JH600 stalling

[bigdamo]

If you have a problem with fork dive, you can experiment with some thicker fork oil.
This will stiffen up the compression and rebound, and you will notice a less pronounced dive (but also a stiffer bike in general - good if you join us on the F-1 circuit....).

E.

And or more volume of fork oil..

[Barry]

Not sure if anyone in BJ is still interested in buying a JH600, or they rather wait for the outcome of the whole stalling issue.

But there are a few 2nd-hand JH600's for sale here:

JH600 with Jing A-plates
JH600 with Hebei-plates
JH600B with Hebei-plates

[marcomagica]

The more I read this thread and the more I am happy I went for the YBR250, as I liked the JH very much.

I have no doubt your problem will be solved eventually, especially because the youku videos and MCM + other forums are source of bad publicity for Jialing. This thing is now very public and that's the only reason they are addressing it.

Good luck you all, hope all your problems will be solved soon!

[MotoKai]

Well you can always consider the JH600 for your next bike - we always welcome you to join us!
This thread has been very useful. Thanks to Milton for starting it, and LJH for pushing the issues and E. for support (for the love of motorcycles & ice cream).

With that said, let's be reminded of the many wonderful experiences all of us JH600 riders on MCM have had. While there's no Forum category for the JH600, I've pulled together some selected threads from different Topics related to the JH600 - Enjoy!!

Impressions
My New JH600
Buckin' Bronco -- breaking in my JH600 in rural Sichuan
JH600 impression
JH600 Impression (2)
The first JH600 in Nanjing?

Ride Reports
Zhejiang to Fujian - JH600 home ride
Shenyang - Mohe
Yunnan Ride 2010
Hubei, Sichuan and the Three Gorges of Yangtze River
Weekend Trip From Shanghai -- QianDaoHu
Rapeseed Blossom
Motokai's Inner Mongolia Ride 2011
Jialing riders visit the West of Beijing
National Day Ride 2010 (Anhui + SW Zhejiang)
JH600 - Wet and Muddy in Fujian
Slabbing to Moganshan (and back)
My first mountain run-JH600
JH600 Off-Road: West Suzhou Tank Grounds Run
Solo Ride to Shaoxing & Xitang (Mid-Autumn Festival 2010)

Mods
My New JH600
Shanghai Muffler Man -- modding my JH600
Jialing JH600 muffler & pipe upgrade

Other
Jialing JH600 sidecar uncovered
What The Hell Is That? (JH600 Experiences)
Jialing JH600 in Brazil
Jialing JH600 Parts/Prices

[euphonius]

Thanks for this, Motokai. Perhaps we can persuade CrazyCarl to set up a new sub-forum specifically for Jialing in the Manufacturer's Info and Discussion forum, where all the various Jialing models can have their place in the MCM sun.

cheers!

[euphonius]

If you have a problem with fork dive, you can experiment with some thicker fork oil.
This will stiffen up the compression and rebound, and you will notice a less pronounced dive (but also a stiffer bike in general - good if you join us on the F-1 circuit....).

E.

Dear Eric,

Thanks for this guidance. I've read and re-read Pfaelzer's discussion of the JH600 fork, its diveyness and his upgrade to progressive springs and different fork oils, but I find myself still intimidated by the whole thing. This should be a good winter project, since my forks have never been serviced. At this point I'm not even sure whether the diveyness that I'm currently experiencing is the way the bike is supposed to behave or if there is a problem (insufficient oil, wrong viscosity, bad spring(s), etc). I only have one other bike (my KLR650) with which to compare, and I can say the JH600 front end is much softer/mushier, and I don't like it at all.

I don't want to hijack this thread, but I am curious about how to proceed. How could I get an independent assessment of the current fork dive and whether it's normal or abnormal? What would be the next steps -- just tinker with different viscosities of fork oil, or go for progressive springs and then start tinkering with oil?

thanks for any and all guidance!

cheers

[998S]

I've read and re-read Pfaelzer's discussion of the JH600 fork

Well, as the fuel injection before, suspension can also be easily broken down in 2 main blocks (and let me forget some of the details):

1) The springs, on which you basically ride / float
2) The damping, which basically tries to control the spring movement
In real life, these of course are very closely related, and working together.

Simply said, the springs are basically supporting the weight of the bike, plus the weight of the rider, passenger, luggage etc.
Springs can come in gradients of stiffness; a stiffer spring will compress less under the same weight.
A good rule of thumb is that the spring should compress 1/4th under the load of the rider sitting on the bike (for a road bike).
This means if your fork movement is 120mm, your spring should compress some 30 mm if you sit on the bike without moving.
This will allow the spring to further compress (if you meet a bump), or retract (in case you meet a hole in the road).

To determine the stiffness of the springs, factories have to compromise.
European riders are heavier then Asian riders; is the set-up for only a rider, or also a passenger / luggage, etc.
I can presume the Jialing is set up with relative soft springs, for a lightweight Asian rider.
Logically that a heavy Caucasian might consider the spring too soft.

Too prevent a uncontrollable movement of the spring under changing loads (riding over humps and holes), damping is needed.
Compression damping to control the compression of the spring, and rebound damping for the outward movement.
This damping is mostly obtained by oil and orifice (small holes) inside the damper or forks.
The oil is pressed through these small holes, and logically that creates friction. This friction prevents dramatic movements of the springs.

Now, to adjust this friction (and adjust the speed at which the spring can compress or rebound), you can change the diameters of the holes.
This can be done by a rebuilt of the fork, and change the orifices. On modern, more expensive forks, this can be done externally, by adjusters.
However, if you don't want to rebuilt the forks, you can change the thickness of the oil.
Thicker oil is more difficult to pass the holes, more friction, more damping,
Thinner oil, easier, less damping, same story.

So in the Jialing case, where you have forks without any adjustment, you basically can only change the oil thickness.
Try a slightly thicker oil, and you will find out that your damping improves.

As said before, if that does not help, there are other small tricks to try to improve things.

Hope this helps a bit in understanding the magic of suspension.

E.

PS. Progressive springs are a kind of compromise, which works good on off road bikes with longer travel.
They bassically combine different stiffness in 1 spring.
So, for the first part of the compression, they feel relative soft (and comfortable), then they start to stiffen up if they compress more.
Because of this, they reduce the dive.

[euphonius]

Dear Eric,

Thanks for that super informative and useful overview. Next step for me is to dive into the JH600 service manual and learn the procedure for extracting the existing oil and replacing it with something thicker. Having read Pfaelzer's recent (April 2011) assessments of his fork's performance, I'm very tempted to spring for a new set of progressive springs.

Not sure if you were aware, but Jialing does sell the JH600 in two flavors -- Asian version and European. Their literature indicates that this is mainly a difference in height, but now I'm wondering if they've tuned the front and rear suspension to accommodat the (presumed) differences in rider size and weight.

Thanks again, and I'll surely post on this when I undertake the process.

Cheers!

[Lao Jia Hou]

Sorry to not be contributing in a timely fashion - life has been rather busy these days.

In conversations with Jialing (CQ), it hinted that it thinks one of the problems (related to stalling) may be related to dirt/dust getting the various electrical connections and/or sensors.

While this appears somewhat sensible, on the face of it, it doesn't explain the hot headers (apparently related to a lean mixture), nor the clockwork-like initial stall (possibly related to the ECU resetting the mixture after X revolutions, as Eric noted).

Eric's diagnosis relating to a lean mixture appears the most sensible primary stalling cause.

I will be turning over the bike within a day or two, and probably have more info by the end of next week (around the 11th).

BTW, my earlier comment that my stalling problem appeared to be reduced by colder weather has been completely discounted by the current cold weather - my "A" is stalling more than ever now, in colder weather, perhaps at almost twice the frequency of what was in the video.

Cheers

[Barry]

In conversations with Jialing (CQ), it hinted that it thinks one of the problems (related to stalling) may be related to dirt/dust getting the various electrical connections and/or sensors.

I don't really like the way some of the electrical parts below the seat look on my bike, some things look a bit porous down there. Was kind of thinking of replacing some of the electrical parts this winter. I'm sure it looks worse on my bike than yours, but then again my bike runs great compared to yours at the moment. So why should I replace something that's not broken yet and works fine (I've been in China to long, as long as the thing runs there's no need for maintenance)!?