Topic: Project "Evolution" 78' CB750K... the morphing continues...

[madmtnmotors]

You guys crack me up!     

[BobbyR]

Great job. Devolution will be worth the work. She will be a runner and a stunner.

[BobbyR]

You do have a good memory, Ron! Of course, those were Georgia boys stuffed in the back of the Van so who could blame me really?  I like Wilbur. I'd stop anytime he asked 

My wife pee'd in a Dillard's shopping bag in the vehicle on one road trip to NM several years ago!

It's not that I didnt stop - we were stranded on I-40 during a blizzard one night, we ended up sleeping in the 4Runner. I pissed in the middle of I-40!

My personal best was 4 am on the center span of the George Washington Bridge. We were stuck for 4 hours because some dickhead drove under a truck.  I dod nt have a Snapple bottle ir anything in the car. Walked in between two 18 wheelers and let her rip.

Homeland Security did not come calling, so I guess I made a clean getaway. 

[madmtnmotors]

After confirming PeWe's assessment of cheap aftermarket cam chain tensioners:

http://forums.sohc4.net/index.php/topic,155043.msg1776359.html#msg1776359


I have decided to keep it and race it! 

[Restoration Fan]

SCHWEET!!!

Now you get to continue to prove to everyone that "78's are the fastest!" 

[madmtnmotors]

What gives with this project, Wilbur? Don't you have a race coming up soon? Have you been spending all your time watching YouTube and snacking on chips and not turning wrenches! Dang son, Billy is up there building 3 bikes at once and you're lazing away in sunny FL... 

I am currently awaiting the return of my freshly bored cylinders...   

[madmtnmotors]

In the meantime, I have managed to accomplish the following:

>Ported the head, mostly smoothing out the factory "swipe" half-a$$ factory port job on the intakes
>Added the "quench band" to the combustion chambers
>Lapped the valves
>HD valve springs with titanium spring retainers
>New HD cylinder studs
>Put the frame on a diet:
             *Smaller led turn signals
             *New plastic rear fender and led taillight to replace the heavy a$$ stock pieces
             *Jettisoned the passenger footpegs (no one will ride with me anyway...)
             *Looking at a plastic front fender as well

I should have time to get the engine back together and put down the obligatory 500 break in miles and get a few passes at the local track before Valdosta. 

[madmtnmotors]

They will be waiting on you to get home from work today. 

Hot damn! Now I will definitely have time to get a little practice in!     

[madmtnmotors]

Pistons and cylinders arrived today. Somebody thought the plain Jane cruzinimage 65mm pistons needed "dolling up":




Looks like my build schedule just got "accelerated"!     

[SOHC4 Cafe Racer Fan]

Jane is all lubed up.

[Stev-o]

In the meantime, I have managed to accomplish the following:

>Ported the head, mostly smoothing out the factory "swipe" half-a$$ factory port job on the intakes
>Added the "quench band" to the combustion chambers
>Lapped the valves
>HD valve springs with titanium spring retainers
>New HD cylinder studs
>Put the frame on a diet:
             *Smaller led turn signals
             *New plastic rear fender and led taillight to replace the heavy a$$ stock pieces
             *Jettisoned the passenger footpegs (no one will ride with me anyway...)
             *Looking at a plastic front fender as well

Yeah right Cal, he's been lazin' in the FL sun!

[madmtnmotors]

Left to do:

>Assemble top end of engine
>Degree the new WebCam 41 cam
>Check valve to piston clearance (for practice if nothing else)
>Install engine in frame
>Fit up drag pipes
>Lower the front and rear 1-1/2 to 2 inches
>Mount up lighter fenders front and rear (rear mock-up complete)
>Swap points/condensers for Dyna S and Dyna coils
>Get the 500 mile break in on the new rings
>Get it to the track and ride the crap out of it! 

[Restoration Fan]

Go, Wilbur, go!
Just remember...78's are the fastest!   

[madmtnmotors]

Fer chrissakes....

After tearing down the motor to replace substandard cam chain tensioner components, as mentioned before, I decided to up the ante with CI's 836 kit and a hotter cam. 

Well... everything's going good, finally working on degreeing the cam, and I see that the end of one of the sprocket mounting ears is snapped off my brand new freaking cam!     

Now I knew the hole was not right, since I had originally planned to use a stock sprocket to establish some baseline numbers, but the holes would not line up. One of the holes was off a little. No big deal, since I have a slotted sprocket that I was going to use anyway. The slotted sprocket seemed to work without issue, and the sprocket bolts went in without any drama.

Yeah right. The only bright spot is that I was able to retrieve the wayward ear piece from the bottom of the crankcase with a telescoping magnet through the cam chain tunnel. If I had to pull the top end off again I likely would have broken something else...

on purpose! 

Picts of the carnage to follow...

[madmtnmotors]

The 65mm CI pistons looked happy in their new home:













The brand spanking new camshaft was not so happy however. These pictures shows the defect pretty clearly:



















I had not even tightened these to final torque. I was still in the process of degreeing the cam.


Damn. 

[Retro Rocket]

Send it back mate...

[madmtnmotors]

Send it back mate...

That's the plan. The Webcam warranty states:

"sprocket flanges can break and are not covered under warranty"

but my contention is that this part is defective. I've started the communication process (with pictures!) and will post results here.

[Retro Rocket]

Send it back mate...

That's the plan. The Webcam warranty states:

"sprocket flanges can break and are not covered under warranty"

but my contention is that this part is defective. I've started the communication process (with pictures!) and will post results here.

To me, it looks like it was drilled off center...

[Stev-o]

Damn...

[Davez134]

It does look off center in the broken picture. Damn, I have that same cam too

[madmtnmotors]

Send it back mate...

That's the plan. The Webcam warranty states:

"sprocket flanges can break and are not covered under warranty"

but my contention is that this part is defective. I've started the communication process (with pictures!) and will post results here.

To me, it looks like it was drilled off center...

Yep. The stock sprocket would not line up. I was going to use the stock sprocket to establish some "baseline" degree data and then switch to the slotted sprocket. The slotted sprocket lined up with the offset hole and the bolts went in by hand without any undue effort. My contention is that the hole was too close to the edge of the sprocket flange. I had not even put final torque on the sprocket bolts because I was still in the process of degreeing the cam when I noticed the missing piece.

[Stev-o]

Send it back mate...

That's the plan. The Webcam warranty states:

"sprocket flanges can break and are not covered under warranty"

but my contention is that this part is defective. I've started the communication process (with pictures!) and will post results here.

Where did you purchase the cam?

[madmtnmotors]

While awaiting a response, I have decided to move forward and dip into the "private stock". I have selected the one pictured in the center:




It had a strange hieroglyph stamped on the end:




Well I'll be "D"amned!




I was reluctant to use a "D" grind at first based strictly on the numbers:

 
Per the "Satanic Mechanic"                                                                         
                                                                         
         Valve   Durat-                                                     In o/c      btc/abc
Cam      lift    ion       Description                                   Ex o/c     bbc/atc
---------------------------------------------------------------------------
D        .345    277       A famous grind. Excellent for a major HP     32/65
          .325    294       increase, yet a wide range of use. Long       77/37
                                 exhaust duration for sustained high speed
                                 cruising without excess combustion chamber
                                 temperature. May be used with stock
                                 springs if desired.



Holy crap! 290 degrees duration on the exhaust? Does the exhaust valve ever close? Intake opens at 32 degrees btc? SOB will have to idle at 3k!

Of course, once I realized that I was comparing apples to oranges, the picture becomes clearer. Kenny Harmon cams are measured at .020" lift while almost every other cam on the planet is measured at .050"! When open/close numbers are measured at .050" the "D" grind seems more sensible:


Intake open/close/duration @.050":  20btc/53abc/253
Exhaust open/close/duration @.050": 62.5bbc/22.5atc/265

I was saving this one for a more aggressive build, but I've got a deadline approaching... 

[madmtnmotors]

Wilbur, just double-check the valve-piston clearance.

Well, I did clay the pistons (more for practice than anything else) with the Webcam 41. Now that everything is bolted up (and re-torqued), how do I check it now? Fish a piece of solder through the spark plug hole? Order another head gasket and rip the head back off? If I had to order a head gasket and rip the head off then I'd just as soon order another Webcam 41 and work on something else while I wait...

[madmtnmotors]

The lift numbers are close:

Webcam 41: 235/235

KHD: 245/225

The durations are the biggest difference:

Webcam 41: 237/234 @.050 lift

KHD: 253/265 @.050 lift

I may try a piece of solder through the spark plug hole.