QuestionI have a 79 Honda ct 125 witha very noisy cam chain ,( no adjustment left )
Should ireplace it & the guide & tensioner - Is it a tricky job ?
What is the procedure ?
AnswerRichard, a CT125 is a pretty rare bike, at least in the US. One year editions, here.
http://www.powersportspro.com/partsfish/login.asp for more illustrations. They actually have your machine listed there! The motor is, of course, related to all the CB/CL/SL/XL100-125s from the 1970s.
Well, if the camchain is noisy, then "yes" do replace it!
"Tricky" is a matter of interpretation. Without tearing down the engine, you will have to remove the dyno cover and the rotor. The rotor needs a special tool to thread in and remove the rotor from the end of the crankshaft.
You can probably squeeze the rear tensioner out from inside, once the bracket is discontinued, but the front one is anchored by the mating of the head and cylinder block, so it ain't coming loose w/o a top end removal job.
Removing the points/cam cover on the head will give you access to the camsprocket. If the chain has been whipping around inside for a long time, the chain can wear grooves in the cylinder head/block, plus wear out the sprocket. You will have to pull the sprocket bolts to dismount the sprocket from the camshaft, then drop it off the camshaft shoulder so you can pull the chain off the sprocket.
Actually, as I am writing this, I recall and verified that the this is the later 2 piece cylinder head, which requires the top half to be removed for removal of the camshaft. Early ones could be removed from the side of the head, so probably this non-teardown method may not work on the later heads.
Obviously, you have to remove the camchain from both sprockets and thread it up/down through the tunnel in the cylinder block and head. Getting the chain off and past the ends of the crankshaft and camshaft may not be possible without tearing it all down. The chain may not sidebend enough for removal and a new one will be less likely to do so, as well. So, more than likely, you will have to pull the motor, then the camsprocket to remove the camchain, then the cylinder head, which will allow you to replace the front camchain guide and give you room to drop the camchain down to attach to the crankshaft, then fish it back up to set up your camtiming on reassembly.
Check for manuals at Ebay, local m/c shops or www.helminc.com
Resetting the camchain requires the piston be at TDC and the camshaft lobes be down, so the valves are loose on the compression stroke. Camsprocket should have a punch mark on the side that goes at 12 o'clock position when the piston is at the T mark on the flywheel alignment.
Bill Silver
