Ignition timing not using marks

jdallen · Posted: November 9, 2008, 12:03 am Post subject: Ignition timing not using marks

I've recently installed a rewound rotor, and I'm thinking it was around that time also that I've had more trouble starting the bike. I've played around with the timing (boyers are timed to full advance) at full advance mark and retarded slightly. I'm hesitant to advance it past the advance mark..... If the rotor mark isn't the same as the stock rotor I previously had, how do I set the timing? Should I use the method where I rotate the boyer plate until I get the highest idle, then back it off a tad?

When it's timed to full advance exactly, at 1200rpms the mark is dancing around about 1/4" behind the F line.

any ideas?

5twins · Full Member Joined: Aug 05, 2006 Posts: 1616

Maybe you could positively locate TDC and see if the "T" mark lines up. If it doesn't, then your timing marks would be off by the same amount.

jayel

jdallen wrote:

When it's timed to full advance exactly, at 1200rpms the mark is dancing around about 1/4" behind the F line.

any ideas?

so it's running full advanced at the unmarked line, but when you let it idle down to 1200 it's a 1/4" behind the "F" ?

5twins · Full Member Joined: Aug 05, 2006 Posts: 1616

I guess the question now is what you mean by "behind". Is the rotor mark to the left or right of the "F" marks?

jdallen

To find TDC, is it accurate enough to just take the spark plugs out and watch the piston?

Yes, I've timed it at 3500-4000 rpms at the far left unmarked line. When I let it go back to idle at about 1200, the rotor mark is now about 1/4" behind the mark to the left of the F. I know there's 2 marks for a range, but it's also to the right of the mark on the right of the F. By behind I meant to the right. I guess that wouldn't be behind b/c the full advance line is BTDC.......

jdallen

OK, I was a little off with the 1/4", the rotor mark is 2-3mm to the left of TDC when the piston is at TDC, so when I'm timed to the full advance mark I am actually 2-3mm retarded. So should I just scribe a new mark or leave it at that?

jayel

did you use a dial indicator to find TDC? just looking at is doesn't work

jdallen

Nah, I don't even know what you're talking about jayel. please tell me how. I just rotated it and watched a couple of times and stopped it when it appeared to be at the top.

jayel

"when it appeared to be at the top."

exactly my point, a dial indicator is a precision gauge that measures in the thousandths of a inch, eyeball measurement could be far enough off to effect your timing, you might be able to find a dial caliper and use it thru the plug hole

5twins · Full Member Joined: Aug 05, 2006 Posts: 1616

Does the Boyer still use the original advance unit? If so, it appears yours may be worn. The timing should advance a set number of degrees (about 23) from idle (retarded) to full advance. It appears yours is advancing more. The stops for the advance weights control this. As they wear, the weights can fling out more and the timing can advance more than it should. The 2 "F" slash marks represent 13°-17°BTDC, a span of 4°. The fact that at retard, your rotor mark is about a quarter inch to the right of the "F" is adding probably 5 or 6° to that 23° of advance range.

You may not be able to accurately dial your timing in if the advance unit is worn. If you set it correctly at full advance, it will be too retarded at idle. Maybe that's why it's difficult to start. If you set it correctly for idle, it will advance too much at full advance. That can hole a piston over time.

To accurately find TDC, you could use a tool something like this .....

www.handsontools.com/I...-6405.html

yamaman

I think this is the info that comes with the boyer, tech 6 might help:

www.xs650.org.au/tech.html

Retiredgentleman

Boyer does not use the advancer weights. They have a threaded rod that goes through the camshaft and supports the spinning magnets. They must have electronic advance.

jdallen

I know using a TDC indicator like 5twins linked to would be best, but I eyeballed it pretty well. If anything, I'm on the conservative side of how far it's off. It is definitely on it's way back down when the 2 marks line up at TDC. I think I'm gonna set it to the full advance mark and since it doesn't ping w/93 octane in the tank, I might try to advance it just a micrometer more and see how it does. 2-3 mm is only a couple of degrees retarded, isn't it? I checked on a few thing. compression is about 140psi on both cylinders. starter relay is working. (according to the yamaha manual's test) I get a click and resistance of .02. I haven't ruled out the starter motor and to be honest retiredgentleman, I'm kinda scared to jumper it, I'd probably goof it up and see sparks flying everywhere!

I noticed that I've got a very small amount of fuel in the rim of the air filter, I'm gonna search for threads about this. I just checked my floats the other day, but what if the float bowl's getting flooded, that'd make it awful hard to start wouldn't it.

anybody know another way to test the starter motor? if not I might have to jumper it like RG recommends.

jdallen

I just read about mikesxs's air pods possibly covering the air jets around intake bell. I've got those same pods, probably the PO purchased them around March of this year. Was this around the time he was still selling the new and unimproved version? Can somebody post a photo of where exactly those air jets are located. Last few times I took off the air filters I really put them on far onto the carb thinking that it would be better to keep from having any air leaks.....not knowing. Perhaps I've covered up those holes.......

yamalama · Full Member Joined: Nov 14, 2008 Posts: 26

If You Doubt The Mark On Your Rotor. Just Check It, An Easy Way To Do This Is To Remove The Plugs, Get A Thin Wooden Dowel Install It In The Spark Plug Hole, Turn Your Motor Over By Hand With A Wrench On The Rotor CCW, Watch The Dowel Rise And Fall As You Do This. As The Piston Reaches Top Dead Center, Right Before The Wooden Dowel Starts To Go Back Down, Your Rotor Mark Should Be At The TDC Mark On The Stator Make Sure The Dowel Doesent Bind In The Cylinder.

yamalama · Full Member Joined: Nov 14, 2008 Posts: 26

I Have A BB Ignition On My Bike As Well, The Boyer Has No Real Fixed RPM For Seting The Timing, You Need A Timing Light To Set It. This Is Done By Reving The Bike Up And Watching The Rotor Mark Move Up To The Advace Mark On The Stator But Not Past It. Ive Found It Reaches This Mark When The Bike Is Reved About 3500- 5000RPM's. It Will Dance Around There A Little. Just Make sure It Doesent Run Past The Advance When You Rev It Up.

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