Puch timing

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Revision as of 02:50, 16 August 2019 by Roffman (talk | contribs) (Words)
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Some thoughts on Puch timing especially for a kit/mild performance build using stock points magneto ignition,

Setting timing by seeing when points start to open is wrong, it's far off compared to using a timing light. You do not need a degree wheel, the flywheel is 360 mm and 360 degrees . You cannot time a puch by ear or eye very accurately it's not a small block Chevy. You got to time about 14-17.5 degrees before top dead center for a e50, which is 14-17.5 mm on the flywheel, the specs on a za50 is more but only stock Applications.

An aluminum cylinder kit will run great at full advance but it gets hot quick  and can seize, it needs a little less then 17 degrees timing many times, most times  14 to 14.5° BTDC 

All timing is Before Top Dead Center (BTDC) not after top dead center, If you set timing after top dead center your engine may run backwards,

Sticking a screwdriver in the spark-plug hole to try to find top dead center (TDC) is not accurate,

To find top dead center correctly use a long reach plug or piston stop. Put it in the plug hole just enough for the piston to hit when you turn the flywheel. When it hits put a mark on the flywheel and case. Then turn the flywheel the other way until piston hits stop then transfer the mark from the flywheel to the case.

You will have 2 marks on the case and one on the flywheel. Measure and find the middle of the two case marks and mark it. Erase/ remove the outer marker marks with alcohol.

If you put the long spark plug or piston stop in just right the marks won't be as far apart so it will be easy to measure.

The flywheel mark when lined up to the middle case mark IS TOP DEAD CENTER.

Now put a mark, (we will use 17 mm as an example) 17 mm before (to the right e50 to the left on a za50) the middle case mark on engine case. When the single mark on the flywheel lines up to the 17 mm mark on the case under a timing light you are at 17 DEGREES BEFORE TOP DEAD CENTER. Your eye and no other way is as accurate,

Note: Flywheel magnetos have a rotation arrow stamped on it. Either Clockwise or Counter Clockwise and make sure it is the correct one for your engine

Za50 is marked backwards then e50 and many people put timing marks on the flywheel instead of case so both will be backwards from description from the Top Dead Center mark on the flywheel and case,

Now you must set points before you run engine to see the timing under a light E50 spec is 16-18 thousand gap when points are full open at just past TDC, A za50 about the same, could be a bit more but at least 16 thou of a inch,

You should always service the magneto before you even attempt to set timing with removing flywheel, cleaning and lubricating the inter cam on the flywheel, oil felt pad, clean the points with fine grit paper, preloosen Stator screws and point gap adjust screw because it’s way easier with flywheel off, otherwise there’s a good chance your strip them all out trying to do it first through the slot in the flywheel 

Here is a za50 with the Timing marks on case with and only one top dead center mark on flywheel https://m.youtube.com/watch?v=KVVKDIjeG3A

Now here can be the flaw with puch point ignitions, if you gap them at 16-18 thou gap then even at full retard you can be almost 20-21 degrees BTDC or 20-21mm on the flywheel under a timing light which is too high for a kit and you will be taking a chance of seizing your engine though for complete stock setup it maybe ok,

You may need to take the stator out and dremel the slots so you can move it for more retard or shrink the point gap like 12 thousand (but shrinking gap can make you lose kv and maybe dwell too). Za50 you dremel opposite side of Stator plate then a e50

High timing is not good for/can blow aftermarket kits because of heat. A 40 buck head temp gauge can save you grief cause you can see head temps and back off before 400 degrees (the danger area) You got issues if your kit don't run and run cool enough with 14-14.5 degrees timing.