I had a bike issue today, bros. I'll greentext it

I had a bike issue today, bros. I'll greentext it.

>be riding my '75 Honda CB550 today
>had been riding for about 35-40 minutes prior
>going 55mph down the road
>suddenly, the engine gets really jerky
>loss of power/return to power variations lasting about 3-4 seconds
>jerking forward and back while riding
>pull in clutch
>motor dies
>coast into gas station (thank god)
>park, take a piss
>come out, bike starts right up and makes it all the way back home (30-45 minutes of combined highway and city riding)
>no further problems for the rest of the day

This has happened before. The bike will lurch a few times and then die when i pull in the clutch, but it starts right back up with no problem and works fine thereafter.

Any idea what's causing this? Sudden loss of oil pressure? Over-heating? It doesn't happen every time i ride, but it still pisses me off.

>pic related

clean the carbs

The carbs were JUST completely rebuilt 1000 miles ago by a professional mechanic. All new floats, gaskets, the whole nine yards.

Maybe rust in the fuel tank blocking my fuel lines?

shameless self bump

nobody knows? one more bump and i"ll fuck off

check your ignition system out if it's not fuel doing it.

Could be as simple as a dodgy ground, who knows.

>Maybe rust in the fuel tank blocking my fuel lines?

Sounds like a good place to start.

Agreed, sounds like electrical gremlin. Clutch switch may be going bad

I understand that God hates faggots

Maybe that's a good place to start

Do a few easy cheap fixes like new wires and plugs (properly installed, with grease) and a quicky carb clean? Make sure your coils still work? Test the generator? Rectifier? Battery?

Guesswork will get you nowhere

This happened sometimes to my Honda CB125E (I am ashamed for having owned one). Turn the fuel to off and drain your fuel line, it's probably got some water that's condensed in there. If that doesn't work I can only suggest new spark plugs.

Jesus Christ. Nothing pisses me off like people who don't get their questions aswered fucking immediately claiming no one knows.

Likely it's the vent on your gas cap on your tank is clogged. Your carb is starving for fuel because the gravity feed isn't working if a vacuum builds up in the tank. Gas is being consumed faster than air is flowing in.

This usually happens after long periods of sustained riding I would guess?

The user that suggested an electronic issue should be made to feel ashamed then executed.

It's a fucking carbed motorcycle you asshole. Electrical shit doesn't show up and disappear.


The float bowl is empty because negative pressure in the gas tank. It's better after it sits cuz it slowly filters down there as air leaks around the seal or through the partially clogged tank vent.

Clutch switch???

There is no switch! It's fucking mechanical. do you have any clue what you are talking about? NO shut the fuck up!!!

You are the most confusing of all!

You say it yourself, guesswork will get you nowhere? Then you spit out a string of wild guesses none of which would cause intermittent fuel starvation.

Which is obviously what op is describing.

Which is a common thing on old bikes.
Which a google search should have made clear.

But some people need their hand held for EVERYTHING

Yes I'm mad. Veeky Forums is less than worthless, it actually would be detrimental to this kids bike if he paid attention and started ripping into a perfectly running bike.

I was going to guess that pressure was building in the fuel tank and force flooding the engine but that makes more sense.

Seriously you make me hurt. Check the battery? Rectifier? The bike will run till it runs out of fuel with no battery or charging system you fucking dunce.

Buy 2 cartons of copper BB's , drain the tank. Replace with BB'S. Shake that fucker for an hour, if you have to, flipping it over to remove the rust particles and continue until happy with the results. You'll Then gas wash the inside of the tank, and if you want to go the extra mile, I think you can buy a lacquer that you can coat the inside of the tank in. Then, buy 2 fuel filters and clean the petcock screen
.replace the fuel filter and let it run.

Wut. Why would it be pressurised? Carbs have jets/floats to control the fuel mixture. Even if the fuel line to the bowls was pressurised it would still function correctly.

Gas is flowing out the bottom of the tank to the carb.

If there's no vent to let air in, a vacuum will build up, and gas will stop flowing out the fuel line at the bottom.

Floats and jet needles stop gas going to the carb.

Op is dealing with gas starvation that fixes itself after the bike sits a few minutes.

He said the carbs were just cleaned. If it was a rusty tank it wouldn't run right.

Pay attention! His problem comes and goes, that's fuel delivery.


It happens in my DRZ sometimes. There's a valve on the fuel cap that's fuckin weird so if the tank sits in the sun pressure builds and forces fuel into the engine and takes a while to start afterwards.

points problems come and go
ground problems come and go
switch problems come and go
rectifier problems come and go

not saying you're wrong pal, but telling someone to pay attention to Veeky Forums instead of providing guidance for troubleshooting makes you sound like a cretin

so a partially clogged petcock screen can't cause a fuel delivery problem?

Holy shit someone who knows what they are talking about on Veeky Forums

idk if you guys are trolling each other but,

maybe he was referring to some kind of ignition interlock switch?

idk how they work or if those old bikes had them though

I said DONT pay attention to Veeky Forums

OP described a common issue with old bikes.

The rest of you need to read to understand, not read to respond.

To the other moron, this bike doesn't have points or a distributor. You're an idiot.

The only thing a bike needs electrically to run is spark, which if he made it home 45 minutes OBVIOUSLY IS NOT AN ISSUE

There's an outside chance a filter could be partially clogged. The likelihood of that vs the likelihood of a tank vent not venting, well, keep it simple and start troubleshooting where hings make sense.
Your closer than the retarded fucks bla.ing plugs and wires but be fucking realistic.

Would the bike run fine for a half hour after if this was the case?

Read to understand, not to respond.



it does actually, this bike still uses contact breakers. the condenser might be fualty. i once had problems with my moped like that. riding for 40 minutes no problems then suddently sputtering and it died. after 10 minutes or so it starts up just fine. replaced the condenser and never had a problem again. though it's just a possibility.