Looking to make a Sachs go real fast!

Chöschi21 C.K. /

Soooooo:

I had a GP40 last Year, Sachs 504/2A(Manual 2 Speed, Short Block, 44mm instead of 42mm Stroke crank, 3 plate cluch) swap, got it up to 93kmh(58mph) with the stock cylinder, crashed it into a tree at about 20-25 in the woods last autumn…

Now i want to do it again!

Well, not the crashing part, but the going over 90(55mph) with a modified stock cylinder, sadly back then i didn't get it over 100(62mph) but now i would like to do it, this time with more compression, and pre-compression and better everything.

I would like to chop the head of a Sachs 535 cylinder, put a puch head on top of it, and use a puch piston, why a puch piston? well, its about 4 or 5mm shorter on the piston crown, wich i am hoping will get me more pre Compression, of course i will probably need to remove a couple of milimeters from the cylinder base, and sealing surface for the head. Mabe make a ZME(Zylindermembraneinlass, or in english cylinderreedvalve) and some Boostports.

What would you Guys(and girls) think about doing something like that?

Friends told me to get a 70ccm or 80ccm kit, but i dont want that, i think there is not much fun in putting on a Cylinder, Exhaust, gearing and carb, tuning the carb and Ignition and going 90(55mph) with that, there is more fun in testing, trial and error ang etting power out of a stock cylinder. Also, my gp40 could Blow the (non existing)

doors of Puchs with e50 engines and 70ccm Athena and airsal kits with a Little shorter gearing.

Re: Looking to make a Sachs go real fast!

Probably Fred /

I think it’s a waste of time in my opinion for the clutch systems on even the manual hand shift bikes aren’t worth a crap when you add a lot of power,

I’d find another bike to build to go fast !

But that’s me I like to build a bike and have it last for years, if you want to build a bike and have the clutch glaze over a a few miles or and starts slipping then ya and go for it !

Re: Looking to make a Sachs go real fast!

55 on a stock sachs is impressive. wait amazing, no unbelieveable.

Re: Looking to make a Sachs go real fast!

Chöschi21 C.K. /

Never realy had problems with the cluch, ran the gp40 with more Plates and 3 Springs, worked well, and if the Automatic cluch can't handle it, i am going to put a Manual one in it.

Re: Looking to make a Sachs go real fast!

Chöschi21 C.K. /

Of course it wasn't stock, it was Modified quite a bit, for the Topspeed run i had a 19mm Bing carb and a Selfmade Chamber based of a Homoeth P4.

In the Woods i only used a 12mm Bing because the intake timing was so high that it wouldn't idle right under about 3'000 rpm and if you got onto the gas fast, the engine would choke with the 19mm bing, i beleve i ran about 165-170° intake, you start to lose bottomend power at over 120° with the 12mm bing and for a streetable bike i would never go over 145° with 50ccm, with 70ccm you can, of course, go higher.

Re: Looking to make a Sachs go real fast!

> Christian K. Wrote:

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

>

> What would you Guys(and girls) think about doing something like that?

>

I'm not sure how the dome of the piston can do anything for pre-compression? You need a blower.

90km/h is impressive, too bad you crashed it before getting a gps or radar run ;)

Re: Looking to make a Sachs go real fast!

Chöschi21 C.K. /

The piston has a lower Dome, the inside of the piston is also lower, just a different dome wouldn't change the pre compression, the crank chamber will be smaller with a Puch Piston.

To get to about 135° on the Transfer Ports would need to remove probably about 1-2mm from the Cylinder base, wich will also shorten the Transfer Ports,, meanig i will get a little more pre compression again.

I tested the Topspeed with a Bicycle Tacho, it showed 97kmh, also tried a "Your speed" sign, that showed 93, sadly i dont have a Radar gun or something like that. (edited)

Re: Looking to make a Sachs go real fast!

> Christian K. Wrote:

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

> The piston has a lower Dome, the inside of the piston is also lower,

> just a different dome wouldn't change the pre compression, the crank

> chamber will be smaller with a Puch Piston.

>

> To get to about 135° on the Transfer Ports would need to remove probably

> about 1-2mm from the Cylinder base, wich will also shorten the Transfer

> Ports,, meanig i will get a little more pre compression again.

>

> I tested the Topspeed with a Bicycle Tacho, it showed 97kmh, also tried

> a "Your speed" sign, that showed 93, sadly i dont have a Radar gun or

> something like that.

The dome is solid, the casting is filled upside down so there shouldn't be a difference.

Even if there is, the crankcase volume is so much larger it's probably like 0.1% difference. Plus what you gain on one side is lost on the other, you lose volume on the intake. There's a sweet spot for sure but you'd need to dyno it to find that.

The gains are really in removing intake restrictions ie;. flow and turbulence. Something like this:

Polished to increase flow, but dished to increase turbulence. At least this is proven to work.

Re: Looking to make a Sachs go real fast!

Chöschi21 C.K. /

Just measured it on the inside of the piston, from the Piston Pin upwards it's 32.6mm on the Sachs Piston, and 26mm on the Puch piston, so it should increase the pre compression, on the ports i only tried polishing, witch actualy lost me some power, i could try something like in the Picture.

Re: Looking to make a Sachs go real fast!

You probably need to measure the volume, you might be able to fill the piston with water and pour it into a graduated cylinder or something. Tough I guess because of the skirts...

Re: Looking to make a Sachs go real fast!

OH MY FUCK. I hate when you write like 5 pages and your shit internet crashes

Re: Looking to make a Sachs go real fast!

I had tried to write this up nicely.

people often make bold and audacious claims like yours and fail to follow through, leading to sometimes rude skepticism and pessimism here. I see you're young and new to the site, some general advice, don't get mad with people, stay objective.

I'm not familiar with the 535, only thing that comes up in a search is the newer 505 style jugs, which are generally more restricted because they downtune to accommodate using the 44mm cranks on everything.

Not sure what your goal is with cutting the head off, why not just use an existing 2 part cylinder, especially if you're going to throw off and have to recorrect for spacing with a different piston? Plus there's not really anywhere to bolt the head to once you cut the original head off. I mean I'm sure you can figure something out but it seems like it'd be easier and more productive to just drill and tap new full length cylinder studs for a complete pair.

Also, i'm very very curious what went into this 58mph stock 504- that seems very dubious. Noone I've seen has gotten close even with kits. I've seen lots of effort go into getting the 2 speeds to even pull close to 50, and you're another 20% on top of that? it'd be real cool if you could share the details.

And finally, I love this idea and really hope you follow through with trying it and keeping us updated. I love sachs and love to see people working on the,, especially as you say trying to see how much you can eke out of tiny modifications. which is why i'm trying to warn you to not bother worrying when people start calling bullshit on 58mph sachs. focus on proving them wrong if you can, not arguing your past claims.

Re: Looking to make a Sachs go real fast!

> Born to be WillD Wrote:

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

> OH MY FUCK. I hate when you write like 5 pages and your shit internet

> crashes

I had that happen two nights ago . Twice . :(

Re: Looking to make a Sachs go real fast!

first name last name /

Maybe if you quit lying about the performance the moped gods will stop placing trees your path.

Have a nice walk of shame.

Re: Looking to make a Sachs go real fast!

Chöschi21 C.K. /

it just happened to me, so now in short form:

I want to take the stock cylinder because for me it's more about going the paht of building smething, than actualy getting to that high of a topspeed, it's about the trying, and i'd like to get there with the stock cylinder.

Don't have any exact infos about the engine, it was a 44mm Crank, a friend put it into the engine and modified the cluch, no clue what he did thou, it had an Italkit ignition, Cylinder was an early one for a 42mm crank, bored to 41.09mm, and had a 41mm Piston, Exhaust port was 3 Piece, intake was 2 piece, dremeld the Transfers, put two 1mm, and one 0.5mm Gasket on the Bottom of the cylinder, Timing of the ports i don't know anymore, i have 173°/139°/195 in my head, but that could just be from another cylinder, i don't write these things down. Exhaust was a extensively modified chamber wich i got free from a guy that i know, modified that one just a little afterwards and put a Kreidler 32mm Pipe on it, also put on a 19mm Bing carb with a realy short intake. With this Setup i couldn't drive it at all because you never realy could be on the Powerband, that's something i want to change with this Project, i want to have a drivable cylinder, even if i don't get to go as fast, and Maybe that was why other people didn't get up to These speeds, because they actualy had good setup's wich could be driven fairly good, because it was nearly undrivable i put on the 12mm Bing, and a 28mm exhaust magnifold to get at least a little better drivability, also, i didn't crash the gp40 with that cylinder, i crashed it with an 80ccm Athena on it.

Re: Looking to make a Sachs go real fast!

> Christian K. Wrote:

> , Timing of the ports i don't know anymore, i have 173°/139°/195 in my head

We can figure it out, just post your port map.

Re: Looking to make a Sachs go real fast!

yea i'd love to see that cylinder.

I don't think it's impossible with the 2 speed, it's 1.7:1 between the 2 speed gears, so 58's got you at 35 in first gear, which it's fair to have a single speed push 40.

mine on the 80 athena at it's fastest got up to a best of 63, that was ripping like 10k on 13x35.

it oughtta be possible to tune 10k out of the stock cylinder bored up to 58cc, I think you just gotta have an unusably high powerband and unusably tall gearing and a downhill and a light rider all tucked, but could be feasible I think.

But I still wanna see how (if) you can push a stock sachs jug to 10k...

Re: Looking to make a Sachs go real fast!

first name last name /

I'm going to put my money on the tree.

Re: Looking to make a Sachs go real fast!

The A2 that I highly modified ha! didn’t come with a clutch. I might have tried to hack a 3 arm and bell in there. Wayne’s chainsaw clutch’ll Fit

Re: Looking to make a Sachs go real fast!

I ran a carbide router back and forth, plowed out a third transfer

6FFED810-B4ED-4557-86A7-287D7D1F9B99.jpeg
D49235FB-BE24-45CE-8C7B-29A0B9F3FAF5.jpeg

Opened the sides a little too

0E7C7E88-FD5D-4A29-8F4E-CA04DE016B74.jpeg

Re: Looking to make a Sachs go real fast!

A ruff ideaR of how it went on.

EF204BA1-2810-4D04-A038-8B472B252F35.jpeg
04D38B42-1568-400E-B0F4-7544F27B49C3.jpeg
61B992FD-F3BD-4F61-9EEA-9EE844574953.jpeg

2.75mm spacer needed and lop off 1mm

Re: Looking to make a Sachs go real fast!

Chöschi21 C.K. /

I don't know if i have one, i don't like to to Portmaps, because it's quite easy to fuck them up and measure 10° more on a Port.

I think i made one of it and scanned it when it still was a 38mm cylinder, if i can find it i will post it here.

Re: Looking to make a Sachs go real fast!

Chöschi21 C.K. /

Well, 10k is easy to get to, , 1 Piece ports, intake and exhaust port 24mm wide, 13mm Bing carb, 28mm header, 28mm/70mm Pipe, and 150° intake, 120° Transfers, 165° Exhaust ports and there you have your 10'000rpm, but on the stock gearing, that setup won't get you up to 70kmh(43mph) but to 10'000rpm.

Re: Looking to make a Sachs go real fast!

yeah sure you can pull 10k, but with enough power to pull a person to 10k with 58mph wind and high gearing. I think that porting could get more aggressive even, and just really hammer on the manual clutch to get it moving. My point was with the 80 I got it over 60 pulling about 10k on 13:35 gearing with a 2 speed. So I dunno the exact gear ratios, but you could hit 58 at 10k on 13:35, and that same gearing'd have 1st pulling you to 35 ish. Pretty doable on the 80kit, hell on clutches, gotta be near impossible on stock jug but near impossible isn't necessarily all the way impossible. I definitely would love to see it.

Re: Looking to make a Sachs go real fast!

Chöschi21 C.K. /

Searched for it today, i don't have any original Portmaps of the cylinder, but i might still have a scanned one om my old PC, would need to take it down from the attic and look through it. I am also thinking of just taking a Sachs 50's cylinder instead of the 535.

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