Honda Twins banner
1 - 13 of 13 Posts

·
Registered
Joined
·
64 Posts
Discussion Starter · #1 ·
I just bought a 1973 CB350G for $300 that had been sitting for 2 years in a garage. It doesn't appear to be in that bad of shape. I thought I'd change the oil (among other things) before I tried to start her up but I can't for the life of me get the oil drain pug out. Granted I'm only using a standard 3/8" socket, but it shouldn't be this difficult. I'm using all of my force and it's not budging. I also soaked it with WD-40 and then brake cleaner to no effect.

My first thought was to go get a breaker bar, but I wanted to come here first and see if anyone has had a similar issue. The plug isn't threaded backwards is it? It may be that the previous owner put loc-tite on it due to a leak. I'm not sure.

Thanks for any help.

Rob
[attachment=0:311rv382]CIMG0275.JPG[/attachment:311rv382]
 

Attachments

·
Premium Member
Joined
·
1,612 Posts
Give it a couple good smacks with a hammer and then try the breaker bar.
 

·
Registered
Joined
·
3,926 Posts
Please read this: viewtopic.php?f=4&t=3797

Then, if you search a little, all of the info you need should be covered here already. I know I've posted it here before. Heat, a breaker bar, an impact, etc.. They all may be necessary.


GB :)
 

·
Registered
Joined
·
6,495 Posts
I'd look for a new one first - chances are you'll screw it up trying to get it off.
If all else fails, a big honkin' pipe wrench usually works.

Even Lok-Tite won't stand up to a major breaker bar with a six-point 19 mm socket or a pipe wrench.
 

·
Registered
Joined
·
275 Posts
Also,buy or borrow a 6 point socket if you don't already have one (as opposed to the most common 12 point). The 6 point puts more contact on the full flats of the nut rather than a 12 point that only touches 1/2 of the flat. Less chance of gnarling up the plug.
A breaker bar, a 6 point and a sharp "snap" (rather than a steady pull) has always worked for me if the nut is in good shape.
 

·
Premium Member
Joined
·
10,203 Posts
And when you do get it out, I have one laying around here someplace to replace whatever is left of it. :roll:
 

·
Registered
Joined
·
64 Posts
Discussion Starter · #8 ·
Thanks for all the answers. A breaker bar did the trick, and without damage to the plug. Unfortunately, what came out of the hole was probably 75% oil and 25% gas. After searching this forum I've learned that this could mean any number of things from a leaky petcock or carbs to damaged rings. I'm hoping the cause is that the petcock was left in the open position while it was sitting for 2 years. But is there any way to verify that? I'd rather not pull apart the top end if I don't have to.

I tried a cold compression test by screwing the gauge into the spark plug hole and working the kick starter vigorously a few times with the bike on the center stand. The ignition was off. I got 90psi on both pistons, which I know is really low, but it seemed strange that both pistons were at the same pressure. Is the low number due to the cold compression test or are both pistons equally screwed?

The spark plugs are black, but not oily, which (according to the chart linked to on this site) means they are carbon fouled. But what is that indicative of?

I bought a cb750 a month ago in my hometown in NC with the intent of fixing it up into a street fighter or cafe. But I won't be moving back there until the end of July so I got this little 350 to keep me busy until then. I have a feeling this is going to be a long, arduous, but rewarding trip.

Rob
 

·
Registered
Joined
·
64 Posts
Discussion Starter · #9 ·
I just did a little more research and it seems that carbon fouling is indicative of low compression. I guess it's a top-end rebuild for me.
 

·
Premium Member
Joined
·
667 Posts
Did you have the throttle wide open when you did the compression test?
 

·
Registered
Joined
·
64 Posts
Discussion Starter · #11 ·
No. I'll try it and see if it makes a difference. Because I'm learning as I go, can you please explain why having the throttle open on a non-running bike affects compression?

Also, the gas tank is not currently attached to the bike, but everything else is. I took it off to coat it with POR-15 and haven't put it back on yet.
 

·
Premium Member
Joined
·
667 Posts
If the throttle plates are closed then the cylinders cant pull in as much air to make the compression.
Don
 

·
Registered
Joined
·
64 Posts
Discussion Starter · #13 ·
Wow. Turns out I have 160psi cold compression. Thanks for that important tidbit Don! I guess the rings are fine then?

That would mean low compression didn't foul the spark plugs. Some of the other causes are running too rich and a weak ignition system. I'm already planning on doing the xs650 coil swap if I can find them. I guess I'll also replace the condenser while I'm at it since it doesn't cost much. I'll adjust the carbs once I'm ready to put gas in this thing.

On a down note, it's so windy here in NY today that the wind blew over the bike. The only thing that appears to be broken is the tail light housing. I'll have to do a more thorough inspection when it's light tomorrow. Now I'm going to be worried all night that it's going to be knocked over again. There's not much I can do about it. The wind is gusting from all sides so it doesn't matter what angle I park the bike at. Luckily, the gas tank is still in my room or it could've been a real disaster.
 
1 - 13 of 13 Posts
Top