Hitchcocks Forum

I've been helping an elderly friend with his 1950 J2 twin port single - the electrics were not charging and I found several broken wires and a non-functioning dynamo regulator all now sorted but now the problem is poor running.
I should explain that the bike has not been ridden for around twenty years and the owner has forgotten if it is slack wire or tight wire advance - the cable enters the magneto on the right when viewed from the drive side. I have tried both and slack wire seems to give the best starting without kick back but tightening the wire results in the engine firing unevenly and eventually dies. On the road the only way to get the bike to run anywhere near acceptably is to leave the cable slack. If I set the cable half way between slack and tight the bike kicks back every time and refuses to start.
After such a length of time I suppose a magneto rebuild will be required but the owner was hoping to get it running again without too much expense as he only intends pottering around the lanes near his home.
He does not have a manual and I am reluctant to start pulling things apart due to his circumstances but any advice regarding the magneto and possibly ignition timing would be much appreciated.

It sounds as if the timing is wrong, probably too far advanced, but probably not by much. It is fiddly rather than difficult to reset the timing, it involves removing the (magneto) drive gear and re-positioning it on the magneto drive shaft which means removing the timing cover. I'd get a manual, they aren't expensive and it will be useful for other info when re-commissioning a bike that's been laid up. In my experience bikes that have been laid up were always "running perfectly before the break" so I'd check everything and assume nothing!

REgards, Mark

Hi, with the advance wire on the right hand side of the magdyno the magneto will be slack wire retard. The ignition timing is 5/16" BTDC full advance with the magneto points set at 0.012". Cheers.