Tank Slap - Motorcycle Forum

Thanks all for the helpful (and not so helpful ) advice.
Hopefully I'll hit all the salient points but if I miss something please ask again!
@StM I changed the CPS in my old bike not the one I crashed so not that anyway luckily.
I'm hoping it's not the starter as that looks like a pain to get at. The service manual says remove the throttle bodies which means removing a ton of wiring to get at the clips so I'm going to ignore that for now! If the starter was damaged and I start the bike again it's unlikely to cause any further damage right?
I haven't looked at the cam chain yet as if I pull the bottom cover I'm going to need a new gasket and I'm not sure if I'd see any problems just by pulling the bottom cover?
I've taken the airbox off and pulled the plugs. The top of the throttle bodies looked a little petrol/oily which I think is normal? Spark plugs looked a bit murky but ok? @Deegee I had no idea the battery could drain off like that, I'll have a look. I'd assumed the battery was sealed so nothing could leak. The bike has gbracing engine covers so I think the cases are straight but will check.
There were stones and mud everywhere when I pulled it open but I don't think there were any past the air filter in the airbox.

StMarks wrote:Ok having read some of the suggestions above, & watching your video a few times again, I'm going to make another suggestion.
Not a nice one..
Could it be that hot thin engine oil leaked past the piston whilst it was on it's side.?
Could it then be that the engine was tried again that oil would hydraulically lock that cylinder, making it virtually impossible for the starter to turn the engine over.?
Eventually something would have to give, perhaps a valve.?

I've got to admit this is my big fear. Immediately after the crash I was very unhappy at how the bike didn't want to turn over. It 'felt wrong' somehow but put it down to ignorance/paranoia. Talking to a guy in the pits he said hydraulic lock was unlikely on a modern bike but not impossible. We tried getting the bike into 6th and pushing it but struggled to really get the wheel to turn by pushing the bike but have no idea how hard it should be?
If I get the bike on a stand, put the bike in 6th and turn the rear wheel should it move reasonably easily? Can I turn the engine over like this slowly to try and detect any noises?

I'm 'ok' with spanners but my knowledge is fairly basic so apologies and thanks!

DaytonAndy wrote:..... We tried getting the bike into 6th and pushing it but struggled to really get the wheel to turn by pushing the bike but have no idea how hard it should be?
If I get the bike on a stand, put the bike in 6th and turn the rear wheel should it move reasonably easily? Can I turn the engine over like this slowly to try and detect any noises?

Fwiw I've never used top gear, only bottom.: small turn of the wheel in 6th would have the engine spinning far too fast. Also the effort required is almost unachievable IMHO.
1st gear will allow slow & controlled turning of the engine with little effort, I believe.?
Good luck.

Oh & that spark plug looks pretty perfect to me. If you had a hydraulically locked barrel, then I would expect the spark plug from the offending cylinder to be soaked in oil.?

Did you check all plugs? I'd take the airfilter out and take a look anyway if I were you

I can't turn the back wheel at all when it's in gear! That doesn't feel like good news

Cav wrote:Did you check all plugs? I'd take the airfilter out and take a look anyway if I were you

Plugs have been out. There's a photo just up there

DaytonAndy wrote:I can't turn the back wheel at all when it's in gear! That doesn't feel like good news

Unless your still trying to turn it in 6th, of course.!
Fwiw I would leave all the spark plugs out, until you've identified the source of the problem. That way you will be able to tell better if any resistance is mechanical, rather than compression resistance.
This is one of those times where it would be useful to have a portable Deegee in your toolbox.

Ha if only! Tried in first and second and can't budge it at all. I almost want to try to start it again to see what happens so I'll pull the plugs again if just to remove that temptation!

I've never been able to move the wheel with the bike in gear... didn't think you were able to

I would have thought with the plugs out it would be relatively easy to turn the engine by hand. You would also be able to hear any nasty noises or resistance.

Plugs out. Doesn't seem to turn at all. Unless I'm missing something obvious it seems locked solid

drain the oil , look for any foreign objects or bits of metal in it

Also check the header pipes. Any valve/piston interaction generally leads to metal shrapnel in the exhaust headers.

Andy you can get cheap boroscope type cameras that plug into your lap top via USB point.

Not sure of the quality but maybe some help for an internal inspection.

Jack wrote:drain the oil , look for any foreign objects or bits of metal in it

Next on the list. 'Luckily' the oil is probably less than 100 miles old so should be easy to spot anything.
Assuming I find nothing in the oil would you put it back in given it's so new? I can nip out for a new washing up bowl to drain it into to keep it clean.

Blade wrote:Andy you can get cheap boroscope type cameras that plug into your lap top via USB point.
Not sure of the quality but maybe some help for an internal inspection.

Great idea thanks just ordered one.

kiwikrasher wrote:Also check the header pipes. Any valve/piston interaction generally leads to metal shrapnel in the exhaust headers.

Would I have to take the exhaust off or could I poke the boroscope up the exhaust to look?

I'm in two minds about the oil. If you do drain it out then it'll need to go into a bottle or something you can seal up.

Part of me thinks that it should go, regardless of what you find. The other part thinks it might be worth using as a flush through once you've done all of the work you need to. Either way you're looking at needing some new oil. I wouldn't be using it until your next planned oil change.

*sigh*
You're probably right. Trying to desperately save £50 worth of oil when I might have f£$@€d my engine is a bit pointless

If you're going to use a boroscope I'd just be going in thru' the spark plug ports, easiest entry and you'll soon see if your pistons are shot

IMHO it would depend on what you discover has caused the problem DA.
If the oil comes out with no visible contaminants & your problem proves to be one that has not introduced a quantity of debris, then fwiw I personally would have no qualms whatsoever about retrieving it to re-use.