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Dave,Are you running Monoblocs or Concentrics? Are they worn? I would try the guys at Dresda who took over from Dave Degens - they might have ideas about jet sizes to start from. Also Les at Norvil might be able to advise before you throw rolling road money at it. Is it on electronic ignition or a mag or something else? What camshafts do you have - perhaps E3134's? A steady tick-over can be elusive with lumpy cams but you ought to be able to get the mixture pretty close.Ian
Could it be worth an educated guess start point Dave ?If so, I'd err on caution with base level ignition advance (if too much it may have contributed to nipping the pistons) based on shorter stroke.Burn time would stay the same for an equivalent combustion chamber and mix, but the piston linear approach would be slower at any given rpm. The combustion time constant vs shift in timing angle measured in degrees doesnt show the full picture.Effectively I'd see it as a shorter stroke needs less advance (in degrees) to match the combustion time of mixture burnt to prevent the whole event going off too far before tdc and trying to go backwards against forward inertia of crank etc. The start point would be sensible at the lowest degrees specification to allow safer margin.Jetting, some hold the view that excess fuel should be used to "cool" the combustion and compensate for other compromise in design spec, unless quantified its hard to support this.Worthwhile taking 10% off (from existing Degens spec) main jet size, running conservstive advance (perhaps- 2 from lowest listed conventional spec) and run on equivalent of NGK 7 heat range plugs to see what it'll give you. Note:- you'd not use a 7 grade plug on a dyno as it's likely to overheat the ti0 and give you problems.Getting hot under light load suggests static advance is too high as there's not much other input to it without wide open big load running conditions. Promotes erratic tickover too.Also, if the main jets are much above a decent range for that carb it starts to loose the fine metering effect in comparison to the needle taper, making it difficult to resolve apparent errors.