CB 500 resurrection

[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.

[gary123]

The camshaft cleaned up with minimal effort and no sign of pitting.
What do you think of the bores? [ Guests cannot view attachments ] [ Guests cannot view attachments ] [ Guests cannot view attachments ]

[Trigger]

You can not go by looks. You need to take it to a machine shop to be measured up and the pistons must match the bores. Using Honda pistons, bore to piston clearance needs to be 0.0200 mm  And a lot of machine shops do not understand how tight it needs to be. Any machine shop who says, it is too tight and will seize, walk away 

[gary123]

Got it . Thanks

[Nurse Julie]

The bores don't look good, I would definitely have a rebore

[Bryanj]

DO NOT use a 3 legged, or 2 legged, puller on the rotor, you need the proper tool or yo will wreck both it and the crank

[Bryanj]

From what i see of the bores i agree with Julie.
Is Trigger still doing rebores?

[gary123]

DO NOT use a 3 legged, or 2 legged, puller on the rotor, you need the proper tool or yo will wreck both it and the crank

OK.  Ill look into that, thanks.

[gary123]

From what i see of the bores i agree with Julie.
Is Trigger still doing rebores?

Could you elaborate on why you think that. I'm not disagreeing or arguing just keen to learn.

[Bryanj]

Rust patches and water marks always leave pits which make for oil consumtion, high ring wear and sometimes noises

[gary123]

Spent the last day or two stripping both engines and no real good news. Of the three camshafts I have only one looks even half decent.
The lower case on the 500 has a piece broken off, not sure how critical that is. 550 crank looks the better of the two but I need expert advice on that.
500 clutch is bust but plenty on ebay. Julie if your reading this can you PM a phone number to discuss taking on the rebuild for me. [ Guests cannot view attachments ] [ Guests cannot view attachments ] [ Guests cannot view attachments ] [ Guests cannot view attachments ] [ Guests cannot view attachments ]