CB750 K2- How Delightfully Old School.

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Lucien Harpress
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CB750 K2- How Delightfully Old School.

Post #1 by Lucien Harpress » Sun Mar 13, 2016 5:23 pm

So, I just had a buddy pick up a barn-find '73 Honda CB750. He paid $100 for it and, well

THE BAD
It looks like a $100 bike. It's been sitting a LONG time, so all the tires and cables are shot. Gas tank is really rough, both inside and out. Lots of rust on everything.

THE GOOD
Apart from the seat (non-stock) and air box (missing), everything looks like it's there. It still has the original 4-into-4 exhaust which, while rusty, appears solid. Motor turns over, and seems to have compression. The outer cylinders do for sure, and at least one of the inner cylinders do as well. We couldn't pull the spark plugs to be sure.

He's not looking to do a full restoration, but could probably clean it up and ride it pretty easily. My question- what should he be looking for? Are there known problem areas with this bike? I'm doing my best to help, but my experience is limited to Goldwings and my KZ1300. Any advice would be appreciated.

Thanks! Pic to follow...
Last edited by Lucien Harpress on Mon Jul 15, 2019 7:19 pm, edited 19 times in total.
1969 CT90- Needs rear tube and possibly rings
1976 GL1000 (Yellow)- Carb Shenanigans.
1984 GL1200 Standard- For Sale!
1980 KZ1300- Carb balancing when the weather warms up
1972 CB750 Barn Find- Tires and Head Bearings

All advice I give is only valid until an expert corrects me.

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salukispeed
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Re: CB750 Experts?

Post #2 by salukispeed » Sun Mar 13, 2016 6:49 pm

Good solid bikes. Dry sump oil system so much of the engine oil is actually retained in the tank under the right side cover and after years of sitting can drain in to the block. If the dip stick shows oil on the stick it is likely ok. Cant think of many weak areas. Does it have pods or just the aircleaner assembly missing? Often I have seen guys check the oil and connect a fresh battery and crank a bit til the oil light goes out and see what happens. Points are under the right side cover and crank operated unlike the GL's with cam driven. But same type of ignition and really like the Dyna upgrade. Carbs are more simple than the CV types on the Wings. The 750 K3 were nice bikes and really identical to My 74 K4. They weep oil from the head gaskets ( Between cyl and head ) but rarely have a failure only the mess. Good luck.
http://forums.sohc4.net. Pretty good group of guys here and lots of info and help.
Honda 72 CL100 sold
74 CB750 K4 nice driver
1966 CA77/305 Dream nostalgic driver
84 GL1200I work in progress
1970 CT 70
1982 GL500 Interstate

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Lucien Harpress
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Re: CB750 Experts?

Post #3 by Lucien Harpress » Sun Mar 13, 2016 6:52 pm

Photo of the beast.
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1969 CT90- Needs rear tube and possibly rings
1976 GL1000 (Yellow)- Carb Shenanigans.
1984 GL1200 Standard- For Sale!
1980 KZ1300- Carb balancing when the weather warms up
1972 CB750 Barn Find- Tires and Head Bearings

All advice I give is only valid until an expert corrects me.

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salukispeed
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Re: CB750 Experts?

Post #4 by salukispeed » Sun Mar 13, 2016 8:23 pm

After market velocity stacks. really not necessary since the stock air box had them built into it and was really was a built with tuned runner lengths and with a chamber that eliminated any issues with side wind or dirt. Little or no gain but was popular. Unless it has the 300 series exhaust there was nothing to gain with the stacks. Good reliable but different charging system from our Goldwings. When you get it running consider a new top quality riveted chain becauses if it breaks it often rolls up around the front sprocket and trashes the cases. Another thought. Be exrtremely careful when reinstalling the center plugs. Very easy to cross thread. If the tool kit is under the seat it has one of the best plug sockets to use. Be sure they thread in a long way or all the way with your fingers. . I can look to see if I have a spare. normal 18mm deep sockets may not fit in there straight.
Honda 72 CL100 sold
74 CB750 K4 nice driver
1966 CA77/305 Dream nostalgic driver
84 GL1200I work in progress
1970 CT 70
1982 GL500 Interstate

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robin1731
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Re: CB750 Experts?

Post #5 by robin1731 » Sun Mar 13, 2016 9:37 pm

Stacks with no filters?! If they ran it that way it wasn't good. A lot of dirt gets in to the cylinders and can scratch up pistons and cylinder walls. Put air pods on it, good ones. Other than that just the same things as any other bike. Check compression. Check valve lash, same setup as a GL.

And yes, the ignition upgrade is good. I put a Dyna setup on a CB500 a couple years ago. Much easier to start.
1975 GL1000 parts bike (parts for sale)
1976 Goldwing Super Sport
1985 Honda Elite
1976 KZ900 Dragbike
1992 ZX7 Dragbike (KZ900 style motor w/NOS)
and a rotation of various purchases
Randakk approved Carb Rebuilder

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Re: CB750 Experts?

Post #6 by Pinball » Tue Mar 15, 2016 3:38 pm

Nice looking bike! I
He got a great deal on that on that one. I love barn finds :)

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Gowing
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Re: CB750 Experts?

Post #7 by Gowing » Tue Mar 15, 2016 4:32 pm

Orange metal flake! You got to love that color. I graduated from high school in 1973.
Those were the bikes to have. So cool. Great memories.
Fantastic deal. Even if you just lean it against the wall and look at it all day.
But I know you can't resist bringing it back to the road.
Dave

1975 GL 1000
1976 GL 1000
1980 XS650
2003 ST 1300
1971 CT90
1972 F7 KAW 175
1984 elite 80
Chiwawa (Ellie)
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Lucien Harpress
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Re: CB750 Experts?

Post #8 by Lucien Harpress » Tue Mar 15, 2016 6:45 pm

Not gonna lie. I might be a LEEEEEEETLE bit jealous. ;)

I might swing by after work tomorrow and give him a hand to start tearing into it.
1969 CT90- Needs rear tube and possibly rings
1976 GL1000 (Yellow)- Carb Shenanigans.
1984 GL1200 Standard- For Sale!
1980 KZ1300- Carb balancing when the weather warms up
1972 CB750 Barn Find- Tires and Head Bearings

All advice I give is only valid until an expert corrects me.

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Re: CB750 Experts?

Post #9 by JSBail » Fri Mar 18, 2016 6:36 pm

If that original 4 into 4 exhaust is still in solid shape with nothing more than surface rust then your friend scored a deal. Restorers are paying serious $ for the original 4/4 exhausts even in used condition. What I'm saying is don't let your friend unknowingly toss the exhaust ...... however if he does you can tell him he can toss it my way, I've got a 73 as well that it would look really good on :-D

Seriously though, provided the bike just needs a good dose of TLC to bring it back to life then that original exhaust assuming that it still is solid makes a BIG difference in the bikes resale value.
Scott

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Lucien Harpress
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Re: CB750 Experts?

Post #10 by Lucien Harpress » Fri Mar 18, 2016 9:19 pm

I let him know that exhaust is big money. If it doesn't clean up he may sell it to help pay for restoration stuff elsewhere.

What's the going rate for those? Are they up to 4 digit prices, or am I just making things up again?

He just got a key for it today, so he's eager to tear into it. I was going to help, then my brother proposed we have the manliest of man days ever (drive up to Lansing to drop off a transmission, go trap shooting for a bit, then go to a place literally called "Meat" to get some BBQ). If he can get the carbs clean, I feel good about his chances of getting it started.
1969 CT90- Needs rear tube and possibly rings
1976 GL1000 (Yellow)- Carb Shenanigans.
1984 GL1200 Standard- For Sale!
1980 KZ1300- Carb balancing when the weather warms up
1972 CB750 Barn Find- Tires and Head Bearings

All advice I give is only valid until an expert corrects me.

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Gowing
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Re: CB750 Experts?

Post #11 by Gowing » Fri Mar 18, 2016 11:53 pm

A real nice reproduction four pipe, looks good to me is available now for the
Cb750's for under two grand.
Dave

1975 GL 1000
1976 GL 1000
1980 XS650
2003 ST 1300
1971 CT90
1972 F7 KAW 175
1984 elite 80
Chiwawa (Ellie)
Chiwawai #2 (Dot)

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fish
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Re: CB750 Experts?

Post #12 by fish » Sat Mar 19, 2016 12:45 am

Lucien
first...
Have him get the title transfefered into his name so he know it is a clear title
do the minimum to make it run & ride
take it out & ride it everyday.
no restoration!
BTW those SOHC motors do have timing chain issues.
tension the timing chain using the proper approved factory procedure
Timothy Mark Fisher
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salukispeed
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Re: CB750 Experts?

Post #13 by salukispeed » Sat Mar 19, 2016 8:23 am

I may be mistaken but I believe the stamped numbers on the mufflers will have 341 in the middle if by chance someone swapped them with a set of 300 they are from the early K0 bikes and are even more rare. They look remarkably similar but are different internally . If you get in trouble I have a disassembled and ultrasonically cleaned set of K5 1975 carbs with everything to rebuild them even the rubber boots that cover the linkage and all the Mother Honda rebuild parts. I bought a set to put on my 750 Auto for kicks. I found some water damage inside but think they can be saved with some care. I think I also have new OE manifolds and needle and seats too.
Honda 72 CL100 sold
74 CB750 K4 nice driver
1966 CA77/305 Dream nostalgic driver
84 GL1200I work in progress
1970 CT 70
1982 GL500 Interstate

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Re: CB750 Experts?

Post #14 by JSBail » Sat Mar 19, 2016 6:32 pm

Lucien Harpress wrote:I let him know that exhaust is big money. If it doesn't clean up he may sell it to help pay for restoration stuff elsewhere.

What's the going rate for those? Are they up to 4 digit prices, or am I just making things up again?


The value of the exhaust depends on how solid it is and how much a restorer is willing to pay so I'm hesitant on giving any value #'s. I would recommend checking ebay out to get a general idea on what the going prices are.
If (the key word is IF) it's in solid shape then I would advise keeping it because once it's sold then your friend will just have to spend to get another to replace it unless of course he actually would prefer an aftermarket 4/2 or 4/1 setup. It's your friends call as to what he wants to do with the bike and all the power to him but he might want to keep in mind that the 750's the generally sell the quickest and get the most $ are the ones that are as close to stock as possible and one of the first things to get a potential buyers attention is that factory exhaust. I recommend your friend checking out the sohc4.net site as well, I go there often and there is a load of helpful info there
Scott

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salukispeed
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Re: CB750 Experts?

Post #15 by salukispeed » Thu Mar 31, 2016 11:49 am

Any Progress??
Honda 72 CL100 sold
74 CB750 K4 nice driver
1966 CA77/305 Dream nostalgic driver
84 GL1200I work in progress
1970 CT 70
1982 GL500 Interstate


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