Topic: why is a 1969/70 faster than the remaining years ?

[754]

I think most of this is all speculation and fond memories. Does anybody have some Industry Standard RWHP #'s like off a Dynojet? There have to be some "original" 69's and 70's out there to test. Do it and put this thing to rest. Personally I get tired of the 2 degrees more duration, .003 more squish, 2 degrees more advance @ 5,000RPM etc etc etc etc etc.
 Get some of these "ponies" on a dyno and lets see. They are out there!
 Other than that I think this Unicorn chasing. No disrespect to Dick.....I've spoken with him and he is a nice fella.....wish I had the time to help him out.
BTW....I think my CB is faster and quicker than any 1969.

yup... stock k1 is certainly faster than stock k5, but it is mostly set up stuff.  Most of these Honda only guys have not had their minds blown by a Z1 or a Suzi gs...or even a V4 Honda for that matter.  Hell, they think an f2/3 is only good for bad valve guides...I have witnessed a kz650 spank the pants off a K0 before.

 There are quick Is 650 and there are quick cb 750s. Depends on the rider, tuner, gearing etc.   Some guys know how to holeshot.. the guy that doesnt always looks bad..
 I surprised a few guys with my 836 up to 60 or 70 mph.  They usually catch up, but I could mzke a lot of them look bad off the line.. The higher the bikes horsepower, the harder it gets to launch it quickly.
 I can remember racing a Duster one day and the guy said, I ran against a lot of bikes like yours, but yours is quicker.. and that was the 73, with a header and pods, and points.,  CBO of course..

[754]

 A lot of guys dont know how quick their bike is with them on it cause they won't race. Run into a few Magnas at say a gas station, they spout off their memorized magazine stats, and I say , do you want to race against mine, let's go.. show me...
 That usually shuts them up really fast.. yeah they should spank our old CB s, but they won't if they don't try..

[PeWe]

Small tuning as later pistons, 391 to compensate for thicker gasket in K0-K6.
Is F0/ K7/K8 cam stronger than earlier? I know, small differences.
Fun to tune these small things for best performance. And compare dyno's. 45-55whp range?

No problem to get 80-85 whp with 836cc 10.5:1, ported head, cam, OK exhaust maybe carbs.
10-15 more with 1000cc and carbs.
Just order from a shop/ guys like Mike Rieck.

A refurbished stocker will cost some too. Head job seems always be needed on these old bikes

[madmtnmotors]

Everyone knows the K8's are the fastest:

[HondaMan]

Everyone knows the K8's are the fastest:

Great hole shot!

[scottly]

I tried to find the period magazine road tests on the club page, but none of the links work.  

[PeWe]

Everyone knows the K8's are the fastest:

Stock cam or something that open more and longer?

[madmtnmotors]

Stock cam or something that open more and longer?

Mild cam, CycleX CX-1 similar to Webcam 41, flat top C.I. 836 pistons, 16/52 sprockets put me at 9800 rpm in 5th gear @101mph as I cross the stripe. Hovering right around 13.00 sec E.T. with 12.91 being my best so far. 

I'm having fun with it!

[PeWe]

Ok, that setup must run rather cool and soft running, no need of higher octane fuel either as the  CR 10.5:1 and up pistons.

Head is stock? No port, chamber job?

[HondaMan]

Stock cam or something that open more and longer?

Mild cam, CycleX CX-1 similar to Webcam 41, flat top C.I. 836 pistons, 16/52 sprockets put me at 9800 rpm in 5th gear @101mph as I cross the stripe. Hovering right around 13.00 sec E.T. with 12.91 being my best so far. 

I'm having fun with it!

That's very much like the early K0 bikes' results seen in Cycle magazine and others, circa 1970. They were passing the 100 MPH mark at 12.9x seconds. I think the fastest one I remember was 102 at 12.93 seconds. It was a K0 with the original 16/45T sprockets, as that was all there were in those early days. By the K1 they were more like 100 flat at 13.1 seconds, and by the K5 they were at 96 MPH at 13.4 seconds, or in that neighborhood. Local riders in Peoria and Macomb/Blandinsville (near my shop) were besting those numbers, but with stripped bikes (and sometimes my help). While I didn't trust the local dragstrips' timers as much as NHRA equipment (they printed out a little ticket of your speed and time, though), one of the 750K1 bikes with 16/54 gearing and an R/C cam feeding 836cc Action Fours' pistons underneath was in the low 12s and past 110 MPH on his ticket. He only got into the 12s after he removed his velocity stacks (when one fell off) and put on the airbox upper half one night in its place (because it had velocity stacks), and after that he always ran it with the empty airbox (no filter) as he got better times. That was one of "those things" that ended up sending riders to my shop for 750 work, because I told him about the airbox...

[Spanner 1]

Engine mods ' 69 thru' '78 ?... bull#$%* ! The very first owners of the CB 750 were all young 'go fast ' fellas. Only in the later years more mature buyers were attracted to them . About youth and throttle twisting. I bet a lot of older fellas here have not opened the throttle to the stop or rode between 6 and 9 k rpm ( all the time ). IMHO.

[754]

When I was young I wound the pies out  my stock motor with headers , and webers, all the time.
 Right up till about 07, I was over 50 then.
 These days, these laws  this wallet  I can't afford to #$%* around..  I rarely get near redline.. and no tickets..

[754]

Engine mods ' 69 thru' '78 ?... bull#$%* ! The very first owners of the CB 750 were all young 'go fast ' fellas. Only in the later years more mature buyers were attracted to them . About youth and throttle twisting. I bet a lot of older fellas here have not opened the throttle to the stop or rode between 6 and 9 k rpm ( all the time ). IMHO.

Lots of changes thru the years and the early bikes were lighter. With a 10mm wrench you could change your exhaust   like you never could since 1972.,

[MRieck]

I think most of this is all speculation and fond memories. Does anybody have some Industry Standard RWHP #'s like off a Dynojet? There have to be some "original" 69's and 70's out there to test. Do it and put this thing to rest. Personally I get tired of the 2 degrees more duration, .003 more squish, 2 degrees more advance @ 5,000RPM etc etc etc etc etc.
 Get some of these "ponies" on a dyno and lets see. They are out there!
 Other than that I think this Unicorn chasing. No disrespect to Dick.....I've spoken with him and he is a nice fella.....wish I had the time to help him out.
BTW....I think my CB is faster and quicker than any 1969.

yup... stock k1 is certainly faster than stock k5, but it is mostly set up stuff.  Most of these Honda only guys have not had their minds blown by a Z1 or a Suzi gs...or even a V4 Honda for that matter.  Hell, they think an f2/3 is only good for bad valve guides...I have witnessed a kz650 spank the pants off a K0 before.

The Kawasaki KZ650 had a great engine.....i got spanked by one up at Loudon back in 1978.