Timing mark confirmation

Status
Not open for further replies.
C

Commando75

Joined
Aug 25, 2008
Messages
134
I finally got around to making sure I had my timing marks confirmed. After checking the little 28 BTDC window on my 75 MK3 I concluded that my primary timing mark was, as has been noted by many, not accurate.

Today I carefully located TDC by making a little tool consisting of a wooden dowel and a piece of rubber tubing. Then I printed a timing wheel from here on the forum. Here is the real TDC.
Timing mark confirmation


Here is TDC on my primary timing scale
Timing mark confirmation


Here is THE REAL 28 BTDC on the primary scale
Timing mark confirmation


Check your timing scales boys and girls!
 
OK, I've been looking for about 5 minuets and cannot find the printable timing wheel. Help, I need one.

edit: I found it.

Dave
69S
 
Oh yea. I'm probably not the only one who didn't know but of course using the wheel on the camshaft is way easier than digging into the primary case. You just use 2 camshaft degrees to every one on the crank. Example:

28 TBDC crank = 14 TBDC camshaft. Simple.
 
Sometimes it's not the scale but play in the rotor key and keyway.

Cash
 
OK, I am more confused again. I was just confirming my timing mark after I installed the timing cover so I could static time my points. Using the timing wheel, I again found TDC like Mick does in his DVD with the wheel on the drive side and checking the mark BTDC and ATDC to find the true TDC. Trouble is, my timing mark on the rotor is showing 28 deg. when my pistons are at true TDC. What is going on here? If I put the pistons 28 deg BTDC, the mark on the rotor is not even visible in my primary cover. I don't see how I could have installed anything wrong on the crank, there are keys for everything and nothing that I know changed. Please help.

Dave
69S
 
Clam down - worse you could of done is get it wrong by 180', which is non issue to electronic ignition but not the points.
1. You got TDC if splitting the stops and pistons are indeed both at top not bottom.
2. Mark this TDC-0 on the case for rotor line to line up.
3. Back up degree wheel on crank or cam 28 or 14', or what ever you've determined you beast likes and mark that on case to line up with rotor mark.
4. Make note of what factory scale reads in your case vs degree wheel facts.

hobot
 
Well, I really can't figure out what I have done. Yes, I did the back and forth thing to determine TDC, but I have the head off, so am watching the push rods to determine which valve is closed, that seems to be good, just like Micks DVD, it is just that the mark on the rotor is showing 28 BTDC when actually the pistons are at 0 TDC. I've been wracking the brain, and nothing makes any sense, there is nothing that could have changed on the drive side crank, nothing could be put together 28 deg. out. The keyways in the crank for the rotor could not have changed and there is only one keyway on the crank and the rotor. I cannot put the crank together wrong. The con-rods and pistons are fixed in position on the crank. This is one of those times when you just have to step back and wait.

I'll have to pull the rotor to see that the key is in proper, but I remember putting it in.

Time for Margarita.

Dave
69S
 
You can't accurately determine any of this without a piston stop in conjunction with the degree wheel. If you are doing it any other way - eye ball, a rod/pencil sticking in the spark plug hole, even a dial indicator, it is not accurate. It has to be done with a piston stop/degree wheel; it's the only way you will accurately determine TDC and then be able to determine if the timing "gauge" is correct.

When I checked mine shortly after buying the bike it was off by less than 1 degree which IMO isn't worth worrying about.
 
MexicoMike said:
You can't accurately determine any of this without a piston stop in conjunction with the degree wheel. If you are doing it any other way - eye ball, a rod/pencil sticking in the spark plug hole, even a dial indicator, it is not accurate. It has to be done with a piston stop/degree wheel; it's the only way you will accurately determine TDC and then be able to determine if the timing "gauge" is correct.

When I checked mine shortly after buying the bike it was off by less than 1 degree which IMO isn't worth worrying about.
Click to expand...

What's the difference between a piston stop and a dial indicator?
 
I'm using a degree wheel on the drive side crank and a vernier caliper to determine the depth of the pistons either side of TDC. The rotor must have not registered with the key, it is coming off for inspection.

Dave
69S
 
I'd really recommend you use a piston stop. No engine building shop uses anything but a piston stop/degree wheel to do such checking.
 
It is more of a hassle but crank shaft degrees are more accurate than cam. Also your dead stop is best if it stops the piston at least 30 degrees on each side of TDC.
Now when you have found TDC and checked it a few times you can go back to the 28 mark than a bit more so as to land on 28 going in the right direction. The action of the valves should not be ignored in fact it’s a good time to check the points of opening and closing. A while you in there kind of thing.
 
Real crank end hassle is attaching *wheel to its end.
DynoDave gave me one of his mount widgets, but don't know if he markets it.
Might consider another doodad to add to your inventory of handy kits.

Timing mark confirmation


hobot
 
Gday Hobot,
thank you for posting that timing wheel adapter. I wonderd how some mounted them. Off to the lathe I go!
Foxy
 
Status
Not open for further replies.

Similar threads

Kjell
Timing mark- engine backfiring through carburetor
Replies
11
Views
747
ashman
ashman
R
Can’t Get Timing Correct
2
Replies
30
Views
1,586
Ian James
I
gpzkat
Confirmation of my Wassell ignition setup on N15CS
Replies
9
Views
504
Schwany
Schwany
Dan1950
  • Locked
Verifying Ignition Timing Marks
2
Replies
32
Views
2,550
marshg246
marshg246
Pup
  • Locked
Confirmation that I am a dinosaur of a biker
2 3 4 5 6 7
Replies
138
Views
8,012
concours
concours
Back
Top