Did a valve shim change, now bike won't start

**Default_WLG** · 19th June 2016, 22:30

Hi all,

First post here, it's rare for Google to let me down!

Anyway, I have a 2011 G650GS. It has 31000km on it and last valve check was at 20000km so thought I'd better do one. I haven't done a valve check before so it was a bit of a learning curve for me. I pretty much followed the faq.f650.com GS Valve Check/Adjustment guide and this video: https://www.youtube.com/watch?v=T1mLPdSWCLM. It was easy enough to get the valve cover off and check clearance, just tedious. One of the exhaust valves was a bit loose (it was somewhere between 0.35mm and 0.38mm, spec is 0.25-0.33) so I cable tied the timing chain to its sprockets, pulled off the cam carrier and put in the next shim size up ($18 for a tiny metal disc

) as per that video. Pretty sure I didn't change the timing (i.e. chain didn't skip any teeth), though I didn't use the bolt to keep it at TDC and it wasn't quite at TDC any more (i.e. timing marks/tappets had moved a bit) after I put the cam carrier back together. I turned the engine by hand until the timing marks on the timing chain sprockets lined up with each other and were parallel to the edge of the case - does that mean timing is OK? In total, I turned it over maybe 10 times forwards and twice backwards (until Google told me it's bad to turn the engine backwards).

Put it all back together and now the bike won't start. The starter is turning it over OK and I can hear the fuel pump doing its thing when I turn the killswitch on/off. I've also gone through the throttle range 3 times without the engine running as per FAQs. I could smell fuel after running the starter a bit, so figured it must be flooded from turning engine over by hand. Pulled the spark plugs (they're such a PITA to get to!) and they certainly had fuel on them. I blasted some canned air into the cylinder and replaced the spark plugs with new ones. Reassembled and this time it got closer to starting while turning over (bit of popping that wasn't happening before), but still won't start.

It's a good AGM battery (not crappy stock one) and started straight away when I took it for a decent ride a couple of weeks ago.

Does anyone have any ideas for what I should do next? Could turning it over 10 times by hand flood it so badly that replacing the plugs and blasting it with canned air doesn't resolve it?

Thanks

**jellywrestler** · 19th June 2016, 23:02

check the cam timing and hopefully you didn't bend any valves if it's wrong. as for $18 for the shim, what do you pay for a coffee, or a glass of beer? stop ya fucking whinging and appreciate that someone is stocking that shit, if you think it's a tiny metal disc get on you tube and make one the same

**OddDuck** · 20th June 2016, 07:45

Did you check clearance again after fitting the new shim and getting the timing chain and sprockets sorted out?

It's sounding a lot like the valve is now resting off its seat and you've lost compression. Run a compression test if you can and if you haven't already, re-measure clearance.

It's bad to run with too much clearance, but it can be disastrous to run with too little - most of the valve head's cooling is through conduction to its seat. The stem will lengthen a bit as the engine warms up, that's the reason for a slight clearance gap with the engine cold. If the valve ends up being held off its seat, the stem can overheat, the valve head starts to flex, and you can have the head of the valve pop off and fall into the cylinder. Much learning then follows.

Also, comment above about bending valves: if you've been doing things with the timing and you want to check that things aren't interfering, turn the motor over by hand, not the starter motor. You can do this by putting the bike onto a center or engine stand, removing the spark plug/s, selecting top gear and then turning the back wheel by hand - slowly. If there's interference you'll feel it. The trick is to stop before things get damaged.

**Moise** · 20th June 2016, 08:53

Personally, I wouldn't have adjusted one slightly loose valve.

Anyway, have you rechecked the valve timing? Even a tooth out could make it harder to start without causing interference.

If the valve timing and clearances are OK, then it's most likely that something hasn't been reconnected or turned back on when you put everything back.