JH600 stalling

[milton]

[FONT=Arial]
I actually found that your Jialings are equipped not only with a Euro III fuel injection (save the planet!), but also with a start/stop system....

What you all thought was stalling, is actually a very advanced system, controlled by the latest Bosch black box.
....
You pay at least 2.000 bucks for that on a BMW, and here it is for free.

Thread closed .....

Say what?? All we need to do is just to turn off or disable that Start/Stop System??
Are we at that stage yet that we need to get the ice cream ready?

[998S]

Problem - Analysis - Conclusion - Solution ....

Ok, kidding aside, I just spent the last couple of hours taking Milton's bike a bit apart.
I did not want to take his whole bike apart, but disassembling it partly, left me with enough room to check the main functions, and have a better idea of the problem itself.

Problem:
I rode it for a bit of time, and I think there is only one type of stalling.
The 30sec stall and the stall occurring while decelerating are the same.
I also think it has nothing to do with the deceleration itself, but to the fact that the rpm drops below a certain value, and then something else happens.

I also rode the bike at idle, in first, in second and in third gear without any throttle input.
Specially in 2nd and 3rd gear, the bike need a bit of time to settle at ~1.700rpm, then goes pretty smooth for a while (a little bit surging), but almost always hits a stall after time.
This again seems the same conditions for the stall as at idle & deceleration.

Analysis:
I have checked the function of some sensors, but they seem fine to me.
I have measured the battery, but it is totally fine. It is full, and holds the voltage under full load. No problem.
I have measured the charging. It is a bit low, but definitely charging at already lower rpm's. I guess if your battery is in good condition, no problem.
I did not change the spark plug. Milton just fitted a new one which is of a different heat grade. I will change it back to the old one once the engine is cold.
I checked some of the electric connectors and the fuse boxes, but they seem to be clean. No suspicion here.

I then took the step to cover the air intake from the airbox.
This results into a richer mixture.
The idle dropped down from some 1800 to 1500 rpm, and the idle stall basically disappeared.
But I need to say that by that time the engine was pretty hot (the fan even kicked in every now and then), and I agree after today with Motokai's observations that a hotter engine has less stalls.
It of course dramatically reduced the engine power, but also reduced the stalling; For a period of 15 min city riding I experienced one stall.

Conclusion:
I am fairly sure that the problem is in the black box.
I think the problem is in a transition, which happens under certain conditions; no throttle input + low RPM (<2.000).
It is either a fuel cut caused by a tooooo low fuel field in the map, or an error in the spark map (spark advance error at a certain field in the map).
I don't think that my first conclusion of a lean mixture is the real cause, but (as many other factors) contributes certainly to it (hence the less stalling with a rag into the intake).

Solution:
Anyone who knows may say it, I guess Bosch is the only one who will be able to help us.
As long as I can not have a peak into the map, I am afraid I can not do much.
It looks like a glitch which can not be easily solved by an "over-ride".
Alternative is to take everything off, put an nice old carburetor on it, or buy an aftermarket EFI unit, and start playing from there.
Not easy though.

[euphonius]

Dear Eric,

This is a most impressive piece of wrench-based field sleuthing, and your conclusions ring logical and true. I'm sure I speak for others in saying I feel deeply indebted to you for it. (I look forward to measuring this debt in beer or other vices.)

I think an important next step would be to translate your findings into Chinese, and get them to Liu Zhidong (Shanghai warranty service agent, mentioned earlier today) and Zhang Haitao (Beijing), so they can present them to Jialing CQ.

Any volunteers to translate? Milton? Fon? I'm happy to help with this, but my Chinese will not be authoritative. This calls for a native Chinese-speaking motorcyclist!

thanks again, and cheers!

[ChinaV]

Alternative is to take everything off, put an nice old carburetor on it, or buy an aftermarket EFI unit, and start playing from there.Not easy though.

It's frustrating that you can't get a Powercommander from Dynojet. I wonder if any of their systems could be adapted to work with the JH600

Keep up the good work Eric.

Cheers!
ChinaV

[milton]

I have no problem helping translate the findings into Chinese. However, I actually speak "Taiwanese Chinese", even that is recovered from 30 years of disuse while I lived in the States and definitely not "authoritative".

Before translating it, I need to get my arms around it first. I still have a few questions:
1. If it is due to a bug in the ECU logic, how do we explain the fact that for some people this is a recurring problem, which implies something that deteriorates over time and is unlikely a "logic" issue. Also, how can swapping parts repair a problem in the logic?
2. How about the repair Dr. Cui put in for the decompression valve in my bike, which made my bike run nicely for almost 4000km?

Perhaps what has just been sleuthed out by Eric is just a single problem inherent in all the JH600 which causes stalls, and there are many other unrelated problems lurking in the background waiting to be triggered by weak battery, bad gas, poor electric contact, deteriorating sensors, failing decompression valve, etc.?

[998S]

It's frustrating that you can't get a Powercommander from Dynojet. I wonder if any of their systems could be adapted to work with the JH600

Well, I should say that the bike has no bad fuelling. It is pretty smooth from 2.000 to 6.000 rpm, did not really feel flat spots.
Just runs out of steam in the higher RPM's, but that is part of the concept. Don't think many of you will be there often.

If I am right (and I still say 'IF'), then it is most likely one ittipitty little small number in the spreadsheet which is wrong.
Basically no need to spend any money for aftermarket stuff.

I still have a concept in my head to "override" the CO sensor, and trick the ECU into a richer mixture. But as mentioned, I don't think it is the main problem, so I will wait a bit with that one.

Is there no one who is good friends with the big BOSCH boss? Been silent on that matter.
I guess the only solution lays in some friendly favour from a German to a German ...

[998S]

How about the repair Dr. Cui put in for the decompression valve in my bike, which made my bike run nicely for almost 4000km?

Perhaps something to ask Dr. Cui .....
-Can it be that the the decompression kicks in unwanted at a certain rpm?
-How is the decompression valve operated, by ECU?

It should make sense, as I notice the stall is quite HARSH.
That is why I thought more about the spark then the fuel.
It sounds feasable to me that the decompression is part of it, and at those lower RPM's, it need just a bit of compression loss to kill the momentum, and stall.

ADDED:
I checked the pictures of Motokai again: http://www.mychinamoto.com/forums/sh...-Valve-Problem
: It seems the decompression device is spring operated. Anyone seen this and can confirm?
If that spring is weakening over time (very well plausable with Chinese steel quality - don't tell me anything about that), the timing might go off.
That might be the reason the decompression comes in at a higher rpm then the original 1.500.
That also means that if I reduce the idle, stalling will increase. Something to try tomorrow.
Shoot me ...

[euphonius]

Is there no one who is good friends with the big BOSCH boss? Been silent on that matter.
I guess the only solution lays in some friendly favour from a German to a German ...

I think we have a JH600-riding colleague in Fuzhou who could fit the bill....

[MotoKai]

If no one is a drinking buddy with the guy at Bosch, then Jeff's recommendation to have "The Pfaelz" call them directly (cold) is a good option.
Jeff, here is the link for Bosch contact info to pass on to Pfaelzer: http://rbcn.vicp.net/web/contact/contact.jsp?lan=en

Bosch Automotive Products (Suzhou) Co. Ltd.
126 Su Hong Xi Road, Suzhou, Jiangsu 215021,
P. R. China
Tel: (86 512) 6767-6999
Fax: (86 512) 6256-1818

Bosch (China) Investment Ltd.
Add: 333 Fuquan Road North,Changning District Shanghai 200335,P.R.China
Postal code:200335
Tel: +86-21-22181111
Fax: +86-21-22182388

Contact info of head of Bosch China (these are Chinese Executives)

Other Bosch Automotive Links (I don't see anything specifically for motorcycle on their China Site):
Bosch China Website
ECUs
ETC

[td_ref]

Any volunteers to translate? Milton? Fon? I'm happy to help with this, but my Chinese will not be authoritative. This calls for a native Chinese-speaking motorcyclist!

For authoritative writing style you would need someone who has office secretary experience, prefer one work for gov. departments.
I don't know how much I can help with translation, proof-reading I guess.