I ride 80 miles a day like yesterday and will be going tommorow, takes me 1.5 hours to go 40 miles and 1.5 back, at 18 mph how much earlier do I need to leave to be on time?
laugh-u-turn.jpg
 
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Citi-sporter

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I have a motorcycle for that. it will easily cruise at 48 mph Distances you're covering on a bike engine, that your heat soaking in Summer? Naw no thanks I don't have the patience to constantly fettle a touchy engine being ran too hard.

I treat my bike engine like it was intended and it will last years.

Horses for courses.
 
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Jimmy Bloodmaker

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Nov 24, 2018
176
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midwest
I have a motorcycle for that. it will easily cruise at 48 mph Distances you're covering on a bike engine, that your heat soaking in Summer? Naw no thanks I don't have the patience to constantly fettle a touchy engine being ran too hard.

I treat my bike engine like it was intended and it will last years.

Horses for courses.
i ride regularly 3 hours at a time on one of my bikes. while the others collect dust, they get rode now and then. just last weekend i rode 3 hours, stopped for lunch, and rode 3 hours back. weekend before that, same thing, different route. an so on and on. long as you are moving forward at a decent speed, an your engine is tuned right and in good condition, you can run the motor till it runs out of gas and it wont over heat. these little engine may be cheap, but they are pretty tough. try taking tht motorcycle down a bike path or cutting through a field or on mountain bike trails, you'll end up getting a ticket or arrested.

i get tired, not my bike.
 

Lorenzo Guevara

New Member
Apr 28, 2019
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if your drops outs allow it, get rid of tht kit tensioner and go with a engine case mounted spring loaded one. they mount on top of the clutch cover. i got 3 mph gain on my first bike by removing it and going with the spring loaded one. i never realized how much friction they put on the drive chain. blew my mind how awesome my first bike felt after removing it. i'd say it was the part tht got me addicted to these bikes. they are like $10 bucks on ebay or amazon. removing it on my first bike gave me way better mileage too. i'll never go back to the kit tensioner if i don't have to use it. nice bike, by the way. simple and sexy.
Im putting one on now but I have to gring down my petal arm so it won't hit.
 
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javy mcdees

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Jul 30, 2018
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the stock engine is dangerous to take out on the road thins is cough cough slow, it will cough 2 times accelerating and pow to
i ride regularly 3 hours at a time on one of my bikes. while the others collect dust, they get rode now and then. just last weekend i rode 3 hours, stopped for lunch, and rode 3 hours back. weekend before that, same thing, different route. an so on and on. long as you are moving forward at a decent speed, an your engine is tuned right and in good condition, you can run the motor till it runs out of gas and it wont over heat. these little engine may be cheap, but they are pretty tough. try taking tht motorcycle down a bike path or cutting through a field or on mountain bike trails, you'll end up getting a ticket or arrested.

i get tired, not my bike.
If they even smell you had a bicycle you get arrested.
 
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Citi-sporter

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It's a different world riding here with 25 to 30 mph headwinds and hills with larger than 5% gradients for more than a half mile. I actually think my weedie powered bike is better at long hills as it's geared at about 27:1, and it's forced aircooled.
 
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