Author Topic: 1971 CB750 Chopper Project with Adams Quadracycle motor (Read 2097 times)

tdf700 · « **on:** July 25, 2024, 03:42:09 PM »

I picked this up from a guy who was slowly parting it out. The guy I bought it from bought it complete(ish) from an estate sale. The story he was told was that the estate sale was for a gentleman who had passed away. The 1971 CB750 was purchased new in Austin Texas for the purpose of building a chopper. I was told the frame is an A.E.E. and the motor was taken to Brent Adams at Adams Quadracycle to be "built". The man started the project but never finished it and it sat in his garage in Austin unfinished until last year when it was sold in the estate stale. It came with a manual and some boxes of wires and parts. The seat, carbs, and pipes are the obvious parts that were parted out. I don't know what any of it is worth dollar wise or historical value. I bought it because I found it to be intersting and wanted to try and keep the rest of it together. I was told later the frame looked more like a C&G frame. My wish plan is to get it back on the road, we will see. Any thoughts or obeservations are apprectiated. Thank you.
oh and it is just like I found it, I have not done anything other than move it from point a to point b.

tdf700 · « **Reply #1 on:** July 25, 2024, 03:42:48 PM »

tdf700 · « **Reply #2 on:** July 25, 2024, 03:43:47 PM »

tdf700 · « **Reply #3 on:** July 25, 2024, 03:44:25 PM »

Box of parts

tdf700 · « **Reply #4 on:** July 25, 2024, 03:44:53 PM »

Manual

tdf700 · « **Reply #5 on:** July 25, 2024, 03:47:20 PM »

top down

CycleRanger · « **Reply #6 on:** July 25, 2024, 04:11:51 PM »

Adams Quadracycle, now there's a name I haven't heard in a while.
I remember them from back in the '80's in Austin.
Put it back together, it should be fine runner!

BenelliSEI · « **Reply #7 on:** July 25, 2024, 05:21:23 PM »

Engine number?

tdf700 · « **Reply #8 on:** July 25, 2024, 05:36:19 PM »

Engine Number

tdf700 · « **Reply #9 on:** July 25, 2024, 05:40:55 PM »

I was told this was the orginal frame as well.

BenelliSEI · « **Reply #10 on:** July 25, 2024, 06:01:09 PM »

Definitely a 1971 cb750K1 engine. The frame should have a number plate and stamped number on the headstock too.

newday777 · « **Reply #11 on:** July 25, 2024, 06:07:19 PM »

Quote from: tdf700 on July 25, 2024, 05:40:55 PM

I was told this was the orginal frame as well.

The motor numbers are K1. Vin tag on the original frame? Did you get a title for the frame?
Might be better to restore the original bike?

tdf700 · « **Reply #12 on:** July 25, 2024, 06:11:39 PM »

frame plate

Medyo Bastos · « **Reply #13 on:** July 25, 2024, 07:06:21 PM »

Cool! The neck and seat area do look like a c&g frame; the motor mounts don’t. The oil tank is a corbin gentry, not the same company.

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PeWe · « **Reply #14 on:** July 26, 2024, 05:46:37 AM »

Quote from: tdf700 on July 25, 2024, 05:40:55 PM

I was told this was the orginal frame as well.

Why not use that frame for a "stockish" build?
Easier to get right parts and easier to sell in the future.

Shtonecb500 · « **Reply #15 on:** July 26, 2024, 06:18:51 AM »

restore that K1!

BenelliSEI · « **Reply #16 on:** July 26, 2024, 02:49:25 PM »

+1 to that. Mine is my favourite ride. Spent time on it today.

scottly · « **Reply #17 on:** July 26, 2024, 07:42:55 PM »

The K1 is missing too many parts! A restoration would cost over $10K in repro parts alone. I would keep the rare unicorn triple with the frame, as they are usually broken, and use a newer triple for the chopper.
What is the condition of the engine? Is there any evidence it was ever run, like carbon in the exhaust ports? Were all the ports plugged up/covered and spark plugs in the head?

tdf700 · « **Reply #18 on:** July 27, 2024, 01:59:17 PM »

The exhaust ports were not covered, but the pipes were there at one time, it was one of the parts that was parted out.

tdf700 · « **Reply #19 on:** July 27, 2024, 02:00:07 PM »

The spark plugs are in and I have not taken them out until now.

tdf700 · « **Reply #20 on:** July 27, 2024, 02:00:44 PM »

Spark plug 1

tdf700 · « **Reply #21 on:** July 27, 2024, 02:01:19 PM »

Spark plug picture

CycleRanger · « **Reply #22 on:** July 27, 2024, 02:23:00 PM »

Looks unfired. Amazing.

You'll have to pull the valve cover and see what cam is in there.
Drop the oil pan and peer up in there to look at the rods.
There's just no telling what you might find.

HondaMan · « **Reply #23 on:** August 10, 2024, 09:30:57 PM »

From Texas...my [sad] experience is that when the exhaust (and/or intake) ports are left open that long, the cylinders rust to piston-lockup stage, requiring a rebore. The valves are usually rusty, too. The good part is: that serial number engine has Stellite valve guides, so they will likely be fine! That's the expensive part of rebuilding a head, when those must be changed out. From a performance standpoint, the K1 was a streak BEFORE it was built up, too.

Is either frame titled? I'm in need of a titled frame in the K1-K4 range as I have a complete bike with 'lost' title, which Colorado will not retitle, period.

PeWe · « **Reply #24 on:** August 11, 2024, 01:38:00 AM »

My K6 did not have rust in bores after 19 years in a barn. Engine rotated a little each year by the kickstarter. Good amount of oil in engine when oil pump let the oil fill it.

Lucky that oil tank did not have lots of deep rust.

But, the valve seats had pores due to rust.
Nearby shop cut them and refreshed the head with new valves too.

newday777 · « **Reply #25 on:** August 11, 2024, 02:53:30 AM »

Quote from: tdf700 on July 27, 2024, 02:00:07 PM

The spark plugs are in and I have not taken them out until now.

Put a couple squirts of oil in the cylinders with a squirt can to lube the rings, then see if the motor is free to kick over with the plugs out.

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Author Topic: 1971 CB750 Chopper Project with Adams Quadracycle motor (Read 2097 times)