Topic: Difference between 1970 CB750K1 and 1971K1 ??

[Impala]

Just picked up a project bike. Bike pretty clean but missing many parts, seat, exhaust, gauges,ect, but to my unexpected delight it has a rolled rear rim in great shape! Frame and motor are both 1067xxx and close matching. MFG. date on frame plate is 11/70. Is the cut off from one model year to the next the obvious MFG date? I guess this is technically a 70K1?  I looked up in Kelly Blue Book values and they list a 70K1 as more valuable than a 71K1  Was 70K1 bike/parts any different than a 71K1?  Thanks, Paul.

[Kevin D]

Impala, your CB is just a smidgen older than my 11/70 K1. Yes technically a 70 K1 but they were titled with the date they were sold, not when they were built. I have most, but not all, original parts. I have spiffed it up a bit, but it had pitted chrome and faded paint, cracked plastic, original exhaust rusted out a loooong time ago.
What prices did Kelley put on it?.... (not that mine is for sale)

I look at the motorera page to check out model differences:
http://www.motorera.com/honda/h0750/four.htm
http://www.motorera.com/honda/index.htm

EDIT: Original DID rims front and rear. Sorry, I dont know rolled rims.

[goldarrow]

I don't think 70 model comes equip with rolled rim, if yours does, may be PO switched it out sometimes in the past and wouldn't be surprise to see 2-holes hub

[harisuluv]

the manufacturing date 11/70 means it is a 1971 model.  On the vin it should say in the biggest font on the plate "1971 CB750" or something, no?

[mrbreeze]

There is usually a cut off month. Most cars I've noticed do it in June. Not positive on our bikes. On a car you can see for example 2015 on the reg. card and on the under hood sticker but like 8-14 on the door sticker.

[Don R]

 They regularly wrote new titles for bikes unsold the previous year. I think that ended in 76 with a class action lawsuit. I got $37 for my retitled K2, 1973 cb500.

[dusterdude]

Mine is an 8/71 build and titled as a 72 but it is most definitely a k1

[mrbreeze]

Maybe their cutoff month was October back then. Some parts carried over to different years so they could be used up. What confuses everything is when some states put the year on when it sells...not when it was made. Just like some states will title it with the engine # while others use the frame (the way I believe it should be).

[guitarkev66]

"K0-K1: These were the "performance years". The carbs were jetted 120 mains, the spark advancers were quick-advance units (all in by 2000 RPM) and the pipes were straight-through with fiberglass-wrapped tube inserts. Gearing was 16T/45T on K0, 17T/48T on K1. Gas mileage was about 32 MPG on premium (95 octane). These bikes developed about 67 HP, peaking at 8500 RPM, putting about 61 HP "on the ground". The K0 had 4 cables on the carbs, while the K1 had the bellcrank system most folks recognize.

Late K1/Early K2: The cam changed, getting advanced about 3 degrees instead of  5, but the duration was the same (so the overlap moved, too!). On the K2, the straight-thru pipes were changed to a 5-chamber baffled design. The spark advancer was delayed to full advance at 2500 RPM. The main jets on the K1 were 120 (old factory bikes) or 115 (bikes after 11/70 build), on the K2 110. The K2 jet needles were dropped 1 notch from the K1 settings (middle notch, K1 was 2nd from the bottom). The sprockets changed to 18T/48T. These bikes put about 58 HP on the rear wheel at 8000 RPM in 3rd gear."    Quote from Hondaman


I have had a few K1 bikes and a few K0's as well.  I currently have a 9/70 K1 105 serial numbers and it is noticeably faster than the later K1's ive owned or ridden especially at the top end.  Not sure when they started to reduce the performance of the K1's but I had two others a 12/70 and 7/71 had less power.  But anyway you look at it K1's were all great bikes arguably some of the best or the zenith of cb750 production. My k1 is my favorite motorcycle

[Don R]

 Honda was issuing updated titles, not the states. I once had all the class action lawsuit paperwork from 1975. I believe it was the Attorney General in New York state that filed it and proved it. That's why there aren't as many 1975 bikes, Honda lost, said OK and went right into 76 production in early/mid 75.
 My dealer assured me my 73 500 was the latest newest model in the spring of 73 (my brother worked there and asked) but as the summer went on I noticed everyone else's 73's had the big gauges. Then when I needed parts K2 parts fit it.

[mrbreeze]

Good info Don. I have a 75K. There were more differences between it and a 74. Other than the paint colors I don't know much difference between a 75 & 76. Any history we can come across on our bikes is cool with me. The differences between 74 & 75 off the top of my head were the moving of the petcock to the left side. Larger turn signals, different design side stand, of course paint colors. I know there are lists out there that have other changes including things in the engines. These were the EPA years and right before the gas war era. Even though the early ones had more power from the factory some of the newer ones had improvements in design.

[Impala]

Great Info! Thank You everyone! Its a Keeper, time to get busy and make it Roar again. Paul.