No mark on flywheel?
Posted October 15, 2008 - 03:30 PM
I'm trying my first valve adjustment. When placing the bike in TDC, I can see the dimples on the cams line up as they are supposed to.
However, I'm looking for the mark on the flywheel to indicate it is in TDC and it is not there.
I can't see a mark on the entire rotor (flywheel). Has anyone had this happen and any suggestions.
Posted October 15, 2008 - 03:36 PM
You can find TDC with a dial indicator, then scribe the flywheel for future reference.
Posted October 15, 2008 - 03:42 PM
Posted October 15, 2008 - 04:02 PM
Google 'Dial Indicator" for more info.
Posted October 15, 2008 - 04:20 PM
Posted October 15, 2008 - 05:14 PM
Personally, I would only trust a dial indicator to do this.
Posted October 15, 2008 - 06:13 PM
I will pick one up tomorrow. I can see that the dial indicator will have other applications that will be beneficial to me.
Still hard to believe that some flywheels don't have the markings.
Thanks for the help.
Posted October 16, 2008 - 02:26 AM
Scribe carefully, you really only get one shot at it.
Posted October 16, 2008 - 04:31 AM
Posted October 16, 2008 - 07:00 AM
The ultimate means of locating TDC is to create a piston stop, which can be anything that will screw into the plug hole, and has a rod that extends down far enough to contact the piston at some point before it goes over top. Attach a degree wheel to the crank, eyeballing the approximate location of TDC, and rotate the engine forward until it stops. Note the reading on the wheel. Then, rotate the crank the other way until it stops again. Adjust the degree wheel so that it shows the same number of degrees at both stops, and you will have true TDC where the degree wheel says it is.
You can vary this by using a dial instead of a stop by using rolling the engine both ways form TDC to the same distance and centering the dergee wheel based on that, or even by using a simple vernier caliper and doing the same thing.
If you have no degree wheel, and no caliper, you can still be very accurate by bending up a T shaped probe from a piece of coat hanger. Trim the length so that it can be inserted down the plug hole until the "handle" rests on the cam cover and is barely lifted by the piston as it goes over top. Use the same method as above, bumping the rod from both directions to make two marks close together on the flywheel. TDC is right between them.
And, of course, Matt is actually correct in that if you just feel for it carefully enough, you can get within a couple degrees of true TDC reliably enough to time the cams in almost every case.
Posted October 16, 2008 - 08:49 AM
A piston stop can be made easily from an old sparkplug by breaking out the procelin and threading the steel plug body treading a bolt into the now internally treaded plug body. the point of the bolt that will touches the piston should be smooth so as not to mark the piston.
As described above insert piston stop roll the piston up to the stop then mark the flywheel at the case reference mark. Then roll the piston up to the stop from the other direction mark the flywheel again. TDC is exactly half way between the two marks.