JH600 Valve Problem

[MotoKai]

A week ago I was riding in Suzhou and started to hear a rattling noise upon arrival. I've had chain issues with the JH600 before (emailed some of you on the rubber guard issue), as well as general chain slack which has needed tightening. While out in Suzhou, it was tightened up once again but the tapping sound could still be heard on the way back to Shanghai.

Few days later I rode out to local mechanic in Shanghai to have him check the chain. We opened the front sprocket cover and could see the chain "jumping" a bit. Upon further inspection of the chain, it was obvious that as it rotated around the sprockets it went from being taught to loose to taught. Seems there was damage to the chain which created irregularities throughout. A call was made to the local Shanghai Jialing representative to discuss all the issues, and we agreed to swap the chain for a new KISS O-link.

The change was magical. There was more consistent pull through the gears and it moved from 1st thru 5th without effort. [FYI: Mechanic suggested I find a better chain lube which can penetrate the inner-core of the links and keep it properly conditioned.]

Pleased with my new ride I was off to install my new Taobao handguards, but the noise was coming back again, this time more noticeable. Louder now, I could tell it was coming from the front of the bike, and the sound was more clear. A pinging (Shit, my engine! )

After handguard installation, I rode back home with one of the guys from the Jiaoji Lu Motomarket, and it was now loud enough that he could hear it from on his bike sitting next to me at the red light. He suggested it was the timing chain.

Next day I was back at the mechanic, and he checked the timing chain adjuster, but this didn't solve anything. Another call was made to the local Jialing representative, and he suggested to take it to Pudong to see "The Dr." He's The Dr. because he can confidently strip down a bike and reassemble before I can finish looking up translations of the first few parts that come off!

Rode out to Pudong to meet him with euphonius and watched him go into action. After opening up the bike to check, he determined that it wasn't the adjuster or the timing chain itself....but the 减压阀 (jianyafa) - the valve.



Before the replacement could be sent from Chongqing, I was asked to bring the bike back to The Dr. so he can actually open the cylinder head to inspect the valve. This was done with amazing speed (The Dr. cursed Chinese engine design thru the whole process - he normally works on Japanese bikes which have much better design which makes working on them much easier). Well yes, it was as he determined - bad valve (see red circle below indicating area of issue which was loose and creating the rattle).

Enough backstory, on to the photos: