Topic: Complete newbie with a vintage bike....advice?

[Beef_Destiny]

Look at this beauty...That's a 1978 CB750K.

Okay, so as the title says I'm a first time bike owner (1 month).  Automotive experience consists of changing brake pads, rotors, lines, and oil changes.  I'm a great book learner though, but I need some time to feel out this bike.  It's the boner mistakes that will get me and already are.  The bike was sold to me with dirty oil and many other problems to fix.  It was the deal of a lifetime however and I'm enjoying putting the work into it. 

So what I need are basic tips that don't pop up in forums and shop manuals for someone who is clueless.  Example, clutch cable had no play in it when it was sold to me (originally thought it had some because the lever is slightly damaged).  Ironically the night I discussed it with a friend the clutch started slipping and couldn't push 70mph.  Also going on a long and reckless road trip as soon as this bike is perfect so road advice is welcome also.

Scheduled/completed maintenance=Cam chain adj, Valve clearance adj, ignition timing, new points and condensers, new spark plugs,  check coils, new friction plates and springs, compression test, carb cleaning, carb sync, new tires (one's leaky), oil change/filter, and fuzzy dice.  Also need to find a way to check if they rejetted with this aftermarket exhaust. 

Thank you.  Love these forums. 

[lrutt]

Google shop manual download. Plenty of free downloads for both shop and owners manual on the net. Between those 2 you will most all the information you will need. That is the best place to start. Once you read through that then you can ask some informed questions.

[madmtnmotors]

More pictures would help too. You have a "half breed" there. The seat, tank, sidecovers, and probably the engine (grey) are all 77/78 "K" model. The rear grab bar, tail light, chain guard, rear footpegs, wheels, brakes, headlight bucket, and front forks are all 77/78 "F" model. I'm going to go out on a limb and guess that you also have the stock 4-into-1 exhaust from the "F" model as well. The "F" engine was painted black, but that could have been painted over.

Frame numbers and engine numbers can help further sort what you have. Looks fairly well put together.

[Beef_Destiny]

"Google shop manual download. Plenty of free downloads for both shop and owners manual on the net. Between those 2 you will most all the information you will need. That is the best place to start. Once you read through that then you can ask some informed questions."

Got'em and skimmed some sections, read others.  Usually there's a forum on here that answers the question already for technical stuff.  Like there's a few CB models that use 1 friction plate made of fiber instead of steel was answered by Hondaman, or yada yada.  I'm just trying not to miss something obvious or shop tricks.  Like a friend mentioned to me last night that with tubeless tires you can over inflate them to reseal the rims in a pinch, or if your tire seems to wag you have a flat.  Tricks and warnings that won't be in the book that some might take for granted.

[madmtnmotors]

Add this to your list of "must read":

https://www.amazon.com/Proficient-Motorcycling-Ultimate-Guide-Riding/dp/1889540536

[Beef_Destiny]

"More pictures would help too. You have a "half breed" there. The seat, tank, sidecovers, and probably the engine (grey) are all 77/78 "K" model. The rear grab bar, tail light, chain guard, rear footpegs, wheels, brakes, headlight bucket, and front forks are all 77/78 "F" model. I'm going to go out on a limb and guess that you also have the stock 4-into-1 exhaust from the "F" model as well. The "F" engine was painted black, but that could have been painted over.

Frame numbers and engine numbers can help further sort what you have. Looks fairly well put together."


Excellent.  That is solid information.  The VIN is 1978 K, but some of the pieces didn't fit, like the exhaust as you said.  I might have a Frankenstein on my hands.  Wasn't aware the frame and engine had separate numbers to identify them.  It's a four-in-one exhaust as you said, but I thought maybe it was aftermarket rather than stock because the chrome is blued on the pipes as they leave the engine.  I thought that was a sign of cheap chrome plating, and therefore aftermarket parts.  I will see if I can find a part # on it and the engine as soon as it stops raining.

[madmtnmotors]

Based on the rear footpegs, you may have a "K" model steering neck grafted onto an "F" frame. You might compare the tin vin plate on the right side of the neck to the vin number that is actually stamped into the frame on the left side of the steering neck. The rear footpeg mounts were part of the frame on the "K" model, while the "F" model used the aluminum extensions to mount the rear footpegs like the ones you have. The engine number is on top of the engine case just forward of the front sprocket cover.

[Beef_Destiny]

Add this to your list of "must read":

https://www.amazon.com/Proficient-Motorcycling-Ultimate-Guide-Riding/dp/1889540536

Ordered it.  $2 no less, what a steal.   I don't have a book on riding, just maintenance.  Hadn't occurred to me.  I'll give it a read. 

[Beef_Destiny]

Based on the rear footpegs, you may have a "K" model steering neck grafted onto an "F" frame. You might compare the tin vin plate on the right side of the neck to the vin number that is actually stamped into the frame on the left side of the steering neck. The rear footpeg mounts were part of the frame on the "K" model, while the "F" model used the aluminum extensions to mount the rear footpegs like the ones you have. The engine number is on top of the engine case just forward of the front sprocket cover.

You just saved my ass.  turns out the engine is a K3 while the frame is a K8.  Luckily all my parts ordered still work, but when I work on my clutch I would've installed an extra fiber plate that K3's don't use.  I wonder what effect that would have.  Good news is the carb rebuild kits are in stock for 73 but not 78 at cb750supply.com, so I can knock that out if necessary when I take them apart now. 

[madmtnmotors]

Good news is the carb rebuild kits are in stock for 73 but not 78 at cb750supply.com, so I can knock that out if necessary when I take them apart now. 

Some more picts would help. The numbers on the carbs can help determine which carbs you have as well.

[Gene]

 Good news is the carb rebuild kits are in stock for 73 but not 78 at cb750supply.com, so I can knock that out if necessary when I take them apart now.

If/when you do get to the carb work, all you really need are the O-rings.  The original brass is probably still good, just needs cleaning.  Cheapo carb kits are fine for the soft bits, but not the brass - usually.  The manual(s) will guide you to the original size jets and you can compare to see if they're correct.  The 4-into-1 was original for the F model.

Pipes are bluing because you are running lean.  May want to check that too.

Tips:  If you suddenly feel like the bike is dying while you're riding, make sure you haven't somehow activated the choke.

don't ask.

I'm sure you'll get plenty more valuable tips.

[Beef_Destiny]

 Good news is the carb rebuild kits are in stock for 73 but not 78 at cb750supply.com, so I can knock that out if necessary when I take them apart now.

If/when you do get to the carb work, all you really need are the O-rings.  The original brass is probably still good, just needs cleaning.  Cheapo carb kits are fine for the soft bits, but not the brass - usually.  The manual(s) will guide you to the original size jets and you can compare to see if they're correct.  The 4-into-1 was original for the F model.

Pipes are bluing because you are running lean.  May want to check that too.

Tips:  If you suddenly feel like the bike is dying while you're riding, make sure you haven't somehow activated the choke.

don't ask.

I'm sure you'll get plenty more valuable tips.

Will do.  Thanks again.

[flybox1]

Based on the rear footpegs, you may have a "K" model steering neck grafted onto an "F" frame. You might compare the tin vin plate on the right side of the neck to the vin number that is actually stamped into the frame on the left side of the steering neck. The rear footpeg mounts were part of the frame on the "K" model, while the "F" model used the aluminum extensions to mount the rear footpegs like the ones you have. The engine number is on top of the engine case just forward of the front sprocket cover.

You just saved my ass.  turns out the engine is a K3 while the frame is a K8.  Luckily all my parts ordered still work, but when I work on my clutch I would've installed an extra fiber plate that K3's don't use.  I wonder what effect that would have.  Good news is the carb rebuild kits are in stock for 73 but not 78 at cb750supply.com, so I can knock that out if necessary when I take them apart now.

My K8 came with a K1 engine in it...and now it has an F engine in it 
Aftermarket jets are crap. dont use the brass jets or needles from any carb kit.  clean and reuse what you have.  If theyre buggered from the last owner, only buy genuine Keihin jets from jetsrus.com
Which model carbs do you have on it (should be stamped on the right end just above the carb bowl)

And get Hondaman's (Mark Paris') book....  It and the shop manual are all you need.

madmtnmotors has a lot of good links in his signature.   

[BomberMann650]

Welcome to the sohc4 clubhouse.
Make sure the brakes are working best they can.
With any luck you'll be tuned up, greased up,
and practiced up for that roadtrip!

[kidrcth]

 Good news is the carb rebuild kits are in stock for 73 but not 78 at cb750supply.com, so I can knock that out if necessary when I take them apart now.

If/when you do get to the carb work, all you really need are the O-rings.  The original brass is probably still good, just needs cleaning.  Cheapo carb kits are fine for the soft bits, but not the brass - usually.  The manual(s) will guide you to the original size jets and you can compare to see if they're correct.  The 4-into-1 was original for the F model.

Pipes are bluing because you are running lean.  May want to check that too.

Tips:  If you suddenly feel like the bike is dying while you're riding, make sure you haven't somehow activated the choke.

don't ask.

I'm sure you'll get plenty more valuable tips.

this is seriously true. Just finished rebuilding my 72 K motor and the carbs are a breeze to clean and work on. Vinegar will clean all the brass internals of your carb to look like brand new, just place then in a zip lock after and spray wd-40 in the bag and they will stay shiny brass color for ya. All i needed were float seals, fuel T o-rings, float drain o-rings and main jet o-rings.