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Resurrecting Yamaha 750 Sportbike

1811 Views 28 Replies 8 Participants Last post by  enos
Whats up, Im Chris and am wanting to get my Grandpa's 1978 Yamaha 750 Sportbike up and running. He passed about 5 years ago and his bike is sitting in the garage rotting away. I need to do something with it.

What do you suggest for a bike that has been sitting for 10 years? Battery, tires, plugs, oil, carb rebuild? Is there a way to see if it is worth the money and not locked up? Throw in a battery and some oil with a bit in the plug holes and fire away? What kind of oil and how much do they take anyway?

Sorry guys, Im a car man. I just getting into the biking scene. Help me get this thing back on the road!
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To add to Ray..

probably closer to 4 quarts of oil. There will probably be a sight glass somewhere on the bottom rear of the right side of the engine/trans. That has two marks, a low and a high. That's your dipstick (unless the bike has an actual dipstick). Bike needs to be vertical but on both wheels when you look at this.

As for brakes, change the fluid and inspect the rest. If they work, keep em. If the lines need replacing, get stainless steel lines. Lots of places make them for the old bikes, and their cost is comparable to regular ones.

Carbs will certainly be dirty, so the bike probably won't start (it might on starting fluid). You can clean them yourself, or have a shop do it for a few hundred.

Check the chain, and LUBE IT.

Change the tires.

Decide what you want to do to this bike. It can be on the road for a few hundred. If you want to keep it, clean the carbs yourself. It will get you familiar with working on the bike.

Try searching on this site:
It's a site for the old Suzukis ('76+) but there are some crazy knowledgable people on there and lots of threads about how to resusitate old junkers. They also have a carb cleanup series (a picture guide) on the main page. Pretty much everything will apply to your bike except part numbers.

Oh, and the general advice for brining an old bike to life is to get it to run, take care of safety issues (brakes, chain, wheel bearings, etc), then do NOTHING else for a few hundred miles. Things will fix themselves, and things will break. After you ride it a bit then start fixing things.
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Oh, and get yourself a shop manual. If you can't get an actual Yamaha one, a Clymer manual should be a piece of cake to get at a dealer/online. The manual will explain the procedures in detail for that particular bike.

edit: if you really want to make sure it's not seized, take off the cover on the right side of the engine. You'll have your ignition points behind there (no electronic ignition for you.. hope the points aren't rusty) along with a big nut. That big nut is connected directly to the crank. You can turn it clockwise and turn the engine. Don't turn it backwards, and if you encounter hard resistance for the love of god stop.
You can also put it on the center stand, in the top gear, and just turn the rear wheel the way it would normally turn. Don't turn it backwards without being in neutral or have the clutch in.
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As for holding the bike up, you can get away without stands. Your bike has a built in centerstand which holds the bike vertical with the back tire off the ground. All you need to do is use a jack to tilt the balance so it's resting on the centerstand and the back tire, with the front tire off the ground. You also probably have two convenient frame rails going down the bottom which you can use jackstands or wood blocks or what have you to hold the bike up. You can make it very stable this way (that's how i've done it).

On new bikes you can't do this. First, they don't have center stands (too heavy..). Second, the frame rails are high up. So on these bikes you use a special stand to grab onto the swinarm in the back and the bottom of the forks in the front. If you have to take the forks off, though, you need a stand that grabs by the steering head. an expense you don't need.

get a manual and it will tell you how to do the forks. basically there's a drain on the bottom then you open the top and put new stuff in. Every fork needs a different amount, and i doubt anyone here will know how much your bike needs. You do this by oil level, which you measure by taking out the spring and compressing the whole thing.
You should do this sometime, but it's probably not a priority. I bet that your fork oil seals will be leaking soon so you might want to just change those while you have the forks off the bike.

seriously, at the beginning keep it minimal. do only what you have to, and run through the regular maintenance from the manual.
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carb cleanup picture guide in excruciating detail:

no, you can't throw the whole carbs into the cleaner because there are rubber parts in there that will get eaten by the cleaner. You basically have to take those out. There are pics in that series that show which parts you dip. It helps to blow the passages and jets out with compressed air to make sure there's nothing blocking them. You can buy canned air for like $7, or just use a tire pump with that needle attachment for soccer balls.

Since you got to this point i'm assuming you know all about the wonders of penetrating oil.. and i don't mean the rubbish that is wd40.

oh, do you have a shop manual or just the owner's manual?

either way, it's looking pretty good.. you're gonna love that bike..
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it's like car paint (no clear coat). so you can use a regular car wax on it.
no, don't use water. You risk rust. Rinse it with some gasoline.

If it's already rusty, then it will be hard. There are rust removing/sealing kits. POR15 comes to mind, though you can get acid at home depot (forget the name, though) that will clean it out. I was too chicken to do it, though.
Look up Dyna. They make electronic ignitions for those old bikes. Basically get rid of points altogether.
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