Top end rebuild, my discoveries and disappointments
Posted: Sun Dec 16, 2018 8:36 pm
I just finished a top end rebuild of by 1982 CB650SC and wanted to share some things I discovered, was worried about and disappointments.
The first thing I found was decent oversize pistons:
https://www.cruzinimage.net/?s=cb650+pistons
Original, .5 and 1.0 mm over. Good quality with fast shipping. Do allow 10 days for USPS to deliver to your door once thru customs.
I read so much about the cam chain tensioner missing the lower slot. I even watched YouTube videos of folks having trouble. I was freaking
out! If you follow the technical guide, you're golden. BEFORE sliding the cylinders over the first set of pistons, make sure the cam chain
tensioner is installed into the cylinders finger tight. It slid right in for me.
I read a lot of confusing inormation about aligning the index mark on the cam. That index mark is 1/4" wide. It should point forward towards the exhaust and the MIDDLE of the Index mark aligns with the surface of the head. Not the top or bottom of the index mark with the head surface. Basically the top of the index mark will be parallel with the head surface and about 1/8" above it.
While I had my head and head cover off, I polished the head cover and also removed the tach drive. The CB550 tach drive block offs work perfectly, but of course you have to completely remove the tach drive. I saw several, and bought one that was polished aluminum like my head cover.
http://www.fastfromthepast.com/dtdbop-cb5c
I purchased a top end gasket set off ebay, but it seems to be offered on many of the parts houses. Here is a link to one at 4into1.com
https://4into1.com/top-end-gasket-set-h ... 1978-1982/
It's good quality, but it doesn't include the two 11 x 2.5 mm o-rings that go around the oil delivery channels. It has the base gasket, just not the o-rings. You can still source them at Bike Bandit, etc. but that's pricey and irritating! The full gasket set, however, does include those o-rings.
That's my 2 cents for anyone undertaking this same task.
The first thing I found was decent oversize pistons:
https://www.cruzinimage.net/?s=cb650+pistons
Original, .5 and 1.0 mm over. Good quality with fast shipping. Do allow 10 days for USPS to deliver to your door once thru customs.
I read so much about the cam chain tensioner missing the lower slot. I even watched YouTube videos of folks having trouble. I was freaking
out! If you follow the technical guide, you're golden. BEFORE sliding the cylinders over the first set of pistons, make sure the cam chain
tensioner is installed into the cylinders finger tight. It slid right in for me.
I read a lot of confusing inormation about aligning the index mark on the cam. That index mark is 1/4" wide. It should point forward towards the exhaust and the MIDDLE of the Index mark aligns with the surface of the head. Not the top or bottom of the index mark with the head surface. Basically the top of the index mark will be parallel with the head surface and about 1/8" above it.
While I had my head and head cover off, I polished the head cover and also removed the tach drive. The CB550 tach drive block offs work perfectly, but of course you have to completely remove the tach drive. I saw several, and bought one that was polished aluminum like my head cover.
http://www.fastfromthepast.com/dtdbop-cb5c
I purchased a top end gasket set off ebay, but it seems to be offered on many of the parts houses. Here is a link to one at 4into1.com
https://4into1.com/top-end-gasket-set-h ... 1978-1982/
It's good quality, but it doesn't include the two 11 x 2.5 mm o-rings that go around the oil delivery channels. It has the base gasket, just not the o-rings. You can still source them at Bike Bandit, etc. but that's pricey and irritating! The full gasket set, however, does include those o-rings.
That's my 2 cents for anyone undertaking this same task.