71 R50/5 ignition timing ?

[jdvorchak]

I got the new points and condenser installed and meticulously set to .16 with the tool I got from Paul Tavenier. Now I always thought the timing sounded retarded and once the points were set doing a static check showed I was right. I had to rotate the points plate CCW a good bit to the S in the center of the timing widow when the plugs sparked. So I think all is good with the world.

then I fired her up and used my MAC timing light and at idle no S in the hole. I reduced the idle quite a bit as the advanced timing now has it idling smoother and faster. Still no S in the hole. At about 3K rpm I showing the F but it's at the bottom of the hole. That tells me I'm a little retarded at 3 K but fast or advanced at idle. Maybe the advancer springs are a little worn. Now it runs great and just purrs at idle after some balancing of carbs mixture and idle speed. I'm inclined to leave it as is but then thought maybe I'm missing something. It starts easily and takes the throttle well.

Thoughts?

[Kurt in S.A.]

Change your gap setting. The 0.016" setting is not gospel...it's nice to have but is really a starting point. A small change in gap makes a big change on timing. The amount of dwell time change from the 0.016" that affects the saturation of the coils is negligible and the bike will run just fine.

You really want timing for the F-mark to be in the middle of the window at full advance. This is where you are spending most of your time. Make sure you get the F-mark in the window and take what you get at idle. If the S-mark is so far off that the bike doesn't start, then you need to look further for the problem. But typically, it will be OK.

Kurt in S.A.

[jdvorchak]

thank you and what you said makes sense. When I started the OT was in the window at idle so I moved it so S was in the window. So it seems pretty tolerant at idle and starting. I'll bump it up a little to get that F in the center of the window and see how it starts. If it starts easily then I'll call it done.

[jimmyg]

FWIW, going from a .016" points gap to .015" will retard timing slightly.

This is useful if your plate is rotated completely clockwise (fully retarded) and you're still having issues getting the marks at idle to appear.

I agree with Kurt about the full advance setting being more important since that's where you're riding most of the time, but a nice crisp idle (on my R90s anyway) seems to require a proper timing mark at idle (S in the window) as well.

jimmyg

[jdvorchak]

No the plate is not up against either stop so I have lots of wiggle room. The trick is to not over shoot and then go back too far then over shoot....LOL you get the idea. If there is a way to adjust that plate while the engine is running it would be nice. I just don't see it.

[Kurt in S.A.]

If there is a way to adjust that plate while the engine is running it would be nice.

There is, at least for the /2 machines. It's called a Pentacomm plate. Most feel that it's a solution looking for a problem.

I think you're on the right track. What I've heard people do is set the gap at 0.016" but find they have to rotate the plate fully to the stops, but still it's not in time. Then they get out a rattail file and hog out the holes. OMG! Don't do that!! Just adjust the gap slightly so that you have some movement either way in the slot. Sounds like you're OK.

Kurt in S.A.

[jdvorchak]

Thank you. I've done a quite a few points and timing on old Hondas, Suzuki's etc. I know that if I run out of room to adjust the point gap but this one seems like I'm right in the middle of the travel for the points plate. Doesn't get any better than that. When I first got in there and set the points the timing lined up perfectly with OT so I guess that last tech didn't know about the S marks for starting point. It ran sluggish and wasn't all that easy to start. Now from cold, I tickle for 2 seconds each side and hit the starter holding a little throttle. It's running in less than one or two turns. So I know that the initial timing is pretty darn close. I'll run it like this for a while before I decide to swap out the advancer springs with new. They are right on the verge of needing to be replaced.... I think... They do hold the arms all the way closed and the advance mechanism was clean and free moving even before I lubed it. Sometimes I think I'm just too much of a perfectionist for my own good. LOL

[Duane Ausherman]

thank you and what you said makes sense. When I started the OT was in the window at idle so I moved it so S was in the window. So it seems pretty tolerant at idle and starting. I'll bump it up a little to get that F in the center of the window and see how it starts. If it starts easily then I'll call it done.

jdvorchak, your problem has nothing to do with the gap. You want the gap to be between .012" and .020". More or less than that may cause trouble. Too little and you will not get cooling. Too much gap and they may float.

You have the wrong amount of timing excursion. It is either moving too far, or not far enough with the advance mechanism.

I would rotate the points plate until the F is in the middle of the window. That is just a starting point. Now see where the S is located. It really isn't important, as you don't ride it at idle, mostly at full advance. It the S is too retarded, then you most likely need new springs. We just tested that by changing to a known good advance, but you probably don't have one laying around

Now, ride it up to around 55-60 mph in 4th gear, as you should now be fully advanced. Open the throttle fully and see if it pings (pinks for the Brits). If it does, retard the timing a tiny bit.

If you don't find any pinging, you could advance the timing a bit. However, with a R50/5, there is no reason to tune for that very slight increase in hp. If you want more speed, or acceleration, take it up in an airplane and shove it out. That is the best way to increase the speed.

I owned and rode one for a couple of years. I only used it at lower speeds and never on the freeway. It was great. I got it for nothing and sold it for twice as much. I know business.

[jdvorchak]

Thanks for the suggestion on the F mark. Looks like only a couple of degrees slow but I'll tend to it tomorrow. Also want to touch up the float setting on the left carb as it dripped a couple of drops through the overflow after I hooked up the IV tank.

I have been preparing the owner for the lack of performance expected. Especially since he bought a CB1000 from me. But he says he just loves the BMW and wants to ride it around town. I don't blame him. It is a beautiful bike and there are so few of those old airheads around here (Harley Country) that I'm sure he won't be able to go anywhere without spending a few minutes to talk about the bike. He is a young guy so I'm sure there will be some bar hopping involved....

He was asking me about maybe new pistons and rings and bore it out to a 600. I told him to do some research but that is for next year. For now I should have it on the road in a week or so. Waiting for new tires/tubes and liners. Also going to do a quick flush on the fuel tank which is in pretty good shape for it's age. I want to drain the forks and of course trans and rear end. Then I'll ride it for a few miles to see if it needs anything else like steering bearings etc. Like I said this is in really nice shape but was stored in a well insulated garage for 20 years or so. It's not even that dirty and chrome looks like new under the dust.