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Discussion Starter #1
With some free time (and I'm going to need a lot of it) I finally got a bike I've been looking at for some time.

Mostly, I just wanted a good before picture, so that in a couple of years I can see what was done to this thing.

I've never rebuilt anything mechanically... but I've rebuild a house, built a shop to work in, and rebuilt a POS 1988 Jamboree with a leaky roof into a 1988 Jamboree with a working electrical system and a new DIY roof.

So glad to be on the forums, and thanks for all the info!


 

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Looks fine. Put some air in the tires and go!

Are those pipes in reasonable shape? The only thing that sounds better (street-pipe wise) than the hm341's that are on that are the k0's ('69) hm300's.

Weird front fender on that... and rear.... and it has comstars, which is weird. Off of a later bike.
 

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First things first... Getting the rear wheel to turn. Either a locked up brake, or something with the clutch... Not sure which one yet. It's raining in Texas for the first time in a while and I haven't had the chance to get into the bike.
 

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Easy to figure out which. If the wheel turns a bit then stops moving when the chain runs out of slack, clutch. If just doesn't move at all, brake or other.
 

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holy Crap! Throw that back into the lake where you found it.

Kidding.

First off, I am shocked that it still has the original 4-4 pipes and they look to be in reasonably good shape. I am doubly shocked since everything else on the bike looks to have been changed from the rear tire to the front. The only thing that is stock 1972 on the bike is the tank, the frame, the airbox and carbs, the oil tank and the pipes. Everything from the gauges on down has been fucked with.

So, did you get a title? If not STOP! Do not put a single cent into the bike until you get ownership papers in your name. if so then carry on.

The first thing I would do is assess the engine. CB750s if they are not locked up are pretty robust. they make oil pressure like a car so usually everything is well oiled and moving, even if it has low cold compression they usually pump back up once they have been heat cycled. So look in the oil tank - if there is no oil in it chances are it has sumped and you will need to drain it out of the bottom of the engine. Before you do that give it a few kicks to see if the motor is free. Don't kick fast - you don't need a lot of pressure to turn it over (I can usually hand crank start my cb with the kickstarter) and if there is some scale in the cyl it will wipe out the ring in a hurry. Plus if you have a stuck valve you'll bend it. so kick it through slowly. After you have done that, drain the oil and see what it looks like. If you can drain it through some old pantyhose I wrap it around the open mouth of a solo cup and cut the bottom out so it drains into the oil catch pan and doesn't get too messy) and so any metal bits get caught and you can see how damaged it is. Look for water in the oil.

If the thing rotates over I would focus on trying to start the bike. That means a carb clean, a battery, fuilds, and a fuel delivery system (cuz that tank is probably shot inside). Once it runs and you've heat cycled it a few times, you'll know what the engine needs - sometimes they don't need anything - other times a full top end.

the rear wheel is probably stuck because the shoes are rusted to the brake liner. YOu are going to want to throw away that old 16" comstar anyway so it's no big deal to pull the wheel and spray penetrant oil in there till it breaks free.
 

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Discussion Starter #7
holy Crap! Throw that back into the lake where you found it.

Kidding.

First off, I am shocked that it still has the original 4-4 pipes and they look to be in reasonably good shape. I am doubly shocked since everything else on the bike looks to have been changed from the rear tire to the front. The only thing that is stock 1972 on the bike is the tank, the frame, the airbox and carbs, the oil tank and the pipes. Everything from the gauges on down has been fucked with.

So, did you get a title? If not STOP! Do not put a single cent into the bike until you get ownership papers in your name. if so then carry on.

The first thing I would do is assess the engine. CB750s if they are not locked up are pretty robust. they make oil pressure like a car so usually everything is well oiled and moving, even if it has low cold compression they usually pump back up once they have been heat cycled. So look in the oil tank - if there is no oil in it chances are it has sumped and you will need to drain it out of the bottom of the engine. Before you do that give it a few kicks to see if the motor is free. Don't kick fast - you don't need a lot of pressure to turn it over (I can usually hand crank start my cb with the kickstarter) and if there is some scale in the cyl it will wipe out the ring in a hurry. Plus if you have a stuck valve you'll bend it. so kick it through slowly. After you have done that, drain the oil and see what it looks like. If you can drain it through some old pantyhose I wrap it around the open mouth of a solo cup and cut the bottom out so it drains into the oil catch pan and doesn't get too messy) and so any metal bits get caught and you can see how damaged it is. Look for water in the oil.

If the thing rotates over I would focus on trying to start the bike. That means a carb clean, a battery, fuilds, and a fuel delivery system (cuz that tank is probably shot inside). Once it runs and you've heat cycled it a few times, you'll know what the engine needs - sometimes they don't need anything - other times a full top end.

the rear wheel is probably stuck because the shoes are rusted to the brake liner. YOu are going to want to throw away that old 16" comstar anyway so it's no big deal to pull the wheel and spray penetrant oil in there till it breaks free.

Awesome info! I'm glad someone knows what they are looking at.

1. Papers are legit, VIN checked out, so it's not a hot bike. Just an old, abused bike.
2. The engine isn't locked up. It's definetly not turning over, but there's plenty to do before it's running.
3. Clutch may have issues? Any bike I've owned before can easily slip through all the gears with the clutch pedal... this one seems to be missing neutral and 5.... not sure where to start with that other than pulling the clutch and seeing what is messed up inside, checking the clutch line, etc... but I also haven't ever worked on a bike this old, so I'm not sure if it should feel any different switching gears.

Seriously, THANKS for the great info! You guys are what is ultimately going to make this a successful project, or a pile of parts on ebay.
 

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These old Hondas are not real keen on going through the gears when not moving.
Or at least with a push back and forward between gear changes.
 

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What does this mean? Sounds contradictory to me.

" The engine isn't locked up, it's definitely not turning over"
 

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Discussion Starter #10
What does this mean? Sounds contradictory to me.

" The engine isn't locked up, it's definitely not turning over"

Sorry. What I mean to say is, it's turning over, but it won't start. :)
 

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Well, he did say that. Just not as concisely, technically speaking.
 

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Seriously, you are chasing waterfalls thinking it is a clutch issue. Yes the clutch plates are probably fused together because of the bike sitting and the age - but freeing the clutch probably isn't going to help you get the rear wheel unstuck. Even with the bike in gear I can still sometimes turn over the engine pushing it. I don't know why you are so target focused on the clutch - that's like item number 34 and you are on item 1.

Get a manual. Before you even look at that bike with a tool in your hand get a proper workshop manual. You can download a free Honda factory one from SOHC4.net.

If the engine turns over - I would focus on getting it to run. That means cleaning the carbs, getting electrical power to the engine, and delivering fuel. From there you can then figure out how fucked your charging system is, how fucked the engine is, etc.....

CB750 parts are no longer cheap. Turning that wreck with unknown issues into something you are proud to be seen in public with in my head costs $5K if everything is wrong. You could probably do it for less ($2500) if you knew what some of the issues are and the best way to know that is to evaluate a running bike.

It looks like the front end is a 78 and up GL1000 front end (might even be a late 1977). The bad news is that if you keep the front end you married that comstar mag wheel, ain't no way you are getting a spoke on there without some time in the machine shop or custom parts. The good news is that those forks are a nice upgrade over the 35mm stockers and you can use all sorts of other mag wheels like boomerang comstars, nighthawk mags, etc...
 

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oh I will add a CB750 SOHC's gear selector is about as precise as a broomstick in a bucket of butter. Even when the bike is running you have to select gears like a man, any pussy footing will be met with a terrible grinding sound but if you pick a gear like you own the fucking thing it drops in with a healty clunk. Neutral is near impossible to find running or not, but is silightly easier when not running. That gearbox hasn't had oil circulating in it since I don't know when so don't expect it to tell you anything until you have had the bike running up on the center stand and the gears get to taste gear fluid again.

Whatever you do, don't be a total fucking noob and take the entire thing apart. Right now your best bet for evaluation is to get that fucker running. Pick your jobs, make a punch list, and have at it. If you blow it completely apart the only thing you will build is a craigslist ad in may.
 

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Curious what you paid, if anything, for that bike. It would fall into the "free motorcycle" category. I think I would pass, I already have a free motorcycle.
 

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just get it running. bypass what you have to with jumpers. just get it running. and congrats you have a mega bitsa there. no need to dismantle it to swap random parts on, its predone.
 

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Discussion Starter #18
Pulling the rear wheel tomorrow. I've got to get that brake loose.

I've got it setting up overnight with some penetrating fluid so I can get some bolts moving tomorrow.

The electronics are f*kd. Someone did a hack job and it looks like they used the same spool of 14 gauge green wire to do the entire bike... that'll be fun.

Ya'll have to understand, there was no bad buy for me. My goal was to get an old screwed up bike and learn from it. Per my typical M.O., I've diving head first into the deep end of the puddle. Even if I find it's a total loss, I'll be out $150, some time, but able to trade that for some extra know-how. Sounds like a deal to me. My only other experience has been riding bikes and taking them to shops.
 

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Pulling the rear wheel tomorrow. I've got to get that brake loose.

I've got it setting up overnight with some penetrating fluid so I can get some bolts moving tomorrow.

The electronics are f*kd. Someone did a hack job and it looks like they used the same spool of 14 gauge green wire to do the entire bike... that'll be fun.

Ya'll have to understand, there was no bad buy for me. My goal was to get an old screwed up bike and learn from it. Per my typical M.O., I've diving head first into the deep end of the puddle. Even if I find it's a total loss, I'll be out $150, some time, but able to trade that for some extra know-how. Sounds like a deal to me. My only other experience has been riding bikes and taking them to shops.
Just remember "there is nothing more expensive than free motorcycle", $150 certainly falls into that territory.:)
 

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Discussion Starter #20
Story of my life. I have an addiction to buying old pieces of shit and spending more money than it would take to buy a new not piece of shit.
Case. In. Point. ;)
 
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