- Sat Sep 15, 2018 11:38 am
#79170
@ bumpkin,
let's just say that the carburation has to be right for the bike to start as well as run, if the mixture's off it can spit back. An air leak at the carb mounting will mess things up nicely.
Over-advanced ignition is the other cause. With the Electra-X the importers were getting lots of warranty claims for destroyed sprag clutches in the e's gear train whern the bikes backfired. Some electronic (TCI) ignitions are over-sensitive to voltage drops and can go onto full advance, not what you want when starting. Boyer Mk3s were a classic example when fitted to MK3 Norton Commandos, the extra load on the battery caused by the starter motor kicking in would send the ignition full advance and BANG-CRUNCH. Goodbye Commando sprag clutch. Sadly the Electra-X had a similarly expensive habit. The Watsonian-Squire solution was to introduce an add-on spark delay device for the original black TCI box. This would allow the enginge to get to a proper cranking speed before allowing the ignition to function, by which time the battery should have recovered enough from the voltage drop to allow the ignition to fire at the right time. Vroom vroom rather than bang crunch. Later Elextra-X bikes should have been fitted with a green TCI box with the spark delay built in, by 2007 your bike should have had one, but it would be worth ckecking.
However THE biggest help to electric starting an Electra-X after getting the valve lifter to work or replacing it with a decompressor valve has to be a really healthy battery, and the OEM batteries just weren't up to it. Fitting a Motobat 14AH AGM battery should make a big improvement.
@ wheaters,
yes, they changed quite a lot in the engine, it was because the factory felt they needed to introduce a "lean burn" engine in the late 1990's with an eye on future emissions regs. They cylinder head has a more modern combustion chamber design, and which needs to run at a higher compression ratio to get hot enough for the lean burn, but with an alloy cylinder barrel to stop things getting too hot. To achieve this with any sort of reliability they knew the classic Bullet needed a beefed-up bottom end, which came in the form of a steel conrod and needle roller big-end, and they also changed the oil pumps from plunger to gear type with much higher capacity. Only the crankcase castings were the same, though there are detail machining differences.
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