Kick start leg breakers.

[pancho]

 Question for theory thinkers. What makes some two strokes vicious on kick-backs, e.g. pre read valve RT1, compared to later model RT series?
 I have my own theory for part of the cause, what do the 'boffins' say?
pancho.

[Tim754]

Pancho having owned both pre and reed valve models RT360's.... both types were/are monstrous kick back devils!!!! Later DT360/DT400 model electronic ignition (which bolts on to early engines) was a vast improvement.
Also the early models were neat at starting and running     backwards       

Points ignition with 2 degrees before top dead centre firing and owners not very careful,  precise tuning ,  may answer some of your question   

Strangely I love the old Yammie 360"s

[Iain Cameron]

Once I learnt that the DT400 cdi fitted have never had a problem since . Mind you a RT1m with a gyt high comp head makes a British 500 single look easy . Iain

[Rossvickicampbell]

agree with Iain - the timing was out on my YZ 360 - what a bastard of a thing - and broke the kickstarter crank boss 

[Hoony]

early CR500's (1984 -86) aren't much better, its a real knack to fire them when cold.

[pancho]

 I believe PART of the problem is weak spark=poor flame travel.  Evidence= it's a lot worse with the engine cold. Plus When I put total loss battery coil ignition on, getting over 10mm spark at kickover a big improvement.  (But I still took the kicker off)
 
 pancho.