Topic: My 73 barn find with 15k original miles!

[goldarrow]

We're following....

You need those orings?

No, Dave does.  But Thanks Mr Lestor.  You open those boxes yet?

Not yet.  Still sitting in the same spot by the front door lol

[Stev-o]

We're following....

You need those orings?

No, Dave does.  But Thanks Mr Lestor.  You open those boxes yet?

Not yet.  Still sitting in the same spot by the front door lol

In the rain??

[goldarrow]

We're following....

You need those orings?

No, Dave does.  But Thanks Mr Lestor.  You open those boxes yet?

Not yet.  Still sitting in the same spot by the front door lol

In the rain??

Half under rain

[sulphurdave]

Yea I'm gonna need 8 of them. Good thing is those o-rings I bought only cost $1.73

[sulphurdave]

is that a factory seat? I need one like it

I'm not sure what kind of seat it is but its in really good shape new padding and leather and everything but someone on here already wants it when I'm ready to sell it. I'll let you know if he backs out though.

[sulphurdave]

The tank has been rebuilt and being shipped back to me now. I have a brand new petcock waiting for its return. The carbs have been all cleaned up, rebuilt and put back together. Hopefully I have the floats adjusted correctly. Drained the Marvel mystery oil and replaced it with Honda 10w40 and a new oil filter, changed the spark plugs with genuine Honda plugs, I'll be replacing the fuel lines and fuel filters when I get the tank back. The battery has a full charge so I think I'm pretty close to firing this thing up for the first time ::praying::

[sulphurdave]

Does anyone know the size screws that hold the fuel petcock to the tank?

[calj737]

6mm

[sulphurdave]

Rebuilt tank and carburetors back on the bike.

[calj737]

Fire that dude up!

And Merry Christmas, Dave! Glad to see you're on your way to getting that bike in the road.

[sulphurdave]

Alright I've had the bike since September and have VERY slowly worked on it here and there in my spare time and today I finally got to hear it run... kinda. I rigged up a temporary fuel tank and this is what happened.

I was very shocked it fired up but here's some pointers that I noticed.

• It would not start when choked initially
• Turned the choke off and it fired up but RPMs went to 3k steady
• Once it was running, closing the choke 100% killed it. Partially closing the choke brought the idle down but once I opened it slightly RPMs jumped back up to 3k
• Made sure idle mixture screws were 1.5 turns out. Adjusting them didn't audibly do much.
• My first thought was an air leak from the intake boots since they are really hard and don't bend much at all without heat and the 2 and 3 boots didn't slide on the intake ports as far as 1 and 4 did
• I sprayed carb cleaner around the intake boots and sure enough the idle changed slightly
• Then something happened while blipping the throttle in excitement and the RPMs jumped extremely high probably around 7-8k and wouldn't go down so I freaked out and turned the key off
• If I start it up the RPMs immediately rev extremely high again to redline

It got dark and it's time to pop fireworks with the kids so that's where I left it for now.

Thoughts?

[BPellerine]

check for sticking cables or linkage?bill

[calj737]

Sounds pretty good. Your high idle may be also be due to running without the airbox installed. Without it, you're very lean. When you rebuilt the carbs, did you find stock Honda brass inside or had the PO used aftermarket? And did you get the carbs set up per the specs in the manual?

Getting close to rode worthy now 

[sulphurdave]

Yea I'm gonna hook up the air box tomorrow and tinker with it some more. It was hard to tell if it was stock Honda parts in the carbs or not. What specific specs are you referring to? Floats? Idle mixture screws? I wanna know if I missed anything. 

[calj737]

Yep, all those pesky carb settings and measurements (jet sizes, needle positions, screw turns, etc). Also, once you do set the idle perform a vacuum synch.

[sulphurdave]

I ordered the same size jets that were in there 110/40s because I'm running the stock air box and for now the same pipes that are on it which look and sound pretty restrictive. The only parts I reused in the carbs were the needle jet because it looked fine after the carb dunk cleaning and I reused the idle mixture screw/jet because it looked better made. The rest of the parts I used from the rebuild kit. So the needle position is in the same location as it was. Previous owner said it ran fine when the old man had it before him. I think the crack head that I bought the bike from didn't have the know-how or the money to get the bike running.

I think I found out why it all if a sudden started revving to redline. I just went back to look at it out of curiosity and noticed the throttle linkage jumped out of the bracket on the bottom. Whoops forgot to tighten it in all of the excitement. I'll hook up the air box and tinker with it tomorrow and report back.

Happy New Year everyone!

[calj737]

Simple mistakes=simple fixes! BTW, the rebuild kits you ordered and used, were they genuine Honda or some no-name brand? The no-name brass can be quite low quality and differ tremendously from stock. I mention this in case as you go forward and get unexpected tuning issues, you'll have a culprit readily identifiable to aide in your repair.

[sulphurdave]

I got the ones from Vintage CB750

[sulphurdave]

Alright here's a video from today. Let me know your thoughts.

[sulphurdave]

Nothing?

[BPellerine]

when your bike is at idle when warm and you have it set low,let it cool and use the choke to warm it up and see if it will idle back down,if you start it with no choke when cold you have to keep it going with the throttle or turn the idle up it seems,a carb sync wouldn't hurt.bill

[sulphurdave]

I will be doing a carb sync at some point I just wanted to see how close I could get it running correctly without doing much at all and just learn what it's doing and not doing. Basically I want to see what kind of running condition it was in before I got it. So far I have not touched the points, haven't adjusted the valves and even though I bought new spark plugs, when I pulled the ones that were already installed they looked brand new as if it hadn't ran at all since they were put in.

Currently if on a cold motor it won't crank if it's choked. Open choke and it starts up just fine and idles low where it should. After it warms up is where it's inconsistent. Sometimes when I rev it it'll idle down slowly. Other times it'll hang up around 3k and if I wait long enough it'll idle back down. That's of today which has only been the 4th time I've cranked it and went through the warming up cycle. Still learning what it's doing.

[sulphurdave]

From earlier today..

[ozpacman]

She's sounding pretty good to me Dave - well done!

Russ.

[calj737]

Sounds better! It's now time to perform the 3,000 mile service on it per the manual. It sounds desperate for a vacuum synch, perhaps even a bit of cam chain rattle? I understand you wanted to get it running to have a baseline (succeeded) but now before you continue, service it fully and properly.

It's got just a bit of "bubble" in the idle and that should smooth straight out with valve adjustments, cam chain, and vacuum synch. Then your bike will idle like a well-used Singer stitching away. You'll be astonished at how smoothly it will run once dialed in.

It's also the best method to truly get fully aquainted with your bike and its condition (3k service).