79 CB650 Popping Main 30A Fuse

If it's broken or just needs tweaked

Moderators: Volker_P, tidd650

RideOrDie
Posts: 7
Joined: Fri Sep 04, 2015 7:23 am

79 CB650 Popping Main 30A Fuse

Postby RideOrDie » Fri Sep 04, 2015 7:33 am

Good morning all!

I just stumbled across this forum and I am so glad (but also saddened by the amount of issues with the bikes) to see such a support group and mechanical geniuses dealing with the same problems!

I have a 79 CB650. Engine runs great, console is kinda screwed up... doesn't record mileage also, but I don't really mind the pretty stuff. Just want the bike to run.

Bought bike with stater turned around. Bike would run fine off battery, weird power issues due to not charging and low battery... After a new battery, realized stater was turned around. Purchased new stator and installed. After install, starting bike would pop main fuse. Knowing nothing about electrics, I gave up and let the bike sit through the winter in the basement. Just had the bike in the shop (for 7 weeks..) and they said it was the starter, did a rebuild, put in a starter relay, new fuse, fixed some chewed wiring. Starter cranks loud, and after I fixed the fuel line, and tank, engine roars to life. Unfortunately, (and also my disappointment with the shop) the fuse blew 5 seconds into the engine coming to life. I will not be taking it back, since apparently they have no idea what they are doing (they tried to start it and said it won't start. But they didn't even check for obvious issues... fuel tank was empty and battery was dead... outstanding) Which leads me to ask... did I even need a new starter???

I am tempted to just throw on a brass connector like I read in a few other posts, because the ride season in Maine is coming to an end and I'd like to hit the road.

Any thoughts? Suggestions? Thanks all. Can provide pictures later.

Chuck

jdsun6780
Posts: 8
Joined: Fri Apr 03, 2015 4:49 am

Re: 79 CB650 Popping Main 30A Fuse

Postby jdsun6780 » Fri Sep 04, 2015 7:51 am

Sounds like a short somewhere. Are you doing anything while the bike is running that may cause a short ie. Switching on turn signals, brake light, etc. I pinched a turn signal wire that cause the main fuse to blow on my other bike. Took 3 fuses for me to make that mental connection.

RideOrDie
Posts: 7
Joined: Fri Sep 04, 2015 7:23 am

Re: 79 CB650 Popping Main 30A Fuse

Postby RideOrDie » Fri Sep 04, 2015 7:58 am

Bike won't run long enough for me to even try to flip any switches. A short in the signals could pop the fuse?? Yikes. What's the way to figure that out... pull all the wiring for the console and lights and plug in one at a time till it pops?

jdsun6780
Posts: 8
Joined: Fri Apr 03, 2015 4:49 am

Re: 79 CB650 Popping Main 30A Fuse

Postby jdsun6780 » Fri Sep 04, 2015 8:02 am

In my case it went when I turned the left signal on since it was the left wire. It grounded out on the frame and pop. I'm not as familiar with the common electrical gremlins on this model as I am on my other bike but checking exposed wires and the rats nest of wiring stuffed in the headlight bucket may be a good place to start to see if any of the insulation is worn through and grounding out.

RideOrDie
Posts: 7
Joined: Fri Sep 04, 2015 7:23 am

Re: 79 CB650 Popping Main 30A Fuse

Postby RideOrDie » Fri Sep 04, 2015 8:18 am

I'll give that a look over this weekend. The oil light and the speedometer work, but nothing else works on the console. Head light works... some signals don't work. This could be the issue? I'm kind of wishing I hadn't taken it to the shop, since they apparently didn't even look into this.

User avatar
tario
Posts: 166
Joined: Sat Mar 07, 2015 2:26 pm

Re: 79 CB650 Popping Main 30A Fuse

Postby tario » Fri Sep 04, 2015 3:54 pm

You will have to start from the positive side of the battery checking resistance to ground on different wires. Anything that reads about 3 ohms or less is likely your short.
1979 cb650
1980 cb650

RideOrDie
Posts: 7
Joined: Fri Sep 04, 2015 7:23 am

Re: 79 CB650 Popping Main 30A Fuse

Postby RideOrDie » Tue Sep 08, 2015 5:42 am

Tore the thing open. Discovered the stator was put in wrong, and shorting my wiring. Traced all the wires, taped them up AGAIN... looks a lot better now, harness is all in one piece.

After getting another 79 bike for parts, threw the stator cover on with the brush mount and the bike revved right up.

Now the issue is without the choke mid-on the bike stalls out. We adjusted the idle speed, but can't release the throttle or choke, which means not drive-able! Would the next step be carbs?

User avatar
tario
Posts: 166
Joined: Sat Mar 07, 2015 2:26 pm

Re: 79 CB650 Popping Main 30A Fuse

Postby tario » Tue Sep 08, 2015 10:20 pm

Sounds like you need to clean out all the varnished gas on your jets. If you have some sync gauges and feeler gauges you could set the valves then sync the carbs to make sure that isn't your problem.


From your description it sounds like adjusting the idle screw doesn't help?
1979 cb650
1980 cb650

RideOrDie
Posts: 7
Joined: Fri Sep 04, 2015 7:23 am

Re: 79 CB650 Popping Main 30A Fuse

Postby RideOrDie » Wed Sep 09, 2015 6:10 am

Last night I pulled the carbs off, and they were all just full of crystal sludge. Blew everything out, carb cleaner, whole 9. Gaskets that came off the heads were hell to put back on, but managed.

Now that the bike has free flowing fuel.....

Yes, I adjusted the idle screw but it hasn't changed anything. The bike has a more solid idle now, and will run with choke on for a few minutes before shutting off. Replaced two spark lines which seemed to help a lot also. Now it will idle from 2-3k rpm without fluctuating much and sounds nice. But choke cannot come off, or it dies.

I feel like it's so close, but so far. What other components are there that could be causing the issue?

I will have to get a picture up later, but I don't know if my fuel line is helping anything... it is a bit too long and sticks out the side, so the fuel isn't flowing straight down into the carbs it's flowing kinda down, then back up a little bit.

User avatar
tario
Posts: 166
Joined: Sat Mar 07, 2015 2:26 pm

Re: 79 CB650 Popping Main 30A Fuse

Postby tario » Wed Sep 09, 2015 5:19 pm

Do the valves if you have some feeler gauges.>

http://www.motopsyco.com/2013/10/25/how ... b650-sohc/

If your spark plug wires are old replace the last two. Maybe pull off the coils to clean the connections and make sure they have a fairly clean contact with the bike. New spark plugs that are properly gaped would help.

I assume the tank is clean enough that you didn't just suck a bunch of crap back into your carbs? The Jets were pulled and cleaned? Slow jets as well? They play a large role in fuel supply during idle.
New dyna coils (stickied in this subsection) would be better than the stock ones if you want to get into spending money. Also spark units can be replaced to help get a better spark. I would leave these things till the end though.
1979 cb650
1980 cb650


Return to “Technical Discussion”

Who is online

Users browsing this forum: No registered users and 47 guests