I'm rebuilding my first moped and I have a Sachs motor. 505/1. I searched the wiki first and found a few helpful articles like the Sachs Motor Differences.
http://www.mopedarmy.com/wiki/Sachs_Motor_Differences
However, I didn't find anything if the motor didn't designate A, B, C, or D. See pictures. Any ideas?
Tapered head. A or B. On the jug fins there is a km designation on the right hand side. A should be 40 kph, B should be 35kph.
Pretty sure it's an A.
If you pick up a D cylinder and mount it on your A you have a C. Confused yet?
Mine is the same too.
You know it's a D when .. you get up 2 Warp factor 8.3 page speed , or 43 mph real life speed .
A,B,C = rectangle intake and tapered head.
D = neither.
rectangle
Oh Don, we know it's a D when it's a hand full, right?
Bingo ^ ! ~
Found the 40 km. Looks like I have A.
Thanks
c/d are different, even though fins are externally the same the C has a short stroke so the cylinder is shorter
@ Graham .. I beg 2 differ good sir , the rist pin on said piston has been moved , thus allowing 4 a longer stroke ...
hmmm yeah i think you are right about that. there was something different between the cylinders... flat port vs slant port? porting? i don't have either anymore...
I can't find a stamp on mine.
47cc = shorter crank - not a D
tapered head = not a C
14mm intake = not a B
40km on the jug confirms - it's an A. unsurprisingly, theyre by FAR the most common. enjoy the sachsing.
This is all in the motor differences page but there's no moving the wrist pin. the pin height is different on A/B vs D/C pistons. But as long as the piston and jug are matched it works. you can put an A/B piston and cylinder on a D crank, and you can put a D piston and cylinder on an A crank (making it a "C"). you just can't put an A piston in a D or it'll hit the head. it's not about the stroke difference, it's just that the piston and cyl must be a matched pair.
The other holdup is the cylinder studs are a little differently placed. you can easily Dremel out the slots for the studholes to swap cylinders though, the kits and gaskets are already wider slots to accommodate either stud placement. just match the holes to the base gasket, see below
The only clear factor for D motors is the jug looks square and the crank rod hole is closer to the edge of the wall of the crank
yeah, and if the engine plate is present, it's not always filled out with the letter designation but it IS always filled out with the cc, either 47cc or 49cc. The D is the only one that's 49, so that's a pretty reliable check.
The C&D share the same piston , rod ,cylinder and carb. Putting a C or D cylinder on an A or B doesn’t make it a D. The carb on C and D has no needle jet. I have the rare 1C it runs about 25-28 on flat ground.
technically they're all the same rod, D just places it 1mm farther out the lobes on the case end for +2mm
Man I've been fucking with these for years and I'm still confused. I have an A piston in my weird euro flange port that's supposed to be d specs and it's like 3 mm from the top of the bore, it's too short!
It's such a mind fuck because of the head being attached. I wish I had money to buy one of each of these and actually measure all the dims.
Ohhh f me, yeah, I got an a crank with an a piston in a d cylinder. Still it's way too short. I thought the a piston would make up for the d cylinder being on the a crank but I guess not, wtf do I know. Someday I'll put a d crank in it like a fancy boy.
Still, it runs pretty good, does a honest 35 and tractors along like a good sachsyboi, feel like the proper compression would really wake it up though.
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