Troubleshooting Part 2

[BPT]

Since my last post I've replaced the coil, HT leads and ignition module.  I did this hoping it would fix the problems, of course, but they were all original and/or old so needed to be done anyway.  I was able to ride it now but it's still not right.  I took it to the local place, turns out I'd managed to get it within specs as far as timing goes. He checked that and the carbs and both were ok.  But I have a real lack of power and a sputter at certain spots, usually under load.

The mechanic says either a carb problem (like torn diaphragm)  or a problem with the bean can.  For some reason he's leaning towards the bean can.  I'm hoping for a bad diaphragm.  So I have a couple of questions and hypotheticals about the bean can and sensor:

If the sensor "goes bad", does what I've described sound right, where it will run but run badly?  I thought if the sensor went it would be more pronounced or wouldn't run at all?  And with the difficulty in sourcing the sensors now, what have most of you done if it does go out?  Try to source an old replacement bean can?  I've seen a ton of posts online about this but looks like it's not an easy process to fix these.  And,of course, buying one is expensive.  I do see that Motobins has the sensor assembly for about $130.

The mechanic said I should consider going electronic since the cost would be the same or less as replacing the old stuff.  But then that brings about another bunch of decisions.  He said several customers have gone to the Dyna 3.  I can't tell from the reviews I've read if that's a good choice or not.  And he's not trying to sell me one because he encouraged me to shop around.

So I'll be happy to hear your opinions on this.  The hypothetical being if your bean can/sensor is no good, what's the best course of action?  Unfortunately, budget is a factor and I'd really rather not spend $300-400 if possible.

As for the carbs, I just haven't had a chance to open them up yet but will be checking the diaphragms and hoping to see something obvious there.

            Thanks

[mrclubike]

First off
Did the tech check the timing at low idle (aprox 1000rpm)
He should have seen the "S" in the timing hole

Then it should have been checked at 4000 rpm
He should have seen the "Z" in the timing hole

The bean can doesn't really sense load it only knows rpm and the sensor  can operate in a broad voltage range
But the sensor is electronic and anything is possible when it comes to failing

As far as I know the Dyna conversion are for points can
But I am sure it would be possible to fit one to a electronic bean can if someone wants to do it bad enough
So you only alternatives are  the 450.00 USD new style OEM   BMW Bean can  or the Emerald Island ignition system at about 400.00 USD
(this system works but don't expect the timing curve to be as advertised)


Carb maintenance is really a routine thing
So What I would do is do a complete carb overhaul
That includes
Floats and Float needles
Slide Needles and needle jets (they do wear out)
Throttle shaft seals They swell with age and start sticking)
and of course diaphragms and all other O rings and gasket
Just do it all and be done with it

Unfortunately Their isn't anything cheap or low maintenance about driving a 33 year old motor cycle

By the way I have done all of this

PS get a Timing light 

[BPT]

Yes, yes, I promise I will get a timing light. In this case, I've been in a bit of time crunch lately. I knew I'd only have a limited amount of hours to deal with this and needed to get it running and inspected. I figured I wouldn't turn down an offer of help, especially if it would save me some time....

I can't remember the details but he put the light on it when I pulled in and ran it through a range of revs. He said it was slightly advanced but "within specs".  We talked about a couple of other things and I thought it was good enough for now.  While I was talking to one of the old timers there, he had taken my cover off and started tweaking it. So I missed what he did but he said he retarded it just a bit.

As for carbs, I intended to get the entire gasket kit, I was going to ask here about the rest.  My most pressing thing right now is figuring out what has happened to make it run so badly since it seems to have happened kind of suddenly.  I keep hoping to have the A-Ha moment where I find something actually and obviously broken but that hasn't happened yet. The carbs would be (I think?) the last possibly obvious thing to check, as in a tear or pin hole in a diaphragm.  So far, no luck with that. 

When you say you've done "all this" are you talking about the aftermarket ignitions?  And can you explain (in simple terms) what you mean about the timing curve?

And I'll attach a pic of the $130 part I was talking about.  Since you put up one of the complete trigger unit are you saying just replacing the sensor part isn't advisable?

[mrclubike]

The new trigger is fine if the rest of the can is good and it probably is
New springs and cleaning is all it may need

I just think rebuilding the carberaters is the best thing to start with and they may be needing it anyway

Yes I have done everything

I have used the Emerald Island system
I was never able to get the 26 deg. of advance they advertise
I was only able to get 20deg
So I had to set the base timing at 12deg in order to get the full 32deg at 4000rpm
It ran fine this way but wanted stumble sometimes when taking off from a standstill
I tried 3 different ign modules all marked 26deg and they all were the same

[mrclubike]

You can google timing advane curve for more information

[BPT]

I think that I saw an old post from you about that somewhere.  That's one of the things that makes me leery of going that route.  I'm ignorant enough on the basics, I don't want to get a set-up that is going to be a pain to get straight since I haven’t even learned the stock setup yet.

I'll Google to get an idea but that's not encouraging.  I'm all for improvements that are improvements. But I was looking for simplicity in an Airhead. 

Thanks for the info, appreciate you taking the time.

[Justin B.]

I think you can get just the Hall-effect sensor for under $25 and repair your own. 

http://www.bmwr65.org/YaBB2.612/cgi-bin/yabb2/YaBB.pl?num=1399223311/10#10

[tunnelrider]

Like you said BPT, I'd also think about pulling apart the carbs in the hope of finding something obviously wrong, but did your bike have this problem before though?  If not, perhaps revisit your last work, in your case the HT leads and coil, by trying this easy tip from Snowbum:
Cut down a couple of spark plug ground electrodes, (I used new NGK's BP7ES, which I normally use for the bike), to increase the electrode gap and load the spark system more; ground both test plugs securely, turn off the lights in the garage or wait until dark (better!) and hit the starter, the sparks should be bright, purple-ish and similar both sides.  At least then you have a feel for how good the ignition system is.  As has been mentioned already, the timing sensor probably shouldn't be prone to load, the problem it'd cause is not advancing, leading to compromised engine performance,  so I recommend also MrClubike's advice that the advance line needs to be seen with a timing light to eliminate the ignition system and start looking into the carbs.

[Tony Smith]

I think you can get just the Hall-effect sensor for under $25 and repair your own. 

http://www.bmwr65.org/YaBB2.612/cgi-bin/yabb2/YaBB.pl?num=1399223311/10#10

Beware - there is a Chinese manufacturer making 2AV54s and they are poor quality, I fitted one to a friend;s beancan and it failed after only a few hundred kilometers, I replaced it and the 2nd one failed even quicker than the first.

I did some research and fitted a Siemens HKZ101, which worked perfectly and is still doing so nearly two years later

The Siemens part is readily available in Australia for around $20.

[Burt]

Tony, 

Jaycar has them for AUD24.95.  I would assume they are one and the same? 

Dave.

[BPT]

Justin/Tony - I had been looking into gettting the sensor and doing that myself.  A search for the HKZ 101 is now pulling up an HME 301 saying it is a replacement for the HKZ.  Do you all know if this one is a direct replacement?  Or is this the one that you're talking about Tony that could be problematic?

I think that they are all Asian made now so is it a particular one (that failed on your friend) that should be avoided?  Or are you saying that there is one that has the original part number and that is the bad one?

I saw a few of the HME 301's for around $25 ish in the US.  So far though, Jaycar is the only one I've found that uses the actual HKZ part # but I think it will be around $40 or so with shipping to the US.  I'd pay the extra if this is the only one to consider but wondering how to tell?

[BPT]

Tunnelrider - it was checked out with a timing light (and by someone that I HOPE knows what they're doing) so that should be good.  He said the timing was fine and didn't mention any difficulties with getting it there. 

For when the problem came about, it was worse before I changed the leads and coil.  When it first popped up, I couldn't get down the street.  Now I can ride but I have a lack of power.  The sputtering thing was there before also and also a little worse.  Now I can avoid it (mostly) if I really go easy and slowly up through the gears.  But if I rev it, it starts to sputter at between 3-4000 RPM.  Also, at the very beginning of this, I had a problem where it would start and idle just fine but then suddenly get really rough after it ran for a bit (and no power at all even from a dead stop).  But that seems to have gone away as well.  I did some miles of highway riding as a test ride from the shop and then got it home.  So it is better than it was, but something is still very wrong.  And when this came about, it came from nowhere.  I'd ridden a couple of times within a week and it ran great.  Then one afternoon I was planning to take a ride and it was crap.  No gradual decline in performance.

Carbs will be the next thing.  I'm going to take the tops off to check for something obvious with the diaphragm (in an earlier post someone here said they had the same symptoms I started with and ended up finding a pin hole there).  I am going out of town so will not be able to mess with it for another week or so.  I'm trying to gather info to get prepared for that and also to get some things ordered so that I have them on hand for when I get the time.

[Justin B.]

What you are now describing sure sounds like a carb issue.  I know that when I leave a bike unridden for several months the mid-range power is $hit unless I feed it a little choke/enricher.  There is an intermediate jet that has a central hole and a bunch of tiny holes that help to emulsify (I think) the fuel mix.  I find these jets to clog in short order if not ridden regularly.

[BPT]

I am hoping that it is a carb issue since that would be easier to deal with than the bean can.  As far as the riding frequency, it hasn't been as much as I'd like for sure, but most recently it would be weeks rather than months that it would sit.  Kind of a double edged sword - I know that it needs to be ridden but I keep having problems that make it not convenient to ride. 

It seemed to be running really well just a week or so before.  Since I ironed out my charging problems a while back, this is the first time where it just won't run (well, technically it runs but I'd say it's not rideable). 

So carbs will be next, when I get back in town.  I just wanted to be prepared for the bean can scenario.   I was going to order the carb parts from Motobins so that's the other reason I was wondering if I should get that sensor since it would be cheaper shipping-wise to do it in one order.

[Tony Smith]

Tony, 

Jaycar has them for AUD24.95.  I would assume they are one and the same? 

Dave.

Yes, specialty electronic component shops can beat their price by a small amount. If you have a local Jaycar I'd just buy there.