New to me GS550 won't run without choke

[roeme]

The oxidation will rub off with on my finger. I'm just wondering what the effects are of it coming off and flowing into the cylinder with the gas. The instructions for the chem dip mention treating low alloy metals with penetrating oil, but I also don't necessarily want that mixing with the gas.

I'm probably being paranoid.

Yup. That minute amount of crap is come and gone within a few combustion cycles, and unless you dump oil (which is not compressible) down the cylinder, the engine wont care much. That wee bit of oil mist doesn't really matter to anything other than maaaaaybe your nose.

Maybe put them briefly into an ultrasonic bath for a few minutes. The equivalent of hundreds of tiny little fingers rubbing ten-thousands times per second might knock off the oxidation...

 

[Isoparmesan]

What about spraying them with penetrant lube post dip. Is that likely to have any ill effects?

 

[Big T]

Just wipe off the residue and squirt some carb cleaner thru the various holes, it will be fine

after you reassemble the carb rack, put the fuel line on, prop up the rack to vertical and run gas into the rack (I use a tiny funnel) It may leak a bit at first, but should seal up
Like Roeme, my 41 year old T still seals fine

You are building this bike for your wife? It better be perfect

 

[Nessism]

WD-40 helps reduce the chalky residue.

 

[Isoparmesan]

You are building this bike for your wife? It better be perfect

Yep, pressure's on.

Also, I lucked out on the fuel rail. In the "box-o-parts" that came with the bike were a set of VM carbs for a 650. The fuel rail parts are all the same size and practically new.

 

[Nessism]

The 650 didn't use VM's, unless you are talking about a Kawasaki!

 

[Isoparmesan]

The 650 didn't use VM's, unless you are talking about a Kawasaki!

Yeah, I was just doing some googling to double check that. They're definitely round slide carbs and not CV. Did the GS650 have CV? The guy said they were from "a 650" but he could have been wrong. They look nearly identical to the VM22SS's from the gs550, but larger. Either way, the fuel connectors are identical.

Edit: attached a photo. Carb on left is the mystery one. Carb body on right is from the GS550

Edit edit: Actually, googling "KZ650 Mikuni vm" produces images that look just like them, so maybe they are from a kz650.

 

[Isoparmesan]

I'm sure it will come as no surprise to anyone, cleaning the carbs fixed the idle jet problem!

I replaced all the o-rings, including the carb boot ones. Installed a in-line fuel filter (just the regular trackside one from cycle gear). Also, flushed out some sediment that had built up in the tank with gas. Condition of the tank is fair, but I'm probably going to give it a evapo-rust treatment to get rid of some oxidation on the top most surface of the tank.

As far as the fuel connectors on the carbs, I did end up needing to recycle the original ones. The ones from the other set of carbs were the right diameter, but the wrong length. And, alas, there was fuel leaking from the T-joint last night. However, this morning there wasn't. so, I'm going to subscribe to the theory that the rubber has expanded after soaking in gas overnight.

So, this is the state now. I will start cold with choke, but will backfire pretty consistently. I hear popping come from both the carbs and from the exhaust. Once it's warm and the choke is off, this goes away. It idles just fine. I can give it throttle enough to ride it around, but if I quickly snap the throttle open it bogs, but generally doesn't die.

Would I be correct in thinking the needle jets may need adjustment for this type of bogging? I haven't synced the carbs yet either.

As far as the popping while on choke, would that be a timing thing? I also haven't done valves, or inspected the points, etc.

Sorry if these are dumb questions, I'm really just starting to learn this stuff.

 

[Big T]

Popping on choke is dirty pilot circuit/jets

You did remove everything from the carb bodies?

 

[Isoparmesan]

You did remove everything from the carb bodies?

Yes. First attempt, I used an ultrasonic cleaner with vinegar and soaked the brass bits, but didn’t take the upper part of the pilot jet out by mistake. Second attempt I pulled everything out of the carb body and soaked everything except for the choke plunger itself floats, and external screws in chem dip. I did not disassemble the slides, but I did soak/rinse them.

the pilot jets were very clogged, but are completely clear now.

 

[Steve]

Do you have the air filter/box installed? If you don't, it is hard to get much above idle, let alone being able to ride around the block.

You soaked the slides in chem dip? Hope the diaphragms survived. Generally speaking, NO RUBBER in the dip.

.

 

[Isoparmesan]

Do you have the air filter/box installed? If you don't, it is hard to get much above idle, let alone being able to ride around the block.

You soaked the slides in chem dip? Hope the diaphragms survived. Generally speaking, NO RUBBER in the dip.

.

Previous owner installed velocity stacks and rejetted accordingly. I do not have the original airbox.

As far as the slides, I don't believe there's any rubber in the slide assembly on these VM22ss's. Unless I'm missing something. I didn't put any rubber in the chem dip.

 

[Big T]

Previous owner installed velocity stacks and rejetted accordingly. I do not have the original airbox.

As far as the slides, I don't believe there's any rubber in the slide assembly on these VM22ss's. Unless I'm missing something. I didn't put any rubber in the chem dip.
View attachment 58760

Steve is incredibly knowledgable, but he does skip a beat on VM carbs

You are correct, VM carbs have no diaphragm, just some O rings.

Velocity stacks can be troublesome, so it's hard to know if they were actually jetted correctly

Did you inspect the jets for their sizes?

 

[Isoparmesan]

Did you inspect the jets for their sizes?

I definitely inspected them, but like the amateur I am, I forgot to note the sizes. Since there?s no airbox, they?re easy enough to pull off, so I?ll check next time I?m working on it.

 

[Big T]

Be sure to check for the Mikuni symbol, so you know how the numbers correspond.

 

[Steve]

Steve is incredibly knowledgable, but he does skip a beat on VM carbs

True and regrettably true.

Yes, it was mentioned early on that it's an early 550, and was even mentioned somewhat recently in reference to some other carbs, but the 550 had VM carbs and BS carbs, depending on the year, so I lost track of which ones he had.

You still don't want to dip any rubber, though. :-\\\

I don't know if velocity stacks need jetting any different than pods, but the critical thing is that there is SOMETHING on the inlet of the carb that smoothes out the air flow going in. A stock airbox has boots that go to the carbs. If you look on the inside of the airbox, those tubes are actually velocity stacks that just happen to all breathe filtered air in a common chamber. Most of the better pods also have some sort of radiused edge where they connect to the carb. Smooth airflow through the carbs is about as important as feeding the correct amount of fuel to the incoming air.

.

 

[Isoparmesan]

Just inspected and adjusted the points. Timing was spot on, but the gap for cylinders 2-3 was way too small. After adjusting it ran very well, didn?t pop on choke, or bog on hard throttle. I actually rode it around the block for the first time. This bike is super fun!

still going to do the valves. It sounds like there?s a hissing noise coming from the cam cover, which I?m assuming there shouldn?t be.

 

[Isoparmesan]

Just inspected the valves. They are mostly in spec. Some aren?t, and I discovered how necessary the shim removal tool is. I will order this before proceeding further.

I did did notice a lot of oil pooled up around the tappets on the kickstand side. Is this normal?

 

[cowboyup3371]

The oil pooling up is normal and okay. You can also use a zip tie - instructions can be found on Basscliff's site http://members.dslextreme.com/users/bikecliff/images/valve_tool_zip_tie.pdf

I also did a video of how to use it - https://youtu.be/DhmGBkje-dY

 

[Isoparmesan]

The oil pooling up is normal and okay. You can also use a zip tie - instructions can be found on Basscliff's site http://members.dslextreme.com/users/bikecliff/images/valve_tool_zip_tie.pdf

I also did a video of how to use it - https://youtu.be/DhmGBkje-dY

That?s pretty ingenious! I?ll give it a try.