QuestionI have a 1971 cl175 and the engine is seized. We have tried to take it apart and find out exactly why it is stuck, but we have hit an impass.
We can not remove the top end to see if the pistons are rusted and/or pitted because the timing chain is on, and will not turn to find the master link and remove it.
We can not see what is going on with the bottom end because we can not get the clutch plates all the way off because of the (I believe it's a dampener) that is to the right of it will not come off. We have removed the screw from the center, but it wont budge, and it blocks the holder for the clutch plates from coming off completely.
We tried the easy method that a few suggested to us (putting some marvel's mystery oil in the spark plug holes and letting it sit).
Any help would be greatly appreciated. We would at least like to find out why it is stuck, but I don't know what else to do. :/
AnswerDamion, I hope this is just a learning exercise, as it will cost a lot to revive a stuck motor.. new rebore, pistons, rings, gaskets, seals at the very least. Do your shopping at Ebay if you can, in going forward with this motor repair.
If you can't see far enough down the side of the camchain to get to the master link, then you can just remove the cambearing holders on each end of the camshaft. This will allow the camshaft to drop down low enough to get the camchain off the sprocket, in most cases. You can either wiggle the camshaft out of the head, around the chain or drop the chain down enough to get it to disengage from the crankshaft sprocket, so you can move it around enough to get the master link off. Worst case scenario, you cut the chain. Depends a lot on what kind of shape the whole thing is in and how many miles are on it. Will probably need a new camchain anyway, if the motor has more than about 10k miles on it.
Honda twins often seize up from sitting for years. Moisture build up inside the cylinders and runs down into the ring lands, rusting the rings to the cylinder bores. Kroil or Magic Mystery oil are good solvents to help break up the rust, if you are lucky. Sometimes a little heat from a heat gun or propane torch will help out, but be sure that all the oil/fuel is out of the cylinders or you will have a small fire on your hands. DO NOT hit the pistons with a hammer! At least try some pieces of hardwood and be sure that nothing is holding the crankshaft from turning, as the pistons begin to move. I have rigged up a steering wheel puller on the 250-305s, but the bore size of the little twins may limit that kind of application. IF you have access to some flat metal plates you can drill some holes in the stud pattern, then one in the middle and use some threaded rod stock and nuts/washers to try to make up a piston pusher tool. It is much easier on the crankshaft bearings if you don't bang on the directly with hammers, etc. The rods are on needle bearings and mains are all ball and/or roller bearings.
Even if you could get it loose enough to turn over, the rings are glued into the piston ring lands, so you have to get it apart to inspect and clean the parts. More than likely, the cylinder bores are rusted and will be beyond a hone job to clean them up. Once the size of the pistons are determined, you will have to figure out how much larger you can go and get the matching pistons and rings to fit.
Look at the camchain tensioners/rollers for dishing and hardness. They were rubber once.
The closest thing to free illustrations online is at
http://www.powersportspro.com/partsfish/login.asp
Sign up, choose HONDA MoTORCYCLE, then CB200T, which is the next generation after the 175 twins and similar in design, for reference. A shop manual will be helpful, as will be an impact driver, good screwdrivers, some snap ring pliers, perhaps, gasket scraper, stainless steel brushes for cleaning carbon and gasket materials, etc.
Bill Silver
