still not starting

[Barnsey]

I tried retarding by a couple of degrees.  I got a few coughs out of her and then she gave up again.

[rhyatt]

Have you definitively checked your ignition timing against tdc on the compression stroke.

[Barnsey]

Actually I have always worked on the assumption that the timing hasn't changed since it last run, but since we have eliminated the fuel supply and the spark, there isn't much else left.  I've ordered a timing disc and one of those feeler things for checking the position of the piston.  Yeah.. I know, I have used a pencil,in the past, but it is always easier with the right kit. 

I did wonder if it is just possible that there is an issue with the advance / redard? 

[iansoady]

You don't need much easy start - a couple of seconds into the carb inlet is usually enough.

[rhyatt]

Plug out
Turn engine over with your thumb over the plug hole feeling for compression
When compression starts to build
old spoke down the plug hole (marked at thc and whatever distance before tdc)
Put bike in 3rd or 4th gear and rotate rear wheel forwards bringing it to tdc holding spoke vertical.
Now using rear wheel turn rear wheel backwards until the 2nd mark on spoke is correct btdc
Put in neutral
Hold adv/ret fully advanced and move till points just open (I use a multimeter on beep)
Lock it up and kick start

[Barnsey]

old spoke down the plug hole (marked at thc and whatever distance before tdc)

Thanks for your help.  Could you please break down this bit? Especially THC, or was that a typo?   

[ducati2242]

When I finished the rebuild on my DB500 I must have kicked it over 200 times and still no start . firing occasionally but no start . I double checked everything at least 10 times . I kicked it over that many times I strained my leg muscle and had to wait a week to get better . During that week i watched many videos on utube on how to start a bsa gold star . When i went back to it i used that information and it started 2nd kick . Now if it doesn't start first kick it starts on the second , even after 6 months , If everything is correct and it wont go  its down to technic .

[rhyatt]

Old spoke down the plug hole
When the piston is definitely at tdc the file a line on it at a convenient place on the spoke.

Then

Just below this mark , file another mark at the distance the book says before tdc it should fire.
So, if it is 3/16" before tdc , put your lower mark 3/16" apart.

Ok, now , using a 2nd piece of wire fixed somewhere solid, bend this wire so it makes a pointer against your spoke.
This pointer allows you to move the piston up and down a bit to get the exact firing point

[Barnsey]

Super, thanks!  I was thinking of going with crank angles. I didn't know that info was available as a linear piston position. 

[Barnsey]

All the demos I have seen say to kick the engine with the engine just past TDC.  My bike doesn't have a decompressor so it tends to roll past TDC and stop at the point where the points are open and current is reading 0.  Is that OK? Or should I be kicking from just before that point so as to get the spark?   

  BR,  Ian

[rhyatt]

this is 1 reason that you have the rear wheel and 3rd gear involved, to stop it rolling past tdc - and you can rock the wheel and the engine back and forth to get the right position

the spark HAS to happen JUST BEFORE tdc (by whatever distance the manufacturer says) - only then - with the spark before tdc (btdc) - will the fuel /air mixture start to burn and develop its combustion pressure just after tdc and this burning pressure pushes the piston down the stroke and the bike down the road.

if you have it sparking after tdc the the piston will be half way down the stroke and the energy non-existent.

try the aforementioned routine to check your timing but the piston must be on its way UP the compression stroke and just before it reaches tdc the points must open.

an easy way of watching for when the points open is to watch the ammeter needle(obviously have the ignition on) with the points closed the needle will be on the minus side and the instant the points open the needle come to the 0 centre



with my C15s (no decrompressor) , ignition on  - whatever tickle or choke - ease up to compression and just a whisker over the top - release the kick start lever and bring it back to starting point and then a good swing with your foot down

[scifi]

Just to be pedantic, you said...
Then

Just below this mark , file another mark at the distance the book says before tdc it should fire.
So, if it is 3/16" before tdc , put your lower mark 3/16" apart.

You would need to put the second mark -above- the first mark.   Making the length of wire 3/16 longer.

Also when kicking from TDC, try to extend your swing forwards, for the maximum kick rotation.

[Barnsey]

That is great thanks!   I am putting the parts of the jigsaw together in my mind. 

 It sounds like we are starting at TDC so that the spark has already occured.  Hence we are starting the kick at the start of the suck stroke and the engine should go through two rotations or all four strokes during the kick and finishing with the spark just at the end of the kick.

  In normal running the spark is just before TDC to allow time for the flame to build, but if the engine is stopped, or turning slowly by hand it will be in the fully retarded state. Might it spark just after TDC?

  Just an observation, but I was watching Hugh Ferrier's wonderful series on YouTube. He, unwittingly bought a Triumph points unit for his BSA C15, and he had to file a bit of the cam to reduce the amount of retard.  I did wonder if this might be the case with my bike. 

  Also I watched a video on how to start a BSA from an 'expert'  and it took him about seven kicks to start his B40(?).  I suspect he might have edited out a few attempts.

  I am off to my cabin to find a spoke, or something similar. 

   Thanks for you continued support.    Ian

[cornishbob]

capacitor(er?)

[Barnsey]

Okay.  I found a little fibreglass stick to use in lieu of a spoke.  Right now the timing is at about 2.25 mm  before TDC, but will that be advanced or retarded?  A quick search on Google suggested that it should be around 7.1 mm.  (How the heck do you measure to 0.1 of a mm?!)