QuestionHi,
I have a 1983 Honda Nighthawk CB550SC. DOHC inline four. It has hydraulic tappets and an automatic tensioner located in the center of the engine. 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 determine what is wrong. Can't feel much play in the cam chain or see much signs of wear. How can you tell if a chain is worn?
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 master link? 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
AnswerHarry... here are some prices from the 650cc version of your bike...
14401-ME5-013 CHAIN, CAM 1 $98.95
14434-ME5-000 GUIDE, L. 1 $22.95
14451-ME5-003 ADJUSTER 4 $22.95
14514-ME5-010 SPRING, TENSIONER 4 $3.95
14539-ME5-010 TUBE 4 $3.95
14620-ME5-000 GUIDE A, CAM CHAIN 2 $55.95
061A1-ME5-000 GASKET KIT A 1 $121.95
061B1-ME5-000 GASKET B KIT 4 $42.95
from www.westernhillshonda.com site
http://www.servicehonda.com/parts/genuinehondamanuals.html
for $36.
I did a quick search on the web and found this road test:
http://www.postaldave.com/honda/83-550SC_Magazine_Article.html
I have never worked on one of these engines and don't know of any camchains that can be installed w/o tearing down the whole motor.
Honda had problems with camchain tensioners on a lot of their bikes, including the V-4s and those had a rubber sleeve around the tensioner spring that would harden and prevent the tensioner from moving properly. Yours could be having this problem or the camchain and tensioner may just be worn out from miles/abuse. Engine hydraulics need clean, fresh oil to maintain their function. Dirty, burnt oils will create varnish and wear internally.
It probably isn't a worthwhile effort to overhaul this engine. Either check around salvage yards for a replacement low-miles replacement or or perhaps the 650 version will fit in the chassis.
Bill Silver
