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CB500/550 / Rebuild History to date with Pics
« on: February 08, 2016, 02:08:20 PM »
Thought you folks might like to see how my project is progressing.
Bought this K0 500 1971 (US Import) rom D&K in Staffs in October as had been looking for aproject for a while. Why this one?
1) I got it at a decent price because engine was totally seized (i think they'd had a go at it but couldnt free it)
2) The mileage was indicated at 13,000 and looking at the condition of the frame, chrome etc I was prepared to believe this was genuine. This was a really nice original US spec original bike. Only bad point no original HOnda 4-1 pipes.
3) I had no fear of an engine rebuild and reckoned cosmetic parts (new wheels, fenders, ...............would end up costing more than some engine bits).
So step 1 was to free off the engine. Tried all the "magic" potions - oil down the bore, rocking in gear -- absolutely nothing. Ended up splitting cranks undoing big ends and trying to hammer each piston up. All I managed to do was 1/2 push out the liners.
. So off to my local machine shop who pressed the pistons out, honed the bores and relapped the liners in.
Essentialy the seizure was just Pistons massively seized in their bores. No idea why as rest of engine really good. Just to make matters worse the gudgeon pins were so seized on the pistons I ended up milling half the piston away in our machine shop at work just to get the buggers out. See the attached picture
Measured the bores and they were still on "new" spec so now I was sure I had a genuine low mileager. In fact, inside the engine was really clean, no mucky oil or other horrors awaited me, again confirming my low mileage suspicions. So off to CMS for new pistons, pins and rings and to David Silver for Gasket set, set of oil seals, new big end shells .....
Engine rebuild took me about 3 week ends and went OK (with the usual 3 steps forward 2 back moments along the way). Long story about the timing chain and putting the front tensioner iin the wrong way round but that needs beer and a summer pub garden for the tale. Anyway got it all back together in the end and all goes round and round and up and down as intended
Once I had engine rebuilt I decided to take a big plunge and buy a set of CMS 4-1 aftermarket pipes as the original bike came with 2 OK but a bit battered MAC 2-1s. Big expense but I reckon I would always kick myself for not doing it. Obvioulsy haven't fitted yet but they look good quality.
Next job was a full carb rebuild as all the slides were also seized (dropping them in hot water freed them off a treat). As with rest of bike carbs were cosmetically really clean and no real horrors inside so did a full strip and clean (discovered that Cellulose thinners is really good for getting paint varnish off jets and bodies !!!) and treated them to all new O rings and a good clean up. Really pleased with how they ended up.
Next step was to decide how far to go with the rest of the project given that cosmetically the rest of the bike was very good with virtually no rust and even the frame showed only a small piece of surface rust around the main stand area and some scratches . In the end my view was that whilst the engine was out why not go for a full restore so I just pulled evertying down to a bare frame.
Next decision was powder coat or paint or what. Budget was by now getting a bit stretched (blame those CMS pipes !!) so given that the basic frame was so good decided just to see what a couple of coats of Hammerite rattle can gloss black would do and I was really pleased with the results.
Now I have pretty much all the bits cleaned and polished ready to go back together.
Jobs still to do
Rebuild Master Cylinder and Front Caliper
Get new Rubber fitted (don't fancy my chances on at least 20 year old rubber)
Bench sync carbs
Bolt it all back together
Press starter and see what happens !!!!!!
I will post more as I progress.
Bought this K0 500 1971 (US Import) rom D&K in Staffs in October as had been looking for aproject for a while. Why this one?
1) I got it at a decent price because engine was totally seized (i think they'd had a go at it but couldnt free it)
2) The mileage was indicated at 13,000 and looking at the condition of the frame, chrome etc I was prepared to believe this was genuine. This was a really nice original US spec original bike. Only bad point no original HOnda 4-1 pipes.
3) I had no fear of an engine rebuild and reckoned cosmetic parts (new wheels, fenders, ...............would end up costing more than some engine bits).
So step 1 was to free off the engine. Tried all the "magic" potions - oil down the bore, rocking in gear -- absolutely nothing. Ended up splitting cranks undoing big ends and trying to hammer each piston up. All I managed to do was 1/2 push out the liners.
. So off to my local machine shop who pressed the pistons out, honed the bores and relapped the liners in.Essentialy the seizure was just Pistons massively seized in their bores. No idea why as rest of engine really good. Just to make matters worse the gudgeon pins were so seized on the pistons I ended up milling half the piston away in our machine shop at work just to get the buggers out. See the attached picture
Measured the bores and they were still on "new" spec so now I was sure I had a genuine low mileager. In fact, inside the engine was really clean, no mucky oil or other horrors awaited me, again confirming my low mileage suspicions. So off to CMS for new pistons, pins and rings and to David Silver for Gasket set, set of oil seals, new big end shells .....
Engine rebuild took me about 3 week ends and went OK (with the usual 3 steps forward 2 back moments along the way). Long story about the timing chain and putting the front tensioner iin the wrong way round but that needs beer and a summer pub garden for the tale. Anyway got it all back together in the end and all goes round and round and up and down as intended
Once I had engine rebuilt I decided to take a big plunge and buy a set of CMS 4-1 aftermarket pipes as the original bike came with 2 OK but a bit battered MAC 2-1s. Big expense but I reckon I would always kick myself for not doing it. Obvioulsy haven't fitted yet but they look good quality.
Next job was a full carb rebuild as all the slides were also seized (dropping them in hot water freed them off a treat). As with rest of bike carbs were cosmetically really clean and no real horrors inside so did a full strip and clean (discovered that Cellulose thinners is really good for getting paint varnish off jets and bodies !!!) and treated them to all new O rings and a good clean up. Really pleased with how they ended up.
Next step was to decide how far to go with the rest of the project given that cosmetically the rest of the bike was very good with virtually no rust and even the frame showed only a small piece of surface rust around the main stand area and some scratches . In the end my view was that whilst the engine was out why not go for a full restore so I just pulled evertying down to a bare frame.
Next decision was powder coat or paint or what. Budget was by now getting a bit stretched (blame those CMS pipes !!) so given that the basic frame was so good decided just to see what a couple of coats of Hammerite rattle can gloss black would do and I was really pleased with the results.
Now I have pretty much all the bits cleaned and polished ready to go back together.
Jobs still to do
Rebuild Master Cylinder and Front Caliper
Get new Rubber fitted (don't fancy my chances on at least 20 year old rubber)
Bench sync carbs
Bolt it all back together
Press starter and see what happens !!!!!!
I will post more as I progress.
