I know about the scientific method of changing one variable at a time and all that, but I like the blunderbuss method for problems like this. In the end it's usually quicker and you personally acquire a certain amount of knowledge in the particular issue. Buy a rebuild kit for the carb, take it off and go through it. It could be; the air enrichment plunger isn't sealing off completely when you turn it off, the air jet in the pilot circuit is plugged, the float valve isn't set right or isn't sealing completely, the floats are filled with gas and don't float like they're supposed to. There has to be lots of other reasons too, but you'll come across it all on dissection. Or it's as simple as the air screw that's screwed in all the way, (base setting is one and a half turns out from lightly seated and turning it out makes idle and low throttle settings leaner.)cjatwell said:Hi all.
I have a '74 MK 11 A 850 Commando. Noticed it getting bit harder to start recently .
Until the other day had no spark at all and wouldnt start.
Pulled out plugs and replaced with new.
Started fine.
The plugs were only in the bike a few months and are now useless.
The electrodes are black in colour and are what i would describe as 'sooty'.
What is the cause of this and how do i prevent it happening .
I run a single mikuni carb .
L.A.B said:As I understand it, the bigger the gap, the greater the voltage has to be to jump a spark across that gap?
And while any standard coil may be able to produce a spark across a .040" or so gap in free air with a new plug, it may not continue to do so under compression,-especially once the plug has become worn or slightly fouled, as I believe more voltage is needed to fire a worn plug than a relatively new one?
highdesert said:You tried to start it up with NO choke?
40 degrees here, just took the commando for a ride. Depressed choke lever and one good firm kick to get it lit up, then immediately raised
the choke and kept the idle going with the throttle. You NEED the choke lever down with NO throttle and a good kick to start it,
the choke is NOT for warmup, but starting only. Have you verified Mikuni settings?
cjatwell said:I have just tried to start her again today after riding yesterday.
Bike tries to fire up with no choke but wont run.
When i depress the choke and try to kick her , there is completely nothing. Doesn't attempt to fire up.
Just ruined another set of plugs.
Whats my problem.
highdesert said:Fullauto, curious what altitude you are at?
Don Tovey said:If that fails get a Suzuki Bandit