A year ago I bought a TTR 600 2001. I hadnt touched a bike before so Im no expert. It had done 27 000 km. I had issues starting it from the start and sometimes I had to kick it for maybe 30 min before it started. While running it was fine. Never a problem to start it when hot/recently used.

I went on a 20 000 km trip and the same characteristics continued, but since I rode the bike every day it usually started "ok". Sometimes I started the day sweaty from kicking and if it stopped before getting hot I needed to let it rest or get someone to push-start (yes, a PITA but I managed). After about 10 000 km it wouldnt start, the plug was fouled and a new plug fixed it. At that time I was on 3k+ altitude and soon I had to change plug again. Then once more. So 3 changes in a short time. After that I was on lower altitude and it lasted the remaining maybe 5000 km.

After getting home it rested for a few months. Then it was hard to start but again.. after 30 min it did. After a bit more it wouldnt start. Another spark plug change and it started well. I hardly drove it and after a week I tried again and it was hard to start again... (i.e. I had bike on for maybe 10 min with new spark plug, left it for a week then hard to start. So potential oil leaks should not have had time to foul plug?).

Spark plugs have always looked the same when fouled. Sooty, like pictures shown for "too rich mixture". I attach a photo of it.

I dont think that the carb is dirty. It was cleaned (it didnt look dirty) once during all this and nothing changed. During that cleaning I also got help to "lean" the mix by a half or one turn (cant remember for sure). I didnt notice any change.

Easy answer would be "too rich" and maybe it is. But shouldnt a "too rich" mix be easy to start with a spark plug that ran for ~10 min? Although the fouling looks like rich mix, it doesnt make sense to me that an almost new plug is hard to start cold due to rich mix (because then it wants richer mix?).

Attaching photo of latest fouled spark plug.

Also, I got help checking valves by some mechanic who seemed a bit sloppy. He did change 1 or 2 of the valves which were out of spec, but the bike didnt behave any different after that.


Any ideas?

Attached Thumbnails