Hi all.
I had to do a top end rebuild on my bike(KTM EXC 04) as it lost a lot of compression and would barely run. Did leak down test which confirmed it. Cylinder was grazed and had lots of deep scuff marks when I took it all apart. Got my cylinder machined and re plated, fitted brand new piston kit(rings, gaskets and all that). Followed the workshop manual exactly, lined the cam up with the 2 circle markings with the top of the block on either side, etc. Turned flywheel by hand and all turned smoothly...was all good til I had to fit the rocker cover.
At first, once the rocker cover was installed and bolted down, I could no longer turn the flywheel the full 360 degrees by hand and instead had to use a ratchet and socket on the flywheel nut. Not sure if that's normal or not?(I thought it was still able to turn by hand). To me it was like I had coil binding or something. The flywheel was just hard to turn at a certain point and before installing the rocker arm cover, I was able to turn the flywheel the full 360 degrees by hand very easily.
Anyway as I was tourqing down the bolts to correct spec, I heard a massive 'ding' type sound that you normally hear from a spring breaking or decompressing. Not sure if it is broken or not but that's the type of sound it sounded like.
I also was unable to check valve clearances because the KTM feeler gauge would not go under the adjusters no matter how loose I turned/loosened the adjuster screw.
All this doesn't sound very normal or promising to me.
I'm just wondering what the possible cause or issue is? Or if I need to replace valves or valve springs, etc. And also, what would that 'ding' sound of been? Personally if i had to guess, i'd say it was the rocker arms/tappets compressing too much on the springs.
I had to do a top end rebuild on my bike(KTM EXC 04) as it lost a lot of compression and would barely run. Did leak down test which confirmed it. Cylinder was grazed and had lots of deep scuff marks when I took it all apart. Got my cylinder machined and re plated, fitted brand new piston kit(rings, gaskets and all that). Followed the workshop manual exactly, lined the cam up with the 2 circle markings with the top of the block on either side, etc. Turned flywheel by hand and all turned smoothly...was all good til I had to fit the rocker cover.
At first, once the rocker cover was installed and bolted down, I could no longer turn the flywheel the full 360 degrees by hand and instead had to use a ratchet and socket on the flywheel nut. Not sure if that's normal or not?(I thought it was still able to turn by hand). To me it was like I had coil binding or something. The flywheel was just hard to turn at a certain point and before installing the rocker arm cover, I was able to turn the flywheel the full 360 degrees by hand very easily.
Anyway as I was tourqing down the bolts to correct spec, I heard a massive 'ding' type sound that you normally hear from a spring breaking or decompressing. Not sure if it is broken or not but that's the type of sound it sounded like.
I also was unable to check valve clearances because the KTM feeler gauge would not go under the adjusters no matter how loose I turned/loosened the adjuster screw.
All this doesn't sound very normal or promising to me.
I'm just wondering what the possible cause or issue is? Or if I need to replace valves or valve springs, etc. And also, what would that 'ding' sound of been? Personally if i had to guess, i'd say it was the rocker arms/tappets compressing too much on the springs.
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