Re: Sachs 505 c/d Debate

haha yeah

i've got a balboa D myself, just like the one in the above pics, fantastic bike, i'm planning on keeping it stock or going to 70cc piston port at the most.

what 65cc kit is there available for sachs?

Re: Sachs 505 c/d Debate

Jafar, since we're all on the topic Ive been thinking about doing a reverse. I want to put the D cylinder and piston onto a 504 bottom end. Will the difference in rod length require a timing adjustment or will it not work at all?

Re: Sachs 505 c/d Debate

Well there's the Athena 70cc which is actually a 65cc and then there's the Autisa 64.5cc that I've got. Be wary of going after rare kits like the Autisa, should something happen like the rings get worn out finding a replacement will be a real job, I'm still looking.

Re: Sachs 505 c/d Debate

good point roberto, how does the 504 factor into all of this? do they use the same scheme with those, or were they 'A' rod and crank, or 'D' rod and cranks?

is the austia kit still in production? if it is, i bet my guy in deutschland could find those rings.

Re: Sachs 505 c/d Debate

Well from my experience there's not much difference between the 504's and the 505's except for the pedals no being inside the case.

You could file the head deck in the manner I suggested to Graham (0.25mm increments but no more than 1.5mm), you'd also need to retard your timing by several degrees (or millimetres on the stator plate). As long as you change both the cylinder and the piston you should be fine, however, the shorter crank may mean that the piston skirt could hit the crank bottom end at high rpms and that would really eff things up. Before you do any work at all check the piston skirt clearance and make sure you have at least 4mm clearance between the crank and the bottom of the skirt by cranking the flywheel.

Re: Sachs 505 c/d Debate

I haven't seen any sign of Autisa since the early 2000's, and have only seen one kit on the net, mine, since I bought it. You've got a guy in Germany??!?! Ask him, ask him!

Re: Sachs 505 c/d Debate

yeah, i'll shoot my buddy an email, he's going into the 'local' moped shop (yes, the town he lives in has a moped shop, that he can like, ride his moped to, how rad is that?!) this week for me to check on some prices and find out if they can get some parts. i'll add 'austia rings for sachs 65 cc kit' to the list. What size are the rings, you should measure it and try to find a cross refrence, i'm sure something else out there uses the same rings.

So does the 504 use the short 'A' stroke or the long 'D' stroke? If i were going to mod a cylinder/kit to fit on a mismatched engine, i certainly wouldnt do it with a file. that would definitely be a 'lathe' job. I would probably put some modelling clay/silly putty in the D cylinder spark plug hole, put the cylinder on, crank it around, pull out the clay and measure the thickness at the thinnest part. Add, say, half a mm, and have a machinist remove it from the bottom of the jug. If you dont know a machinist, send it up here and i'll make quick work of it. CHEAP!

Re: Sachs 505 c/d Debate

yikes, I thought this would prompt some debate, and it has, but nobody seem to know what I have.

I appear to have a 505/1C

as the lable says.

Although to me it seemes to be a 505/d

Im Just saying.

And here's what else im saying:

There are 50 puch head that would be able to itemize and catogize what im asking while all us sachs head ( no pun (

debate the question..........

Why IS sachs info so hard to find?

Re: Sachs 505 c/d Debate

yikes. Ive got a motor stamped 504/1c

and i think its got a d head.

Who wants to arugue LOL

Re: Sachs 505 c/d Debate

i've got the same exact bike in the shop right now, in pieces. I'll go over there tomorrow night if i have time, see if it says 'c' on it, and make some measurements. but i'm pretty sure its all D.

Re: Sachs 505 c/d Debate

I think Brendan already commented on your C stamping no?

_how many times can I say that the square heads are all exactly same.


Re: Sachs 505 c/d Debate

Brendan's statement is not entirely true, as I mentioned the ports are farther inside of the cylinder on the A-C cylinders than the D cylinder as well as the intake and exhaust port sizes being different. If look only at engine spec or data sheets those glaring differences in the bottom end will probably stick out, I would look at the timing of the transfer, intake, and exhaust port.

Well no I guess a file is a bit inaccurate but I don't have nor know how to use a lathe, all of the work I do is done by myself with the exception of two port jobs I sent to Smitty last year. Since then I do all my own work having read a number of books, no boat anchors so far :D !

I've looked over and over again for 64.5cc rings ffor the Autisa kit but I'm not sure what material they are made of, nor did I check the type of ring they use weigher "GI" or "FG" type. If you can find other brands of speed kit through your friend I'd be glad to ditch this Autisa, it's a strong kit but nothing special. It's got enlarged ports, and 5 ports instead of the standard 4 (intake and piston) but I'm hoping for something a little grander.

Re: Sachs 505 c/d Debate

Could the "C" be a "D" but with the 10mm carb like the "B"?

Re: Sachs 505 c/d Debate

In general, the 505D engines come with the square head and all others come with the tapered head. Carb numbers have little to do with the engine itself since carbs can be and are readily exchange at the whim of the owner.

Were I to sell my Sachs in its current condition and insist to the buyer that it is completely stock (IF he was a layman) he would have an excruciating task of finding OEM parts should anything get mussed up. Many of my crucial system components are from different brands. The Sachs I recently rebuilt came with a 10mm square bing in mind, I've replaced it with the 12mm version but it is still classified as a "D" only now the top speed will increase.

Re: Sachs 505 c/d Debate

naw it has a 12mm carb.

Re: Sachs 505 c/d Debate

What has a 12mm carb? wiffleball's?

Re: Sachs 505 c/d Debate

Sorry the whatever it is motor on my bike, the one at the top of the thread.

Re: Sachs 505 c/d Debate

The 508 engine on some Westlakes came with square cylinders. It is exactly like a 504 except it accepts square heads. Almost all Balboa's came with square heads, but not all were D engines.

Re: Sachs 505 c/d Debate


What i was trying to do by asking this is two fold. I don't doubt that brendan is the knowlegeable dude and even if he's right or not.

Im trying to figure out what is on my bike , just for shits and grins.

Secondly, this points out a SERIOUS case of lack of empirical knowlege about what is , after all a very very common motor. Its a 505 for the love of god, they made a ton of em. But service manuals and actual data is very difficult to find if it can be found at all, and people do have different thoughts on the matter.

Odd isnt it that there is no manuals out there?

I have a 504 manual, and it lists every variation of the motor, all 5 of em and the technical data reflects what the differences are, from carb and jet sizes to exhaust ports.

It would be cool to have that written out for the 505.

Re: Sachs 505 c/d Debate

For the record, despite the arguments either way, i think brendan is right.

I think i have a 505/a with a square head. Its a 30mph bike, but its not a d motor. That what I think.

Re: Sachs 505 c/d Debate

to put the D crank in a 504 you have to press the crank apart, and change the shaft that mounts the smaller bosch/motoplat flywheel and magneto set up for the 504. It's a huge pain in the ass. The process is as follows, assuming you have access to a good quality press, like a piston pin press at a machine shop. This is something that you really don't want to do unless you have the parts, time and are willing to make a rare part a super-rare part and them hammer on it for a day or so untill it lines up again.

You will need the 505 D crankshaft, and a 504 crankshaft.

an engine case that you don't care much about

a heavy brass hammer

Piston pin press

1. Press the connecting rod pin out of the flywheel side of the D crankshaft. The connecting rod and it's bearing can be changed at this point if needed.

2 Mark where the keyway needs to be on the D crankshaft half. Use the 504 crank as your reference. Use a chisel or punch to make the mark.

3 Press the connecting rod pin out of the 504 crank on the flywheel side.

4 Press the flywheel shaft out of both crankshaft halves.

5 Swap the 504 shaft into the 505D crankshaft half, making sure the keyway is lined up with the timing mark.

6 Press the crankshaft pin back to full height on the clutch side of the 505 crankshaft

7 press both 505 crankshaft pieces together.

Alignment. Al the shafts press flush with the crankshaft There needs to be enough space between the two crankshaft halves to allow the connecting rod to spin around with no resistance.

To make suer the 2 halves are put together straight, re mount the bearings on both sides of the crankshaft. Spin the crankshaft and watch for the clutch and flywheel shafts' movement . If one wobbles up and down, you have to use the heavy brass hammer to align them. It's a process of one hard hit to one side of the crankshaft, and checking, over and over untill there is no more wobble or run out. That's why a brass hammer- the hammer will take the brunt of any deformation, but will still allow you to move the crank pieces around the connecting rod shaft.

After doing this, and letting the parts sit for about a year, I put the engine together. It gave me a huge increase in compression, and was a little quicker off the line. The bad thing is, I've been thru 3 pistons since then. one circlip getting loose, and opening up the piston skirt. One set of broken rings that gouged the piston and the cylinder, and the current piston that is OK but with the cylinder in such bad shape, I need an overbore piston.

No Kit

Chris Slamminson #116 /

Keep Sachs Stock.

Kitted Sachs Eat Clutch Pads.

Re: Sachs 505 c/d Debate

to sum up, the whole thing about sachs engines

Engine case

504- no pedals in the case

505- pedals in the case


A/B head tapered, small ports

C/D head square, large ports. D acutally has slightly larger side transfer ports than C


A and B engines come with 2 2mm rings and very long skirts with small transfer port windows. Most widly available replacement piston.


Upper ring is 1.5 mm bottom ring is 2mm. Not available for replacement. intake skirt is shorter than exhaust, and transfer port windows larger


Upper ring is 1.5 mm bottom is 2mm (not available) Intake and exhaust skirts

D designation on 505's mean the engine has a longer crank stroke length. The connecting rods are the same length.

The Crankshafts between D and the others are the same size.

the spacing between the shaft and te connecting rod shaft are bigger- I'd measure, but it's in m runner right now.

Jafar- make some port maps of what you have. It'll be a good reference!

Sachs 505 c/d Debate

Andrew- what you have is what you engine says it is. A 505 C 1

505- pedals in the engine case

C - square head, but not the longer stroke of the D

1 - single speed transmission.

What else do you need to know?

No Kit

unless you can make a stronger clutch.

Re: Sachs 505 c/d Debate

Argh but port mapping is so damned tedious! I suppose the tracing paper in the cylinde is the easiest way huh? It's what I usually do, any suggestions?

Re: Sachs 505 c/d Debate

woah, so the balboa's have the 'A-C' case with a square jug? So they have the short connecting rod after all? this shit is so crazy, what makes up for the difference, are the cylinders different heights?

If anybody wants to put a 'D' cylinder on a 'A' case, contact me, i'll machine the cylinder to the right deck height. I've got an 'A' engine. a 'D' engine (from a G-3) and a 'C' engine -if thats what is on my red balboa. I'll get into the shop tonight or tomorrow night and measure them all up.

crazy germans.

Re: Sachs 505 c/d Debate

connecting rod is the same length. Think about it. The stroke of a motor is determined by the distance from the center of the crankshaft. A longer connecting rod would give you the same displacement, but would put the piston further down the bore.

You won't need to machine anything. What would the piston hit? Even with the longest skirt, the piston will not his the crankshaft.

Balboas have a 505 case. The jug is the difference.

to put a D cylinder on a case that was set up for an A cylinder, you may need to open up one of the bolt holes that mounts the cylinder to the case. It will be obvious which one and how much when you match it up. Who are you offering your machining services to, and what do you think you would accomplish?

Re: Sachs 505 c/d Debate

I used graph paper, but because everything is usually metric, it won't help much(1/4 " grid) I think it would be most important to re-copy the ports cleanly, with some sort of scale on it, a mark where the top and bottom of the jug is, the make model year of the moped that it came from, and what piston was in there.

Re: Sachs 505 c/d Debate

Andrew- what you have is what you engine says it is. A 505 C 1

505- pedals in the engine case

C – square head, but not the longer stroke of the D

1 – single speed transmission.

What else do you need to know?

You sir, are absolutely correct.

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