Topic: What's the quickest way to tell if a bike's worth repairing.

[ger87410]

I got a 1978 CD750f that I got as a complete parts bike when I purchased my '76 CB750k.  It's unknown how long it sat for.

It's complete, as near as I can tell.  The only thing completely missing is something electrical that's under the cover on the left side of the bike.  I think it's something to do with the ignition.  The guy I bought it from said it was suppose to run.

What's the quickest way of telling if this thing is worth fixing or should just be parted out?

I've rebuilt and engine before, but I'm not a mechanic.  If I can't get the engine running, I'm not sure I wanna mess with it....

Thanx for the input, guys!  Hopefully I get the pictures on here correctly. 

[UnCrash]

The quickest way to tell if it is worth it is to assess your skill, interest, and repair funds -- no one here can help you with that.

Second, assess the condition of the bike as best you can.

Third, and I hate to tell you this, but this is not a 1978 CD750f, or a CB750F for that matter.  This is a K with a 4 into 1 exhaust.  Look on the neck of the bike and you will see a vin number that will tell you the model and year.

This one looks like it has been out in the weather (or something) for a while and looks like it could be missing the fuse panel which isn't that big of a deal.  You won't get it started without sorting out the wiring first.  It will need some loving care and a few, or multiple new parts.

Best of luck to ya.

[KB02]

If you are able to kick it over and you've got compression in the engine (all 4 cylinders), then you should have a good candidate for a rebuild.

Granted, stuck motors can sometimes be rebuilt as well (check out my avatar pic), but be prepared to pay for them.   

[KB02]

Third, and I hate to tell you this, but this is not a 1978 CD750f, or a CB750F for that matter.  This is a K with a 4 into 1 exhaust.  Look on the neck of the bike and you will see a vin number that will tell you the model and year.

I didn't even think to look at that. You're right. I'd say 75/76 K. Or around there, anyway...

[pbelanger]

Hi,

Looking at the pictures, it looks to me as if it could make you a better parts bike than a daily runner. I have to agree with the answer in the previous post: how much energy (time, time, time, and more time, plus money, money, money and more money) are you willing to put into it?

Assuming your 1976 K is in very good shape, I would keep what I can salvage from this one. Do you have the space to part it out and clean the parts? If so, do you realise the chance you'll have to be able to work on something without having to put yopur regular bike in the shop for a month? (on these old ladies, you never know how much time you'll spend on a repair that seemd SO easy at first glance...) All you need is a good shop manual and fair manual skills; you'll then be able to undertake 80% of all repairs.

All the chrome seems to be in good shape; could you use some of the parts to replace a scratched / bent fender, or a pitted/rusted kick start lever?

The frame on this one would need attention; is it only rust? As it begun to show some signs of fracture?

Maybe the engine parts are still in good shape? You could use 80% of them.

Maybe you could dismantle all 4 carbs, do a complete rebuilt and then swap them on your other bike?

Did you notice that both switches on the handlebars look to in good condition as well? Lors knows I had to put some patience in getting mine working... wish I had a parts bike like that one at the time!

All the other little knick knacks, you can find on eBay or, better, within the SOHC4 community.

Just a thought.

Good luck with whatever you decide to do with it.

Regards,

Paul

[ger87410]

Thanx for the replies, guys!  It's a 1978 CB750.  Don't know what's the diff between F and K.  1 guy told me: "The F model had a 4 into 1 exhaust and a duck tail behind the seat and a slimmer gas tank".

I asked the wrong question, but somehow you guys gave me the answer I was looking for.

It turns and feels like she's got good compression.

I don't need parts.  My storage is pretty full. The bike I got is in perfect condition.  I can't think of a reason to swap anything on the parts bike with what I got on the 1 I'm riding.  Why swap the carbs??

I can't sell it, so I think I want to see if she'll run.  What's the process that I should take to try to get it running?  I've never messed with multiple carbs and am a little apprehentious.

I was thinking: thorough cleaning the external of the engine, cracking all the covers and cleaning parts under there (stator, etc), changing the oil, cleaning the carbs (anyone think a rebuild is necessary?), and repair the wiring. 

Is there anything else I should do before I try cranking her over?

I'd expect any work on her I do to take months before completion.

[Johnie]

You did not mention cleaning and possibly sealing the gas tank which you want to do before you run that into your clean carbs.  I had a radiator shop do mine for $100.  A good thing is I see the petcock is in the off position.  Hopefully the carbs were drained too.  You said it turns over and feels like compression is there which is a great start to your project.  Heck, if you like doing this as a hobby go for it   sounds like you got the parts around your shop.  Your not in a hurry as you already have another rider.  Case settled...get 'er done.  Keep us informed of your progress...

[754]

Looks like a 1974 to me..

check the neck tag..

[Gregorymoto]

1. Do i have the paper work.
2. How Fed is the motor.
The rest is just details

[rbirkhan]

Thats in cherry condition compared to what I started with. If it has compression it should be pretty easy to get running. I would change the oil before you try starting it.

[crazypj]

I'd rebuild it if you have a title (I like building)
PJ

[upperlake04]

   ..but this is not a 1978 CD750f, or a CB750F for that matter.  This is a K with a 4 into 1 exhaust.  Look on the neck of the bike and you will see a vin number that will tell you the model and year.

Thanx for the replies, guys!  It's a 1978 CB750. 
I asked the wrong question, but somehow you guys gave me the answer I was looking for.

Looks like a 1974 to me..

check the neck tag..

 
   Better double check before you get a 78F shop manual. 

[ger87410]

You did not mention cleaning and possibly sealing the gas tank which you want to do before you run that into your clean carbs.  I had a radiator shop do mine for $100.  A good thing is I see the petcock is in the off position.  Hopefully the carbs were drained too.  You said it turns over and feels like compression is there which is a great start to your project.  Heck, if you like doing this as a hobby go for it   sounds like you got the parts around your shop.  Your not in a hurry as you already have another rider.  Case settled...get 'er done.  Keep us informed of your progress...

Yes!  Gas tank.  Thanx.
The line going to the carbs is broken off and something, maybe wooden, is plugging it up.

Looks like a 1974 to me..

check the neck tag..

It's a 1978.  I checked the tags.  Funny thing is I was calling it an '81 before I checked. 

[upperlake04]

Ger - sorry to be a pest but if the pics are the bike we're talking about it seems you have a 78 ID tag

edit- this is a 78F

[ger87410]

Ger - sorry to be a pest but if the pics are the bike we're talking about it seems you have a 78 ID tag

U're not pesting. 

The tag says 1978.  I could take a pic and post it after work if anyone would like.
I don't know a darned thing about these bikes in particular.

[Johnie]

Don't worry Ger...you are going to learn to luv 'em!!!   

[ger87410]

edit- this is a 78F

It doesn't seem to look like a 78k either.



Any guesses what she is?

[Chicago550]

That bikes definitely not a 78 so something is funky with that VIN tag. It looks like a 74 K. It has the 74 style of oil and gas tank, gauges, signals, seat, even fork gaiters. The engine may have been swapped out also but check the number there as well.

[ger87410]

Here's a pic of it.  (uploaded thanx to my wife.)




EDIT: The engine number is caked with dirt.  I'll have to look at it when I get home.

[mystic_1]

I'm looking at the rear footpeg/exhaust support, and that definitely looks like an earlier frame to me.  The later frames, or Gen2 as Matty puts it, had more of an upward angle to the lower tube of this triangle, whereas in the earlier frames this tube was more or less parallel to bottom of the engine cradle.

I could be wrong though.

mystic_1

[ger87410]

Since it looks like a newer frame with older components, will this make fixing it anymore difficult in the way of getting parts?

I already know I need to get an exhaust pipe for it.

I probably shouldn't be that concerned about keeping this thing looking stock, since it doesn't look anything like.  What do you guys think?  Just throw whatever year parts I can find on there?

[Gordon]

One easy way to tell for sure is to make sure the VIN printed on the tag matches the VIN stamped into the opposite side of the steering neck.

[mystic_1]

There's lots of 750 parts out there, you shouldn't have too many problems finding things.

Regarding looks, the question is, what do YOU like?

cheers,
mystic_1

[upperlake04]

Thats an excellent suggestion Gordon.

  ..it looks like a newer frame with older components..

  With the previously mentioned frame details, its looking more and more like the VIN tag might be the only "newer"  part on your bike Ger.

[hopterfixer]

Thats an excellent suggestion Gordon.

  ..it looks like a newer frame with older components..

  With the previously mentioned frame details, its looking more and more like the VIN tag might be the only "newer"  part on your bike Ger.

I was thinking the same thing.  My guess is a '75 or '76 (LH side petcock, idiot lights in clamp, LH side seat latch, big a@@ rear blinkers, long chain guard, seat cover design, etc.) with a 1978 data plate.  Good luck with it.