Topic: Late CB750 K0 Mold to Gold, the nugget.

[Kook652]

This is great thread for the newby. Thank you to all.

[Don R]

 I'm glad you enjoyed it, Kook.
 I got in a Christmas eve ride on the nugget today. I do not like the sound of the 341's repro pipes with the baffles in. They make a rattly, almost tapping sound like something is tapping or clicking at every exhaust pulse. With the baffles out they have a good note and no annoying noise.
  I'm tempted to remove the smallest of the 3 concentric rings on the tips. My brother said that's what he used to do with them. These pipes belong on his k4 but I can only do so many at a time.

[Don R]

 It appears the 60*F weather made a little condensation. I promptly took it back out and cooked them dry. You can see the Eastwood coating inside. You can see the 5 position sandcast Z1 parts shock adjusters.

[Don R]

  The nugget was voted Feb. bike of the month. Thank you.
  This bike attracted the attention of the guy that wanted me to own his two sohc750 based drag bikes. I made a new friend and got two unexpected projects. He owned a gold one in 72 and a red light runner cost him the bike and two weeks in the hospital. That didn't deter him from buying more and racing them for years.
  He now races a Hayabusa and street rides a Harley.

[BenelliSEI]

Congrats Don. Well deserved! John D.

[PeWe]

Congrats again! That bike look as a winner.
It should be nice to have a golden costume for one of my bikes
/Per

[Terry in Australia]

Well done Don!

[seanbarney41]

congrats Don!

[Don R]

 And thanks to Mark B who sold me the painted tins. They made the bike totally.

[SOHC4 Cafe Racer Fan]

Gorgeous bike, Don!  Well-deserved W.

[atm cycles]

Vermont is awesome. I’ve gone that route half a dozen times myself. On a Sandcast I paid the higher NADA amount for taxes and they sent me a check back also. Vt. Uses NADA “good”
For taxes.

[Don R]

 I did the exact same thing Tim. The lady could not have been nicer, good news they were refunding the difference, bad news due to covid at the time it would take a couple weeks. I took that as good/good.

[Don R]

 I took the nugget out for a ride, it idles fast when warm. The timing looks ok but the #3 carb screw was turned in further. I'll need to remove the airbox and do a bench synch or bite the bullet and get the carbtune while they are cheaper. About $110 from the Czech republic. 
 
  Cyl #4 has a miss that I can feel at the pipe, it goes away when I pull off the 341 exhaust's baffle. It has valve lash hot, I wondered if it has a sticky valve so I gave it a dose of seafoam.
  It sounds like a pilot jet still partially plugged so I'll go there next and I'll swap out the plug. I believe the plug caps are all new and the wires looked good.
  Today is the most I've ridden it since I got it years ago.

[Don R]

 I checked the compression on 1 and 4, then swapped the plugs, both pump up to 100psi on a long snap on gauge, cleaned the #4 pilot jet, adjusted the pilot screws to 3/4 out, checked the #4 float, the level seemed a bit low, fuel stopped flowing with the float down and when I opened the gas cap it began again. I rebuilt that cap in the house last winter. Hmmm. Air bubble in the right fuel hose? It flows downhill as much as possible, no additional filters.
  It's not popping or pulsing out of the 4 pipe now, but the annoying exhaust rattle is full time now lol. I may just remove the 341 baffles, that seems to cure the noise.
  I wonder if the gas cap vent is making it run lean since the idle is always high after a ride?  I'll pop the guts out of it and swap them or fix it. 

[PeWe]

I had one CB750 tank with blocked fuel cap air vent. It suddenly died within 15 minutes ride.

Like no fuel at all. How much fuel vs air in tank might affect time.

[Don R]

   That sounds right to me, the tank is pretty full of storage fuel.  It's a surprise because it's either a cap I made from parts or bought new.
   I honestly have only put a few miles on this one. My goal was to have all three colors of K0. Now that I do, it's a goal with no end purpose. I showed them once last year and met the guy I bought the drag bikes from.
  The tank was cleaned, painted and Caswell lined by Vic Worlds painter so it's clean inside. It's a gold wrinkle tank, if it was gold when new it would be one of a rare few. There is argument whether any existed in the wild, that's possibly why it came up for sale.
 
 

[PeWe]

My tank had new paint. Old restored tank. Except the rusty fuel cap. It got a new.

Use Honda gasket another thing. I tried an afternarket that I noticed was wider and covered the vent hole. Honda gasket has to be mounted correct, one side is wider if I remember correctly.

[Don R]

 The gasket is aftermarket, I think. Even removed from the cap, I could not get it to vent with the gasket on.  I swapped to another inside assembly with the same gasket. It vents ok now. I may have fixed it by accident or with inferior parts, not sure. 
  The muffler clatter is on the right side, top or bottom but now sounds like bottom. I siliconed in those two baffles hoping one of them is rattling inside where it goes through the loop. It's riding good now and is pretty clean for a tent garage find.
  I wondered if there was a tube insert in the balance tube like Yamiya includes, thinking maybe I made a set. There was not one in there. These pipes are lined with Eastwood inside the pipe exhaust coating, the fourth set I've done.
  One baffle does protrude over the balance tube covering it 2/3 of the way much like whistling in a bottle, if nothing else helps I may notch one side or the other.

[Don R]

 I went 16 miles or so, on the highway and blacktops. I'm guessing distance since the speedometer cable is broken. Hopefully the speedometer isn't stuck.  I had overfilled the oil and it spilled out lubing the right side. Off idle needs some more tuning but it runs out great.
 It's nothing like a ported and cammed 836 but still fun.
 These cheapo small and magnifying acorn style mirrors suck, and the left control has no locating stud. All are things I can fix easily. 

[seanbarney41]

I went 16 miles or so, on the highway and blacktops. I'm guessing distance since the speedometer cable is broken. Hopefully the speedometer isn't stuck.  I had overfilled the oil and it spilled out lubing the right side. Off idle needs some more tuning but it runs out great.
 It's nothing like a ported and cammed 836 but still fun.
 These cheapo small and magnifying acorn style mirrors suck, and the left control has no locating stud. All are things I can fix easily. 

This is why vintage motorcycles need to be used...

[Don R]

 True, I intended to buff and fluff and flip it but daaaang it's so pretty. I never did give it a real shakedown or test and tune because other shiny things got my attention.

 The things you own end up owning you and I am owned by too many things.

[Don R]

 I made up a decent left mirror from old parts and got the left control tighter. It does have a locating pin but the hole in the handlebar is oversized. I despise magnifying mirrors, prefer a wide view. 

[Don R]

 I got the speedometer fixed, it was the cable, of course the screw stripped I used a left hand bit with the extractor built onto it. Spun it out just before drilling the head off.
 I lubed up a used cable and found a screw so no out of pocket on this one. I did wash the rear tire where the oil overflowed. It needs a good detailing now. I made it to the car wash and back without blowing another fuse. I'll work on the fuse holder bypass next.

[Don R]

 I'm convinced the exhaust clack sound in number 4 is the exhaust pulse from the pipe passing over the too tall balance tube. Since I siliconed the baffles in the right side the noise is worse and more constant.
   I plan to pull the baffles (hopefully) and look again to see any difference between the left and right sides. I've heard of a baffle rattle in the cmsnl exhausts, this may be an example of that sound.

 Edit; I'm now not convinced of anything. lol.

[Don R]

https://photos.app.goo.gl/a5RTP8CfZVionQAi9