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Anthony fish
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I was riding the other day when all of a sudden the motor bogged down and staled. I pulled over let it set for a minute then started it and it ran for a couple of blocks then staled the same way. It seems like it’s getting fuel based on movement in the filter.
The plugs have a spark when grounded to the fins, I’m not thinking the carbs because up till then it was running and idling fine. And what are the chances of both carbs failing at the same time.
One thing I did notice is when I was riding just before having the problem is that the idle would stay high for a couple of seconds then stabilize.
Now when I attempt to start it, the bike starts and Boggs down and stalls right away.

Any suggestions would be appreciated.

Anthony

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Anthony

1969 R60/2, 1977 R100/7, 1988 K100RS, 2017 R Nine T

schrader7032
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Seized pistons??

Seized pistons??

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Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

Anthony fish
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pistons are fine

The bike turns over and I have pressure at the spark plugs

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Anthony

1969 R60/2, 1977 R100/7, 1988 K100RS, 2017 R Nine T

schrader7032
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I've never experienced it and

I've never experienced it and don't really understand the phenomenon, but Duane mentions seizure here:

http://w6rec.com/duane/bmw/piston/index.htm

I was under the impression that the piston can seize but then after a bit of time, the bike will run again, until the next seizure. I suspect there's some damage being done with each seizure.

That's about all I could think of initially when you said that you were running along fine and then the engine just bogged down.

Check the simple stuff. Make sure that the air filter hasn't collapsed or is blocked.

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Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

The Plunger
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My first thought was a

My first thought was a tankful of bad gas or something in the gas clogging the jets. Did you switch to reserve just before this occurred? Maybe some junk in the bottom of the tank.

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Brian
'52 R67/2
'63 R69 S
In what space, sir. In what space!?

stagewex
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I'm also thinking crap/debris

I'm also thinking crap/debris in the gas. Yes, that will affect both carbs at the same time.
And your description sounds all to familiar.
Have you flushed or ever flushed your tank and fuel lines?
Are you running filters to each carb?
Have you personally cleaned and tuned your carbs?

You only need the smallest bit of crap the size of several of your hairs to bog things up.
Lets hope it's something like this and not a seized motor. If you can turn the motor with your foot that is a good sign.

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mike wex/stagewex
1969 BMW r60/2, US Model, 1995 BMW K75, 2006 Yamaha TW200, 2007 Ural Patrol

312Icarus
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Not to belabor the obvious,

Not to belabor the obvious, but have you checked the oil? (Both condition and quantity?). I might lean to a a clogged peacock screen however.

You might also consider the condensor, as they will allow a quick start and then stop!

Icarus

bstratton
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All good suggestions - and I

All good suggestions - and I would check them out but my first guess would be a fuel supply problem. Petcock screen, fuel filter, bad gas, no gas.....

If you decide you may have contaminated gas you will need to remove the carbs and clean them. No big deal but record your adjustment screws settings so you can get close when you put them back together before you re-balance them. Do them separately so you don't mix up parts between them. Sometimes just some carb/choke cleaner and compressed air in the right places will get the job done.

And also if you suspect contaminated gas, flush the tank and replace your fuel lines and filter(s), of course.

Good luck!

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Bstratton
1971 R60/5
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MA

Anthony fish
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The items I’ve checked

It’s strange, I do not think it is a fuel problem because the tank is clean, new gas and plenty of flow thru the gas filters. What I have noticed today after draining and refilling the tank, changing the plugs and cleaning the points is, the bike started up fine and runs great. I allow it to warm up, rev the engine a few times and the engine idles fine with minimal back firing. I ride it up and down the block a few times the all of a sudden it bogs and stalls. I remove one plug to find I have no spark. I think after it cools down the spark comes back. Richard from Bench Mark said it might be a weak or damaged coil.
Any thoughts

Anthony

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Anthony

1969 R60/2, 1977 R100/7, 1988 K100RS, 2017 R Nine T

312Icarus
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Bad coil, (tired OEM?)or bad

Bad coil, (tired OEM?)or bad condensor sounds good to me.

Icarus

MikeL46
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I would think your gas cap is

I would think your gas cap is poorly vented, or not vented at all. Try running until it stalls, then remove the cap and see if it runs for more than a minute.

Mike

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69 R60/2 76 R90S 78 R100RS
70 Triumph w/Spirit Eagle Sidecar

stagewex
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I think you should try a

I think you should try a couple of these almost zero labor and no cost things or you are just going to keep guessing (and us too).
I'm the "it doesn't mean crap if you think your fuel tank is clean its now in your carbs" guy.
Do a full fuel douche and carb bath in an ultrasonic cleaner to eliminate that from the equation. If it is not the problem then move-on knowing that this issue has been taken care of as a regular maintenance exercise anyway. Not a bad thing.

The fuel cap venting (or lack of) that was/is suggested is another easy simple task to check. Never had that problem on my /2 but did on other motorcycles.

More times than often these things are something simple that was overlooked and dismissed before settling in on the heavy and serious stuff.

From a "clean" fuel tank. Of course my '69 is almost 49 years old.

All my non-expert knowledge is from stuff screwing up and getting out of it (after awhile and I'm lucky).

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Cliff
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Timing

I would also check the ignition timing. I once had the advance spring break and caused the advance to go too far. This caused an overheating problem and then new pistons.

Anthony fish
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I think I got it

The bike started and stalled after about 5 minutes of riding. Then I emediatlly pulled the plug and I did not have a spark. Checked for spark again today and very weak at first then none at all again. I checked the gap on the points and that fine. I think I’m gonna try the coil and condensor, makes the most sense because when I’d was running it ran terrific. So I still rule out the carbs or gas.

Thanks for all the advise, it really helped.

I’ll Keep you posted on my results.

Anthony

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Anthony

1969 R60/2, 1977 R100/7, 1988 K100RS, 2017 R Nine T

schrader7032
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What about the safety gap at

What about the safety gap at the magneto? The gap should be around 10mm. I wonder if the spark is jumping to ground first rather than going to the spark plugs.

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Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

Anthony fish
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Staten Island, NY
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I will check that before

I will check that before replacing the coil and condenser

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Anthony

1969 R60/2, 1977 R100/7, 1988 K100RS, 2017 R Nine T

Daves79x
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The Original

IMHO opinion and somewhat limited experience, any original coil should be replaced. I'm quite sure that's your problem, and you have the classic symptoms of it.

Dave

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Captonzap
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Classic case of a failing

Classic case of a failing capacitor. Magneto's are like that.

CZ

Danedg
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Take the whole magneto apart

Take the whole magneto apart and clean it. The coil won't fire if the housing is dirty...A properly grounded magneto is essential for the ignition system to fire reliably. Your plugs, caps, wires and coil all need to be zero resistance and thoroughly grounded. Often overlooked is the magneto assembly itself. It looks clean, but after 50 years, electrically it is not. Add heat and your magneto resistance to the block goes up, and your ground is compromised. This is why these bikes will start fine when cold but can be a bugger when hot. Remove the whole deal and carefully "clean" all mating surfaces from the points plate back to the timing case cover. 300 grit sandpaper works well. Your magneto assembly will then regain zero resistance (continuity) to ground, allowing the coil to "fire" properly. Try it, you'll like it!

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Anthony fish
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Staten Island, NY
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Cleaning

Yes, I ordered a new coil and capacitor to play it safe, When I ordered it Richard from Bench Mark Works stated the same thing clean the whole assembly.

Thanks

Anthony

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Anthony

1969 R60/2, 1977 R100/7, 1988 K100RS, 2017 R Nine T

Anthony fish
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Staten Island, NY
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Replaced coil and condenser

That was it.
After replacing the coil and condenser the bike starts and runs great. The bike now starts on 2-3 kicks and idles smooth right after starting. When the old coil was working it would take 10 or so kicks to start and would have to completely warm up to idle smoothly. I did not realize this was not normal because it was the first time starting the bike.
Now I know.

Now to adjust the carbs and possible the timing

Thanks for all the help, what a great group!

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Anthony

1969 R60/2, 1977 R100/7, 1988 K100RS, 2017 R Nine T

hooverbj
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I've been following this saga

I've been following this saga and I'm glad to hear it turned out well!

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