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Tiger cub
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iain govan
exmouth
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January 11, 2020 - 4:58 pm
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Hi, I have got the rebuilt engine back in the frame and when in gear I can turn the rotor by hand and the rear wheel will spin and the valves work, but I can’t turn the engine by turning the rear wheel by hand or by pushing the bike. What have I done wrong please? 

1950 D1 OSV 323 on and off the road, some of a 1959 triumph T20 on the bench

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Sponge
Lancashire (A chip shop somewhere near Preston)
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January 11, 2020 - 6:25 pm
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It actually takes quite a lot to bump start a 4 stroke single, even a tiddler like the Tiger Cub. So spinning the back wheel is the same sort of challenge.  So ......have you got the spark plug in ?

If so take it out and try again without it. It should, now, be possible to spin the engine by turning the back wheel.    

If that doesn't work there is a sort of one way action ratchett problem somewhere and more investigation is no doubt required. 

Sponge 

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iain govan
exmouth
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January 11, 2020 - 6:38 pm
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The plug is in but the carb and exhaust pipe are not fitted, I’m trying to find out if I have a working oil system, the rebuild has been bearings, seals, big end, rebore all the fun stuff, I enjoy a challenge! 
 Thanks

1950 D1 OSV 323 on and off the road, some of a 1959 triumph T20 on the bench

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Sponge
Lancashire (A chip shop somewhere near Preston)
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January 12, 2020 - 12:41 pm
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Well, remove the spark plug and try again. I think you will find that, without teh plug,  it is now possible to spin the engine from the back wheel. 

The traditional way to test and prime your oiling system is to remove the spark plug, tie the HT lead safely out of the way and then put the bike in 2nd gear and push it up and down the road several times.   You will be able to see the oil returning to the oil tank through the spout and if you look in the rocker cover you should see some evidence of oil getting up there as well.   This is a good idea with a newly rebuilt engine and gives you confidence that your new engine will be properly lubricated and that you have no major oil leaks from pipes washers and gaskets.   

Alternatively you can take the spark plug out and, gearbox in neutral,  operate the kick-starter about 50 times. Once again you should see oil returning to the tank having had a great trip around your nice clean engine.  Check for leaks afterwards.    

If all is well then once you have fitted the carburetor and exhaust system and put the gapped spark plug back in,  you should oil-prime your engine like this before your first start up.   

When you start it the first time let it settle into just above a tickover and check the oil return into the tank.  Put your finger over the hole for about 5 seconds and this will prime up your rocker feed and send a good squirt of fresh oil to your rockerbox and top end mechanisms to help bed them in.   

Hope this makes sense

Sponge

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iain govan
exmouth
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January 12, 2020 - 6:31 pm
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Thanks, that’s very useful. Still can’t turn the wheel with plug out but everything turns happily when kicked over in gear. Clutch isn’t right, maybe new plates are too thick, I’ll sort that next, wish I had a bike lift, not built for low work! Gears select so more upbeat than yesterday  

thanks again

1950 D1 OSV 323 on and off the road, some of a 1959 triumph T20 on the bench

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