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Pitted tappets, mashed valve ends and a loose primary chain?

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DayvW:
After starting on a clean up of the engine ('76 400-4) I have decided to go the whole hog and strip her down completely for some soda blasting.  In doing so I have found some tappets are pitted and on one or two valve stem ends they seem quite hammered (though the pitted tappets do not coincide with the mashed valve stems).  Has any one seen this before?  I'm going to replace the tappets - but regarding the valve can I grind these back to smoothness (or is there a risk I'll grind through the hardened surface?).

On a separate note - having removed the sump and finding so much gunge in there (mainly, I think, from gasket gunge!) - plus a lump of alloy about 1/4" dia - all of which persuaded me that a full strip down is in order now I have the head off and the engine on a bench  - I poked the primary drive chain on the sprocket (the one that protrudes into the into the sump a little way)  - and it seems so so loose.  Is that how it's supposed to be?  And how long do they last?  The mileage on the speedo reads 23,000 (no idea if genuine of course).  I'll replace it if need be - but they aint cheap.

Any experience of any of the above much appreciated.  Thanks.

Trigger:
You will have to replace the damaged Valves and Tappets. The engine will need a total strip and any damaged parts replaced.
Your parts list will be long, but it is all worth it in the end.

Bitsa (Ralph Wright - RIP):
Plus one with trigger dont cheap skate you get what you pay for trust me
Cheers
Bitsa

DayvW:
Thanks guys - and yeah - I thought so  - do you think just poorly adjusted tappets may have caused the probs?

And on the primary chain - should it feel loose or would you expect it to be tight -and if so - what is it that makes it tight?

Trigger:
Dayv, the best thing to do is check all the part and look up the cost. It maybe cheaper in the long run to find another engine. But, can you trust a second hand unit?
Primary chain                                   Â£75
Cam chain                                        £30
Shells                                               Â£8 each
Main bearing's                                  £12 each
Oil seal set                                       Â£30
Gasket set                                       Â£50 - £95
Piston's                                            £45 each
Piston ring's                                     Â£15 each
This is just your basic parts you may need. Without any tappets, valves or machine work.The average cost for a CB400/4 is £$??? these days. Any short cuts will bite you back.

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