Topic: Electrical problem or fuel?

[B.O.X.N.I.F.E.]

Little background, bike was bogging down and dying at low speed unless I had it choked. Took it in and paid 75$ for them to 'run a ton of carb cleaner through it'. Not super stoked, but it came back running better. I really wanted a tuneup but didn't get the impression they wanted to do it. I was hoping to get it running well as a jump off point and then learn to work on it by doing regular maitenence.

So I put about 25 miles on the bike this evening running around town at about 45mph, frequent stops. No problems.

Get out on the highway, run for about two minutes at 65. She starts losing power, more throttle makes it worse. I slow down, shifting as I go, and it keeps bogging and losing power. When I pull the clutch it just about dies each time. Get to second gear at the end of the off ramp, pull the clutch and it dies. I pull over, kill the lights and try to start. Battery is weak and dies within about ten seconds of trying to start it.

Cabbie gives me a jump, she starts and makes it about two miles and does the same thing. I let it sit about 10 minutes, call the same cabbie and jump it. Runs Ok at highway speed for 6 miles, with little variation in speed and no shifting. I get it home and run it around the neighborhood at about 30mph, no problems.

School the newb!


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[bryanj]

WHAT BIKE

[TwoTired]

Battery exhausted.  Charging system kaput?  Does it run longer without the headlight on?

Measure the battery voltage.

Tells us.

[fuzzybutt]

it's likely that your charging system isnt doing it's job whether theres a problem in it or youre running too much off of it  (halogen lamp, heated grips) and as the battery loses it's charge theres less and less power for your ignition, that would cause a severe loss of power especially at higher rpms. when youre doing your checks also try and do a load test on the battery and make sure it doesnt have a bad cell. oh yeah, when asking technical questions it's always best to tell us the year, and model of the motorcycle youre working on.

[B.O.X.N.I.F.E.]

Sorry, 1974 CB550.

Electronic Dyna III ignition, new battery, regular bulbs.

I ran it with no lights the second time, no difference. Didn't do it at low speed, just at and right after highway speed.

I'm not sure how to test the charging system, especially because there's no problem at idle or low speed.

[TwoTired]

Does it run better with the gas cap off?  Maybe the vent is plugged?

Place the digital voltmeter leads on each battery terminal and record the reading.

[B.O.X.N.I.F.E.]

When the bike was dying the first time I did a thread search and read about the plugged vent and checked.

Should I test the battery as-is after sitting and only having been run a short time after it was jumped, or should I trickle charge it tonight and test tomorrow?

[TwoTired]

It is standard practice to test the battery after it is fully charged.  It is best to load test it then.  If you don't have a load tester, then test the open circuit voltage after a 2 hour rest period.
  You also check a charging system with a good, fully charged battery.

But, there is information to be gained (problem verification), by measuring the battery before doing anything else.

Cheers,

[B.O.X.N.I.F.E.]

Not sure how I need to load test it? Can I do that with a voltmeter?

Probably know less about electrical things than anything else.

[Duke McDukiedook]

Hook up voltmeter to battery terminals and record voltages at different RPM settings (1000, 2000, 3000, 4000) as it says in the manual. The voltage should be a certain value at different RPM readings. Make sure you have a separate tachometer to measure your engine speed, the tach on your bike is not accurate.

[KingCustomCycles.com]

Quick and dirty, start the bike and rev it up with a VOM on the battery. 13-14 volts is good.  12 or lower and you have a charging issue.  Your battery is going dead and taking your ignition system with it.  That is either a bad battery or a bad charging system component or wiring. 

[bistromath]

hey, second TT's suggestion on the gas cap vent. it'll bite you on the highway but rarely in town. to check, just open the gas cap and let it rest on top of the tank. take it out for a spin. see if it improves things.

[Spanner 1]

0 charging from charging system, I think, it's a battery powered ( only ) bike at the moment...T.T. is the 550 guru, I hope it's not the dreaded no charge/ carb. jets combo !!

[B.O.X.N.I.F.E.]

Sounds good, i had a list of things and not a ton of money, so the voltmeter is plan B right now. But, I replaced a really nasty battery cable that had tons of broken strands and green stuff (positive cable). I changed the oil and filter with a K&N and yamalube 10/40. Removed the tank and a handful of rust shards came out into my hand. tons of it. Tank is getting The Works toilet bowl cleaner right now. Bought some Lucas top end treatment for the next tank of gas. When I removed the tank the petcock only worked on reserve, so there's something in there.

I can't find the post, but what was the procedure for cleaning out the float bowls, something like 1 part carb cleaner to 3 parts gasoline into the fuel line with a syringe/turkey baster. something like that...

I'm praying it's not electrical, and if it was the cable was the culprit. After all this if she still dies at high speed I'll spring for the voltmeter, which I probably need anyways.

[TwoTired]

You can't afford this?

http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=90899

[Duke McDukiedook]

Yep, voltmeter and a circuit tester would take care of you electrically. Make sure your tank and petcock are spic and span clean before you hook them back up to your carbs.
If you can see rust in the tank moving around odds are it is in your carbs too. Eventually when you get the green, you'll have to clean the carbs, jets and buy new gaskets for it.

[B.O.X.N.I.F.E.]

You can't afford this?

http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=90899

Thats funny, I called a friend who has an electronics background and he said 'whatever you do, don't get one from harbor freight'. Like a cheapskate, I was hoping to hold out until I saw him this weekend and could borrow one.

also, and I should have taken a picture, the petcock had about 1/4 inch of packed in rust particles. I actually have no idea how fuel was even getting through it.

[B.O.X.N.I.F.E.]

Oh yeah, what about the carb clean. I should have saved that post, it was some mixture of carb cleaner and gas into the line with some turkey baster contraption.

[Spanner 1]

Bro., don't listen to anyone except go ( immediately ) to CARB. F.A.Q.'s..it's all there for you !!

[Duke McDukiedook]

For 5 bucks can you really go wrong? Are you going to perform precise lab work?
If not, then buy away. You can spend quite a bit more at sears for one that says Craftsman but I'll guarantee you they are probably both made in Taiwan or China.

[TwoTired]

You can't afford this?

http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=90899

Thats funny, I called a friend who has an electronics background and he said 'whatever you do, don't get one from harbor freight'. Like a cheapskate, I was hoping to hold out until I saw him this weekend and could borrow one.

I was in the electronics industry for 30 years.  Technician to Sr. engineer designing high speed communication circuits.  I ran and bought equipment in the design lab for more than a few years.  Yes, there are better and more expensive DMMs available to buy.  For design lab work, I'd want a better instrument than that Harbor freight unit, yes.
 About 15 years ago I bought an entire tool kit (suitcase style) from them and the little dinky multimeter was included.  I think they were $10 back then if bought individually.  I still have that unit and, in fact, I used it today. It's fine for general purpose work, and certainly more than adequate for getting all the information you need about 30 year old charging and electrical systems.

IMO

Cheers,

[B.O.X.N.I.F.E.]

You should go to work for HF, you convinced me. I'll swing by and pick one up tomorrow on my way to get the tank cleaned at a radiator shop. Two bottles of The Works and the bare metal looks awesome, but there's giant spots of a bad Kreem job that didn't budge. I pulled the float bowls, and couldn't believe it, pristine. Ran carb cleaner through the lines, drained, got a lot of Kreem particles, repeated, nice and clear. I don't think I'll be tank lining.

I also pulled out the petcock and disassembled it. Let soak and blew through with compressed air. After reassembly stop and run work as they should, but with the lever in the reserve position I cant blow any air through the tube. Is that normal?

[TwoTired]

I also pulled out the petcock and disassembled it. Let soak and blew through with compressed air. After reassembly stop and run work as they should, but with the lever in the reserve position I cant blow any air through the tube. Is that normal?

No.  The reserve setting is fed from the bottom of the tank (where all that rust scale was).  I'd guess you have some more cleaning to do.

Cheers,

[Duke McDukiedook]

You'll still want to pull your jets also to check for crap.

[B.O.X.N.I.F.E.]

Ok, went to harbor freight and picked this little red one up:



I can't figure it out though. Is it red in the middle, black on bottom, with it set to 750 on the ACV setting?