CB750 F 1980 Speedo

[Archwillard]

Hi guys, total newbee here so please be gentle with me.

Ive been nosing about for a few weeks looking to get me a CB 750 and was looking at various models and performance etc when I came
across something that has me a little confused...???

If the SOHC pre 80 and DOHC 80 onwards are reasonably comparable when it comes to performance (BHP top speed etc) why is it that on most
of the pre 1980 models the Speedo goes up to approx 140 MPH and on the CB 750F (1980) I've been looking at it only goes up to about 80 MPH ??

Surely there cant be that much performance difference ??

What is the top end (MPH) on the CB750F DOHC 1980 ?

Guidance much appreciated

 

[amc49]

The '79 DOHC F went to 150 mph. Thank Joan Claybrook (NHTSA) who back in the day postured the theory that young people seeing 150 on the speedo would be lured into seeing if the vehicle could actually do it. She lobbied the US Congress hard and got the regulations changed for a very few years to have 85 mph max speedos installed on a lot of stuff.

The max number in no way limits the performance of the vehicle. Later on the numbers went back up.

My '80 F would run 120+ mph all day long. You can simply plop a correct higher reading one in place of the other if it fits early DOHC and instant higher numbers, I used the '79 one as the style contrasted with the tach (red vs. green) on the '80 and unlike many I thought it looked great.

 

[Archwillard]

Wow !! Now that's what I call an educated comprehensive reply. Very much appreciated amc49 thank you.

So now I'm off to look for either a replacement DOHC clock with better numbers or just spotted these.....d'you think they would do the job ?

https://www.ebay.co.uk/itm/HONDA-CB...e=STRK:MEBIDX:IT&_trksid=p2060353.m1438.l2649

or

https://www.ebay.co.uk/itm/HONDA-CB...e=STRK:MEBIDX:IT&_trksid=p2060353.m1438.l2649

Thoughts ?

Thanks again

 

[amc49]

Likely, that's the '79 style I had. Be aware also the two types used a different needle pointer design. also there is the issue of getting inside the units with no seal damage to let moisture in. I hear some of them were liquid filled too, you can't store them upside down or leaks.