Author Topic: Senior project for high school - 78 CB750K (Read 172809 times)

Restoration Fan · « **Reply #1200 on:** May 24, 2015, 02:51:20 PM »

So, today I had the distinct pleasure of helping Mark (mark52) and his brother Barry to put the engine into Mark's 75 CB750K. You talk about perfection...this guy has literally everything on the bike in a showroom, mint condition. Mark, this bike REALLY deserves its own build thread...it is literally gorgeous.

Jerry Rxman Griffin aka MuthaF'er · « **Reply #1201 on:** May 24, 2015, 11:26:28 PM »

The polishing is fantastic. Lot of work but worth it.

mark52 · « **Reply #1202 on:** May 26, 2015, 09:40:09 AM »

Thanks Ron, and a really big thank you for your help this weekend. I thought about starting a build thread but feared I would win the award for the longest running thread without getting a bike done!! But with yours and Bill's help, plus many others here on the forum, I just may hear this thing run for the first time in over two years.
Hope your team did good yesterday.

Restoration Fan · « **Reply #1203 on:** May 28, 2015, 06:08:05 PM »

Stella is about to get a heart (edited: Stev-o says lung

) transplant. Unfortunately, the camera on my old iPhone doesn't do these beauties justice. The chrome on them absolutely sparkles!

I kept seeing these at Bill's ever since he painted them the same color as Stella's engine and I think he noticed how I eyed them enviously because he offered to sell them to me. Well, I finally decided I couldn't pass them up so I'm going to put these earlier model round tops on my 78K bike. For anyone else considering doing this, you'll need different A & B throttle cables (possibly not one of them but the longer one (A?) doesn't go around to the far side like it does on the 77's and 78's. Also, the carb boots that match up to the 78K carbs seems to have a larger front end (the side that connects to the carbs) because when I checked my existing carb boots with these carbs, the fit was much too loose. Of course, I got a set from Bill just in case so I'll be installing all of this in the morning. Hopefully it won't be raining tomorrow and I can get out on Stella for a little more wind therapy!

Stev-o · « **Reply #1204 on:** May 28, 2015, 06:11:11 PM »

New heart? Looks like a healthy set of lungs to me!

Also was wondering if you've been riding her much?

Restoration Fan · « **Reply #1205 on:** May 28, 2015, 06:14:40 PM »

Stev-o,
I rode her a few times but we realized that the spring we had taken off of her was the actual correct throttle return spring. So I took the carbs off last week and put the throttle return spring on it. Well, once I put the rack back together, my needles were off so I spent the better part of this week taking them off, adjusting and putting them back on. I finally got them pretty close to correct again but it's been raining so hard and often this week that I haven't had the opportunity to ride.

Well, Bill got back today from his father's funeral and texted me that he was home....and that was all it took. I headed over to his house and bought these.

RobertCB500F · « **Reply #1206 on:** May 28, 2015, 06:19:40 PM »

About as pretty as mine from Harrisluv, (shameless plug) Actually I've been following your build since the beginning and it's beautiful. Thanks for putting it up here.

SOHC4 Cafe Racer Fan · « **Reply #1207 on:** May 28, 2015, 07:27:15 PM »

Very comparable to James' (harisuluv) carburetors. Very very nice.

AintNoEasyWay · « **Reply #1208 on:** May 29, 2015, 05:27:01 AM »

You'll be scootin' in high fashion, Ron.

evanphi · « **Reply #1209 on:** May 29, 2015, 06:14:48 AM »

WOW shiny!

Restoration Fan · « **Reply #1210 on:** June 02, 2015, 03:32:47 PM »

Are the petcocks different on earlier model 750's than on the 78's?
I had to buy a new one for this bike and I purchased it early on in the build from eBay. Now that I finally had time to get to work on the carbs, I fired it up for the first time with the new carbs on it and, boy, does she ever run so much better with properly tuned carbs! HOWEVER, when I put the gas tank on and connected the hose to the petcock, I can see steady drops coming from the bottom of the petcock...not from the connection to the hose...but from the bottom of the petcock.

I'm going to try turning the tank upside down and removing the petcock, just to make sure the o-ring hasn't gotten smashed or something. But if that doesn't work, I'm wondering if I need to try and find a better 77/78 petcock? Or can I try getting an earlier model petcock from Bill and seeing if that will work on mine?

madmtnmotors · « **Reply #1211 on:** June 02, 2015, 04:24:56 PM »

The 77 is unique and the 78 is unique, but they are interchangeable. The 77 discharges to the rear, and the 78 discharges to the center of bike but they have the same connection. The only ones that seem to be available are the 77 (rear discharge) but they will work on the 78, just need a little longer fuel line, or rotate the fuel valve slightly.

Restoration Fan · « **Reply #1212 on:** June 02, 2015, 04:46:51 PM »

Quote from: madmtnmotors on June 02, 2015, 04:24:56 PM

The 77 is unique and the 78 is unique, but they are interchangeable. The 77 discharges to the rear, and the 78 discharges to the center of bike but they have the same connection. The only ones that seem to be available are the 77 (rear discharge) but they will work on the 78, just need a little longer fuel line, or rotate the fuel valve slightly.

Thanks, Wilbur. I apparently have a 77 but it appears to be made by the POS company.

madmtnmotors · « **Reply #1213 on:** June 02, 2015, 07:28:54 PM »

I used one of the aftermarket fuel valves that mounted a little different than stock. The stock valve uses a "captured" nut with an internal (blind) circlip that holds the nut in place. Tighten the nut and the valve tightens up to the tank. The aftermarket one that I had was manufactured by threading the body of the valve to accept the nut. Tighten the nut and it threads onto the tank as it's threading off of the valve! For that type of valve you would have to hold the valve up to the tank, thread the nut part way on to the tank, and then hold the nut while you turn the valve to tighten! Definitely a P.O.S., but I was able to get mine to work without leaking, once I figured out W.T.F. was happening.

Stoli · « **Reply #1214 on:** June 16, 2015, 09:37:38 AM »

My POS '77 petcock didn't do that until year #2. I just tightened up the rivets with a vice and that fixed it.

madmtnmotors · « **Reply #1215 on:** June 16, 2015, 09:47:23 AM »

Quote from: Stoli on June 16, 2015, 09:37:38 AM

My POS '77 petcock didn't do that until year #2. I just tightened up the rivets with a vise and that fixed it.

Yeah, that's a different seal. The seal you describe is the internal seal, which from what Ron describes is a new part. I was just describing my experience with an aftermarket valve and how it attached a little differently to the tank. The stock valves on the later model (77/78 K/F, and maybe "A") can be rebuilt, but probably only once:

Contrary to popular belief, the later model fuel valves can be rebuilt:

Can anyone tell which one is the new seal?

Leave as much of the nubs as possible:

Voila'! (as opposed to "viola'" which everyone knows is a musical instrument)

Good for another 40 years! Good thing too, since this can only probably be done once, which is okay... because 40 years from now I won't care!

Stoli · « **Reply #1216 on:** June 16, 2015, 09:57:16 AM »

On another one, I drilled holes where the rivet was and sealed it back up with some small screws and nuts. Very Rube G but it still works and doesn't leak..

Restoration Fan · « **Reply #1217 on:** June 16, 2015, 12:24:09 PM »

You guys are much smarter and more handy than I am apparently. I went the "buy an original 78 model petcock that's still functioning properly from Bill Benton and replace the POS Chinese made one" route.

madmtnmotors · « **Reply #1218 on:** June 16, 2015, 12:26:14 PM »

That works too!

dave the welder · « **Reply #1219 on:** June 16, 2015, 05:27:26 PM »

+1 for STOLI did the drill and tap route on my 77 matic.works great

Restoration Fan · « **Reply #1220 on:** August 12, 2015, 04:47:16 AM »

Sorry for reviving this thread but I thought it was an appropriate place to say a HUGE 'Thank you' to every one of you guys who were so adamant that I should take the Motorcycle Safety Foundation course.

I completed the course on Monday and Tuesday and had an absolute blast doing it! Our rider coaches were great people and even though the heat was oppressive on Monday afternoon, the entire class wanted to stay out and keep riding when it was time to come in.

There's no doubt that the course not only made me it possible for me to get my license and be a safer rider, it also taught me some bike handling skills at lower speeds that I had never practiced and am glad to have.

Anyway, thank you to everyone who constantly encourages other members of this board to take the class. Please keep doing so because it may save a life and will definitely make them a safer/better rider.

AintNoEasyWay · « **Reply #1221 on:** August 12, 2015, 05:44:33 AM »

Awesome, Ron! Glad to see you survived the weather.

In addition to the course, here's an excellent video:

evanphi · « **Reply #1222 on:** August 12, 2015, 05:56:24 AM »

Another useful one... Ignore the terrible acting!

callmejarob · « **Reply #1223 on:** August 12, 2015, 11:14:45 AM »

Awesome glad to see you're out there enjoying the bikes!

SOHC4 Cafe Racer Fan · « **Reply #1224 on:** August 12, 2015, 12:43:59 PM »

Quote from: evanphi on August 12, 2015, 05:56:24 AM

Another useful one... Ignore the terrible acting!

Yes, terribly acted, but the Keith Code stuff isn't bad. It's a little preachy, but still valuable.

News:

Author Topic: Senior project for high school - 78 CB750K (Read 172809 times)