Timing Question

62benly · #1 08-18-2010, 09:11 AM

Hi there,

I finally got my benly put back together, I cant wait to wake this baby up.

The motor would not start and I checked the timing situation and was sure I had it wrong the first time so I fixed it as I saw others had on this forum. What the one guy did with the laser was pretty nifty and I thought I'd just eyeball it instead sorta.

I found this mark to the left of the seam up top. Is that what I am to align the little cam gear 'O' mark to? Then I imagined a line like the laser and set the drive shaft gear 'O' mark to line up on the low side of the shaft.

I drew a screwball picture and took some pictures.

P.S. When the T mark on the magneto is lined up with the timing mark, the cam shafts 'O' mark is straight up aligned with the seam. If its like that the timing is good, right?

Spokes · #2 08-18-2010, 08:07 PM

The only way to tell for sure is to remove the points and advance mechanism. The keyway on the crankshaft/flywheel should be at 12 oclock.

So if the cam sprocket is at 12 and the keyway is at 12, you should be ok.

Assuming you have spark and fuel, I would guess that you need to check the valve adjustment. If the valve lash is not correct the motor will not start and if you keep cranking the engine, you should get a nice shotgun blast out of the exaust.

62benly · #3 08-19-2010, 09:43 AM

Thanks Spokes.

So I tore it down a little and took some pictures of the key and the cam sproket.

Looks like when the key is at 12 the sproket is at 11:55 or so. Looks like I need to adjust it just a tad.

Do I have the right idea here?

Spokes · #4 08-19-2010, 01:04 PM

The cam sprocket "12 oclock" mark is as shown. Move the mark to said position and check your keyway.

Or,since you have the engine disassembled to this point and to make sure the timing is set, or needs to be set, remove the remaining housing to expose the timing mark on the crankshaft.

62benly · #5 08-19-2010, 01:22 PM

Hello,

Here are some pictures of the cam sproket 'O' and the drive shaft 'O'.

Your picture of the 12 0 clock mark is great help.

Spokes · #6 08-19-2010, 02:31 PM

It looks like the timing is OK. Check the pic

The next thing to check is the rocker clearance to the valve stem (valve lash) They should be at .003 each.

62benly · #7 08-19-2010, 02:51 PM

I measured them a loose .004, and made sure they wiggled just a tad. The spacer fits in there very easily. should it be difficult to push the spacer inbetween the tappet and the end of the valve? I took some pictures of one of the tappets.

Spokes · #8 08-19-2010, 03:55 PM

Well I have to say that .004 is OK and the spacer should glide in and out without play. But, being that your at an angle when you try to measure, it may seem tight. So again if .004 is accurate then you shold be good.

So the timing is good and the valve lash is good (from my perspective)

Sam Green · #9 08-19-2010, 11:13 PM

All you need to do now is put the split link the right way round on your cam chain or it will come of and smash all your hard work.

Sam.

62benly · #10 08-20-2010, 07:07 PM

Your right sam. Thanks for the pointer. I will fix it right away. Thats the last thing I need is something terrible happening like my motor getting smashed.

Still no start. Not sure why. Got spark, gas. A little smoke comes out the wrong way out the carburetor. It kinda sputters out of it quick like.

Im sure Ill figure this out soon enouph.

Spokes · #11 08-20-2010, 07:32 PM

Check the tappet clearance on the intake valves. You may still have one (or more) that may not be fully closed. The "smoke" the wrong way through the carb can only occur when an intake valve is not fully seated.
Just for fun, check out the 4 cycle engine animation for a quick refresher.

http://www.animatedengines.com/otto.shtml

62benly · #12 08-21-2010, 11:33 AM

I adjusted the tappets three times, from loose, to snug, to tight againts the .004 spacer. I was getting some sputs of flame out the carb on my last try, so im thinking this is still a timing problem.

I really appreciate your feedback. Im excited to get this dog barking.

Spokes · #13 08-21-2010, 12:44 PM

My pleasure to help. I checked my manual to double check the timing marks. You appear spot on. I hope Sam Green chimes in. I have to revert back to student now that all of my input has failed to get you going.

Sam Green · #14 08-22-2010, 12:15 PM

If the valve timing and tappet clearances are OK, you have spark and fuel but still won't start, chances are the ignition timing is miles out.
Put a small 6v test lamp between the points and earth. If the points are clean and gapped properly, with the ignition on, turn the crank slowly anti clock wise with the spark plugs out untill the f line on the rotor lines up with the ignition timing mark through the hole at 2 oclock just off the timing back plate. You have this hole in one of your pictures that you posted.
As the two line up, the light should come on. If it don't, move the points back plate left or right to correct it.
If there is not enough adjustment in the elongated slots, chances are, the complete cover that the points back plate is fastened to is not in the correct position. You might not think this cover can go on wrong but it can.
You may have to loosen the cover that the clutch cable goes through while you do this as it buts up to the cover that you are trying to adjust and restricts movement of the timing houseing cover.
Good luck.

Sam.

62benly · #15 08-24-2010, 08:24 AM

Look at these two pictures (Smithers Pic is just a link here http://www.fourwheelforum.com/showth...nts+adjustment). When smithers F mark is lined up the high side of the rotor is just beginning to push up on the point arm.

When my F mark is lined up the low side of the rotor is begining.

So the points are suppose begin to open when the F mark comes around but mine begin close, no matter what adjustment I make by rotating the mechanism within its bounds or trying to manuver the whole engine case cover.

Could it be that something else is out of whack. Yeah, yeah, it could be me and thats why I really appreaciate the benly masters who frequent this forum.