|
|
Post by lain on Apr 1, 2016 7:45:14 GMT -5
Yeah, lain - that's pretty much the obvious guess: insufficient starting power, either because of the starter motor, the wiring, or the battery. But the first thing Mark did was rule all that out by using a fully charged car battery (plenty of reserve power), getting a new "high torque" starter motor, and connecting the jumper cables from the battery directly to frame and to the starter + terminal. No change. Then he took the right side cover off and found a distortion in the starter clutch, so he replace that. No change. So the next logical conclusion is that the distortion in the starter clutch was a result of the problem, not the cause. So, not much left other than taking the top end apart. What's odd is - early on he took the spark plug out and the engine spun like a top using the scooter's battery and wiring. That almost certainly points to insufficient starting torque .... but that's all been ruled out. Odd problem, to be sure! If the entire time he has been trying to start with WOT then I believe he's accidentally distorting the results. Even a good battery with new wiring and all good components may have trouble starting at WOT. I can't start my scoots holding them at WOT it sounds the same, but leave the throttle alone they all start up without effort. Not to mention I'm sure when he does get it started it's going to go straight into that bench doing that lol. I'm not entirely sure but doesn't starting at WOT decrease compression? |
|
|
|
Post by rcq92130 on Apr 1, 2016 11:53:51 GMT -5
He cannot get a sensible compression reading because he can't yet get the engine to turn over. it turns until it hits the high point in the compression cycle, and stops. So - compression readings remain meaningless.
WOT should not have any effect at all on the ease of turning over the engine. All that does is make sure the engine breathes as much as it likes. Of course, it might or will affect if the engine actually starts - but not if the engine will turn over. At this point, Mark is still trying to get the thing to just turn over. Something is preventing that - first guess of insufficient starter torque seems to not be the culprit. Starter clutch seems to not be the culprit. To my knowledge the variator belt is off, so some weird lockup on the transmission side seems to not be the culprit. Not much left other than the top end and the crank itself. (Oh - and he took pix some time ago to verify the valve timing was correct). The oddest thing is that when the spark plug is out the engine spins just fine - which, again, implies insufficient starter torque - except Mark ruled that out.
|
|
|
|
Post by rcq92130 on May 26, 2016 13:29:04 GMT -5
Mark - did you ever get this figured out?
|
|
