Topic: Bike tipped over

[Schnell]

Talking about a 1975 cb750. On Easter weekend I was able to go on my first ride of the season. I stopped at a friend's place, parking on some grass. While in his garage, my bike tipped over onto its left side because of the soft ground. Gas was leaking out when we got to it. It had been on its side for a minute or 2. No cosmetic damage, due to landing on soft grass. It started but ran rough. After a mile it ran okay again and I got home no problem. That was about a 20 mile trip.

Yesterday, after 2 weeks of more crappy weather, I start my bike for the first time after the tip, but it runs rough and backfires. I'm going to install new spark plugs this weekend, but I'm thinking that the tip over could have jarred the carb floats, so I'll remove the bowls and wiggle on the floats too. I'll check the air filter for oil.

Can you think of another reason for the crappy running? This bike, before the tip over ran very smoothly and reliably. It's all stock except for aftermarket 4 into 2 exhaust.

[calj737]

Along with those likely "culprits" I'd suggest you run through the spark plug wires, coil connections, etc. The impact may have jarred a plug cap loose or caused an electrical connection to become tweaked.

Any possibility that debris from the tank may have been stirred up? When you don't see cosmetic damage, we too often think nothing was effected. Be thorough and inspect everything from the tank to tail, metaphorically speaking.

[Bootlegger56]

Check for a cracked porcelain on the plug  too.  If it fell right and the plug resistor cap got hit it might have cracked a plug.  I would bet on the electrical issue since it backfires.

[LesterPiglet]

Is the petcock on the left? Maybe some crap in the tank got dislodged.

[Schnell]

Is the petcock on the left? Maybe some crap in the tank got dislodged.

Yes it is.

We replaced the plug on the left at buddy's place.

[iron_worker]

I would place my bets on crap getting swirled up in the tank when it was shook and then made it's way through the carbs. I'd try pulling the fuel bowls and jets to see if there is junk in there. Checking the floats at the same time is a good idea.

IW

[Schnell]

I would place my bets on crap getting swirled up in the tank when it was shook and then made it's way through the carbs. I'd try pulling the fuel bowls and jets to see if there is junk in there. Checking the floats at the same time is a good idea.

IW

Thanks. Now, I've never been into these carbs. Can I remove the jets without removing the carbs from the bike, just be removing the bowls?

[iron_worker]

If your bike has the correct carbs then it should be the same as what I have (74 750 ... though you don't mention K or F). The bowls are just held in place with clips and both the main jet and idle jet are screw in (probably need a stubby screwdriver to get in there though). For the main jet, I actually find it easier to just use a wrench and remove the whole main jet holder. That way you can check the emulsion tube as well.

You should be able to see light through all the holes of each jet.

The tough part will be getting the bowl gasket back in the correct place when going back together.

IW

[Schnell]

If your bike has the correct carbs then it should be the same as what I have (74 750 ... though you don't mention K or F). The bowls are just held in place with clips and both the main jet and idle jet are screw in (probably need a stubby screwdriver to get in there though). For the main jet, I actually find it easier to just use a wrench and remove the whole main jet holder. That way you can check the emulsion tube as well.

You should be able to see light through all the holes of each jet.

The tough part will be getting the bowl gasket back in the correct place when going back together.

IW

Thank you! Yes, it is a K.

[bjbuchanan]

Just drop the bowls. You don't have have gummy carbs, they just have sediment now. Pop em out, shoot with brake cleaner, snug back in to place.

You are gonnna enjoy getting all those bowl gas jets back on lol

Make sure the wire is sceewed tight to the cap. May be time to trim a 1/4" off the wire for a fresh snug fit

[iron_worker]

A helpful trick I used on my carbs if you ever do take them off and clean them. I put a drop of superglue in each corner of the bowl gasket (on the carb body) so my gaskets stay on the carbs now. Much easier to drop a bowl and get it back in place without fighting the gaskets now. If I want to change the gaskets now though I'd probably have to pull the carbs and clean the gasket surface though but I accept that since it should last a couple years or more.

IW

[bjbuchanan]

IW

It will come right off anyway once some fuel touches it. Good non destructive tip

[Kevin D]

You don't want this happening on your trip. You're going to be parking on all sorts of surfaces. Is a sidestand prop plate on your carry list?

[Schnell]

You don't want this happening on your trip. You're going to be parking on all sorts of surfaces. Is a sidestand prop plate on your carry list?

You're right! This would be a pain to have happen on a trip! Seems that life gives you the lessons you need to learn. I'll be much more aware of the surface I'm putting my side stand on, after this experience.

[Schnell]

She runs smooth again!

I installed new plugs. #3 was wet and black. I drained out the old gas (from last fall) and rinsed out the tank with the last few ounces, and filled in new gas.

Luckily I didn't have to unscrew any jets! Thanks all for your help.

[HondanutRider]

Did you check and clean the petcock strainer/filter?  Assuming you have one.

[Schnell]

Did you check and clean the petcock strainer/filter?  Assuming you have one.

No I didn't. I'm hoping the issue is resolved. If I don't have to mess with the petcock, I won't. Sometimes when you touch something you end up creating a problem. I'm sure that if I were to remove the petcock, which doesn't leak, I'll need a new gasket to fix the new leak created with its removal and re-installation.

[HondanutRider]

Did you check and clean the petcock strainer/filter?  Assuming you have one.

No I didn't. I'm hoping the issue is resolved. If I don't have to mess with the petcock, I won't. Sometimes when you touch something you end up creating a problem. I'm sure that if I were to remove the petcock, which doesn't leak, I'll need a new gasket to fix the new leak created with its removal and re-installation.

You shouldn't have to remove the petcock to clean the strainer.  All that is needed is to turn it off and and unscrew the bottom cap where the strainer is located.  Check your shop manual.

[Schnell]

Thanks Bob, I'll do that tomorrow!

[HondanutRider]

May the Fourth be with you.