LC4 rocker arms

[matsplatuk]

During my firts valve clearance check (Thanks Creeper for your exelent guide) i noticed that the inlet rocker arm moved laterally along its shaft. This didn't seem to heppen with the exhaust rocker arm 'till i took the upper cylinder head assembaly off. Now they both move about 1mm side to side on their shafts. Is this OK?

I did a search but only found one mention of inlet rocker arms failing on older machines but that was it. Does anyone know more on this?

Thanks, in advance - Mat

[Loadedagain]

whoa.... now i see why that bearing needs replacing at regular interval... it's flippin tiny!

[Loadedagain]

ps... rockers should float on the shafts. i'm not sure of allowable end play, but 1mm doesn't seem too bad. i'll have a peek in the manual for a spec... betcha creeper beats me to it though.

[Loadedagain]

Originally Posted by Loadedagain

betcha creeper beats me to it though.

told ya....

[creeper]

Originally Posted by Loadedagain

ps... rockers should float on the shafts. i'm not sure of allowable end play, but 1mm doesn't seem too bad. i'll have a peek in the manual for a spec... betcha creeper beats me to it though.

Just did one a few days ago...

[matsplatuk]

Oh OK, i think i understand,

I leave the 1mm shim on the cam chain side but then add shims to the spark plug side so the total play/gap on the shaft is 0.2 - 0.3mm?

Is this something worth doing or will it be safe to leave it till another day?

I suppose i just go to a dealer and ask for LC4 rocker shaft shims?

Funny that this procedure isn't mentioned in the LC4 motor manual ive got.

Many Thanks Guys - Mat

[creeper]

Originally Posted by matsplatuk

Oh OK, i think i understand,

I leave the 1mm shim on the cam chain side but then add shims to the spark plug side so the total play/gap on the shaft is 0.2 - 0.3mm?

Is this something worth doing or will it be safe to leave it till another day?

I suppose i just go to a dealer and ask for LC4 rocker shaft shims?

Funny that this procedure isn't mentioned in the LC4 motor manual ive got.

Many Thanks Guys - Mat

Right out of the book...

NOTE: Discs bl are available 0.15 mm, 0.30 mm and 0.50 mm thick.
– Mount new O-rings bp on rocker arm shafts 1.
– Mount rocker arms 2, thrust washers 3 and rocker arm shafts 1.
– On the side of the water pump one thrust washer bn ≪ 1.0 mm (0.04
in) must be mounted.
– The axial play on the opposite side is roughly equalized with thrust
washers 3 ≪ 1.0 (0.04 in) and ≪ 0.5 mm (0.02 in).
The axial clearance of the rocker arm axles must be 0.20 - 0.30 mm.

Considering 1.0mm is over three times what KTM recommends as a maximum end play, you should probably take care of it now.
It's not just end play, but potential acceleration and deceleration of the rocker arm laterally. The more play, the greater those forces, the greater those forces the more thrust and wear they can generate.
At least that's the viewpoint I would take.

C

[creeper]

Using your photo as a reference, see the shims on the drive side of the cover? KTM recommends those to be 1.00mm thick to establish rocker arm position.
Then you fill the gap on the spark plug side with shims to obtain an end clearance of 0.20mm to 0.030mm.

Shims are available in 0.015, 0.030, 0.050 and 1.00mm.

C