Hitchcocks Forum

I converted my head for the twin spark mod using the twin lead coil Part number 92075 Caps not included ( I used NGK resistor types ) and good God what a difference , smoother power , no spitbacks and the slowest tick over speed ever ! I found by looking at my combustion chamber that it was burning on one side and now it's even , still doing the 60 mile big end test with the double flow oil pump and still no knock after the silver bits in my rocker caps , might be new piston rub off , 10 miles into a 60 mile test but combustion is now correct in the center ..each flame meeting in the middle less soot and no timming changes needed me thinks , the tickover is so slow ..never missing a beat ....fantastic .

Thanks for the feedback Phil, perhaps you could let us know more after the 60 miles? Specifically fuel economy improvement/deterioration and your similar perceptions of power delivery?
REgards, Mark

Twin plugged a 612 about 6 months ago, used a twin outlet coil from one of my Hondas, no noticeable difference, if it was it was very small

Hey Mark M , the improved fuel economy should be true in theory as so will the sooty burn so it's kind of a lean burn classic now , a real tan on the spark plugs so less need for the dreaded de-coke , the bike aint cut out yet as it used to do at tick over and I have big ports , valves and the sports cams , it really does tick over like my Grandfathers 1935 Dennis wide blade lawn mower ( 600cc side valve with cast iron piston ) , this is an improvement fuel usage , it still crackles on the over run but I really do recomend the mod .
The twin lead coil gives a very fat spark with the digi ignition conversion , first kick cold starts at last !

I should have said the way to start the engine using the MK2 concentric ( the choke dont work ) is a hand made thin foam S&B filter cover with 2 induction kicks too suck the fuel level higher as the carb has no tickler float level over ride , wets the plugs just right .

Thanks Phil and do come back later on!
REgards, Mark

I used to race/run Ducati singles with twin plug heads. With high comp. pistons it was vital to have a spark either side of the piston but with a flat topped piston I'm surprised it makes any great difference. At least it's a mod that does n't actually change anything, it just improves things. Do keep us updated on this one.

Say Norm - would the twin plug set-up on a 612 reduce its tendency to ping do you think? And is it much of a chore to get it past compression for starting?

Hi Barry that is one improvement we think has happened, less likely to ping and getting it over TDC isn't really a problem because it has the long folding kickstarter

Eddie implies Bullet, flat top piston, is that so?