Lemans 2 Flywheel doubt

Sorry to say that I am questioning whether I aligned my flywheel correctly in relation to TDC when reassembling the engine. Bike now back together but with some running issues hence my revisiting the various processes. Is there a way to establish whether the flywheel and its associated ID timing marks are correctly positioned in relation to the crank shaft without splitting the engine and gearbox again. I have set the tappets and ignition timing and all seemed to ring true.



There are 6 bolts holding the flywheel onto the crank so, if it’s wrong, it’s going to be a minimum of 60° out and can only be a multiple of that. It can’t be just a few degrees out. Given that you have set the timing and it runs I would think it unlikely that you’ve got the flywheel on wrong.If you want to be sure check TDC on the right hand cylinder. Take the rocker cover off and take the spark plugs out. put a pencil or something in the plug hole and turn the engine till the piston’s at the top of it’s stroke and both valves are shut. The rockers should then be loose like when you set tappets. If the valves aren’t shut keep turning the engine till the piston comes up again. This time the valves should be shut. At this point the “D” should be in the centre of the bellhousing hole.Oh, and don’t jam the pencil and snap it.


I have been searching my memory on this and you’re absolutely right. Haynes, which I was following at the time mentions aligning TDC white index mark on crankshaft boss with TDC mark on flywheel. I think I recall this now. What threw me was a chance review of ‘This Old Tractor’ photographic instructions on this where he aligns the flywheel mark with a nib projecting on the inside lip of the crank case after having set the crank shaft so that one of the piston is set at TDC. (I can’t understand how it could be either at this stage) see '.
‘To re-install the clutch line one of the pistons up at
TDC, doesn’t matter which stroke. On the edge of
the flywheel you will see either a line or an arrow
on the edge of the flywheel that will align with the
little cast in tit in the inner edge of the crankcase’
Any way as you say I would have been out 60 degrees or more so I guess starting and running the engine would have been a tad tricky.

Thanks for the support on this and the pencil tips.


Worth saying what led me to question everything was running problems which have deteriorated. The bike is still in the workshop and when initially fired up ran and ticked over quite well. Then after about 10-15 minutes it began faltering and would not tick over. Tried numerous adjustments to the carbs mixture and idle screws. Noticed that fuel was collecting at the mouth of the intake on the rear of the carb and in the sun light I could see spits of fuel coming out the rear (intake of the carb with cones off)Surely it should be sucking rather than blowing in this direction. This made me question my timing of both valves and ignition. Going to start again this weekend going over settings plus do a strobe check on ignition timing if I can get it running sufficiently. Have to assume carbs are OK as I have cleaned, fully blown with air and replaced main needle and jet, pilot jet and float needle valve plus checked my float heights - all ok. Not sure about diaphragm pump setting as I have not fiddled with this. Sorry going off at tangent but I’m getting desperate.

Don’t know what ignition system you are running but symptoms that appear after 10 to 15 minutes, i.e. things getting warmer, sound like coils or condensors failing. Is everything sparking ok? If fuel is collecting it suggests it’s not being ignited and burnt off. Check your ignition…

If in that short time as it warms up run it as long as possible remove rocker covers and check valve clearance as you could have them to tight and when warm they are not fully seating with the expansion

Italian Motor is likely right. I’ve got a couple of these http://www.ebay.co.uk/itm/Spark-plug-tester-new-universal-easy-to-use-tool-/360920602013?pt=UK_Diagnostic_Tools_Equipment&hash=item54088b559d which will show if you’re getting a spark when the plug is fitted and engine is hot. You can probably pick them up at a local parts shop or Halfords.Yes. check valves are closing once things are hot but I still think it’s likely to be ignition.
v7john2014-06-05 09:11:37

Just BTW, I think the manual(s) say mark the flywheel and crank before taking the flywheel off, so it goes back on exactly the same. I agree though if it starts and runs cold then it can’t be wrong. Even 60 degrees (one bolt hole) out would be too large an error to run. (?)

Plenty of avenues to explore there. Thanks

I’ll post results drecly

If you want to get more into checking the valve timing and have a degree wheel, there is a good guide hereGuzzi Valve timingThis will also confirm you have the cam chain in the correct position. Once running it is surprising how much you can rotate the distributor and it will keep running.