Timing conundrums
- Thread starter Uglyox
- Start date
Midnightpromises
Active Member
Are the rockers lose? If not, rotate the cam gear 180.
REmember, to Fire, the piston must be just coming up to TDC, the valves have to be closed, and the points need to just be opening at the "F". mark,
REmember, to Fire, the piston must be just coming up to TDC, the valves have to be closed, and the points need to just be opening at the "F". mark,
Last edited:
OldGuy
New Member
The points assembly, and the timing advance weights can be reassembled in either of 2 orientations... but only one is the correct way. Take that assembly apart again, and reassemble with a 180 deg rotation. Easy mistake if you had it all apart for cleaning/lube/etc.
That's Murphy's law... if there are 2 ways to assemble, the first try will be wrong 90% of the time.
That's Murphy's law... if there are 2 ways to assemble, the first try will be wrong 90% of the time.
b52bombardier1
Well-Known Member
The timing weights and springs are on the camshaft behind the points plate.
Rick
Rick
Midnightpromises
Active Member
Are you sure on the CT90?
b52bombardier1
Well-Known Member
Absolutely iron clad sure - same for an ST90. They also rust, the springs get weak and leave the advancer assembly stuck too spark advanced. A place called "David Silver Spares" used to carry new springs but I'm not sure anymore - five bucks per spring. That same spring was used in a lot of old Honda bikes.
Rick
Rick
Midnightpromises
Active Member
I wasn't talking to you actually I was trying to figure out how you can reverse the weights on a CT90 advance mechanism. I know you can do it where the advance mechanism is part of the Magneto like on the XR75s
b52bombardier1
Well-Known Member
The 90 CC spark advance mechanism looks like a one-piece assembly but its actually two piece-parts together. At a quick glance, it would appear that there is no wrong way to reassemble it but yes, there is. It's a 50-50 shot as to whether the advancer puts the hump on the camshaft in correct synchronization for properly phased ignition spark, or not.
Please don't ask me how I know this. That day was a very dark day for me early in my 90 CC wrenching career as I had not yet reached the 24th stage of 90 CC engine awareness.
Rick
Please don't ask me how I know this. That day was a very dark day for me early in my 90 CC wrenching career as I had not yet reached the 24th stage of 90 CC engine awareness.
Rick
Midnightpromises
Active Member
Well I'm glad I'm aware of this now I've done quite a few ST90s, matter of fact I have five right now that I'm working on. I never found a spark advance so rusty I even had to think twice about it but I know I prefer the way the points are set up on those rather than those XR and SL70s where they're r behind the damn Magneto and you got to be a young man with good vision and three index fingers to set the damn points and timing LOL