93 R100R intermittent power loss on long trips

[SCJACK]

It's directly related to the tank venting based on your description of when it happens.

[GUENTHER]

Chris,

with...

Air box solenoids are long gone.

...now the wrath of the emission god is haunting your Beemer.

Cheers,
Guenther

[ISAMEMON]

another thought
do you have aftermarket fuel filters in place also.....some people run them, some dont.
I do and a while back I read an article I think in snobums site, about how much fuel should flow through the filters in "X" number of seconds

the fuel filters I was running at that time failed the test and was causing my bike to lean out on heavy demand for fuel

[edwarddieck]

Funny. I was having the same problem on my '94 R100R. Finally the problem became consistant. It was running on one side. I ruled out electrical and started on the carb.

The main jet needle fell out. The clip came off so nothing was holding the needle in place. Checking the needle I found it to be worn so ordered new needles and replaced both. I thought I had the problem solved but when I started the bike it was still running on one cylinder. Then I checked the float.

When stopping the bike and checking the bowl there was hardly any gas in the bowl. Somehow the float was out of adjustment. After adjusting the float the bike is running fine.

Well, maybe I had two problems. I know the needle should not be worn and the clip should stay on. However, how does a float get out of adjustment? Bending the tab wasn't easy. What inside the carb could exert enough pressure to bend the tab?

Any ideas on that.

Thanks,

Ed

[jbcollier]

Intermittent problems can be quite the character builders. The worst part being that the solution usually seems painfully obvious after you have found it. I am glad to hear the problem is getting worse, having to ride two or three days between repair attempts, while great for mileage awards, is a bit of pain.

Some suggestions:

It is unlikely to be something that is "out" all the time. Otherwise it would cause problems all the time. So sticking, hanging and overheating come to mind.

- sticking float needle and seats. Doesn't happen often but it can happen. Completely overhaul the carbs and fit new float needle and seats and floats. While you are in there, change ALL o-rings and seals and fit new jet needles and needle jets as well.

- intermittent open in the secondary ignition circuit (heat related). Fit new ignition wires and caps and a used coil pack (I have a known good one you can have for free if you ping me your address).

- overheating of the ignition control module (known issue but usually results in complete ignition failure). Remove the control module and carefully clean its back and the mounting surface of the heat sink. Apply a new coating of di-electric grease and remount.

- intermittent opens or grounds in the ignition primary circuit. Remove the engine's front cover and the gas tank. Rig up a fuel supply to the carbs. Start the engine up. Wiggle, pull and poke at all the wiring and connectors and see if you can cause the problem to appear. Check wire routing for places the wires might be rubbing and worn. Open all wiring connectors, check for corrosion and coat with di-electric grease.

- find the $#@%!! thing it really is.

Good luck!

[Yarddog]

I had the same problem...ruled out carb problems because both banks were losing power... I tried loosening the fuel cap, no difference, so I figured it was ignition related. New spark plug cables...again, both cylinders...I finally figured it had to do with the new Dyna III ignition, maybe the ground to the box...tried wiggling the ground to the engine, it was tight, but...the problem hasn't recurred!

Something like that is almost always simple...like a ground wire not making contact. If both cylinders are affected, then ya gotta look for things up the line from carbs, coils, etc...both carbs or both coils aren't gonna usually go out and clear up at the very same moment!

[101736]

All of your suggestions are very helpful. JB, I'm going to wait on the ignition coil until I sort the carbs. I'm putting together an order for Bing Agency, and 1 for Max.

Wishing all of you the very best!

[Yarddog]

My problem came back over the last two days, but I loosened the gas cap, waited a few seconds, and the problem went away...As I recall, previously this didn't work, but hey, it's been several months, maybe this was my problem all along

[bmweuro]

Look for cracks in the ignition coil. If it is fuel tank related put your spare key in the fuel cap and the next time it does it loosen the cap a couple of turns and see if that helps.