Engine Specs

ferball · Apr 2, 2011

Factory specs for my "X80" two stroke motor. Maybe we can add other models, and make a sticky. Or maybe it has been done and I missed it.

Model : X80
Mode of Engine : Single cylinder, air-cooling, 2-stroke
Power * Rotary Speed
Rated Power : 1.5Kw / 5000r / min (2.5HP/5000r/min)
Max. Power : 2Kw / 6000r / min (5-6HP/6000r/min)

Ignition Mode : CDI
Compression Ratio : 6 : 01
Driving Ratio : 18 : 01
Fuel type : No. 90
Lubrication Oil : Motorcycle Synthetic 2 Stroke Oil
Mixing Ration for Fuel and Oil : 16:1 for break period (first 300 miles)
25:1 after
Spark Plug : Z4C 14MM
Fuel Consumption : 120-170 MPG
Clutch Type : Friction Plate / Dry
Speed Limitation : 25-40MPH

The 26incher · Apr 3, 2011

5 to 6 HP? Ya right...

ferball · Apr 3, 2011

I never said they were right, 40mph stock? but gear ratio and compression gives you a starting point for some design stuff, and the RPMs give you some idea of operating tach/ power band.

Useful info instead of scouring the forum for bits and pieces here and there if all you really wanted to know the original gear ratio so you had a baseline for re gearing for a 20 inch rear wheel. And to calculate speeds based on the operating RPMs

The 26incher · Apr 4, 2011

That is not what I said man. Your post kicks @$$...

sketchman · Apr 5, 2011

I don't know how to tell what model I have. I bought a generic kit on eBay. The box has different letters on the side and the "H" box has a check in it. Would this be an H80?

Whatever the case, the specs are wrong. Even compression ratio was wrong on mine. Mine said 6:1 too. VERY off. I just checked both displacement and comp myself.

Displacement = 67.54cc
Bore x Stroke = 46.8mm x 39.28mm
Compression Ratio = 10.5:1(average, given the inconsistencies of these things)

MotorBicycleRacing · Apr 5, 2011

Most of the specs are incorrect.
16:1 for break period (first 300 miles) is A REALLY BAD IDEA!

X80? Its 66 cc
The HP figures are a bad Chinese joke along
with the speed and gas mileage for a stock bike.

Why pass along inaccurate info?
Some of us have been trying to correct the misinformation and this post
ain't making it any easier.

ferball said:
Factory specs for my "X80" two stroke motor. Maybe we can add other models, and make a sticky. Or maybe it has been done and I missed it.

Model : X80
Mode of Engine : Single cylinder, air-cooling, 2-stroke
Power * Rotary Speed
Rated Power : 1.5Kw / 5000r / min (2.5HP/5000r/min)
Max. Power : 2Kw / 6000r / min (5-6HP/6000r/min)

Ignition Mode : CDI
Compression Ratio : 6 : 01
Driving Ratio : 18 : 01
Fuel type : No. 90
Lubrication Oil : Motorcycle Synthetic 2 Stroke Oil
Mixing Ration for Fuel and Oil : 16:1 for break period (first 300 miles)
25:1 after
Spark Plug : Z4C 14MM
Fuel Consumption : 120-170 MPG
Clutch Type : Friction Plate / Dry
Speed Limitation : 25-40MPH

ferball · Apr 5, 2011

I understand it is inaccurate, but it is a place to start. I think everyone on this forum knows it is inaccurate. If there was some consistency in these motors someone could post more realistic specs, but I dare say there are no two "x80" out there with the same specs.

sketchman · Apr 5, 2011

6:1 and 10.5:1 are dangerously different ratios. It seems more dangerous to post that the engine has a 6:1 ratio when some obviously have much higher, than to just say, "Measure it yourself, because this is Chinese mass production engineering and it's a crap shoot."

ferball · Apr 5, 2011

I am starting to think this post was a bad idea...I did not realize how serious this information is taken. I know the information is inaccurate, but the information does not exist anywhere else. I suppose if I had a fully equipped shop and more money and time I could spec out my engine and post it here, but I can't. If we could spec out a sample of the "x80" engines say like ten+ of them we could get some realistic numbers, but I can't see any one doing that, so I am left with the factory specs. I would welcome any and all forum users that has the capability to post stock specs.

The 10.5:1 versus the 6:1 is a good start, if we can get 15 other people to post stock compression we may have a large enough sample to give a realistic compression ratio.

MotorBicycleRacing · Apr 5, 2011

sketchman said:
the specs are wrong. Even compression ratio was wrong on mine. Mine said 6:1 too. VERY off. I just checked both displacement and comp myself.

Displacement = 67.54cc
Bore x Stroke = 46.8mm x 39.28mm
Compression Ratio = 10.5:1(average, given the inconsistencies of these things)

No way is the compression ration 10.5 to 1 in a stock Chinese 2 stroke motor.

6:1 to 1 is about right and is one of the few stats that are correct from the factories.

The cc's are a bit more than 66 cc

ferball said:
I never said they were right, 40mph stock? but gear ratio and compression gives you a starting point for some design stuff, and the RPMs give you some idea of operating tach/ power band.

Useful info instead of scouring the forum for bits and pieces here and there if all you really wanted to know the original gear ratio so you had a baseline for re gearing for a 20 inch rear wheel. And to calculate speeds based on the operating RPMs

The Chinese 2 stroke motors have an internal gear ratio of 4.1 to 1 based on 20 to 82 teeth in the small bevel gear to the dry plate clutch.
Some kits come 40 , 44 and maybe 48 tooth rear sprockets and they all have 10 teeth
on the motor.
They redline stock at about 7300 RPM unless you got a dog motor.

Fulltimer · Apr 6, 2011

I see his point. Sometimes people just like to jump on someone though. Thanks for posting the information.

Terry

bairdco · Apr 6, 2011

stole these from the Grubee site:

sketchman · Apr 6, 2011

BiMoPed said:
No way is the compression ration 10.5 to 1 in a stock Chinese 2 stroke motor.

6:1 to 1 is about right and is one of the few stats that are correct from the factories.

The cc's are a bit more than 66 cc

You obviously think you know exactly what you're talking about. Please don't take this as a challenge. I don't know what you know or your experience with these things. So. The benefit of the doubt to you, sir, because I'm a newb here.

Now, assuming I'm wrong, could you please tell me the proper way to calculate compression ratio from my having clayed the CC in the head, and measured the bore and stroke with a mic?

Bikeguy Joe · Apr 6, 2011

In my experience, the cc's are about 65-67. That averages to "about 66cc's".

Unless you have a "50" then they range between 45 and 48.5cc's.

DaveC · Apr 6, 2011

sketchman said:
You obviously think you know exactly what you're talking about. Please don't take this as a challenge. I don't know what you know or your experience with these things. So. The benefit of the doubt to you, sir, because I'm a newb here.

Now, assuming I'm wrong, could you please tell me the proper way to calculate compression ratio from my having clayed the CC in the head, and measured the bore and stroke with a mic?

The bore and stroke calculations have all been done, it's the easiest part of the calculations. To have the rest of the equasion you need the cubic centimeters of the combustion chamber with a sparkplug installed and adding in the volume of the headgasket. A square of plexiglass with a small hole is placed on the greased gasket surface and then I used a large syringe to accurately measure how much fluid is needed to fill the chamber up. Stock head CC volume is just over 8cc's giving a compression ratio of about 8:1. Same head on a 49 equals just over 6:1, just like they say. I have a Puch HiCompression head with just over 5cc(I haven't checked that) so for 66cc it says 13:1 !! Same head on a 49 is almost 10:1. These numbers assume a flat top piston and these pistons [at least mine is] have a slight dome to them, very slight but it does add to the compression.

If my compression is really that high I really do need to use Trick Raceing gas

ferball · Apr 6, 2011

Nougat said:
Grossly inaccurate information purporting to be authoritative is worse than no information at all.

I never claim to be authoritative, I don't want the responsibility that comes with it. And if anyone construed my post as two stroke engine gospel, I am flattered, but you may have bigger issues than the actual displacement of your engine.

Bairdco thanks for the Grubee Specs.

The Grubee Specs are not that far off the specs I posted. Aside from the max power claim of 5 hp at 6000rpm and the 40 mph the "X80" seems is fairly close. So despite people jumping on me for posting the specs, that we have all agreed are inaccurate, the factory specs do seem offer a starting point for rough calculations.

I would still like to have a bunch of guys spec their stock engines and post the results. Then we could figure out the average engine, but just from the argument over compression seems like it will turn into a flame war. So I am gonna stick with the factory info for now, I realize the limitation of this information, and I think everyone on this forum realizes its limitation. It is what it is.

sketchman · Apr 6, 2011

DaveC said:
A square of plexiglass with a small hole is placed on the greased gasket surface and then I used a large syringe to accurately measure how much fluid is needed to fill the chamber up. Stock head CC volume is just over 8cc's giving a compression ratio of about 8:1.

If you clay the CC with the piston at TDC you can then use that clay to more accurately measure the volume including what the piston takes away. Mine is a slant(referring to spark plug orientation) head so maybe it doesn't hold as much as the straight ones. My compression seems to be far from 6:1 or 8:1, and 10.5:1 is what I'll keep in mind when I start tuning it.

I don't mean to flame, and like someone else said, collecting info is great. I personally would not begin to think I have the leeway that 6:1 compression would give me if I were to tune one of these without taking my own measurements.

MotorBicycleRacing · Apr 6, 2011

sketchman said:
If you clay the CC with the piston at TDC you can then use that clay to more accurately measure the volume including what the piston takes away. Mine is a slant(referring to spark plug orientation) head so maybe it doesn't hold as much as the straight ones. My compression seems to be far from 6:1 or 8:1, and 10.5:1 is what I'll keep in mind when I start tuning it.

I don't mean to flame, and like someone else said, collecting info is great. I personally would not begin to think I have the leeway that 6:1 compression would give me if I were to tune one of these without taking my own measurements.

Creative Engineering made a higher compression head with an improved squish band.
Try searching his posts to find what the compression ratio was.
I would send him a PM but he is banned right now and I don't want to bother him at work.

I am pretty sure it was in the 9 to 1 range.

Anyway as brands of engines have different combustion shapes and sizes any data would be brand specific.

linnix13 · Apr 6, 2011

BiMoPed said:
Most of the specs are incorrect.
16:1 for break period (first 300 miles) is A REALLY BAD IDEA!

why? i always put a few hundred kms on my engines when i first get them and i run 16:1, then i bump it to 20:1 for the engines life, i have had many engines and never had a problem, whats the risk of running 16:1??

MotorBicycleRacing · Apr 6, 2011

linnix13 said:
why? i always put a few hundred kms on my engines when i first get them and i run 16:1, then i bump it to 20:1 for the engines life, i have had many engines and never had a problem, whats the risk of running 16:1??

Risk? You just gonna have a slow, oily smokey motor that drips oil on your shoes.
Probably gonna plug your catalytic converter up too as well as depositing
lots of carbon on your piston and combustion chamber.

Also, your engine will not last as long or perform as well.

Having ridden a few 100 to 1 Opti 2 bikes of Bairds it will be what I use when
I build a few 2 stroke motors I have lying around.

You do know that the only reason the Chinese manuals of the engine kit
manufacturers recommend 16 to 1 is because they were using 30 weight
engine oil which was probably used oil to boot?

Good 2 stroke oil was kinda hard to come by in China when they were selling
these kits there. I understand that these smokey little motors are banned in
the large cities of China if not everywhere.

Anyway I would hate to disturb any of your fairytale belief systems so don't
pay any attention to what I just said. LOL Its your smokey, stinky slow motor
not mine.....

linnix13 · Apr 6, 2011

BiMoPed said:
Risk? You just gonna have a slow, oily smokey motor that drips oil on your shoes.
Probably gonna plug your catalytic converter up too as well as depositing
lots of carbon on your piston and combustion chamber.
Your engine will not last as long or perform as well also.

Having ridden a few 100 to 1 Opti 2 bikes of Bairds it will be what I use when
I build a few 2 stroke motors I have lying around.

You do know that the only reason the Chinese manuals of the engine kit
manufacturers recommend 16 to 1 is because they were using 30 weight
engine oil which was probably used oil to boot?

Good 2 stroke oil was kinda hard to come by in China when they were selling
these kits there. I understand that these smokey little motors are banned in the large cities of China if not everywhere.

Anyway I would hate to disturb any of your fairytale belief systems so don't
pay any attention to what I just said. LOL Its your smokey, stinky slow motor
not mine.....

my current build has less than 100kms on it and im running 16:1, it will go from 0-60 in 30 seconds(kph) i have pictures and videos of my first bike which i ran 16:1 for a full 500kms(i have an odometer) and then 20:1 for the next 3500kms, i love the smell of a 2 stroke and a little smoke never hurts anything, there is no harm in running them rich, expecialy for the break in. but you seem to know what your doing though dont you?

almost forgot, catalytic converter? who uses those, i dont even have a cat on my 1984 skylark, and i sure as **** wont have one on my already underpowered bike. every bike i build has the cat hollowed out.

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