I think Ill name it Piper

[Dirty]

Well here we go. This is my stock 78k that i "restored" in 93 or 94. I rode this baby through high school, tech school and colege. needless to say we have seen and done a lot of stuff together! Unfortunately it has been sitting for the last 10 years or so only started once a year to prove a point. Im not quite sure why i decided to do what i am doing to it. (I think I blame this forum!!)

[Piute]

     "O" so now your bikes 15 ,and your ten fresh out of "colege " hmm
  Get that dang thing going ,
               Ya can blame us only if we see what ya doing ,
                  Ya-No what they say about putting the blame
                                                                                   

   

[Dirty]

I just brought it home to clean the carbs and get it running. Then cleaning the carbs turned into this, real quick!

As i had it apart I remembered one of my buddys had a Yamaha YZF at his place that didnt run and plastic was junk on, so i went and did some measuring on it thinking it would be cool to have a mono shock on this, still planning on a stock rebuild. Unfortunately for my K the rear swig arm fit.

Then I thought, boy that front end would look cool on here also.

That also fit ok, so out came the cut off wheel! I think there is still a tear stain in my concrete from when I cut the first tube!!

[Dirty]

Piute, I never said i was 15. I got my 78 when i was 15. Im guessing the reason my valves hit my pistons is because i rebuilt the motor back then

[shinyribs]

LOL. Reading your sig I thought you were 15 years old also.

What did it take to fit that front end on there? Stem swap or was it just a bolt on?

[Dirty]

Well at first i was trying to find a lower bearing/race that would work, the top bearing would work. The problem with the lower one was it was way bigger then cb. Then i looked into a stem cell swap. just so happend to find someone else as sick as me!! So i took his advice.


first I measured both shafts from top to lower tree. Ill need this for reassembly.
Chucked up in lathe and faced of welds.

Pressed out stem on both

I pushed honda shaft and bearing into yam lower tree till shaft was flush. I knew by the measurments that i couldnt weld it flush so i installed it on bike with both bearings so i could pull shaft where it needs so sit. This required me to snug the stem nut down pretty tight and since my channel locks were missing  My blue point fan clutch holder got modifyed a bit.


Once i got the spacing right I removed it and welded it.


After welding the shaft on it was just a matter of sizing the upper tree to fit the shaft.

I got lucky with the upper tree, shaft was smaller on yzf so all i had to do was ream it out some. No need for feeler gauges here!!

[Piute]

    Machining / welding,can't be 15..
 Some of you make me sick or is that look sick,
  Talk about a lucky find with the fit,

[Lincoln Highway Bullitt]

Hold it right there Dirty. What is the chassis in the background of the one picture?

[Piute]

Lincoln Highway Bullitt wrote

Hold it right there Dirty. What is the chassis in the background of the one picture?

                                         GOOD EYE
                                    If talking about bike
                                      Looks Like A F2
                          THee other that aint no dog cage
                                                 

[Dirty]

piutes right its an f2 with my k side covers

[Lincoln Highway Bullitt]

I saw the bike but was inquiring about the roll cage. So you got a lathe. You got fabricating skills so you have to be a racer or part of a race team. So what is the chassis?

[cdaiscool]

I agree. I think you're holding out on us.

I'm thinking sand rail.

[shinyribs]

Alright now,easy with the feeler gauge remarkI am sensitive ya know



I don't know about sandrail,but theres definitely some long travel shocks going on there!

Nice bead on that stem dude. That's as pretty a rope as I've seen in a while

[Dirty]

watch speed channel today at noon! might give you a hint what chassis is.

[rrgunslinger]

Some guys have all the luc...I mean skills...

[cdaiscool]

I checked the speed channel's line-up. German sedan racing.

Are you building a Mercedes in your garage?

[Dirty]

Noon (WI time) was TORC. Short course off road racing. That chassis is a pro 4.

[Dirty]

So guys i got a question, do all cb 750's have vin code on flat casting behind starter? MY K does not have vin in casting instead it is on a plastic tag inboard more. every 750 ive eyeballed had it in casting.

This is were Ive seen the rest. This is my F

And what is the deal with the "Black motors"?
Thanks, Dirty

[cdaiscool]

I can look on my '81 tomorrow, but its a different motor - DOHC vs SOHC. So probably won't really tell you anything.

[shinyribs]

The ''Black Motors'' are the F2's and F3's-77F-78F. They came in the Super Sports. They have a higher domed piston and head to match and a little hotter cam. They are supposed to be the hottest of all the SOHC's. The hotter cam supposedly created poor valvetrain geometry causing fast valve stem/guide wear. I think they fixed the issue in some of the later engines by using different materials for the guides while the rest was unchanged. The general consensus ( no experience here,just interwebs talk I've read) is Honda thought they had tapped out the SOHC to it's full potential at this point and then moved on to the DOHC.

The 76F is the only F ,or Super Sport,engine with heads and pistons interchangeable with all the other K engines.All 69-78 engines and the 76F are identical head wise. 77-78F were their own beast.  

The blank VIN pad is a sign of a replacement engine,or at least the case. Someone musta either blew one up,chain-cracked a case or maybe laid it down and killed the case. The sticker is anyone's guess

If the blank VIN pad engine you have was a "Black Motor" replacement it may have been due to the F2/3 valvetrain issues???

The 77-78 engines(F&K) used a primary sprocket location further outboard (10mm) then any other SOHC engine. If you use a 77-78 engine you have to use a 77-78 cush drive to make the chain alignment correct. All the cush drives will swap from wheel to wheel(even from a spoke to a Comstar),so its not a big issue.Or you can use an offset rear sprocket to correct the alignment issue. They are readily available and not a whole lot more than a standard sprocket,though I believe they are only available in steel.But I could be wrong on that last part.