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Post by crackmastick on Mar 30, 2021 19:21:09 GMT -5
So my buddy and I are cruising around the other night and twice I see him power off and pull to the side of the road. He said he heard a weird noise and the engine just quit. First time was able to use starter. 2nd time needed the kick start. Then the death blow....
Weird noise followed by engine shutdown and the kickstarter was very difficult to turn. We smelled burning rubber. We theorized it was the drive belt shredding itself bit by bit until total shred/tangle failure. We trucked the scooter home and the next day decided to open up the CVT cover and swap for an old belt until his new one could arrive.
Opened up the case and there sits a perfectly fine belt. No shredding. 'uh oh' simultaneously came from both of us.
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Post by crackmastick on Mar 30, 2021 19:28:56 GMT -5
We noticed the bendix was engaged and appeared stuck. We removed/cleaned/and lubricated then reinstalled. We thought that might have been the weird noise. But no. We attempted a restartwere still unsuccessful. The kickstart was tough to turn over still.
So we opened up the valve cover to take a look and everything was as it should be. We were able to slowly kick it through a few rotations and see the valves were working and everything is normal. So after all that we are thinking is this an engine failure of some type?
We checked the oil and it appeared a bit low but not empty. Our next inspection will be to remove the cylinder head and perhaps tear in a bit deeper.
Does anyone have a feeling what direction we are headed? BBK and a new crankshaft?
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Post by captincvmn on Mar 30, 2021 22:38:15 GMT -5
Resistance has appeared from somewhere. Either engine or drivetrain.
You could compression test
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Post by crackmastick on May 12, 2021 1:13:22 GMT -5
Tore down the engine and found the wrist pin was fused to the crank rod, unable to remove. Installed a new crank shaft and 50mm BBK. Suspected low oil as the causing factor.
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Post by GrumpyUnk on May 12, 2021 11:32:05 GMT -5
Wrist pin gets lubed totally by SPLASH. No splash==no lube. The splash is caused by crankshaft or 'dippers' plopping into the small pool of oil in the sump. No pool or 'low' pool limits plopping, limiting or elimination any splash.
You may(repeat may) have been able to drive the wrist pin out of the piston and connecting rod, reamed the rod bushing to size, possibly the piston, and replaced the pin(and piston?) and it may have worked. If the small end bushing was very distorted due to heat, you may be totally unsuccessful, but if just a marginal bit of overtemp, you could have driven it apart, and cleaned things up. Might be an interesting way to get a spare crank..
You do have all the factory air ductwork/shrouding installed after doing the BBK install, right? If it is not installed, or doesn't fit properly, it may overheat and destroy all the work just done. Ductwork is mandatory as the airflow caused by movement won't reach the cylinder head and cylinder wall normally. The blower is needed.
tom
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