Ok Jim. I am not worried about beating you up as much as you taking it that way lol. Learning is why were all here.
Ok so here is the method to get it dead nut right on.
When you rotate the piston to tdc there could be as much as a6 degree dead spot where you can rotate the crank and there will be no piston movement. the idea is to set your degree wheel right in the middle of this to where you have equal amount of dead spot before and after 0 deg on your degree wheel. so you can see by eyballing it you can be as much as 6 deg off right off the bat. there is two methods that can be used to acomplish this. first uses a dial indiacator and the second uses port timming to set the wheel.
first method. you must mount a dial indicator to where you can measure piston travel. i used an old spark plug and made an adapter that goes in the plug hole and then clamps the dial indicator in place. the degree wheel is also installed in this process.
ok so with the dial indicator and the degree wheel installed you rotate the crank till the piston stops moving. set dial indicator to 0 and move deree wheel to zero. rotate the wheel back and then slowly rotate it till the dial indicator just stops. note this number on the degree wheel. keep rotating it till it just starts moving and note this number. the difference is the number of degrees the piston trave is dead. move the degree wheel to where 0 is in the center of this dead spot. ie if you have a 4 degree dead spot there should be 2 deg bfore 0 on the degree wheel and 2 degree after 0 on the wheel. It is absolutly imposible to acuratlysee when the piston stops and starts moving without a dial indicator.
Ok second method. If the piston has a dead spot at tdc then it stands to reason that there is a dead spot at bottom dead center. true tdc can be found by finding true bdc using the port timming. how do we find port timming? install degree wheel and remove muffler. rotate crank through and looking into the exhaust port slowwly rotate and stop when the piston just opens the exhaust port. note this number. keep rotating through and stop when the piston just closes the exhaust port. the difference between the two numbers is the exhaust timming. ie if the exhaust opens at 250 degrees and closes at 110 then the port timming is 140 degrees.
There should be an exact number of degrees from port opening to bottom dead center as there will be BDC to port closing. meaning if port timming is 140 degrees there will be 70 degrees from port opening to bdc and 70 degrees from BDC to port closing.
Ok so we know the port timming and we know how many degrees there should be from port opening to bdc. so rotate the crank till you reach where the port just opens again. set your degree wheel to where it is half the port timming before BDC. rotate through till the port just closes. it should be the exact number of degrees after bdc that you set the degree wheel for when the port opened. if not keep adjusting till you have equal amount of degree before and after BDC from port opening to port closing. now you have true bdc set and it will also be set for true TDC as it is exactly 180 opposite.
Make sense?
ok now we need to set the spark timming. This is the procedure that i was told to use by ralph at ch ignitions and it does work.Dont worry about any of the computerized advancing or retarding of the spark with this procedure as the ignition will know what you aredoing and it will not advance or retard while you are doing this. Ralph saysthe box is smarter than any three areomodelers put together and i think he isso right on this.with degree wheel set at true tdc and all ignition parts installed and battery installed and ignition turned on slowly rotate the crank till the ignition sparks. not this number. this is where the sark timming is set. ie if it sparks a 16 deg before TDC then yo have 16 degrees of advanced timming. do this a few times to make sure you have the right spot. adjust your sensor so that when you rotate the crank through very slowly it will spark at 28 degree before TDC. you will now be set dead nuts at 28 deg BTDC.
This is how i set mine and it runs dead nut perfect. if i move any direction from this setting there is absolutly no power gain and only worsens performance.
I hope now you can see that when you say you set it to 28 degrees as you did in this post
was having a problem with my Ryobi missing a little at WOT. No adjusting on the needles would change anything. I thought it was running rich. Was running an RCexl ignition set at 28 degrees.
is very misleading information. you actually have no idea that you were actuallyat 28 degree. i really think what happened is that you were way off of 28 degrees and by hand and ear tunning you manged to find a spot on or near 28 degrees to where the engine ran satisfactorily. again you have absolutly no idea what your engine is set at.
Again not trying to beat you up on this but just trying to help you understand what you have.