westyfield Posted September 13, 2011 Report Share Posted September 13, 2011 One of my Greeves trials alloy barrels has a head with the combustion chamber offset and with the spark plug in the centre of the off-set. Can anyone tell me which way to position the head? Spark plug off-set to the fore or towards the back? My good friend tells me it should be forward but my engine builder, of cosiderable experience, built it up and marked it to be at the back..I assume it will have been designed with the flow of the transfer ports and exhaust port in mind and it seems to run smoother with it at the front! So is that the answer? Quote Link to comment Share on other sites More sharing options...
woodbutcher Posted September 13, 2011 Report Share Posted September 13, 2011 NO NOTHING ABOUT GREEVES , BUT AIR COOLED ROTAX TRIALS CYL. HEAD COMBUSTION CHAMBER IS OFFSETT TOWARDS THE REAR . Quote Link to comment Share on other sites More sharing options...
trialrider Posted September 13, 2011 Report Share Posted September 13, 2011 its a TES head and off-set to the fore Quote Link to comment Share on other sites More sharing options...
westyfield Posted September 14, 2011 Author Report Share Posted September 14, 2011 ..Thanks for the response and particularly to "Trialrider" re the TES head.. which it is. Another friend who has seen this thread sent me the following message.. "Any 2sT head which doesnt have a proper squish band and a central plug, should have the plug located to the rear. Reason for this is that its not desirable to instigate combustion in an area of the cylinder which, during normal running, will include a greater proportion of combustion end gases, than the rear of the cylinder which is further away from the exhaust port" Conflicting info but I can confirm that the engine does feel to run smoother with the off-set to the front so maybe that is the answer with the Greeves barrel.. Quote Link to comment Share on other sites More sharing options...
woodbutcher Posted September 14, 2011 Report Share Posted September 14, 2011 combustion chamber at rear and squish area at front on 240/280 rotax heads Quote Link to comment Share on other sites More sharing options...
trialrider Posted September 14, 2011 Report Share Posted September 14, 2011 This is taken from an article in the Greeves mag Leading Link No 49 Dec 1992 by Andrew King who is an expert in Greeves "The alloy cylinder head .The head with the off-set squish area is definately a TES item.ie.trials.The squish area should face the front.There is no truth at all in the theory of plug to rear for scrambles. This is pure baloney!.The scrambler has the full ,symetrical,hemisperical head." Quote Link to comment Share on other sites More sharing options...
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