Mon, 09/06/2010 - 00:05
I'm trying to troubleshoot some problem on my bike, and am hoping that the way-more experienced people here can help. My R50/2 has been consistently starting on one kick, with a few tickles and a twist of the throttle. I've ridden it around quite a bit around my work, but finally--after waiting for plates/registration/insurance--I took it out on the streets. It started first kick, ran great, and I took a 20 minute ride to the local BMW shop to try and find a fork lock key. As my luck goes, it wouldn't start. (After closing, on a holiday weekend, in front of a dealer...) I waited awhile, tried again, figured I'd flooded it, waited some more, tried again, etc. I pulled the plugs and they weren't fouled at all, had good spark, but also were not at all wet from gas. I finally had a friend come to pick me up and we gave it a push start just in case, and it started and drove home fine. Today it was sort of hard to start and I drove it to work, let it cool down for a few hours, and adjusted the valves. The same thing happened...good spark, plugs not even wet, and again it started with a push start.
Anyone have any brilliant ideas? It seems like it could be a fuel delivery problem, based on the dry plugs, but I don't know how. The tank was cleaned, the petcock valve is a brand new double karcoma, the fuel lines and in-line filters are brand new, and the carbs have been rebuilt. And, to top it all of, it started and ran perfectly many a time until that fateful ride...
Thanks in advance for any help!
Troy
- 571 reads
Mon, 09/06/2010 - 06:54
#2
Vapor lock?
One my previous /2 I sometimes experienced vapor lock with the carbs on hot days. I would have to wait some 20 minutes before I was able to start it. I never looked into what the best way to fix it.
Mon, 09/06/2010 - 07:35
#3
Check your timing. It might
Check your timing. It might be that the points rubbing block has taken a set, worn down, and you're not longer where you thought you were. That said, the most important part of starting is having the magneto timed correctly as well. Better check that also.
Failing coil is a good thought. Vech has a replacement for the original coil.
You might have to experiment more with your starting technique. My R69S has two different starting routines, one cold and one hot. My bike seems to flood easily so when hot (like after a gas stop) I have to take the time to draw fresh air in the cylinders before trying to start. I open the throttle to full stop, kick through maybe 5-6 times, and then try and start. For starting, I don't touch the throttle at all, just give it a good kick.
What about shutting your gas off before you park it? Many people suggest that you should turn the petcock off about a block before you reach your stopping point. This will reduce the carb dripping situation when the gas expands due to heat soaking. It might also reduce the amount of gas that might flood the engine.
Some ideas...
Mon, 09/06/2010 - 11:03
#4
If I understand correctly,
If I understand correctly, you SUDDENLY have trouble with both hot AND cold starts. Since you say you have dry plugs, I would continue to check the fuel after you confirm your timing, valve adjustment and put in a new set of plugs. Be methodical.
Pull the fuel line at the tank and at the carbs and make sure there is adequate fuel flow. After that, with a cold engine, do your normal starting drill. If it doesn't start, tickle the carbs a bit more. If it doesn't start, check the plugs. If dry, add more tickling until it starts or you are sure it is flooded.
My bikes like only a tiny, tiny bit of throttle for normal starting. Only if I have flooded it do I open the trottle.
Good luck.
Bruce
Mon, 09/06/2010 - 12:29
#5
Thanks much, guys.
Thanks much, guys.
Yeah, the thing that trips me out is that everything was tip top. I had my starting routine dialed in to the point that it took one not even hard kick to get it going. The warm starts I hadn't perfected yet, but they were still just a few kicks. The "morning of" it started right up, and since then...nada. But, pushstarting has worked?!? I don't know if that builds up more compression to suck gas or what, but I much prefer the one kick. I'm going to try and test the coil today, but that still doesn't explain the plugs being dry and clean...
The fun of old stuff.
Troy
Mon, 09/06/2010 - 12:39
#6
Push starting probably spins
Push starting probably spins the engine faster which helps to create a better spark. Kicking speed is relatively slow and the magneto timing must be spot on to get the best spark at this speed. It's possible that the rotor could have slipped on the camshaft taper, thus throwing off the magneto timing. Only takes a few seconds to verify that the magneto timing mark is still within the "vee" when the flywheel is sitting at the S-mark in its timing window.
Tue, 09/07/2010 - 22:44
#7
Well, to add more confusion
Well, to add more confusion to my problem...I tried pushstarting it again for quite a while this morning so I wouldn't have to put it in a truck to take it to my work, and that didn't get it started. I trucked it to work, checked the plugs when I got there and they were a bit moist. I let it be for the next 9 or so hours while I worked, and then after work pulled a plug to check if it had spark...I accidentally started the damn thing on one cylinder with a few weak kicks! I excitedly shut it down, put the other plug in, and it started right up again. Let it run for a minute or so, shut it down, tried to start again (and again and again) and nothing....
I gave up and went home.
Kurt, you mentioned the magneto timing...how do I know when the magneto is in the right place when the S is in the timing window?
Is there a simple way to test the coil/magneto/condensor so I can eliminate them as problems? I'm at a loss right now...
Troy
Wed, 09/08/2010 - 00:43
#8
Did you try Bruce's advice?
Did you try Bruce's advice? His suggestion will narrow things down. Just messing around with it is not going to find the problem and fix it.
- Check the magneto timing: With the S in the timing window, look for the mark on the magneto rotor to be directly in the middle of the V, on the top of the brass points plate.
- Verify your static ignition timing by checking that you have the proper maximum gap on the points and that the points are just openning when the S mark is in the timing window.
- Check twice that the "stack" of wire lugs, washers and insulators that screw together on the points are all in the correct order and lined up. If this is loose or not put together right, your motor might not run.
- While you are under the front cover, make sure that the set screws are tight for the spark plug leads. Check the screw that holds the magneto kill wire, and test to make sure that the wire ISN'T grounded when the key is inserted.
- Verify your head bolt torque. Then verify your valve lash.
- Verify the spark plug gap on each side.
- Pull the fuel lines from each carb in turn and hold it over a clear container. Open the petcock and ensure that you've got a reasonable flow. Check the gas to make sure that it's clean. Verify that there's no water in your gas.
- Follow Bruce's suggestion about tickling and kicking.
Good luck. Intermittent faults are a PITA to find and fix.
Wed, 09/08/2010 - 01:49
#9
Thanks much Darryl.
I took
Thanks much Darryl.
I took Bruce's advice before I started messing around, and the gas flowed freely from both sides when disconnected. The spark plugs I had to track down and am picking them up tomorrow morning. The tickling unfortunately didn't lead to starting, but through tickling and kicking it finally wet the plugs a bit. I'm writing everything that everyone's given me down, and I'm gonna run through the whole list tomorrow (if I have time) to see what happens. Thanks! (And, sorry for all the questions. I'm trying to learn/research as much as I can through the old postings, but this found me stumped.)
Troy
Wed, 09/08/2010 - 03:05
#10
Try the Rinckes manual for
Try the Rinckes manual for some good info and pictures to help, especially on lining up and adjusting the magneto:
http://www.snafu.org/restore/uandm_bmw_v1.pdf
Darryl is right, there is no way to track down the variable in the equation when your trying to hit a moving target- use his list and go step by step.
If everything is fine at speed and the bike idles and runs well it's hard not to think about the magneto. These guys are the opposite of most modern alternator based systems in that they produce great spark at speed and produce low spark at low rpm, i.e. kicking.
I had a similar problem with my 69 R60/2 and changed my starting procedure after reading a post here. I used to use ticklers but no more, too much flooding. Couldn't hurt to give this a try (this is assuming there is fuel in the carbs and it hasn't been sitting forever, cold start):
1) Ignition OFF
2) Kick 2 or 3 times with throttle full OPEN (hold it open if it clicks back after a kick)
3) Close throttle
4) Fuel ON
5) Ignition ON
6) Throttle 1/4 turn (hold it at a 1/4 open)
7) Kick to start (mine starts 2-3 kicks)
This process bypasses the need for the ticklers. My carbs are good and rebuilt recently but those ticklers just seem to be so finicky, they work but the margin is just so damn annoying. I have lever tops.
Thu, 09/09/2010 - 16:53
#11
I'm with everyone else, your
I'm with everyone else, your timings probably off.
After checking your timing, you may want to check the carbs. See if your floats are filling up with fuel (shake them). There are only two screws keeping you from checking if your carb is flooding or not. Check that your bowl and both jets are clean. I run clear fuel filters so I can watch the fuel flow when I tickle the carbs, the right carb doesn't flow as fast as the left on any of my bikes. It becomes really apparent how long it takes for the bowls to fill up before starting.
John
Fri, 09/10/2010 - 02:57
#12
I didn't have time to get too
I didn't have time to get too down and dirty the last few days, but--and I'm almost embarrassed to say this--I started out by putting in a new set of plugs and so far it's been starting and running good. I'm not saying (although I'm hoping) that it will cure the problem, but it worked wonders. When I have time I'm going to go through and make sure the timing and everything else is right, but for now at least it starts again! (I'm keeping it off the road until that's done.) I'm trying to go through everyone's warm start suggestions and see which one works for my bike, though. I still haven't found the perfect method.
Thanks again for all the help. I'll post with progress (or regress...).
Troy
Fri, 09/10/2010 - 09:25
#13
You may be suffering from a
You may be suffering from a weak spark that may not fire easily under compression. Fresh plugs may have improved the situation.
Many have mentioned the coil and if it were a hot start only problem, I would 100% concur.
Other non-coil possibilities that may contribute to a weak spark (hot or cold) could be:
1. Weak magnet
2. Failing condenser (condensers are cheaper than coils, so I would renew yours if you haven't)
3. Poor condenser ground
Bruce
Tue, 09/21/2010 - 22:11
#14
Update...
Well, the BMW gods have smiled upon me. (I had to give them money though, of course.) I ended up just buying a new coil and condensor, and also new points and plug wires. After installation, the bike starts and run like a champ again. It had sat for so long before I got it--26 years or so--that I figured I might as well just replace all the possible shady electric parts so I can start with a clean slate. So, I don't know what the main problem was, but one of those things fixed it. (The coil looked okay, but the outer wrap was kinda greasy and brittle. The plug wires were totally hard but had good continuity. The condensor? Who knows...) I was going to change it out piece by piece and see which one made the difference, but once I got going I just wanted to be done so I could take that hopeful first kick.
So, many thanks for all the help and suggestions...I kinda combined them all!
I think the lack of fuel to the plugs was actually just not being too good at the tickling/kicking, and not knowing how much or little to do while warm. I've started to shut off the fuel a block or so from home as suggested, and hopefully I'll get a warm start routine dialed in now that it will actually start after I've driven for awhile.
Thanks much!
Troy
On my /2 if it doesn't start within 1-3 kicks,it will take 20.........usually flooding is the culprit. You may have a failing ignition coil.If your coil fire the plug when pulled out of the head,that does not mean it is strong enough to fire the plug when it is under compression.Try closing down the spark plug gaps. Resistance increases under cylinder combustion pressure,so a bad coil can still make a spark when the plug is removed,but may not fire when trying to start.