JH600 Valve Problem

[zhu]

yeah what the decompressor does is allow the engine to get a bit of momentum as it dosnt get slowed down by hitting the compression stroke for the first few revolutions.

how it works.. is the problem as they are a complicated arrangement of levers cams springs and other assorted piblets

all of which are prone to sticking or failing to work in the advertised manner

such is the joy of 600 singles

[Lao Jia Hou]

So what you and Lao Jia Huo seem to be saying is this mechanism intervenes in the normal exhaust/intake valve operations during and only during startup to achieve some desired effect, such as, err, starting up the engine? Or starting it up more efficiently/smoothly than in the absence of this mechanism?

Hmmm - I'm missing something. How does an engine fire without compression? Certainly, the starter would more easily turn over the engine with less/zero compression ... so maybe opening one valve decreases compression enough to ease the starter load, but there is still enough compression to fire? Maybe without this mechanism, the bike would need a huge battery & starter motor?

Motokai and I did get a glimpse recently of the phone-book sized JH600 shop manual, all in Chinese of course, and damn I'd like to lay my hands on one of those. The guy who is working on Motokai's engine does NOT have one of these shop manuals. There's probably only one in all of Shanghai.

Wonder if Jialing would sell me one, as they did with the service parts catalog?

OMG - I'm in. I will also ask Mr. ZHT in Beijing if it is possible. This would be enough motivation to learn to properly read Chinese. MUCH more important than a menu!

[Lao Jia Hou]

yeah what the decompressor does is allow the engine to get a bit of momentum as it dosnt get slowed down by hitting the compression stroke for the first few revolutions.

how it works.. is the problem as they are a complicated arrangement of levers cams springs and other assorted piblets

all of which are prone to sticking or failing to work in the advertised manner

such is the joy of 600 singles

ah, ok - thanks a LOT zhu. This site is always helpful.

Cheers

[euphonius]

Speaking of the JH600 engine, I just had a look at the website of the Austrian designer AVL, and came across an amazing description of their Shanghai technical center. Turns out their roots in China go back to the company's founder Hans List, who actually lived in Shanghai between the wars a decade before he started AVL in Graz! Damn, I would LOVE to organize a Jialing owners' "field trip" to their tech center...

cheers!

AVL's business relationships with Chinese customers have been enhanced by the establishment of a new purpose built technical centre in Shanghai.

The founder of AVL, Professor Hans List, began making contacts in China from 1926 when lecturing and researching at Tongji University, Woosung(Shanghai). He lived in China from 1926-1932.

AVL List GmbH was set up by Prof. List in 1947 based in Graz-Austria. Business relations with potential Chinese customers were reestablished in 1974 and actual contracts started to be undertaken from 1975. In 1985 AVL opened a sales office in Beijing.

Today AVL China consists of sale offices through out China and a technical centre formally known as AVL List Technical Centre (Shanghai) Co.,Ltd. based in the Pudong area of Shanghai approx 30 minutes drive from the new international airport.

The main activity of the new Technical Centre is the design, simulation and development of both petrol and diesel engines used in all forms of transport and industrial applications. The work in the Technical Centre is performed in close collaboration with AVLs HQ in Austria. The inter-reaction of staff between the two locations and other AVL affiliates is key to AVL's success.

Using AVL Technical /equipment engine test beds and vehicle chassis dynometers are already in operation upon which customer projects are being carried out.

The new Technical Centre not only implements its own projects, but also sees itself as a bridge between the headquarters in Graz and business partners in China. This ensures both better understanding of the requirements of the Chinese market and personal customer care. The offer of the option of working at clients' test beds and factories both underlines the Centre's strong focus on customer service and helps business partners leverage for significant cost reductions.

By helping Chinese firms to build up their own research and development facilities, and supporting customers all the way through to the manufacturing stage, the China Technical Centre will be laying the groundwork for its future business activities.

[MotoKai]

The exhaust cam arrived today from Chongqing, so went over to Dr. Cui's to watch and learn. Here's a recap of the chinese parts and what I have gathered is going on. [Feel free to chime in with clarifications and any additional insights.]

减压阀 Pressure Reducing Valve
排气门 Exhuast Valve
凸轮抽 Exhaust Cam

As a reminder of what was the diagnosis from last week, see the below photo once again with the red circle indicating area of issue which was loose and creating the rattle.



The part which was sent from Chongqing is a new 凸轮抽 Exhaust Cam. Which up to a limited rpm (approx 1500) will control the 排气门 Exhuast Valve to achieve the right amount of decompression during this critical stage.




The red circle again indicates the original point of rattle detection. Once the new Exhaust Cam arrived, Dr. Cui went in and pulled out the old one allowing the core of the problem to be realized. The part indicated with the yellow rectangle [this is the piblet Zhu referenced above] is supposed to turn (spin) over the Exhaust Cam Shaft controlling the opening and closing of the exhaust (see red circle), but wasn't working properly. This was causing the piece in red to be "loose" and thus create a rattling sound.

After the new part install, Dr. Cui checked my pulg (a NGK spark plug which I purchased at the Shanghai Motomarket on Jiaoji Lu), and it was pretty shot. Most likely this was a fake plug, as I only used it for about 7,500kms and the center electrode was ratty. It was replaced it with a new imported Denso Iridium plug and the Doctor put her back together.

Test spin felt great. There was power back that I didn't realize was lost. And of course the rattle-tinging sound was gone.

So, was it a bad plug the problem that triggered this? No. Jialing rep smiled and said, 你就是骑了太猛。 (fierce riding). Guess I'll have to keep reminding myself it's just a one-banger! But sometimes I just keep chasing that Honda VF500F V4 feeling of days lost.

[Also worthy of mention is the comment after Dr. Cui's first ride on the JH600, 它有力气! (The bike has strength). And this is a guy who repairs and tests out crotch-rockets.]

[Lao Jia Hou]

Thanks a bunch for this info MK. It is truly helpful.

Damn, that cam (and associated "piblets") looks complicated. My farmer Honda 125 is getting more love each day - she might not be the fastest or the prettiest on the dance floor, but she's easy to understand & always reliable.

Real bummer about the fake plug.

Yeah, on the few times I've really pushed my JH600 aggressively, it protested by acting a little weird for a period of time afterwards. Sort of like a teenager pouting. But if I hugged it, and said nice things to it, it returned to normal.

Re service manual: went to Jialing service centre in Beijing last weekend. ZHT wasn't there, but a snarly mechanic was. I asked about the service manual, and he snarled "Hah! Why would I need one of those things?" Oh ... my ... god. I will wait until ZHT is back.

[euphonius]

I'll ask our Jialing guy here in Shanghai about availability of the shop manual.

[milton]

Congratulations on the happy ending of your valve/cam/阀/门/抽 woes.
I made real effort in trying to follow those discussion on various piblets of our JH600 and failed. Fortunately I still have the phone# of Dr. Cui's.
Cheers!

[Lao Jia Hou]

I will wait until ZHT is back.

Got the service manuals for both the A and B - will try to get them into an e-format in the coming days/weeks/months/years (I've never done it before).

[milton]

My JH600 has been stalling like crazy recently, usually during idling or downshifting. I had a new spark plug put in and replaced the following with genuine Bosch parts:
1. cps crankshaft position sensor (曲轴位置传感器)
2. tps throttle position sensor (节气门位置传感器)

Both may affect the idling performance of the bike but did not make much difference to the problem.
Dr. Cui took a listen to the engine and suspected that it might have the same 减压阀 (valve) issue. I will need to take my bike in for an inspection on that valve. It involves some major disassembling and probably takes a few days.
Wondering if this has anything to do with my JH being black.