JH600 stalling

[milton]

Milton, your postbox is full, cant reply your PM.

Just cleaned it. Please try again. Thanks!

[euphonius]

Dear 998S,

This is really a kind and thoughtful gesture on your part, and hopefully all these various avenues of attack will yield some insight into why these JH600s are misbehaving. It's all the more mysterious in these bikes are not misbehaving uniformly -- some are doing it, others (including mine) aren't (at least not nearly as often as many).

Has anyone had a crack at the motofans fix spotted by Milton -- checking the contacts on the spring plugs on the connection between the ECU and ignition circuit?

It's as if it's a conspiracy between clogged fuel lines, poor electrical connections and an overlean mix coming off the ECU. We'll beat it!

thanks again!

[Lao Jia Hou]

Thanks a lot 998S - truly helpful. I suspect Milton has all of the manuals, etc, but if not, other JH600'rs in Shanghai do.

I did a bit of reading on the Ducati forums. Thanks for the tip - looks like a very similar stalling problem. And to think that I was about to purchase a Multistrada ... wow, I would've been damn depressed, jumping from the pan into the fire.

Andy's tip about the fuel filter is also worth pursuing. I looked at the parts/service manuals for the JH600 and couldn't see an external filter. In my experience with other EFI bikes, the fuel pump is internal (inside the fuel tank) with the filter(s) attached to the pickup (pre-entry to the pressure pump). I can't really make out from the manual pics if the pick up arm has a filter attached, and it is not a separate part (it is all one unit - pressure pump & pick up & pressure regulator). It looks like the entire pump assembly might have to be replaced if there is fuel blockage. Fortunately, if needed, the JH600's fuel pump assembly looks like it is easily accessed (no tank removal required), and most probably is relatively inexpensive (versus HD and Victory fuel pumps, which are around $600, US).

I've been pondering this lean fuel situation, in the context of the Jialing's "assistance". It may very well be the case that Jialing knows the problem but it cannot legally "fix" it (remapping to a richer feed) because do so might put the bikes over the emissions standards.

Again, thanks guys!

[998S]

Thanks a lot 998S - truly helpful. I suspect Milton has all of the manuals, etc, but if not, other JH600'rs in Shanghai do.

Yup, got the files downloaded, and an appointment with Milton for tomorrow morning.
Got a 'kind of' day-off today, so will take some time to go through them.

Regarding Ducati's, yes, they got this problem. But it is purely fuel related, and can be solved in 5 minutes if you know what to do.
They even mention it in the offiical workshop manuals, in the way off: "... well, Ducati engines are set very lean to meet the regulations, but to get a good running bike for street and track use, we actually should have set them on this and this CO setting...

The problem however is all the same, even the official Ducati dealer here in SH does not know what to do. They have the diagnostic system, but when I asked him for the procedure, he got lost.
Then, after asking more, he admitted he did not even have CO measure equipment, nor knew it was needed to make setting right.

Let me have a look at Milton's bike tomorrow, and see if there is anything more I could advise afterwards.

E.

[euphonius]

It may very well be the case that Jialing knows the problem but it cannot legally "fix" it (remapping to a richer feed) because do so might put the bikes over the emissions standards.

...Or that Jialing simply is too cheap to pay for the software upgrade from Bosch. I was actually told this way back in early 2010 -- that Jialing was on the Win XP version (or maybe "Bob") of Bosch's EFI software, when Bosch had already moved on to Vista and then Windows 7. The reason: Jialing didn't want to pay for the upgrades.

Wonder if that story was actually true!

[998S]

Wonder if that story was actually true!

Shall we bet it is haha?

[998S]

I have done a several videos of my "A" and my "B" and put them on Youku (with the help of a wonderful friend!)

LJH, I checked all of your video's this night.
I am even more convinced that the problem is fuel related, and it points very much to a lean mixture.
The stalls at cold start are strange though, looks like the ECU changes the mode or map or so (perhaps the decrease or termination of the auto-rich mode after 30 sec.), not sure on that one.

[euphonius]

Dear 998S,

This is another peccadillo of the JH600. We seem universally to have this weird 30-second stall -- even mine, which (knock wood) does not stall a lot. So that's like te least of our worries, though if it helps us sleuth out a solution to our other stalls, so be it!!

[Lao Jia Hou]

The stalls at cold start are strange though, looks like the ECU changes the mode or map or so (perhaps the decrease or termination of the auto-rich mode after 30 sec.), not sure on that one.

Thanks!

At first, I had a theory that maybe the auto-decompressor (on the cam) was responsible. But then I realized that the decom should retract as soon as the bike starts, caused by the centrifical force from the increased idle.

I don't know if this helps, but after each stall (cold idle, or when warm and running/shifting/etc), there is never the smell of fuel around the engine. Come to think of it, I have never experienced any fuel smell from either JH.

[998S]

I had not one, but two Jialings here this morning ... not only looking almost the same, but also stalling the same ... Man, those Chinese are really good at copying .
Motokai showed up together with Milton.
Should say that I found it much nicer in real then on pictures (the Jialings I mean...), and was surprised how big it actually is, even the Asian version already.

After some coffee and a chat, I had a look at the bikes and the problems, and experienced both first hand.
Milton's bike stalls 20 sec after starting at every attempt, and a 500 meter testride had it stalling on me once while coming to stop.
We then did some CO testing with a Gunson Gas Tester, which I also use for tuning my own bikes.


From what I found, I can make the following preliminary conclusions:


1. Stalling after start:
My impression is, that the ECU has a "enriching" program which replaces the choke on a carbureted bike.
To me, I think this program is not related to the actual input from sensors, but is just enriching the mixture for the first e.g. 500 turns.
This because you can almost set a clock on the timing it will stall.
So it means the engine runs the first e.g. 500 turns on an enriched mixture, then the ECU shuts it off, going back to the lean mixture, which is too much of a change and the engine stalls, hot or cold.


2. Stalling at a stop:
This is indeed exact like Ducati's 'too lean' stall, unpredictable, always while coming (almost) to a stop, and being able to just restart and idle fine afterwards.
For this one I am sure that it is caused by the lean running, and can be solved by a richer mixture.
I did a test of the CO percentage in the exhaust gas, and it shows that the CO percentage is less then half (!) then I think it should be, on both bikes!


So what do we need / what do we need to do?

1. I need someone with a slight technical insight, who can help me read the Chinese manual at certain points,

2. I need someone who has a Jialing dealer with diagnostic instruments, and who can ask some questions for me (LJH?),

3. I will then try to work out a solution (if any, depending on the Jialing diagnostics, and the suitability to change certain settings in the ECU with it).
If that feels positive, we can as a last step try it on a bike, and see if there is indeed improvement.


Basically, I am quite convinced that (at least a part of) the problem is the mixture.
It all depends from here if there is a chance to get into the ECU.
If that is possible, at least we can optimise, and see if the problem persists or not.

Eric

On a side note: I don't think that it is a hardware problem in itself.
The bikes run ok, don't make strange noises, don't hiccup, rev up fine, feel smooth, nothing strange.
I can imagine that Jialing is improving their design (never wrong), but in the basic concept these bikes should not stall in the version they are!
They should also run much lower at idle then they do right now.