1975 yamaha 500cc motorcycle


Old 04-02-01, 07:21 PM
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Greetings: I picked up an old motorcycle that had been sitting outside for years. It is still in good enough shape that I would like to restore it to running condition. would someone please describe procedures for "unfreezing" the engine and also for reconditioning the cyclinders and grinding? the valves. Any and all suggestions would be appreciated. Thanx, Mark
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Old 04-02-01, 08:19 PM
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Hello and welcome Mark to the Do It Yourself Web Site and my Small Engine forum.

The part regarding the unfreezing the engine may be more then just the piston. The wrist pin, crankshaft, camshaft, chains and all the bearings may present problems.

In order to attempt to unfreeze the engine, you could try adding some oil into the spark plug hole. Allow it to sit several hours then attempt to foot crank the engine over without the spark plug replaced. Careful, cylinder wall and or bearing scoring may occur.

If this does not work the first time, a repeat of the adding oil and sitting again may be needed. If all attemps this way fail, you may have to tear the engine down.

The valves and cyclinder bores may need the work of a professional.

Based on the fact that the machine sat so long, unforseen problems could occur anytime soon after the engine does fireup. Also to be considered is the transmission.

Main concern is safety while riding. Anything where to go wrong with either the engine or tanny, you might be in harms way. A bad case of road rash is the least of the potential problems.

Ride Safe,
Regards & Good Luck
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Old 04-08-01, 05:36 PM
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Thanks Tom for your response. I'm going try the oil in the cylinders trick and see what developes. This will be as soon as it stops "snowing", hehe. I also will remove the chain to remove any lock up problems there, too. Thanks again, MarkM
Old 04-09-01, 09:52 AM
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Expend the expendables

Also, since it was sitting outside for a while, you might want to give it a once over before relying on it.

Check the brakes and tires throughly. Because it was sitting outside, the tires are probably dry rotted. Also the brakes should get attention.

I would give the bike a good once over before getting on it and going for a good drive .

A Yamaha owner's/service manual is probably going to be the most helpful in this situation.
Old 07-17-06, 01:21 PM
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I have recently begun a similar project on a 1974 400cc honda bike that has been sitting out side for roughly 15 years and I've tried the pouring penatrating oil and WD-40 down the spark plug hole without too much succes atleast as far as the kick starter goes. That is to say that the kick starter still wont kick but by pushing it down a hill and putting it in gear we did get the wheel and chain to move which came with an interesting sound and some oil coming out of the exhaust, now dont think that I just got impatient and rolled the bike down a hill I let the oil sit in the cylinders for over a week checking the kickstarter every day and adding more oil to the cylinders as neccesary.

I kinda see the oil out the exhaust pipe as a sure sign that the engine is unfrozen so i guess my kickstarter must some how be frozen.

If the rear wheel turns when you put the bike in neutral i dont think there is really any need to take off the chain besides the fact that you'll probably have to do it eventually.
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