JH600 stalling

[MotoKai]

Thanks for posting the videos LJH. Good to see full documentation of an issue most of us have struggled with from time to time, in various degrees of pain.

For reference, I had the honor of riding LJH's JH600 (2-wheel) a few months back thru the mountains of Beijing, and LJH was riding the JB600 2-up. The JH turned the odometer at 5,000km that day, and the B was somewhere close to that mark I recall. Both bikes performed amazingly well. Not a stall between them on the 200km ride under blue skies.



It's sad to see the change in behavior from just a few months ago. So yes. the JH's aren't born this way, but some have developed these symptoms with a mysterious cause.

My JH stall issue worsened around 10,000km when there was excessive heat ultimately resulting in a fried stator. The stator was replaced and the stalls were then few and far between (during the Inner Mongolia Ride). Then about 1,000km later I was getting frequent stalls (same type as LJH captured in the videos) - usually occuring when slowing down, and the RPMs are winding down thru the gears, like when approaching an intersection! [dangerous]. After tweaking my idle higher, I'm now only getting the occasional stalls, which is still hen mafan!

Couple of questions/comments:
- I also get the 15s stall after starting up from cold
- My exhaust header also gets red hot when first starting
- You mentioned the JB's idle speed is about 1700, where's the idle with the JH?
- When the the engine actually stalls, where is the RPM at? Is it stalling at the same RPM each time?

[Lao Jia Hou]

You mentioned the JB's idle speed is about 1700, where's the idle with the JH?

Here is a photo of my two-wheeled JH idle:



And here is a photo of my three-wheeled JB idle:



Comments:

1) Looks about the same, with the caveat that these gauges are probably not the most accurate. However, BOTH are the identical Siemens gauges in the Jialings;
2) Ignore the clocks - I need to reset my JH's. I R&R'd my battery to fully refresh its charge and forgot to reset the clock;
3) Yup ... low annual mileage ... consequence of having a full toybox with (last count) seven bikes; and,
4) Why can everyone on MCM take better pics than me?

When the the engine actually stalls, where is the RPM at? Is it stalling at the same RPM each time?

That is a really tough question. I would say that, generally, the stalls happen when the bike is at idle, or on its way down to idle (e.g., cruising along, pull in the clutch to change gears & the RPM drops). I don't recall either bike ever stalling at speed (e.g., driving along at a consistent RPM and experience a "stall").

I should add that, aside from this stalling issue, these are both fun bikes which give me a lot of enjoyment. There are a few other quirks, but those are tolerable. Whomever comes up with a permanent fix to this stalling issue has my dollar.

Although I pull my limited, thinning hair out over Jialing-support, it has not yet reached the low I experienced with my brand new 1976 AMF-Harley Liberty Edition. THAT was an absolutely horrible bike from a company with non-existent customer service. Harley turned itself around from those dark days, after divorcing itself from AMF. There is still hope for Jialing.

[998S]

First I should say that I am not at all experienced with JH-600's (the closest I have been to one was from the other side of the showroom window)..
But I have a lot of wrenching experience on many bikes, including 1, 2, 4 and even the beautifully Benelli-Sei 6 cylinder.
I do all maintenance by myself, including on my Ducati's for the street and the track.

The reason this thread got my interest is that Ducati's have exact the same problem.
The modern series like the 848 and 1098 have persistent stalling issues, on idle, but mostly on slowing down and shifting back.
Sounds familiar, right?

It is correct that 1 & 2 cylinders are more vurnarable for this then e.g. 4 cylinders (specially if they have relative light flywheels - not enough "swinging" weight to keep the engine turning), but it no excuse, and does not need to happen!

In the Ducati case, the stalling is mainly caused by the injection settings, which, due to the stringent pollution regulations of today, are set too lean (simply said; not enough fuel sprayed in the mixture).
If you ride, and reduce speed to a stop, the air mixture sensor measures the lack of "load", and reduces the fuel even more.
By the time you come to a stop, the mixture is simply not enough to turn the engine around, stalling as a result.

The second reason that I think it might be related to a lean mixture, is that I read that someone noticed the very high temperatures on the exhaust.
Although exhausts can be red hot (let a bike run idle for a while at night, and look the headers...), a lean mixture is always hotter, because fuel cools down.

The third reason I think it might be fuel related is that someone else noticed it is getting worse with a more open exhaust.
Same story, an open exhaust leans out the mixture due to less resistance, and therefore an other pulse frequency in the exhaust (simply said, the gasses can escape faster, sucking out more air through the cylinder, which results into a leaner mixture as the fuel-amount does not change. That is also causing the popping on deceleration..).

Although I guess that the fuel setting is probably not the only reason for the stalling issue, I highly wonder if replacing half of the engine is necessary.
Frankly that sounds very much as a TIC solution, not knowing the problem, and just starting to change parts, hoping sooner or later the problem will be fixed.
I suspect that the JH-manufacturer got it wrong on the exhaust gas regulations it has to fulfill for the Chinese approval, then set the injection too lean.

Did anyone ever measure the CO level on the exhaust at idle speed?
It should be interesting to see that value as a starter.

Eric

PS. An idle speed of 1700 is FAR to high for a 2 cylinder.
Even a high compression Ducati 2 cylinder runs perfectly at 1100-1200 rpm idle, and my Chang Jiang with a large flywheel ticks over at 800 rpm ....

[ZMC888]

the injection settings, which, due to the stringent pollution regulations of today, are set too lean (simply said; not enough fuel sprayed in the mixture).
If you ride, and reduce speed to a stop, the air mixture sensor measures the lack of "load", and reduces the fuel even more.
By the time you come to a stop, the mixture is simply not enough to turn the engine around, stalling as a result.

Seems highly plausible. Wouldn't a friendly chat with a Jialing engineer with a new efi map be a likely solution?

[chinabiker]

I've been following this thread from the very beginning, and I must say that I didn't have the slightest idea of what could be wrong.
One thing however disturbed me - the fact that the stalling issue wasn't there from the very beginning. Now, after reading the response from 998S, I recall that I had idle problems on my bike every once in a while, without stalling though.
I further recall that I knew a guy who was with BMW engine development (cars) and who was very excited about getting my used fuel filters for lab purposes. I also dug out from the depth my brain cells that I've emptied my bike's fuel tank once and was stunned about the contents, which I also presented the engine guy.
LJH, if not already done so, try to empty the fuel tank, spill-clean it and replace the fuel filter if there is one. If there is no filter, check out if you could install one (not so easy if the fuel system wasn't designed for a filter in the feed line).

Just another idea.

[998S]

Seems highly plausible. Wouldn't a friendly chat with a Jialing engineer with a new efi map be a likely solution?

As said, I don't have the slightest idea of the JH-600 injection set-up, need to see it in person to come to conclusions.

However, on most injection systems, there is a small idle bypass valve, which can be turned in or out.
The basic function is to get the CO and rpm's right at idle, but you can play with it a bit.

There should further be an adjustment for the overall fuel-trim, either electronically or "old style" potential meter (in the ECU unit).
This one controls the fuel-trim on top of all map-settings.
If it is old style, you can also play with it (if you know what you are doing though).

But I presume it is already completely electronically controlled.
Then you need to connect the bike to the diagnostic system, and see what to change based upon the readings (the first one is easy, the second part is the problem I think, as I have met no engineer here yet who really knows what he is doing with the info from the system).

If someone in Shanghai is willing to show me his bike, I can have a look at the system as a beginning.
If not too many surprises (and I think the injection is pretty basic), I might advise you some next steps.

Eric

PS. I enclose a picture of the basic set-up on a Ducati:
Volt meter to calibrate the ignition pick-up sensor
Vacuum gauges to balance the cylinders (not necessary for a 1-cylinder)
Diagnostic software for control and setting
CO-measure equipment to set the CO at idle (and balance the CO between the cylinders if multi-cylinder)

DSC05736.jpg

[998S]

...try to empty the fuel tank, spill-clean it and replace the fuel filter if there is one. If there is no filter, check out if you could install one (not so easy if the fuel system wasn't designed for a filter in the feed line).

Yup, Filter dirty --> less fuel to the injector --> leaner mixture, same story again.

It is a very plausable reason, but on the other hand, you need to collect a a lot of dirt before a fuel filter really gets clocked.
But probably easier for you guys really riding your bikes in the country side, then us riding our shiny sport bikes just to the track and back...

[milton]

If someone in Shanghai is willing to show me his bike, I can have a look at the system as a beginning.

I am in Shanghai, ready and willing to show you my JH600. My bike has about 18km on it. My stalling problem went from "barely acceptable" to "really bad" a while ago. Then this mechanic "Dr. Cui" did some "repair" to the decompression valve and cam, which made it "acceptable" again and almost "as new" 3 km before. It seems to act up again recently after my Sichuan trip. The problem is sporadic, hard to predicate, but definitely wrong.
Let me know when and where it'll be convenient for you to take a look of my bike. I'll PM you my cell.
Thanks for the offer.

[998S]

I am in Shanghai, ready and willing to show you my JH600. Let me know when and where it'll be convenient for you to take a look of my bike. I'll PM you my cell. Thanks for the offer.

Wow, that is fast ... I will reply your PM. Weekend should be fine for me.

In the meantime, is there any technical information on the bikes? Owner manual, workshop manual, sheets, part diagrams, whatever?
I guess it will be limited, but anything you owners might have, please post it, or make it avaialble to me.

Eric

[998S]

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