I hear reoccurring themes about our motorcycles I just have to comment on .
I do have to thank our Britt cousins for the early lessons in how to start a motorcycle without getting crippled . It was a BSA 441 Victor with a wee bit more compression than stock . Some will understand Energy transfer ignition , AC lighting , back to back zener diodes and positive earth . If you don't those key words will be an interesting read .
Amyl carbs have a tickler . Essentially This allows you to put a bit of raw fuel in the throat of the carb . Just because it may not be quite obvious You can substitute our mixture enrichment knob for the Britt tickler . So here is the drill . With switch off , tickle , establish tdc with the kicker (and or compression release) , hold throttle open and kick , twice , like you mean it .Close throttle. Find tdc again , reload the kick lever , turn the switch on and sell out on the kick lever . I can't stress enough how lame , limp , half hearted attempts at the kicker will fail to start the bike , injure the rider's ankle and pride and generally be a source of humor for weeks to come from your mates .
If you can't find or don't know how to find TDC with the kick lever have someone that does know show you . If you are the one teaching this have your student first do it by hand (with switch off of course ) and then with the foot . Be patient I've had to show this to a few that needed "several" sessions .
Vibration . So you re-phased guys can take a nap here . In something of an order I'll start with engine to chassis mounting . Leave any of the engine mounting bolts loose and not only will the shake get worse it will eventually destroy the rear mount whether it's tight or not . I don't use any locking agent on any of the mounting bolts preferring to regularly re-torque and inspect .
Pipes , mufflers , inner pipe and brackets . The stock header pipes are double wall . If the inner pipe separates at the connection to the muffler that whole 26" some length is unsupported and dancing to harmonics within . You would be surprised at the result if you ever correctly diagnose and fix this one . I just drill the outer in a couple places just ahead of the muffler joint and plug weld them . Make sure the pipe is snugged up at the head and all mounting points .
The next two will require a bit of advanced or remedial reading depending on your experience .
Valve adjust . Yes a sloppy valve adjust will introduce harmonics into the system as sure as an out of balance crankshaft . I've said it over and over again . There is one correct way to adjust valves and that is with a degree wheel and a dial indicator . The short version is when .001" of valve lash can result in a difference in as much as 5 degrees at valve opening you are sure to introduce "noise" at the crankshaft . Ignition timing . All you electronic ignition types can join the twist crank folk in a nap now . Set the set of points fixed to the plate at .014-.015 " an place a dwell meter on them . It doesn't matter what the number of cylinders is set to or what the dwell reading is as long as it's a consistent reading . Move over to the other side and make the dwell the same . Nor set timing for both and check dwell again . Repeat as necessary until both have the same dwell and fall on the same spot at or near the full advance mark viewed with a timing light . Worn point pivot , mechanical advance parts and near fouled plugs can contribute to timing inaccuracies but what I described is for the most part related to vibration .
Finally , now that the mechanical and electrical is squared away tackle the carbs . . First sync then mixture . Repeat as necessary .
Look these thoughts and procedures won't eliminate vibration in the XS650 but they will reduce it .
The above starting procedure works with a near 12:1 alcoholic 750 and an PMA with just a little bit of gasoline dribbled on the filters . I have it timed on the edge of stupidity or ability to cold start without injury , fixed at 42 degrees BTDC .
I've gone on long enough here to give some food for thought . I've got some thoughts on engine operation and ignition timing for later consumption but this is enough for now .
~kop
I do have to thank our Britt cousins for the early lessons in how to start a motorcycle without getting crippled . It was a BSA 441 Victor with a wee bit more compression than stock . Some will understand Energy transfer ignition , AC lighting , back to back zener diodes and positive earth . If you don't those key words will be an interesting read .
Amyl carbs have a tickler . Essentially This allows you to put a bit of raw fuel in the throat of the carb . Just because it may not be quite obvious You can substitute our mixture enrichment knob for the Britt tickler . So here is the drill . With switch off , tickle , establish tdc with the kicker (and or compression release) , hold throttle open and kick , twice , like you mean it .Close throttle. Find tdc again , reload the kick lever , turn the switch on and sell out on the kick lever . I can't stress enough how lame , limp , half hearted attempts at the kicker will fail to start the bike , injure the rider's ankle and pride and generally be a source of humor for weeks to come from your mates .
If you can't find or don't know how to find TDC with the kick lever have someone that does know show you . If you are the one teaching this have your student first do it by hand (with switch off of course ) and then with the foot . Be patient I've had to show this to a few that needed "several" sessions .
Vibration . So you re-phased guys can take a nap here . In something of an order I'll start with engine to chassis mounting . Leave any of the engine mounting bolts loose and not only will the shake get worse it will eventually destroy the rear mount whether it's tight or not . I don't use any locking agent on any of the mounting bolts preferring to regularly re-torque and inspect .
Pipes , mufflers , inner pipe and brackets . The stock header pipes are double wall . If the inner pipe separates at the connection to the muffler that whole 26" some length is unsupported and dancing to harmonics within . You would be surprised at the result if you ever correctly diagnose and fix this one . I just drill the outer in a couple places just ahead of the muffler joint and plug weld them . Make sure the pipe is snugged up at the head and all mounting points .
The next two will require a bit of advanced or remedial reading depending on your experience .
Valve adjust . Yes a sloppy valve adjust will introduce harmonics into the system as sure as an out of balance crankshaft . I've said it over and over again . There is one correct way to adjust valves and that is with a degree wheel and a dial indicator . The short version is when .001" of valve lash can result in a difference in as much as 5 degrees at valve opening you are sure to introduce "noise" at the crankshaft . Ignition timing . All you electronic ignition types can join the twist crank folk in a nap now . Set the set of points fixed to the plate at .014-.015 " an place a dwell meter on them . It doesn't matter what the number of cylinders is set to or what the dwell reading is as long as it's a consistent reading . Move over to the other side and make the dwell the same . Nor set timing for both and check dwell again . Repeat as necessary until both have the same dwell and fall on the same spot at or near the full advance mark viewed with a timing light . Worn point pivot , mechanical advance parts and near fouled plugs can contribute to timing inaccuracies but what I described is for the most part related to vibration .
Finally , now that the mechanical and electrical is squared away tackle the carbs . . First sync then mixture . Repeat as necessary .
Look these thoughts and procedures won't eliminate vibration in the XS650 but they will reduce it .
The above starting procedure works with a near 12:1 alcoholic 750 and an PMA with just a little bit of gasoline dribbled on the filters . I have it timed on the edge of stupidity or ability to cold start without injury , fixed at 42 degrees BTDC .
I've gone on long enough here to give some food for thought . I've got some thoughts on engine operation and ignition timing for later consumption but this is enough for now .
~kop
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