Static timing and points gap for 1940s 2 stoke, low compression engine - Zurcher

kenneth Winter /

Engine - 1945ish Derny Cyclomoteur, Zurcher motor. 98cc.

I need input for setting the static timing for the COOL old engine..

I tried 10 degrees before TDC and a gap of .0015.. NOTHING.

Where to I Start to get it to Start??

What has been done:

Removed cylinder - deglazed bore.

Cleaned piston and ring lands. It had usually Larger rings ( 2)

Seal base gasket and head..

Rebuild carb

Added a buzz box coil to insure HOT SPARK... Good blue spark.

I put it on a stand.. .and it started and would run on choke... rev with throttle, backfire and die... ie would not take throttle..

THUS I figured improper timing..

I DID NOT mark the prior testing timing position (Dumb I know).

1. I found TDC with piston stop.

2. Marked (Keyed) fly wheel and head with TDC and added advance/retart marks for 20 degrees+-

3. Timing is set by clocking the distributor to gear reduction.. I set the timing to 10 degrees of advance...

4. Spin the motor with drill... nothing other than a single pop?

Now I dont know what to do..

moped-army-8a8086c16210d041e67b86fd3b80ae7f.jpg
moped-army-9bc25ddbb6bc6d980b684fb30011bdda.jpg
moped-army-21286afb6d3b6c0d930252b34027feac.jpg

Re: Static timing and points gap for 1940s 2 stoke, low compression engine - Zurcher

Overpriced Parts /

You need more then 10° before top center for most engines Try 20° And you could lower it more if it starts running hot

Re: Static timing and points gap for 1940s 2 stoke, low compression engine - Zurcher

you are screwed up at the points. you have not set the ignition timing. I'm an old smoker but not a moped guy so we talk mm btdc instead of degrees. you need a multimeter to set static timing. when the points open the coil fires. you need to line up the timing marks and set the points gap so they open at your timing marks. the maxi is 17 degrees but I would make marks at 1.8mm btdc. that measurement is almost universal with 2t motorcycles. then I would static time with a meter.

very cool project. as far as I can see from your post you have done everything correctly except timing.

Re: Static timing and points gap for 1940s 2 stoke, low compression engine - Zurcher

Dirty30 Dillon /

15*BTDC should be a better starting point, the 10 degrees is too advanced.

Re: Static timing and points gap for 1940s 2 stoke, low compression engine - Zurcher

kenneth Winter /

OK.. I will try that.. I could get 22 or 10.. I went with 10..

Re: Static timing and points gap for 1940s 2 stoke, low compression engine - Zurcher

kenneth Winter /

your info confuses me.. I am at 10- degrees before TDC.. you say that too much and then say go to 15.. which is more??

Re: Static timing and points gap for 1940s 2 stoke, low compression engine - Zurcher

kenneth Winter /

CORRECTION- I set it to 10 degrees BEFORE TDC

Re: Static timing and points gap for 1940s 2 stoke, low compression engine - Zurcher

> Dirty30 Dillon Wrote:

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

> 15*BTDC should be a better starting point, the 10 degrees is too

> advanced.

... too retarded. 15-20 as others have said. double check you are measuring it correctly.

if you are using a DC coil be sure that you don't have a resistor plug or cap, they can be really touchy about that because they don't have as much power as magneto points.

based on your 'it popped once' comment i'm guessing its too retarded. thats usually what they do, then they foul the plug with raw fuel.

Re: Static timing and points gap for 1940s 2 stoke, low compression engine - Zurcher

kenneth Winter /

May I call you? PM me is so..

Re: Static timing and points gap for 1940s 2 stoke, low compression engine - Zurcher

you really think you can go from not a pop to running perfect with a 5 degree change.

do you not know how to static timing? you just don't pick a gap, you have to set the gap.

as points burn the gap increases, when the gap increases the ignition timing retards. after about 700 miles you need to tune up because the engine looses power. starts and runs fine. anyway when you go to tune up the car you'll be running good not great and you need to advance it 5 degrees.

buzz box is crazy. how do you have it set so it turns on when the points open? I have no experience with 20's tech. I use 60's coil packs. b108 universal.

Re: Static timing and points gap for 1940s 2 stoke, low compression engine - Zurcher

Dirty30 Dillon /

> Graham Motzing Wrote:

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

> > Dirty30 Dillon Wrote:

>

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

>

> > 15*BTDC should be a better starting point, the 10 degrees is too

>

> > advanced.

>

> ... too retarded.

Correct, I mispoke.

Re: Static timing and points gap for 1940s 2 stoke, low compression engine - Zurcher

Pushrod Fifty /

Curious about the exhaust header, is it a double tube exhaust? One side looks different than the other.

I use an analog multimeter set on buzzer mode and attach one lead to the points wire and the other to ground. The reduction in sound tells that the points have opened. That's the BTDC firing point.

If you don't know the spec, as mentioned by others, start out real retarded as that was the norm for those days. Is there a manual spark advance on the distributor? It may have had a bar mount control to advance it as the engine reved.

The easiest way in this case to set the timing is to use a wooden coffee stirrer with pencil marks. Put the stirrer in the plug hole and turn to TDC, turning in running rotation. Mark the stirrer at the top of the head with stirrer hitting piston top. You can feel it pretty close by turning back and forth a hair. Make a mark 1/8" above that line. Turn the flywheel backwards- BTDC until the top Mark is at the top of the head. Set your timing adjustment so that when you turn the flywheel to match the second line (BTDC) , the buzzer reduces in sound. Adjust the measurement as needed once it's running. If it doesnt start and rule out ignition, check the carb and see if the plug is wet. Yet some starting fluid that has top end lube in it, available at a marine supply store.

Re: Static timing and points gap for 1940s 2 stoke, low compression engine - Zurcher

Why a buzz box? Don't trust the mag?

Re: Static timing and points gap for 1940s 2 stoke, low compression engine - Zurcher

> Aaron Blair Wrote:

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

> Why a buzz box? Don't trust the mag?

I asked the same. mag or not 40's points will work fine with the b108 universal coil pack. as far as I know buzz box needs a distributor to time the engine. I still would like to know how the op gets the buzz box to fire with the points.

Re: Static timing and points gap for 1940s 2 stoke, low compression engine - Zurcher

cool motor, more details will be appreciated. my guess is crank seals. timing anywhere is close enough. are u spinning it the right way?

Re: Static timing and points gap for 1940s 2 stoke, low compression engine - Zurcher

> pat splat Wrote:

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

> cool motor, more details will be appreciated. my guess is crank seals.

> timing anywhere is close enough. are u spinning it the right way?

its a 2t. as long as timing is right it runs in either direction.

Re: Static timing and points gap for 1940s 2 stoke, low compression engine - Zurcher

> el pollo Wrote:

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

> > pat splat Wrote:

>

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

>

> > cool motor, more details will be appreciated. my guess is crank

> seals.

>

> > timing anywhere is close enough. are u spinning it the right way?

>

> its a 2t. as long as timing is right it runs in either direction.

true, two strokes dont care as long as u can adjust timing, theres the rub... i've tried by accident many a time to start a motor the wrong way

and i've gotton the ocasional pop just like the op. Now upon realizing the mistake the motor fires right up.

« Go to Topic — end of thread

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

Login or Create Account