Real 80's?????
- Thread starter Bikeguy Joe
- Start date
Except the only displacement measurement to include the combustion chamber as part of the bore and stroke is the chinese bicycle industry.
Nowhere else do they measure the combustion chamber as part of the displacement, so we are still searching for a real 80.
Nowhere else do they measure the combustion chamber as part of the displacement, so we are still searching for a real 80.
I've checked 5: they have all been 47mm X40mm or 69.397CC. I'd call it a 70CC.
Standard truth-in-advertising practice allows for +/-5%
As Joe pointed out, the volume of the cylinder head has nothing to do with displacement.
This would come into play if we were discussing compression ratios.
Jim
Standard truth-in-advertising practice allows for +/-5%
As Joe pointed out, the volume of the cylinder head has nothing to do with displacement.
This would come into play if we were discussing compression ratios.
Jim
EXACTLY.......I couldn`t agree more....They are 70cc motors, Imo....
my motorcycle says 1052cc but they sell it as an 1100cc motorcycle.....
I am re-opening this thread.
Down South, we need the name of the seller you got your engine from.
You have a prototype or one off engine. Your calulations (without the head volume included) equal 82cc's.
You apperently have the only one on the planet, and we need to know where it came from.
Down South, we need the name of the seller you got your engine from.
You have a prototype or one off engine. Your calulations (without the head volume included) equal 82cc's.
You apperently have the only one on the planet, and we need to know where it came from.
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If you got those measurements, then yes it's an 80cc+. Tell us how you measured the stroke?
The stroke measurement has to be done while holding the cylinder down and a finger or two pressing the piston down also(for BDC). I'll try and upload some images with the dial caliper sometime today. I have to pull the engine off the frame to get some good pictures.
This might clear up the issue about the Chris Hill, CH-80. He does not say his engines are 80s and this explains it.
My bicycle engines measure in with a 47mm bore and a 40mm stroke…this works out to be 69.397cc…technically making these bicycle engines a 70cc engine in my opinion. The manufacturer and market still refers to them as an 80cc Bicycle Engine Kit, and I am going with the market on these. It's a lot easier for all you people to find out the truth about the wonderful little Chinese bicycle engine kits if you are able to find information like what I have written here. By this, I mean when people hear of an 80cc engine and do a search on it (google, msn, yahoo) they'll find those that are advertised as 80's. If I don't write the 80cc bicycle engine on my site the search engines won't bring it up to you. At least my engines are not a surprise size between 48-69cc like those that a lot of other people are selling and trying to say that they are 80's. And hopefully what I've written will save a lot of people from getting ripped off like I did when I first got involved with these engines.
From Chris Hill's website
Tom
My bicycle engines measure in with a 47mm bore and a 40mm stroke…this works out to be 69.397cc…technically making these bicycle engines a 70cc engine in my opinion. The manufacturer and market still refers to them as an 80cc Bicycle Engine Kit, and I am going with the market on these. It's a lot easier for all you people to find out the truth about the wonderful little Chinese bicycle engine kits if you are able to find information like what I have written here. By this, I mean when people hear of an 80cc engine and do a search on it (google, msn, yahoo) they'll find those that are advertised as 80's. If I don't write the 80cc bicycle engine on my site the search engines won't bring it up to you. At least my engines are not a surprise size between 48-69cc like those that a lot of other people are selling and trying to say that they are 80's. And hopefully what I've written will save a lot of people from getting ripped off like I did when I first got involved with these engines.
From Chris Hill's website
Tom
DS-
Thank you so much. It is much appreciated.
Well folks, there's one out there, now the mystery deepens.
What say you to this?
Thank you so much. It is much appreciated.
Well folks, there's one out there, now the mystery deepens.
What say you to this?
I guess a couple things come to mind.
Both measurements with a caliper have their limitations. The bore ID measurement may or may not be in error because the inside contact surfaces of the caliper blades are flats, so when measuring, four points of contact are made on the bore ID.
The height from piston top to cylinder "deck" height may not represent true displacement. It needs to be TDC to BDC of the piston.
Kinda tough to measure with a caliper.
Both measurements with a caliper have their limitations. The bore ID measurement may or may not be in error because the inside contact surfaces of the caliper blades are flats, so when measuring, four points of contact are made on the bore ID.
The height from piston top to cylinder "deck" height may not represent true displacement. It needs to be TDC to BDC of the piston.
Kinda tough to measure with a caliper.
It`s going to be close enough to know it IS or ISN`T an 80cc motor, right....It may not give you the measurement to say weather it`s a 69.xxx or a 71.xxx.....JMO...
I guess that depends a lot on where the top of the stroke occurs.
On that note, I have measured all mine the same way- with the piston at the bottom of the stroke, and with the caliper set the was DS has it, on the top of the jug. All mine came in at 67-9cc plus or minus, except the "55's" which came in at 43cc's and 47cc's.
On that note, I have measured all mine the same way- with the piston at the bottom of the stroke, and with the caliper set the was DS has it, on the top of the jug. All mine came in at 67-9cc plus or minus, except the "55's" which came in at 43cc's and 47cc's.
I'm not really challenging that this engine ISN'T an 80cc, I'm just saying there are errors measuring that way.
I've done it this way and got 55cc-75cc depending on how I hold my head.
I've done it this way and got 55cc-75cc depending on how I hold my head.
AAAH, no problems...I just did mine and got 2 to 3 different measurements too...If we weren`t going so many numbers back, like maybe just go to the hundrenths, we might not have so many diff. measurements, huh,LOL...
