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View Full Version : DIY Tech Tip: Marking Triumph Cam Timing



Tyler
01-05-2011, 10:14 AM
This is a brief article to give you some tips on marking your cam wheels when disassembling your Triumph motor so that you can reassemble it with the proper cam timing. If your bike has stock cams in it then this isn't typically an issue, as the cam wheels, idler gear and crank pinion all have timing marks on them so you can line them up properly. The problem arises when you have aftermarket or 'hot' cams in your motor, and you don't realize it and just pull the wheels off willy-nilly.

In the picture below, the top left gear is your intake cam gear, the top right is your exhaust cam gear, the center gear is the idler gear, and the small bottom gear is the crank pinion (it is on the end of the crankshaft).


http://www.lowbrowcustoms.com/tech/marking-triumph-cam-wheels/marking-triumph-cam-wheels-photo-1.jpg

The first step once you pull off your timing cover is to put a zip tie around the idler gear shaft, this gear is a sliding fit and can easily pull or fall off, if that happens and the gears move you just lost your cam timing. Next, remove the nuts from the ends of the cam shafts that hold the cam gears on. These are a left-hand thread, that is, you turn them the opposite direction to remove them than a standard thread. The nut holding the crank pinion in place is a standard right-hand thread. There are a couple ways to remove these nuts, the hard way, and the easy way. The hard way is with a socket and ratchet, you can put a rag between the timing wheels to keep them from turning the crank and try and get the nuts loose. The easy way is to use an air impact wrench to remove them. If you have an air compressor just buy a cheap impact if you don't have one, this tool will make your life so much easier in the world of vintage (or new) motorcycles. With an impact you can just buzz the nuts right off without having to try and stop them from spinning.

http://www.lowbrowcustoms.com/tech/marking-triumph-cam-wheels/marking-triumph-cam-wheels-photo-2.jpg

I use paint markers I got at an art supply store to mark the wheels. Whatever you use just make sure it can't wipe off, a sharpie marker doesn't quite cut it. Some brake cleaner will do the trick to get them nice and clean so the paint sticks.

An important thing to note is that once you remove the nuts you can see the keyways on your cam wheels. On earlier pre unit Triumphs there is only one keyway, though later there are three keyways per cam wheel. Clearly mark which keyway your cam gear is using so you can put it back the same. Then draw some lines between each gear, using different colors, single or double lines, whatever you need to do so they will only match up one way. I like to put an 'I' on the intake cam gear and an 'E' on the exhaust cam gear just for fun.

http://www.lowbrowcustoms.com/tech/marking-triumph-cam-wheels/marking-triumph-cam-wheels-photo-3.jpg

Let the paint dry thoroughly, then go ahead and remove your idler gear, pull the cam wheels and crank pinion with the proper pullers, and you are all set. Stick the gears and woodruff keys (the little square metal keys that are stock in slots on the camshafts and crankshaft) in a bag and set them aside until you are ready to reassemble your motor. Then it is as simple as re-installing the cam pinion and cam gears, rotating them into the right position and sliding the idler gear back home. Of course, if you mess up this whole process or are using new cams, you can always send your bottom end to Wes at Four Aces to time your cams for you.

guschambers
01-05-2011, 12:32 PM
Thank you for posting this. Good to know, as I'll soon be assembling my pre unit. great info. lowbrow rules.

bikesandbitstn
01-17-2011, 10:08 PM
Isn't the piston at bottom dead center or awfully close to there?? Why not do the cam timing at TDC??? TDC and line up the dots and dashes, but remember it is going to be 90+ revolutions before all the marks are going to line up again!!

Tyler
01-18-2011, 9:25 AM
Isn't the piston at bottom dead center or awfully close to there?? Why not do the cam timing at TDC??? TDC and line up the dots and dashes, but remember it is going to be 90+ revolutions before all the marks are going to line up again!!

I didn't bother because I could see that these are H&C cams, not stockers, and that the dots and dashes would do no good in this case, I wanted to be sure when reinstalling cam wheels that I got the cam timing just as the original builder had set it.