C15 engine lock on kick over.

[Barnsey]

Hi All,

    I have reassembled my C15 and decided to try kicking it over with the switches off just to make sure that all was OK. 

 The first kick was fine, but then it got stiffer and stiffer on subsequent kicks.  I took the spark plug out and then I could kick it over no problem, so it looks like a compression issue.  Maybe a stuck valve? 

  Anyway, I took all the covers off again (so annoying!) and checked the strokes.  Yes the valves open and close, and in the right order. Also the piston is going up and down correctly with the valve position. 

 There is just the slightest rattle in the rockers when the valves are closed (I set these up with feeler gauges last week).  So all looks good.   

  Does anyone have any idea what is going on? 



     

[Barnsey]

Also I checked the oil level, which does not appear to have dropped, otherwise I would be asking about a wet sump . 

[rhyatt]

so - all is fine with the plug out - you can kick it over and over no problem - it goes round and round easily with no noises or strange sounds
you could if you wanted put it in gear and push it round the garden (with the spark plug out) and the engine whizz round and round ?

as soon as you screw the plug back in, it locks up - the plug is an Champion N5 (or NGK equivalent) long reach - what do you have?

[Barnsey]

Just for the record, I have a choice of two spark plugs, both NGK:  B8ES and BR8EIX (Iridium).

 I tried again.  It definitely doesn't lock up with the plug out.

  With the plug in, it locks up some time between the 3rd and 7th kick. 

 However, if I am persistent on the kick start lever, I can ease it past the compression, and it is ready to kick again. 

 So, maybe, I am just not kicking quite hard enough to carry it past compression on some attempts.

[rhyatt]

The basic C15 compression ratio is i think 7 :1
The SS80 s are higher from memory 8.5 to 1
Just ease up to tdc and just a shade over then ignition on and kick into life.
Have you changed any other components , ie different piston , that might change things

[limeyrob]

Yes, sounds like is has a lot of compression and needs a good kick.  Has it just been rebored / new piston?  If so they can be a bit stiff and so you loose momentum on the kick.

[Barnsey]

The piston and barrel haven't changed, but I have been all over the gearbox, clutch and alternator.
A half of it is my lack of experience in kick starting.  I'll give it another go next weekend.  I might have a practise on my other bike too.  That is what I bought bike no 2 for. 

[Barnsey]

Re the steel ring which links the kick start spring to the kickstart shaft,  should there be a spacer between this and the side cover to keep it from falling off? 

[Barnsey]

This is what I mean. See photo.  It keeps popping off when the cover is on.  Maybe I could just reduce the height of the cover with a mallet. 

[Tigerfeet]

The end of your ratchet spring looks wrong. The one in the parts book would appear to hold the kickstart anchor plate more tightly.

https://draganfly.co.uk/wp-content/uploads/content/kickstart_c15.jpg

[rhyatt]

Yes the spring has a hook end over that tab.
Also ensure that the profile on kickstart shaft is crisp and not damaged and the mat hing profile of this plate is snug

[Barnsey]

Okay, I found an original stop plate and spring (with turned over end) on ebay.  The existing plate is a little loose on the shaft,  maybe because the shaft is after market. 

 I wonder if the kick start not returning, could have been a cause of the original damage.