How to tell a motor if it's 66/72cc, by not measuring it in person?

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#1
Hello forum!

I have bought a 48cc engine from Wish recently, that had the upper engine destroyed in 2 weeks because of (probably) a casting issue.

Now instead of sending a new upper engine, they decided to refund the whole engine without asking back for it.

I'm going to go to a store where they replate engines on monday, but if it costs more than 2/3 the price to replate it, I want to buy a completely new engine, since this one has blowby on the piston, has bits of metal in the crankcase, and an air leak on top of everything.

I really liked the old engine, but because I'm a bit heavier then what the motor likes, I want to buy a 66/72cc engine. How am I able to tell them apart just by either specs, or looking at them on their website? I have heard something about 30mm being the 66c and the 40mm being the 72cc one. Wich is 30/40mm? The intake?
How else can I make sure I'm getting the 72cc and not the 66cc?

EDIT: If you guys know any good websites, other than Zedamotorsports and Gasbike, please put them down below for me to choose from. The best would be if you put the 72cc one as well, to make things easier for me. I've been looking for 2 hours now! :D

Thanks in advance!
 
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crassius

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#2
look for 40mm stroke and 40mm intake with 8mm mounting studs and all allen head cover bolts - send an email to seller to ask about that BEFORE buying
 

MotorBicycleRacing

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#4
Hello forum!

Now instead of sending a new upper engine, they decided to refund the whole engine without asking back for it.

I really liked the old engine, but because I'm a bit heavier then what the motor likes, I want to buy a 66/72cc engine. How am I able to tell them apart just by either specs, or looking at them on their website? I have heard something about 30mm being the 66c and the 40mm being the 72cc one. Wich is 30/40mm? The intake?
How else can I make sure I'm getting the 72cc and not the 66cc?
This motor is 70cc. There is no such thing as 72cc. They are mainly 66cc or 70cc
Good company to buy from.
https://www.bicycle-engines.com/2-stroke-engine-kits/

They are mainly 66cc or 70cc
47 mm diameter piston with a 38 mm stroke is 65.xx cc
47 mm diameter piston with a 40 mm stroke is 69.xx cc

The intake bolt spacing is 32 mm or 40 mm.
A true PK "80" (70cc) are 40 mm stroke motors with 32mm intake
 
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MotorBicycleRacing

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#6
Thanks. I didn't find any engine only kits there, wich is the thing I'm looking for.

https://www.gasbike.net/collections/engines-only/products/jet-66cc-80cc-bicycle-engine-kit

Is this engine 66 or 70cc? I didn't find it. Should I e-mail them?
How much more is the complete kit than buying that 66 cc motor??
Think about all the extra parts that you will probably need and what they would
cost to buy separately!! ;)
What happened to your decision not to buy from Gasbike?? :D
 
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#7
I was just asking if that one is 66 or 70cc. I'm not buying yet untill I figure it out. Even if it's 70, I'll check other places too. Also, if I want to buy just the engine, it's 40-50 dollars less than to buy the whole kit (Wich I don't need that much spare parts, in 3-4-5 years I'm getting a real motorcycle)
 
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#10
It's a regular 66cc the 80cc is just a chinese label kinda like mph-kph. It's not 70cc I guess you could round it up to that though. I would just make sure you don't get one with cheese bolts. Get one with allen heads they strip alot less and the thicker mount studs too. I would get a silver engine too. Because the black ones are usually painted wrong as in inside the ports and crap and on the bottom of the cylinder head thats no good. The pk80 that umoto sells on ebay is a good engine heres a kit you can also buy just the engine for $99 I don't really like how much shipping is though. https://m.ebay.com/itm/DIY-2-STROKE...380057.m4084.l1313.TR1.TRC0.A0.H0.Xumoto.TRS0
 

crassius

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#12
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#14
This seams a good deal from a great vendor. They also sell Zeda engines.
https://bicyclemotorworks.com/product/pk80-by-runwell/
Thanks, is this one truly 70cc, or just 66cc? It looks like a great deal too.

It's a regular 66cc the 80cc is just a chinese label kinda like mph-kph. It's not 70cc I guess you could round it up to that though. I would just make sure you don't get one with cheese bolts. Get one with allen heads they strip alot less and the thicker mount studs too. I would get a silver engine too. Because the black ones are usually painted wrong as in inside the ports and crap and on the bottom of the cylinder head thats no good. The pk80 that umoto sells on ebay is a good engine heres a kit you can also buy just the engine for $99 I don't really like how much shipping is though. https://m.ebay.com/itm/DIY-2-STROKE-HIGHEST-POWER-PK80-66CC-80CC-MOTORIZED-BIKE-ENGINE-KIT/122598798446?epid=15005379696&hash=item1c8b75346e:g:OHwAAOSwIWVY-ob0&_nkw=umoto+pk80&_from=R40&rt=nc&_trksid=p2380057.m4084.l1313.TR1.TRC0.A0.H0.Xumoto.TRS0
They don't ship here, but thanks anyways.
 
B

Bars

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#15
Thanks. I didn't find any engine only kits there, wich is the thing I'm looking for.

https://www.gasbike.net/collections/engines-only/products/jet-66cc-80cc-bicycle-engine-kit

Is this engine 66 or 70cc? I didn't find it. Should I e-mail them?
There are no 70 cc 2 stroke engines, they are called 66/80 cc,the 66cc is USA measurements and the 80 cc are Chinese measurements, so it's a 66 cc engine,the PK 80 and the Zeda 80's are 69.4 CC's, I prefer the Zeda 80's over the PK 80, I have both and the Zeda will go 45 mph with a 40 tooth rear sprocket and the PK 80 only about 35 mph, but the seeutec PK 80 top speed is 42 mph.
 
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#16
This one is only 68cc and it has a 48mm iron sleeved cylinder. I guess the reason the Chinese call it a 80cc or some other dumb numbers is they count the combustion chamber on the head. Now if it’s a 40mm stroke it is different than the 38mm which this one is but not by much. If the 3mm stroker
2DDF9EA2-5268-41C8-B034-AA735667A8F2.jpeg
crank had worked with the pk80 I have it would be 74cc but this cylinder was meant for the 38mm stroke engine.
 

gary55

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#17
This one is only 68cc and it has a 48mm iron sleeved cylinder. I guess the reason the Chinese call it a 80cc or some other dumb numbers is they count the combustion chamber on the head. Now if it’s a 40mm stroke it is different than the 38mm which this one is but not by much. If the 3mm stroker View attachment 84031 crank had worked with the pk80 I have it would be 74cc but this cylinder was meant for the 38mm stroke engine.
24x24x3.14x40div. 1000=72.3456. 48mm bore 40mm stroke 72cc disp. With 38mm stroke 68.72 so would be considered a 69cc.
 
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crassius

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#18
48mm bore is rare - for others, the significant diff is 38/40 stroke - ignore cc's and get a 40mm stroke motor
 

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