Topic: how to set the points from scratch, including the plate

[Slim_SLC]

recently picked up a 78 550k.  it was running poorly, so I pulled off the points cover and tried to reset the old points (looked still in usable condition).  removed the timing plate thing that the points sit on just to clean up the area a little before reassembly (the bike had been sitting for some time and was a little grungy all over).  when reinstalling the timing plate and new points I am not able to get them set close enough for it to start.  I don't have a timing light.  Is there any way to set it just roughly enough to get it to start so I can set the timing correctly with a borrowed light?  It seems like I would line up the F mark for 1&4, set those points right, rotate the cam, set the 2&3 points correctly, but then it still won't start.  I tried adjusting the timing plate (first to advance timing a little, then to retard a little......readjusting the points each time, but I find myself confused and frustrated.  IS there a trick I am missing.  This doesn't seem like it should be so hard. 

I also only have a manual for a 750, but I assume the procedure would be roughly the same, no?

[greenjeans]

Here's a link to a 550 manual you can download    http://www.sohc4.us/forums/index.php?topic=426.0
Also here:  http://www.cryscom.nb.ca/Documents.htm  (this was working earlier today, but isn't now so check back later)
I downloaded that one a while back and it's a good resolution so you can see all the pics & text clearly

[Slim_SLC]

thanks green.  188 pages.....better not print that at work!

[jdigga]

I just replaced my points and condensors this week, as well as all the screws since they were chewed up.

I found it easiest to set the points gap first.

Then if you notice at the top of the plate there are two tiny hash marks and two corresponding marks on the engine casing.  If you line these up you can get a starting point.

Then you can set your 1/4 timing, then the 2/3.

[luvhonda750]

as well as all the screws since they were chewed up.

Yeah, I did the same, I refer to them as boogered up by someone else! As were some of the valve tappet covers.

Slim, Don't give up, you are almost there, advancing the timing slighty will make it start easier, then you can back it off later. Make sure your spark is coming on or near TDC on the compression stroke.

[jdigga]

Speaking of valve tappet covers...

Slim, have you done any other engine maintenance since you got the bike like a valve adjustment or carb work?

[Slim_SLC]

I have not checked the valve clearance, but I have removed and cleaned the carbs....it was running after that, albiet poorly.  So, that's when I removed the points, etc.  Now new points are on...and here is an update of my problem.  I set the shaft so the F mark for 1-4 is lined up with the hash mark.  Then set the 1-4 points gap to the correct clearance.  Then, the problem is as I rotate the shaft from there, the points open more, increasing the gap! My understanding is that at the F mark should be the max opening of the points gap.  Is this correct? or is is normal for the gap to increase after the F mark?  My battery is fully charged, but until I can get this gap set for the 1-4 there is not even a way to proceed to the 2-3 points gap and clearly no hope of getting it roughly close enough to run and time it correctly.  So, to rehash....I set the F mark for 1-4 to the timing hash mark...set the points gap for 1-4, and rotate the cam to do the 2-3 points gap,  but as I rotate clockwise from the 1-4 F mark, the 1-4 points gap increases.  I don't think it should.  I have tried rotating the backing plate both forward and back to see if that makes a difference, but it doesn't seem to make it any better.  Please help.  I'm so frustrated right now I'm about ready to give up and take it to a mechanic, which I really can't afford.  Plus, I really want to learn this. It's not much use owning a 30 year old bike if you can't work on it.

[jdigga]

You should set the point gap when you can see the advance spring post in the sight hole, not the F mark.  It's just a little bit past.  When you're rotating the engine you can feel the tension release right at this point.

[Slim_SLC]

this clears up so much. I will try this tonight when I get a chance and report back if it doesn't work.  I also had a brainstorm when I was thinking about it this morning and wonder if when I put the backing plate back on the bare shaft, if I might have put it on turned too much in one or the other direction.  The only light I have is a basic test light, the kind with the pointy probe on one end and the alligator clip on the other end.  is this kind possible to use to get it timed very basically? I would feel better about getting the timing dialed in if I could get it running even a little bit.  I will first check the tappet adjustments.  The oil also needs to be changed from sitting, so I may be jumping the gun to want to get it running right now....but you know how it is...when you buy a bike that's been sitting you want to hear it run to give yourself some hope. Maybe that excitement makes me tend to want to put the cart before the horse a little bit here.  Thanks, guys.

[jdigga]

Use the "spark method" as described in the Ignition & plugs FAQ.  You have to take your time but I've found that even after doing it this way, my timing is spot on when checked with a timing light.

I think you're just about there--but with your previous attempt you were inadvertently making your gap too large.

(For my bike, doing a valve adjustment made the difference between not starting at all and firing right up.)

[Slim_SLC]

okay, so to follow up.  I somehow got the bike to run for about 5 seconds on saturday night.  it was a good feeling, but I couldn't reproduce the results.  I am going to a valve adjustment tonight and see if that helps...as I hope it will. 

Regarding the timing plate...I took off the small nut and the large nut holding it on and found that it is impossible to put it on wrong because of the slot and the little nubs on the back. so that was good to know.  I finally got the points adjusted correctly per the instructions here and I think that's what got it to fire.  I got my new bars put on and I'm dying to ride this thing so I hope adjusting the valves will get me closer.  Thanks again guys!

[Slim_SLC]

update:
Okay, I set the crank to the T mark for 1-4 to try to adjust the valves.  removed the tappet covers for 1 & 4 to see which had the rocker arms loose....neither felt loose to me.  maybe #1 wiggled just a tiny bit, but not what I would call loose.  I couldn't even see a place to slide a feeler guage to check clearance, so I gave up on that.  adjusted the timing just a tiny bit again and it fired up....but only with the choke on full.  the airbox (stock) is removed at present, so that would explain some of the lean factors...but is this enough to cause it to not run at all without the choke?  Also, a problem with the choke.  the #4 carb butterfly (actuated by the choke cable), does not close by itself.   I have to reach down and flick it with my finger to get it to close....then, even after the choke is fully pulled, it slides itself back in.  When the bike is running, this causes it to die.  I'm about ready to take this to someone as I feel in over my head.  I know taking the carbs apart to clean them should not big that big of a deal, but I don't have the money to buy a manometer or the knowhow to make one so taking it to someone that can adjust my valves and go through the carbs seems wise at this point.  Also my fork seals are shot.  For $400 for the bike I'm not too disappointed, and yes, I'm confident that I could learn how to do everything on this bike myself, and plan to learn in the future,  but right now I just want to ride.  Summer is burning and gas is outrageous.  Is this smart, or am I going to regret not figuring the whole thing out on the first try?

[jdigga]

Sounds like your valves are too tight also.  At your 1-4 T mark, both valves of either #1 or #4 should have a little play.  You'll need to bend your feeler gauge to get it in there.  I'd recommend going back and completing the procedure.  Once you've done it one time, it's actually very straight forward--I just did mine earlier this afternoon in about 15 minutes).

These engines don't run very well without the airbox--not enough airflow restriction.

Regarding your carbs--you don't necessarily need a manometer to get them in the ballpark.  If you pull them off the bike to work on them, you can use a drill bit to bench sync them--basically use the bit as a gauge for the slides.  As for the #4 butterfly, I'll take a look at mine and see what that might be (they're off the bike at the moment).

Personally I'm too much of a cheapskate to pay somebody to work on my bike.  Beyond that, I just like tinkering with it.  I tore the whole bike down this weekend to open the engine for a head gasket change, and I should be back on the road by Tuesday night (knock on wood I don't have any major oil leaks).  I think you'll get much more satisfaction in getting it running on your own, and your wallet will stay a little fatter for more toys for your bike!

[333]

2 things to remember when checking the valves. 1- Do it when the engine is absolutely cold.  2- when the 1-4 mark is lined up and the #1 valves aren't loose, rotate the crank 1 full turn.  It must be lined up on the compression stroke on cyl #1.  This only happens every OTHER time the 1-4 marks line up.

[jdigga]

Or, if the #1 valves aren't loose, just adjust the ones on #4.    The procedure where you do 4 and 4 to be difficult; I like to do one cylinder at a time even though it means I have to rotate the engine 4 times.

[Killer Canary]

Keep at it! Sounds like you know a lot about your bike already.
You can do a fairly accurate carb synch by sitting the carbs on a table at a slight forward inclination; then place a small ball bearing in each of the carb throats on the air box side, against the slides. Then, open the throttle bellcrank slowly until a bearing falls through. Adjust the carbs so that all the bearings drop at the same time.

[Slim_SLC]

I am tempted to keep at it just because I don't really want to lay down the dough for someone else to do it for me.  So, when doing the valve's....where exactly does the feeler guage slide in?  I don't mind bending it if I have to, but I just cannot see where it's supposed to slide into.  Also, my fingers are huge, so doing anything inside those tiny holes is going to be tough. 

I got it adjusted so it will consistently idle with the choke on now.  I think I'm going to try to put the airbox back on tonight......if I can figure it out.  I received the bike with the airbox and all associated parts behind the carb in a bag.  Actually, that would be dumb.  I think i'd better take the carbs off first and see if I can get them all cleaned up.  I'm scared to death of this, but what's the worst that could happen?  It's just a machine, right?  I think I can probably figure it out.  I'm a little worried about getting the pressed in jets out without marring them up too bad, but I think I'm going to give it a go.  Thanks for all the words of encouragement.  I have rebuilt vespa engines before and that was scary at first too, so I think I can probably do this if I keep a clear head and label all the parts I take off.  I guess I will probably just rebuild the carbs while i'm at it.  Wow.  I'm in way over my head here.

[jdigga]

Nah, you're not in way over your head; if anything you're just psyching yourself out.

Valve adjustment--the gauge will slide in just above the disc you see in there.  To make it easier, just unscrew the adjuster way out the first time so the gap is really obvious.  You'll need to bend about 1.5" of your feeler gauge about 80 degrees to get it in there.  Which is why I prefer to do each cylinder individually so they're as high as possible in the inspection hole.

Yes, do the carbs once so you don't have to take them off a bunch of times (personal experience).  The pressed-in jets will come out with a small twist and straight pull.  I protected the jaws of my vice-grips with something but others have chosen not to.  You really have no choice but to take those out in order to get them truly clean.

[lrutt]

not going to read through all this but I ALWAYS static set timing and never have to mess with them. Set point gap then rotate enginer to the F mark shown at the points plate, doesnt matter wihch cyls. Make sure all wires are disconnected from point and hook up a volt/ohm meter. Then with plugs removed, rotate the enginer by hand to see where you are at with points against the timing mark. Twist the plat until you get meter movement right with the F set on the mark. cinch the plat down and retest. Then do the same with the 2/3 combo. Works every time. I've done this for over 30 years and everytime i've ever check with a light afterwards they are always perfect. It's so easy to do.

[Slim_SLC]

wow, that sounds like a good trick.  I've been meaning to get an ohm testor, so this will be a good excuse.  I am psyching myself out for sure.  It's just intimidating cracking into something that seems so complicated for the first time.