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IT RUNS! With fuel delivery problems?

  • Thread starter Thread starter brainrush
  • Start date Start date
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brainrush

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I just got my 78 gs 550e working! sorta... (bought it in march with a rusted stuck #4 cylinder and a host of other problems)

it'll start with some starting fluid, full choke, and then keep running fine at full choke, it doesn't want to rev. unless you let it idle a little bit, then it'll give you a half second at half throttle before it starts killing itself again. I did a cursory clean of the carbs taking out the bowl and shooting carb cleaner and compressed air into the jets. the petcock works too well (it leaks a little if left on reserve or prime). static timing looks good, I took a timing light to it at idle, but the mark was walking back and forth. for both 1&4 and 2&3 coils. It's got points style ignition, and the mikuni slide carbs (not CVs).
 
You've got your proof of concept the engine isn't trashed. At this point I'd probably test that a little further with a compression check then go ahead and tear those carbs apart and clean them right.
 
Ok, I did a quick check of the sparkplugs. they're all carbon fouled about now. I just got the battery in there, so I took it for a little "test ride" it pulled away just fine, I couldn't go above idle in first gear, so it felt very "putt-putt" and then after about 5 minutes, it refused to keep on going. Kind of sad, but it was a fun, smokey 5 minutes. Wednesday is my next day off, so expect to hear a report on my compression test and carb cleaning.

currently all plugs are gapped at around .032"-.034", a little big, but I couldn't find the recommended gap until later, and lacking anti-seize, I don't want to end up galling the head after all my work. The spark plugs are the ones that came with the bike after some careful wire-brushing and 600 grit. they look fine, but come Wednesday I may replace them with new units. (one thing at a time, so I know exactly what needed attention)
 
I wouldn't bother to compression test until you adjust the valves. Regarding the specs, Basscliff's web site has a free download of the 550 manual, it's all in there.
 
I wouldn't bother to compression test until you adjust the valves. Regarding the specs, Basscliff's web site has a free download of the 550 manual, it's all in there.

Good point Ed.
 
cool cool, For the most part, the valves weren't touched from the previous owner, which means that when it was parked, the #1 exhaust was just a crack open, and the #4 intake was open even more, so I get some valve noise of the #4 intake. unfortunately I don't ahve shims to adjust the valve (this was my first engine rebuild---ever)
 
cool cool, For the most part, the valves weren't touched from the previous owner, which means that when it was parked, the #1 exhaust was just a crack open, and the #4 intake was open even more, so I get some valve noise of the #4 intake. unfortunately I don't ahve shims to adjust the valve (this was my first engine rebuild---ever)

There is a thread in one of the forums for shim trades. I have 2.60 and 2.65 coming out my ears. After rebuild the re-cut seats took me down to all 2.40 and 2.35 that I had to scrounge from a local shop.
 
Did I mention it's got cheapo pod filters and a knock-off Vance&Hines exhaust? The main jets are 80's or 08's, and the temps been hovering around the 50's-60's. Also, it's a California bike, I don't know if this would help things out. I'm getting the tags soon, so I've got that to look forward to.

I started it up this morning, it's quite smokey (my neighbors must love me), and it felt a little happier today, maybe it just need to get completely up to temp as well as get broken in?
 
unfortunately I don't ahve shims to adjust the valve (this was my first engine rebuild---ever)

This is rebuilt? As in new rings?
Breaking it in needs to be done first, starting it up and running it without going hard enough to load the rings may prevent the rings from ever making a proper seal.
Clean the carbs, shim the valves, get everything as right as you can before you start it again. Then ride the snot out of it.
 
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Ok, so maybe it was less of a rebuild and more of a refresh, I honed the cylinders, but the rings were in tolerance (best as I could measure) all new gaskets, and a cleaning of the head/pistons with simple green (valves still attached) to get rid of the carbon/rust that had deposited itself up until that point.

I wish I had $10,000 for a complete toolbox with all the special tools, but as a college student, I'll have to settle for a metric wrench and set of allen keys, a 6 in one screwdriver, and some odds and ends I picked up for the project. except for fluids the entire project bike included has cost me around $600 before registration and insurance, which is what my estimate would be before I fully understood what the engine had in store.

This project was purchased in march, was supposed to be done by june, and has had more ups (it runs!) and downs (tried to part it out on craigslist, fortunately, there were no takers) than could ever be written on these forums (or my attempt at blogging the "progress"). I have expirienced emotions ranging from joy (it runs!) to despair (did it just leak a quart of water?) to frustration (why won't the crank turn?) to delight (I'm actually riding this thing!). needless to say it's been an amazing journey, and I've only been around the block in 1st. Through the bikes disassembly it's story had been told, some kid put some go fast parts on it, and then left it in the rain to die. Without the help of everyone at the GSResource I would probably be out of $600 (a lot by my standards). While I wait for the paperwork to go through, I look back at my project, and can see that no matter what direction the road may take me, it's been a hell of a ride.
 
Took the carbs out, and poked at the jets with wire from a wire wheel. I also cleaned and re-gapped the spark plugs, and adjusted the clutch. it feels healthier now, although it still doesn't like running without some choke and is still smokey. I'm thinking it's maybe a voltage issue, it's very likely that I hooked up the alternator wrong, as the headlight pulses on and off with the battery disconnected and the engine running. In any case, the battery is now on the battery tender, and I'll give it another go tomorrow between classes.
 
Browsing the forums, I found that this bike has the stock 80 main jets even though it's got aftermarket parts, and if I remember correctly, California bikes were intentionally jetted lean for EPA reasons. Could this be a contributing factor, along with bad charge and dirty jets? I know I'm going to be taking off the carbs more than a few times before I get this thing purring, so next time I'll check and set the float height. (p.s. what does the screw on the bottom of the carb do, the one visible with the float bowl put on, these are the VM22SS carbs.)
 
Definately a fuel flow problem, if I wet the filters with fuel it revs fine until the filters dry out. There seems to be a gas leak from the petcock, so tomorrow I'm doing another run of cleaning the carbs and I'll be messing with the petcock while I'm at it.
 
Definately a fuel flow problem, if I wet the filters with fuel it revs fine until the filters dry out. There seems to be a gas leak from the petcock, so tomorrow I'm doing another run of cleaning the carbs and I'll be messing with the petcock while I'm at it.

That in itself tells you that it is lean!!!
 
so I gave the VM22's another thorough cleaning with plenty of compressed air and carb cleaner, set the float height, and checked with compressed air to see if there was good flow, and it seemed like the #3 and 4 carbs are flowing less air, so I removed the floats and put a full 120 psi down there hoping to unblock anything, but nothing changed. I also cleaned the petcock, but the auto shut-off doesn't work so it's always flowing fuel. The tank is fairly rust free and all the jets seem are free and clear.

The result: still the same, it doesn't want to hold any revs and it doesn't like going off choke or above 1/8th throttle. it smokes lots and blows the thick, heavy smoke over to my neighbors yard (she must love me). It cold starts fine, but has trouble hot starting, and when you let off, loves to pop out bits of the muffler packing. if I let it idle for a little bit (or start it) it'll rev for about 1-2 seconds before starving itself. I don't think it's vapor lock, and I'm running 91 octane (my car needs it and it was convenient).

So it definitely seems like a it's starving itself, but where from, I don't know. Maybe one of the Gurus surfing this forum could shed some light onto the subject?


Since I know I'm going to have to re-jet the carbs anyways, I'm going to install a fresh gasket set then, while also ordering an new set of tires and brake pads. I know the recommended kit is the Dynojet, any particular reason?

Thanks a lot, I'll post some video once it's running healthy. :lol:
 
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