477 Installation - Timing Chain too short


477 Owner
I am installing the 477 big bore and got the head on to find that the timing chain won't fit over the cam sprocket. I have pulled it apart again and taken the stator motor cover off and checked everything, and it still doesn't fit when I put the head and can on.

What am I missing here?
I really do not know. I have watched at least 20 477/500 conversions and this problem never came up. So there must be a solution. Maybe @Dool can help!
When you attempt to install the chain, is the cam already sitting in its bearings?
It is not long enough to be fitted with the sprocket on its boss either.
cant be done that way, you probably have guessed the chain is not long enough.
The chain is introduced to the cam which comes in on an angle left side down, the sprocket is just floating on the cam, when chain is over the cam and set into the bearing the sprocket is fitted with the chain and lifted up and on to the boss.
Sorry I cant be more help.
I do remember my mechanic had to fumble quite a bit at that point, so it is not an easy task per se. My BS3 has reached 55.000km so the cam chain is due for replacement, I will video it but it may take a while - few weeks, before I get around doing it.
My mechanic had the engine half way disassembled when he realized one particular tool was missing. I have ordered it from amazon and we had to abort the process (we had 3 cameras in place !!) until the tool arrives around the 15th of July (!!).

Magnet Puller/Flywheel Puller​



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Checked and magneto has to come off for timing chain change
Cam chains were replaced previously so a tool. existed