emdude
Member
Hi All:
Well, it said in the rules that I have to post here first, so here it is:
Having grown up in Europe where as a young person all you could ride was 50 cc mopeds the idea of a motorized bicycle brings back memories and and some sense of nostalgia. With the price of gasoline being what it was lately (better now) and the fact that I live in a small town in Arizona now, the thought of getting some type of moped or small scooter was on my mind for while. Then I saw this guy a few weeks ago riding a motorized bike and thought "man that could be cool". After investigating this a bit and finding the craze has taken off I realized: "Man this IS cool".
I love the fact that it's a DIY thing with endless possibilities and am real happy about the fact that for the most part government bureaucracy has deciced to stay out of it.
I have not yet built a bike. I did buy an engine, the usual Chinese one though and it's already half apart on my work bench. I was so intrigued by the pure simplicity of the thing I just had to investigate it. I was particularly interested in the ignition system, spark generation and any possible spark advance they may have engineered into it.
The mopeds I was familiar with during my very young years did not have any form of ignition advance. Ignition timing was a static adjustment dictated by the setting of a plate in magneto assembly and the opening of the points. The engines always had the same amount of pre-ignition and the best you could do is find the best amount of advance for your engine and riding conditions.
The Chinese engine I have, probably pretty much the same as everyone else's
does have a pretty spiffy no point's ignition system. It also has several degrees of static advance. Ignition timing is set by the exact position of the magnet rotor relative to the magneto coil. If you look at the position of the magnet relative to the coil with the piston TDC you'll see what I mean. I wonder if the magnet is "key'd" onto the crankshaft or if there is any possible adjustment should one want to make any. Anybody know?
If it is keyed, the only way to adjust the timing would be by changing the relative position of the magneto coil. I suppose this could be done. And maybe some on this list have figured all this out already. Guess I'll find out after searching a bit.
After looking at my new engine a bit yesterday I have a few observations. First of all mine was definitely test run. Which is a good thing I suppose. I pulled the head because I just had to know what it looked like inside and it was full of residual oil from what was clearly a test run. Of course one of the cylinder studs decided to come out instead of just the nut coming off. I decided to pull the entire cylinder. After that I noticed another stud loose side so I tightened all 4 real good into the case. They must put these things together in a real hurry.
The fastener quality one my engine is not too good. Every nut and washer are pretty much bottom of the barrel and I would think some better items from the local hardware store could be a worthy upgrade. The studs were particularly bad but I'm not sure how exactly to get something better in there.
At this point I wont worry about it and just install the engine and see what happens.
Further observations:
I am impressed with the cleverness of the overall design but really wonder just how long these engines might go. The fit of the cylinder onto the crankcase and the head on the cylinder is quite sloppy. Since the piston is just slightly out of the top of the cylinder at TDC, the whole assembly has to be carefully adjusted with regards to the aluminum head gasket and head while tightening everything down, other wise the piston will actually hit either the gasket or maybe even the head. I doubt this is something only peculiar to my engine and strongly advise any one having taken the head off for any reason to ensure the engine turns over smoothly before running it. I could also see where this might lead to engine failure if the head bolts ever came loose enough to allow the cylinder or head to slip even just a little bit. Keep the head bolts tightened and check often I guess.
The ports in the cylinder are pretty good size. I did find though that the cylinder to crank case gasket blocks a LOT of the transfer ports. It isn't cut that well to mach. I could even see where the edges of the gasket were slightly bent and frayed from the test run. I could see where after some running time these might wear off to the metal edge opening up the transfer ports. This could account for some of the reported power increase after engine break in.
The piston looked OK to me but the rings were different from what I've ever seen before. The rings are not shiny as in "chromed". They are black, quite stiff and I can only imagine some type of high carbon steel. Hey, whatever works I guess.
Well, I have yet to find a bike to install the engine in. I keep looking at the local thrift stores and garage sales but so far no luck. Maybe everybody else around here had the same idea and used bikes will now become rare and rise in price like gasoline.
I've got my eye on that $90 Huffy cruiser they have at Walmrt if all else fails. I think I read on the forum that someone actually used this model so it must work OK.
BTW, I like that low volt winding off the magneto on the white wire, makes for some interesting possibilities regarding lighting and even a tachometer I guess.
That's it for now.
Regards
emdude
Well, it said in the rules that I have to post here first, so here it is:
Having grown up in Europe where as a young person all you could ride was 50 cc mopeds the idea of a motorized bicycle brings back memories and and some sense of nostalgia. With the price of gasoline being what it was lately (better now) and the fact that I live in a small town in Arizona now, the thought of getting some type of moped or small scooter was on my mind for while. Then I saw this guy a few weeks ago riding a motorized bike and thought "man that could be cool". After investigating this a bit and finding the craze has taken off I realized: "Man this IS cool".
I love the fact that it's a DIY thing with endless possibilities and am real happy about the fact that for the most part government bureaucracy has deciced to stay out of it.
I have not yet built a bike. I did buy an engine, the usual Chinese one though and it's already half apart on my work bench. I was so intrigued by the pure simplicity of the thing I just had to investigate it. I was particularly interested in the ignition system, spark generation and any possible spark advance they may have engineered into it.
The mopeds I was familiar with during my very young years did not have any form of ignition advance. Ignition timing was a static adjustment dictated by the setting of a plate in magneto assembly and the opening of the points. The engines always had the same amount of pre-ignition and the best you could do is find the best amount of advance for your engine and riding conditions.
The Chinese engine I have, probably pretty much the same as everyone else's
does have a pretty spiffy no point's ignition system. It also has several degrees of static advance. Ignition timing is set by the exact position of the magnet rotor relative to the magneto coil. If you look at the position of the magnet relative to the coil with the piston TDC you'll see what I mean. I wonder if the magnet is "key'd" onto the crankshaft or if there is any possible adjustment should one want to make any. Anybody know?
If it is keyed, the only way to adjust the timing would be by changing the relative position of the magneto coil. I suppose this could be done. And maybe some on this list have figured all this out already. Guess I'll find out after searching a bit.
After looking at my new engine a bit yesterday I have a few observations. First of all mine was definitely test run. Which is a good thing I suppose. I pulled the head because I just had to know what it looked like inside and it was full of residual oil from what was clearly a test run. Of course one of the cylinder studs decided to come out instead of just the nut coming off. I decided to pull the entire cylinder. After that I noticed another stud loose side so I tightened all 4 real good into the case. They must put these things together in a real hurry.
The fastener quality one my engine is not too good. Every nut and washer are pretty much bottom of the barrel and I would think some better items from the local hardware store could be a worthy upgrade. The studs were particularly bad but I'm not sure how exactly to get something better in there.
At this point I wont worry about it and just install the engine and see what happens.
Further observations:
I am impressed with the cleverness of the overall design but really wonder just how long these engines might go. The fit of the cylinder onto the crankcase and the head on the cylinder is quite sloppy. Since the piston is just slightly out of the top of the cylinder at TDC, the whole assembly has to be carefully adjusted with regards to the aluminum head gasket and head while tightening everything down, other wise the piston will actually hit either the gasket or maybe even the head. I doubt this is something only peculiar to my engine and strongly advise any one having taken the head off for any reason to ensure the engine turns over smoothly before running it. I could also see where this might lead to engine failure if the head bolts ever came loose enough to allow the cylinder or head to slip even just a little bit. Keep the head bolts tightened and check often I guess.
The ports in the cylinder are pretty good size. I did find though that the cylinder to crank case gasket blocks a LOT of the transfer ports. It isn't cut that well to mach. I could even see where the edges of the gasket were slightly bent and frayed from the test run. I could see where after some running time these might wear off to the metal edge opening up the transfer ports. This could account for some of the reported power increase after engine break in.
The piston looked OK to me but the rings were different from what I've ever seen before. The rings are not shiny as in "chromed". They are black, quite stiff and I can only imagine some type of high carbon steel. Hey, whatever works I guess.
Well, I have yet to find a bike to install the engine in. I keep looking at the local thrift stores and garage sales but so far no luck. Maybe everybody else around here had the same idea and used bikes will now become rare and rise in price like gasoline.
I've got my eye on that $90 Huffy cruiser they have at Walmrt if all else fails. I think I read on the forum that someone actually used this model so it must work OK.
BTW, I like that low volt winding off the magneto on the white wire, makes for some interesting possibilities regarding lighting and even a tachometer I guess.
That's it for now.
Regards
emdude
