Non Running Sachs G3

Francis Cronley /

It has spark and compression. The clutch randomly engages. Not a D motor. I cleaned th Bing, it was covered in a thick layer of shit inside and out. It turns over and sparks, but doesn't want to start. The gaskets on the Bing are now dust, could it be an air leak?

Re: Non Running Sachs G3

take the carb off & & squirt some carb cleaner down the intake to see if it starts

if not check the compression....it should be 120 psi to run (edited)

Re: Non Running Sachs G3

Patrick Keaton /

Decompression valve could be leaking.

If so,service or replace the decompression valve,or remove it and replace it with a correct thread bolt.I put gas and oil mixture into the intake and/or spark plug hole and and put the spark plug back in,to test and do not use carb cleaner for that kind of testing,since carb cleaner has no lubricant in it.

Re: Non Running Sachs G3

♣Slew Foot♣ /

use this as a guide, there is a safety override on the tail light ciruit. if the bulbs are not OEM or there is anything missing in the circuit, it will not fire up even when you can see spark.

when rewiring it, the brake sensors are odd they are n.c. when just about everything else is n.o. including the hardwired version of a sachs. so if you want it to have working brakelights you have to totally rewire the tail circiut replacing the sensors with compatible ones. or get all working OEM bulbs and sensors, the wattages are there.

to test if its the problemo, bridge both sets brake sensor leeds to effectively turn both off or on, idr which, ground the brake coil return. it should fire right up

Sparta-foxi-wiring-diagram.jpg
Wiring-of-Ignition-Ext-Int-Ground-600x658.jpg
Sachs-505_magneto_wiring.jpg

Re: Non Running Sachs G3

Clutch shouldn't be randomly engaging. Did you watch the youtube video and rebuild it?

Re: Non Running Sachs G3

Fix the clutch. I bet the spring in the donut is busted,

Re: Non Running Sachs G3

Francis Cronley /

Thanks all. I dont gave a tail light, but the plug sparks. I'll pick up a new plug today. How can I tell if the spring is broken? Shouldn't I be running even if the clutch is retarded? Why is it so hard to pedal?

Re: Non Running Sachs G3

Dude. It isn't hard just look in there. Find the manual, look at some of Will's old sachs clutch posts, you will understand what I am talking about. Researching it yourself will be 100x more easy than me trying to type it out.

If the spring is busted then there is like 20 metal circles rattling around in your case, and no it won't start if the clutch is in 20 pieces, but you might ruin your internal gears.

Re: Non Running Sachs G3

Francis Cronley /

Oh the spring is fine. Yeah I want will to go to the shop a nd take it apart with will.

Re: Non Running Sachs G3

Francis Cronley /

Soooooo if i got an oem brake light it would fire up?

Re: Non Running Sachs G3

If it engages when you pull the lever and kinda disengages when you let go - it'll start.

If you got spark, you got spark. tail light is irrelevant

The donut rides up the outside ramp of the clutch basket and pushes the clutch stack away from the crankshaft smooshing the fiber friction disks and splined metal plates together engaging your clutch. If you lost shims, there will be too much play and the donut won't smoosh the plates together enough to engage the clutch.

If your nut isn't tight on your crank, it won't turn the engine over when starting or when you finally get it started it'll spin off. The only way to get this nut tight enough is with an impact (not recommended) or using a piston stop or stopping the crankshaft in some other way. The shittiness of sachs is that the splined piece that transmits power from the crankshaft through the splined metal disks is only clamped in place by the pressure from the clutch nut. If it isn't tight - everything is fucked.

TL;DR; If it turns over when you pull the clutch lever it should start at least - maybe not run or engage well, but at least start. Sounds like carb or timing issues since you have spark. (edited)

Re: Non Running Sachs G3

"why is it so hard to pedal?"

when you say it has compression, how did you test it, what psi did you get?

i'll second what ☈ℽ∧⋂ posted, but include the entire fuel system.

healthy fuel delivery is essential, and possibly the top no start repair topic.

hard pedalling could be as simple as the decompression not working, i think it's more then that.

if you're not getting good cranking speeds, it won't start.

roll starting is the perferred daily method, easier on everything.

with the plug out, does it pedal smooth? eliminates compression / decomp.

if not, good chance you need to dig into the motor, getting someone that's been there, done that doubles your chances for success.

Re: Non Running Sachs G3

Francis Cronley /

Ok, thank you Ryan. The reason I sat it has compresstion is because its turning over and trying to start. Those are two different things? It is very much easier to pedal without the spark plug. Im cranking it hard and fast, its just hard to get it there. Besnik told me over the phone to tighten that nut. How much is too much?

Re: Non Running Sachs G3

You should be somewhere around 20-30ft-lbs I think... There's a torque spec for that nut in the manual I sent you on FB though ;)

Re: Non Running Sachs G3

Francis Cronley /

THAAANKKK YOOUUUU RRYYYAAANNNN

Re: Non Running Sachs G3

Brent Bublitz /

Best video on dissection of the Sachs clutch.

As far as compression goes, you need to get a proper compression tester. It's almost impossible to tell the difference between 50psi (terrible) and 120-140psi (perfect)

Re: Non Running Sachs G3

♣Slew Foot♣ /

run all the electricals off the yellow wire and re ground the taillight return to the ht coil mount, cross both brake leeds to bypass to always on. if it starts, it is the tailight safety feature that was on some the sachs motors w/ a bosch ht coil and a cev tail assembly, they slapped them together in NJ. with whatever was on hand.

i have for an example a 85 505 and it needs it to start, some also had a weird wiring in the terminal blocks, so that the horn had to be in the circuit too. the return gnd was running thru them and another thing... dis connect the killswitch to diagnose.

i know this is for a 504 but still has alot of pertanat info.

Magneto-Wires-Chart1-591x800.jpg
Wiring-of-Ignition-Ext-Int-Ground-600x658.jpg
Sparta-foxi-wiring-diagram.jpg
« Go to Topics — end of thread

Want to post in this forum? We'd love to have you join the discussion, but first:

Login or Create Account