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« on: May 23, 2009, 06:12:24 AM »
Have just checked and adjusted the tappets (valve lash) on my LF250 and was glad that I did!
The correct adjustment is as follows:
Inlet 0.08-0.12mm or 0.003-0.005in
Exhaust 0.10-0.14mm or 0.004-0.006in.
As the cam lobes/tappets/rockers wear normally the gap slowly enlarges as the miles are clocked up but out of the four valves (2 per cylinder - inlet and exhaust) all but one had the gap too small which isn't very good for the valve seats. I've only done 4500km since new so hope that I haven't done any lasting damage to the valve seats or valves themselves - I've tried the bike and it pulls okay so I must have got away with it. The job is quite lengthy as there are quite a lot of odd bits to be removed (seat, tank, carb cover, air filter and bits of pipe etc) to simply get at the cylinder heads but it should be within the capabilities of the average mechanical person. When removing the petrol tank the two fuel pipes (main and reserve) will have to be clamped as the on/off valve is not part of the tank. Remove the spark plugs to make turning the engine easier. On the left hand engine cover there is a slotted plug about 30mm in dia which if removed will allow you to use a 17mm socket wrench to turn the engine. For each cylinder turn the engine until the exhaust valve is just closing and the inlet valve is just opening (on the rock) then carefully turn the engine one complete turn further. This allows the tappet adjustment to be made with the cam lobe in the correct place - approximately on the back of each lobe. Each valve has its own round cover set in each rocker cover. When you come to replace the petrol tank do make sure that you don't damage or kink any of the fuel tubing as it could split - happened to me and I lost near a full tank of petrol all over the ground! Hope this helps, Pat