Sachs 504 Misinformations - cranktalk

This one comes up too often and drives me nuts so I took some measurements to settle it. The problem comes up when people talk about making a 504 "D" or putting the aftermarket cranks in a 504.

1) 505 and 504 have different cranks. They are identical except for the stator side, but the ignition and flywheel are not at all interchangeable.

2)There is no 504 44mm "D" length crank. Nor can you stick a D crank from a 505 (or the aftermarket 44mm cranks) in a 504 and have everything work hunky-dory. rumors have it that 44mm 504 D's do exist, but if so, theyre very rare.

3) The tapers are VERY different. The 504 has the 80mm flywheel (103mm OD) and 505 has the standard puch size 90mm (116mm OD). Tapers shown in img below. The 504 case does not fit a larger flywheel.

4) The stators are also very different. different bolt spacing etc. you cannot put a 505 or puch etc onto a 504.

What's that mean? If you got the 44mm 505 D crank, you could get bearings and seals and it plops into the 504, works perfectly with the topend and the clutch side. But the taper is different so the 504 flywheel won't fit. The taper fits the puch flywheels but they do not fit in the 504 cases. You could use a smaller flywheel for puch like HPI or something same taper like later tomos that's got a flywheel OD < 107mm, but YOUR STATOR WONT BOLT UP. so you can also trim and re-drill the stator but this requires a lot of grinding because there's a raised lip around the stator mounts to the 504 cases. You could also cut the 504 case to fit a bigger flywheel but that's probably shitty in the rain and also still has the stator not mounting problem.

My point is I wanted to clear up the misconception NO YOU CANNOT USE THE 505 OR AFTERMARKET SACHS CRANKS IN A 504. and also NO YOU CANNOT MAKE IT WORK JUST BY SWAPPING A SMALLER FLYWHEEL

Sachs flywheel diagram.jpg
Sachs flywheels.gif

Re: Sachs 504 Misinformations - cranktalk

Awesome great info Will. Adding it to the Wiki?

And so when a 504 has a square shaped top end what does that make it? Like a C or something?

Re: Sachs 504 Misinformations - cranktalk

Minarelli bosch stator is the same as 504 motors. You could always have the 504 flywheel taper re cut for 505.

Re: Sachs 504 Misinformations - cranktalk

Chöschi21 C.K. /

Been there, done that for a 504/2 Manual.

Re: Sachs 504 Misinformations - cranktalk

Used a Derbi flywheel with a 505 crank in a 504 case. Lapped the crank + flywheel and ditched the key. Seems legit.

Re: Sachs 504 Misinformations - cranktalk

> Frankie Teardrop Wrote:

> -------------------------------------------------------

> Used a Derbi flywheel with a 505 crank in a 504 case. Lapped the crank +

> flywheel and ditched the key. Seems legit.

now thats a great idea!

i think some early A3's have the big taper with hte small CEV flywheel, it might be close? I had some of those flywheels but i can't tell you what engines/years they came off of. They were like a minarelli flywheel but they had the tomos crank taper in the bore.

Re: Sachs 504 Misinformations - cranktalk

Does the derbi stator bolt on tho? I thought they were all 90mm?

if there's a thing that works fill in some details! because I've only encountered speculation on what will work, and then nothing actually works

the 80mm stator size on the 504's not that uncommon (CEV size?). Minarelli, garelli are that small. but the taper doesn't match. I suppose you could do the v1 HPI stator with puch HPI bell

and for sure any minarelli sized flywheel could possibly work on the 504 stator with the 505 crank taper.

I'm very interested in what would work, even though I'm not trying to do it myself, just so people know. I also just wanted to dispel the "oh you just slap it in and put a puch HPI on it" myth

Re: Sachs 504 Misinformations - cranktalk

could you put a puch HPI flywheel with a backing plate from a V1 or something on it?

Re: Sachs 504 Misinformations - cranktalk

Derbi stator wont bolt on. I dont see how the flywheel could work with the coils so far away.

Re: Sachs 504 Misinformations - cranktalk

I used a 504 stator on my Kreidler. The one you now own Will. The flywheel is different though.

Re: Sachs 504 Misinformations - cranktalk

I gave the Sparta away with the Derbi flywheel on it. Next time I go to his house I’ll do some investigating and report back. I believe he put a 70 Airsal on that bad boi and has not had any issues.

Re: Sachs 504 Misinformations - cranktalk

Oooo Blake coming in with the fire advice. I wonder if the kreidler flywheel goes on a 505 crank? Also I'm not sure the v1 hpi stator w a puch flywheel has the right taper depth for a sachs. It is possible that it could just mount magically, but who knows?(edited)

Re: Sachs 504 Misinformations - cranktalk

> Graham Motzing Wrote:

> -------------------------------------------------------

> could you put a puch HPI flywheel with a backing plate from a V1 or

> something on it?

That's exactly what I said you goober

Re: Sachs 504 Misinformations - cranktalk

Maybe I will try it, just gotta find v1 hpi stator. And between the kriedler and a v1 and a bunch of sachs maybe something magical can happen

Re: Sachs 504 Misinformations - cranktalk

Well, the weather is getting nice.

Here is the flywheel off of a Variant on a 505 large tapered stock crank in 504 1/A cases. Used the same stator from the original 1980 Sparta Motoplat ignition. Coils sit about 0.58mm away from the ID of the flywheel. Cam seems to work the points perfectly. Kewl.

144F6BDA-DEE0-4AFD-B1EA-20096229CE5A.jpeg
5BC2DD95-3F33-41DF-9EA3-B350C98B0A2A.jpeg
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