Topic: Issue causing bike to shut down after running for a period of 15-20 minutes

[04 Mrauder]

Present Situation - bike starts and runs with choke set, warms and idles roughly when choke is released. After warm bike runs at low RPM (up to about 4000) and begins ignition failure above that point. Once engine gets hot ignition fails completely and shuts down until it cools then it will start up and repeat.

I noticed a previous owner rewired the fuse block  which now has a 30A fuse and become very hot when running (I'm looking for a new fuse block to correct issue).

when the bike shuts down it will restart in a mater of 10 min + or-. I believe a relay or something is being tripped due to electrical overheating, possibly the solenoid mounted directly behind the fuse block with the green coil attached to it.

Any help is appreciated

[Bob Wessner]

What bike (model, year, etc.) and what's the maint. history?

[TwoTired]

Are you certain that you are operating the choke properly, regarding the on/ off position.  (Model dependent.)
Are your spark plugs fouling?

[GammaFlat]

If you're running points, it may old capacitor(s) that, once heated, will give you trouble.  They do have a shelf life. 

[Bowswell]

Open your gas cap and try...

[04 Mrauder]

The bike is a 1976 CB550.

I cleaned and gapped the plugs prior to starting the bike at all.

Hadn't considered the capacitors on the points, but was planning on checking the points next and gapping them.

I can get the up to about 4000 rpm in gear under load, but any more throttle and it begins to have ignition breakdown.

I'll check the points and condensers this weekend and go from there.

[Kframe]

What are the symptoms that you call ignition breakdown?

Is it stumbling, missing, or just losing power? 

As TT mentioned, make certain you're operating the choke correctly, many many people (myself included) had it confused when first riding the CB550. 
If the lever is up (turned counter clockwise so the tab is horizontal), choke is ON, a.k.a. in starting position.

Once warmed up, turn the lever down/clockwise, then the choke is OFF, a.k.a. in running position.

-K

[04 Mrauder]

Yeah I'm aware that the choke is on when the lever is in the Horizontal position.

The bike just looses power and shuts down. I'm thinking it may well be a capacitor issue because it will start right back up after only a minute or so.

[Spanner 1]

Ignition failure does not 'come back to normal' IMO.... it's low/slow fuel delivery and/or vacuum in the tank.
+1 on riding with gas cap open....... need to check fuel flow.

[Retro Rocket]

Ignition failure does not 'come back to normal' IMO.... it's low/slow fuel delivery and/or vacuum in the tank.
+1 on riding with gas cap open....... need to check fuel flow.

+1...someone else is having the very same problem on here at the moment, coils can act in a similar fashion when failing as well..

Mick

[Spanner 1]

The 30A fuse heating up is not good..... main fuse is a 15A, never use any fuse rated above this........
If the fuse is heating-up the resistance of the fuse clips will cause a drop in voltage which would produce all the described symtoms..... shine the fuse clips, carefully squeeze 'em together ( must have a firm grip on the fuse )put a 15A fuse in and try again.... OR it's the fuel issue above... good luck 

[04 Mrauder]

Ok, present Status:
-Plugs clean and gapped at .024

-Points are clean and not pitted, Gapped at .014

-Bike runs smooth with choke set at high idle of 3000rpms (adjustable).

-Bike idles at about 1400rpms with choke set 1/2 way and throttles up to  about 5700-6000 rpms then bogs down as if starving for fuel. I removed the fuel cap and ran the bike with no change in performance.

- I have added 1.0 oz of Gumout fuel system cleaner to 3,o gals of fuel and it has helped the bikes performance to achieve the present condition.

I'm thinking the inline fuel filters need to be replaced and the carbs may need some attention.

[flybox1]

clean and inspect your carbs, jets, emulsion tubes, and set your floats.
add 4oz SEAFOAM to a tank of gas.

what other 3000mi maintenance items have you done before this point?

[04 Mrauder]

Nothing, I'm working on it for a friend who had it sitting in a barn for the last 3+years because it was shutting down when it got hot.

the only things I've done is:
-Dump the old fuel from the tank and carbs and replaced it with new fuel and the Gumout.
-Replaced the 30A main fuse with a 20A fuse, after I noticed that someone had rewired the fuse block down to 3 fuses and bypassed the kill switch.
-Replaced the Battery.
-Cleaned the contacts on the solenoid, capacitor and battery cables.

I just took it for a short ride and the engine performance seems to be improving with time and running.

[flybox1]

i bet it will be even better after carbs have been thoroughly cleaned and your valve clearances are set. seafoam = elixer of the bike gods 
sort out the wiring so you can get a 15a in there.

[Kevin D]

Gumout.

I tried gumout once and only once my plugs were fouled so bad afterward that they would not come clean. I replaced the plugs and all was well.

[04 Mrauder]

Gumout.

I tried gumout once and only once my plugs were fouled so bad afterward that they would not come clean. I replaced the plugs and all was well.

Yeah Thanks, I certainly haven't noticed a complication of problems from the Gumout and it sounds like the Gumout removed a considerable amount of debris from your fuel system if it totally fouled your plugs.

[Flying J]

You may have a main jet or some of the emulsion tubes blocked in the carb. This would mess up the top range of the throttle for sure. Pull the carbs and take bowls off. Clean all the jets and i bet it will run fine.