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CB 500 resurrection

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Bryanj:
Not the pistons that matter its the bores, if they are scored,rusty or worn its a rebore and oversize piston kits.
All 500/550 cams are the same, exceept a low power german one for a couple of years(never seen one, only heard of it).
Cam covers can wear the holes the rocker pivot shafts go in, there was a mod on the last couple of years of 550 to stop it.
Most common problem is primary chair wearing a groove into the main galler inside as there is no tensioner and the centre gear selector wears

Nurse Julie:
Measure the piston to bore clearance and see if within spec. If not, have a rebore to +0.50 over and buy new pistons and rings kit from Cruzinimage. The piston / bore clearance is very tight on these old Hondas and a rebore needs to be no more than 1 thou inch (0.0254 millimetre) (with Cruzinimage kits) piston/ bore clearance. If there are any scuffs, water marks, pitting, rust etc on the bores, it will also need a rebore.

gary123:
Thanks both. All noted.

Oddjob:
How come your mechanic didn't spot they were fitted back to front?

You're going to need to dismantle that engine completely. The amount of loose dirt just sitting there right under where the barrels join means that it's a certainty that some has made it's way into the engine itself, you can't have any dirt/rust loose inside the engine or you're asking for a huge amount of trouble.

You can't assume everything is ok on the engine, you need to check and see.

As Bryan says, check the primary chain, rough check is to remove it, sit it on a flat surface upright, so it sits like a tank track. The more it dips in the upper middle the more worn it is, a new chain won't touch the bottom links, the more links that touch the worse it is. Check the primary chain dampers as well, check camchain blade, check camchain. You need to do this now, don't spend money on the engine until you're sure it's a good one.

Lot of surface rust on the cam lobes, if it doesn't just rub off you may need to get one of them reprofiled.

gary123:
Cos he didn't see them till I took them off. But that is strange, one of the eight previous owners cocked up i guess.
The whole lump is coming down to the last nut and bolt, at least thats plan A. Plan b is, well at the moment there is no plan b.
Im currently doing battle trying to get that rusty alternator thingy off the end of the crank. My toytown puller isnt up to it.

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