Topic: 1973 CB750 Four K3 -- Project "Terry's Fault" -- BUILD RESUMED

[edwardmorris]

@mashfu, thanks, but that's not what I was missing. It's a piece internal to the engine. I ended up getting a replacement from 02zdave, and then I found mine! Anyway, thanks for the offer. The engine got put together over the past couple months so no longer an issue.

@Terry, thanks! I was able to look into what was already done, and it feels like I'll have a roller the day the engine goes into the frame. Suspension, wheels, gas tank, oil tank, pretty much everything that needed work is ready to be bolted on, so maybe there is still hope. I just need to get my act together. I'll give dialing in the cam one more try this weekend, and if I fail, I'll try and get someone to come over and help.

[Terry in Australia]

That's the ticket Rafi, I know you're a perfectionist and well organised, so get that thing finished, it's probably another BOTY just waiting to be foisted on the unsuspecting masses! Cheers, Terry.

[edwardmorris]

@Terry haha, highly unlikely, but encouraging, thanks!



OK, trying to dial this cam in, can't seem to get it right. Am I even doing this right?



Valve Lash set to 0.004" measured at lift 0.036"

Crank and 1-4 TDC with compression on #1 cyl, aligned with degreeing wheel TDC.
Dial gauge preloaded to 0.3", then zeroed on the exhaust retainer parallel to valve stem.
Turn the engnie clock wise till dia gauge reads 0.264" (basically 0.036" lift) or 0.036" in the RED/negative.
Reading for exhaust at this point is

40 BBDC (Cam card says 50 at zero lash, so 46 with lash set at 0.04")

Keep turning the engine to go over the lobe hump, then stop at 0.036" before zeroing out at 0.3" on the dial gauge (reset/original position). Reading for exhaust at this point is

16.5 ATDC (Cam card says 23 at zero lash, so 19 with last set at 0.04")

Lobe center (40-16.5+180)/2 = 101.75 or ~102  (Cam card says 103.5, I'm guessing about 99.5 with lash set if that applies)

Leave it here or start over?

[Davez134]

You need to do intake side next and see how close the lobe centerline is to your exhaust numbers. Sorry I missed your call earlier, was out running around.

[edwardmorris]

OK, so after several tries at various cam sprocket positions, I think I'm going to call it a night with these numbers. Too tired to figure out which way to adjust and close that gap.

All readings with valve lash set to 0.004" and lift at 0.036"

Intake:

Open                22 BTDC
Close               50 ABDC
Lobe Center         104=(50-22+180)/2
Duration            257=50+22+180

Exhaust:

Open                50 BBDC
Close               19 ATDC
Lobe Center         105.5 (50-19+180)/2
Duration            249=50+19+180

[Davez134]

What cam is it again? Yeah, that is pretty damn close!

[edwardmorris]

What cam is it again? Yeah, that is pretty damn close!

Its a megacycle 125-65. I fixed my posts above, the lash is 0.004", the lift at which opening and closing needed to be measured were 0.04", so I removed the lash from that and measured at 0.036"

[edwardmorris]

Well, FCUK!

Unless someone has a magical way to fix this without tearing bottom end open, I'm putting all this #$%* away for the winter. I need to get my head straight before I destroy something irreversibly.

[Davez134]

Oh no!! All I can think of is to try and pull it out with the engine on its side, then with the engine stabilized as level as possible try and line up the holes in the shifter forks looking down into the hole. Then, try sliding back in the right way?? Worth a shot? ( hopefully I caught what you were talking about)

[timbo750]

It looks like something broken off in the casing. I think it is the stud that holds some of the shift mechanism.

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[edwardmorris]

Oh no!! All I can think of is to try and pull it out with the engine on its side, then with the engine stabilized as level as possible try and line up the holes in the shifter forks looking down into the hole. Then, try sliding back in the right way?? Worth a shot? ( hopefully I caught what you were talking about)

After I cooled down a little bit, this is what came to mind. Will try it, in theory it should work if I know the internals correctly. I could have sworn on my life I checked everything 10 times over, how did I miss this?

[timbo750]

I think I was on the wrong track. Someone please tell me what I missed.

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[timbo750]

Is it something with the shift fork shaft, should be a recess in the end of it.

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[Terry in Australia]

Is it something with the shift fork shaft, should be a recess in the end of it.

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Bingo! And not a big problem either Rafi, with the sump pan and oil pump off you should be able to manipulate the selectors while withdrawing the shaft with a strong magnet etc, or just do like I did in 1983 when I made the same mistake, I just drilled a hole in the end of the shaft for the tang to go into. I rode that K1 for another 4 years without incident, and if the bike is still alive (I sold it in 1987) it probably hasn't been changed. Cheers, Terry.

[754]

If you are just holding the shaft in should be easy to make something..
Took a look at Hondamans book..looks like you just have to flatten out the end of the arm that holds the shaft, and loctite it.. Then replace that piece later.

[edwardmorris]

First off, sorry folk, not really proud of how I reacted, my anger was more directed at my screw up than the problem itself.

Thanks for helping me out, as many of you suggested, it was surprisingly simple to correct. I pulled out the shaft, slathered it in oil again, flipped it around, took a thin long screwdriver to line up the forks. This wasn't easy as they were floating all over due to abundance of assembly lube. I think the crisis has been averted. I installed the CS bearing retainer cap and went through all the gears a couple times to make sure everything is working. I don't hear or feel any loose parts floating in the engine, fingers crossed.

Is there ANYTHING that I should do to be absolutely certain that I'm good to proceed?

[754]

Yeah have a beer or three, saved yourself a sidecar load of rework..

[Davez134]

Very nice!

[Terry in Australia]

It's all good Rafi, like Frank said, have a beer or three, then move on.

[edwardmorris]

Thanks guys, I will run through the gears one more time today and put the covers on. I have a bit of work to do on the wheels this weekend, then hopefully get my buddies over to try and get the engine in the frame next weekend.

[edwardmorris]

Well, I think the engine is done. The finned covers on the right are just mocked up for now, they'll go on once the engine is in the frame, I just wanted to see how it looked. Front wheel is done but something is binding on the speedo drive when I torque down the axle, so gotta see what's up with that next. Some power plant highlights below, I'm sure I'm forgetting a whole bunch, I'll update as I remember.

Top to bottom specs:

• Megacycle 125-65 billet cam (yes, billet, not the hardweld 125-60, tthese are as rare as the NOS cam on my K2)
  
• Megacycle hardweld rockers
• Near NOS super low miles cam tower assemblies (from Bill Benton)
• JMR Stage 2+ head, the works with all new everything
• Tsubaki cam chain
• APE Adjustable cam chain sprocket
• Stainless roller and sprocket cam chain tensioner
• Wiseco 836 forged kit on JMR cyls
• JMR shot peened, polished and balanced connecting rods
• Kibblewhite HD studs and nuts (these are definitely superior)
• CX MLS head and viton coated steel base gaskets
• APE road race lightened and balanced crankshaft
• JMR balanced dynamo rotor
• Near NOS starter clutch gear (thanks Bill!) with NOS rollers, springs and barrels
• Hondamatic field coil (higher ouput, thanks Bill!) and new terminals on coil wires (thanks Hondaman!)
• NOS rod and crank bearings with NOS o-rings and seals everywhere
• G67HP-6 primary chains with NOS tensioner
• APE HD main bearing studs with CX HD nuts
• JMR back cut trans (2nd, 3rd and 4th gears) with all new SKFs
• NOS neutral switch with added sleeving to connecting wire
• NOS clutch with Barnett springs and Hondaman oiling mods
• Near NOS clutch lifer assembly (thanks Bill!)
• Rebuilt starter motor with NOS everything
• Rebuilt oil pump with Elan's hyper kit
• NOS oil pressure switch
• NOS o-rings and seals throughout, including the one on the cam chain tensioner cover (thanks Markb!)
• ARP bolts throughout with zinc anti-sieze
• SS screws on covers with zinc a/s
• All engine internals were cryo'd
• All engine surfaces were PC'd

[Stev-o]

Impressive!

[edwardmorris]

Thanks! I see that the Park Racer is almost back together, that red looks fantastic! Can't wait to see the fairing.

[Stev-o]

Thanks! I see that the Park Racer is almost back together, that red looks fantastic! Can't wait to see the fairing.

Thanks - it's just a mock up, I still have a short list of things to do.

[SOHC4 Cafe Racer Fan]

Black Beauty