Motorcycle Repair: Cam Chain Rattle?, 1983 honda nighthawk, endless chains

Question
Hi,

I have a 1983 Honda Nighthawk CB550SC. DOHC inline four. It has 42,000 miles on the engine. I've owned it for one year and ridden approximately 2000 miles. I hear a rattle which I believe is the cam chain at rpms above 3000 and now occasionally at idle which has progressively become worse. I don't know if I should replace the cam chain, tensioner, guides or just the tensioner spring to try to get rid of the rattle. I took the valve cover off the engine but can't really determime what is wrong. Can't feel much play in the cam chain or see much signs of wear.
The bike did have a previously hard life.
Is 42,000 a lot of miles for a cam chain. Should I replace the cam chain and tensioner spring? Is it OK to use a cam chain with a master link or rivet so I don't have to tear the engine apart. Do you know where I could purchase a replacement cam chain with a rivet or masterlink? Is it worth it to fix this bike or should I start looking for a replacement? I do like the bike but don't want to spend a lot more than it's worth in parts to fix it.

Thanks for your advice.

Sincerely,

Harry

Answer
Hi Harry,

42K miles is high mileage for most motorcycles with the exception of BMW's and Goldwings. Engine wear becomes evident after about 25-30k miles. Machining tolerances get a bit loose and noises and performance drops off a bit.

You may still have a very dependable MC with plenty of mileage left.

About cam timing chains; they are endless chains only and require complete engine disassembly for replacement. Instead, consider replace the timing chain tension spring. This spring will allow excessive slack which causes noise when it becomes weakened with use.

Visit "www.bikebandit.com" and click on OEM Parts once the homepage opens. Select your SC from the pull down menus and see parts microfiche exploded views and prices. You can use this website as a reference, comparision, or order from them.

I think replacing this tensioner spring and maybe a vlave clearance adjustment will clear up the nioises. At least check valve clearances while the valve cover is removed to replace tensioner spring. Loose valve clearances cause ticking/tapping sounds. Tight valve clearances cause valve and valve seat damage.

Respectfully,
Mark Shively