Help getting 81 GS750L Running

[keeena]

81 GS750L. I bought this bike w/ 14k original miles. Stored for long term, fairly good shape other than oxidation to L+R case covers. Has the usual flooding/fouling on #1 due to sitting on sidestand. Bike wasn't running when I bought it, just cranking (barely...battery fairly dead).

I cleaned carbs (they actually weren't too bad, but replaced all parts anyways...jets, mains, etc...set bowl height). Didn't separate carbs. New plugs & charged the battery.

Bike started on 2nd try, ran 20 seconds and died. Next attempt only ran 5 sec. Then it wouldn't start - battery is already out of juice.

All attempts now to start bike won't work. I'm using a new battery @ this point and new ground from battery to motor & frame. All 4 plugs have spark, though it doesn't seem very strong to me (I'm not a mech, so not sure how bright spark should be). I'm really thinking that it should be able to start and I'm a bit baffled as to what to diagnose with the carbs. I've got Air/Fuel screw out 1 1/4 turns per manual spec. Choke and Throttle cables operate properly.

I noticed that battery and starter relay leads get pretty warm (almost hot), even on the first cold crank attempt (~5sec). Mfr. date on battery is '06, so I'm sure theres a problem w/ the charging system as well. I read the FAQ on the stator issue w/ the GS, so I'm going to look at inspecting all electrical connections now and run all the tests which don't require motor to run.

In the mean time, a couple questions:
1. Will a toasted R/R or Stator prevent the bike from starting? I wouldn't think so, but not sure. Should I stop trying to start this thing until I can test or update charging system?

2. Lights & indicators appear OK, but horn doesn't work. You can hear the horn's diaphram click once as it tries to move, but then nothing. However, if I hook horn directly to 12v, it is perfectly fine. Would this help indicate where in the harness something may be going bad? Or do I have to just trace everything? (note - I did clean terminals and harness plugs at horn).

Any hints and suggestions are appreciated as well. I've read a number of other posts on general starting/carb issues, but I haven't been able to piece together the info I need.

[chuckycheese]

Problems

1. No...that could be somewhat of a problem (it's most likely not) but if the bike turns over, that's not what's keeping it from starting and running.
2. Forget about the horn for now...it's like worrying about a gunshot victim with a hole in his chest and in his foot. (The horn is his foot.) I don't think that's much of an issue, anyway. If it clicks when you push the button, it's probably either frozen or worn out.....an easy $10 fix, if so.

I think you made a big mistake in not separating the carbs. I can't think they were properly cleaned. When you perform a job like that on a bike that has obviously been sitting for so long, you need to truly separate all the parts, clean them thoroughly and replace each and every rubber gasket. In addition, you need to check float levels, bench synch it and adjust your throttle linkage...along with making certain that your boots aren't allowing air leaks. After you get it running, you'll need to synch it properly and adjust your air/fuel mixture. (But don't give that much thought until it runs.)

When I got my bike, I was in exactly the "same boat" as you. It was a beautiful bike that could hardly run...because it had been sitting most of it's life. Give it a good physical, do everything right the first time and you'll have a great ride!!! Good luck and let us know if we can help!!:-D

[keeena]

Where's a good place to get O-rings? I already have the K&L rebuild kit. Came w/ some rings. Off the top of my head I think there may not be enough to replace all the fuel tube (interconnecting carbs) and vent-tee rings. Are there size specs available so I can get these w/o having to buy direct from Suzuki (realizing that they need to be stable in gasoline).

How does one go about removing the fuel adj. screws (the ones on top of the carbs)? The #2 and #3 carb have a cap over the screw...couldn't figure out how to remove this cap & it wasn't in the Carb Rebuild write-up (a great write-up, by the way).

Chem Dip - This the good stuff to use? Found it on Amazon, not sure if I can find it locally... Any suitable alternatives? [edit] Napa autoparts has a similar cleaner w/ dip tray, seems kind of generic. This just as good to use?

I didn't have any sticking parts. But for future ref, how is one supposed to use carb cleaner to free parts up when it will damage the rubber parts (e.g. CV boot, o-rings).

I did set float height first time around (typo in first post...said "bowl height"...haha) and bench-synced.

What should I look at once carbs are fully cleaned? I have a sneaking suspicion that it still won't be able to start. Just want to get an idea @ this point. I really don't have the time to sink into this sucker (was hoping it would be a quicker fix). Not emotionally attached to the bike, its just a starter for the wifey. I'd just as soon part with it if I have to put much more money or time into it.

[txironhead]

Berryman's Carb Dip, available at most auto parts stores.

Someone here sells complete o-ring kits for our bikes. Do a search on o-rings and you should find it.

Those caps have to come off. The factory says they don't need adjusting, but they weren't dealing with a bike that sat for ten years. Drill a tiny, shallow hole (or punch a hole with a nail) and pry them off.

Is your petcock supplying fuel properly? In the "Tips and Tricks" section there is a post on how to test your petcock. Also, replace all of your fuel and vacuum lines with new ones. And just in case you're running an inline fuel filter, take it out. These bikes don't like 'em. Take your petcock out and check the filter that goes into the tank, it may need cleaning. I'm assuming that you have fresh, clean gas in the tank and there's no rust on the inside of the tank.

As for the horn, you probably need to disassemble the horn switch and clean the contacts. If it works with direct 12V, the switch is the likely culprit.

One last thing: Is the airbox installed? These bikes do not run, or run like crap without the airbox installed.

[keeena]

Thanks for the o-ring and fuel mix cap tips.

Petcock is fine. Already replaced fuel line. It did have an in-line, which I removed. It was installed backwards to boot.

I'm *not* running airbox, due to the fact that its such a MASSIVE pain to install (I was cursing the engineers). So I'm just trying to at least get the motor running before dealing w/ that...I only want to put that airbox back in once. Why the heck would they make it so damn tight? I'm no stranger to wrestling with parts, but that airbox is ridiculous. I'd rather use pod filters for ease of installation, but don't have any yet. I just read that removing the vent hoses is helpful when running pods. You really recommend getting that airbox on, huh?

No rust in tank, but there is varnish. Have a POR-15 kit ready. And yes, new gas.

Who wants to buy a low mileage GS750L that needs a little TLC to get running?

[chuckycheese]

O-rings

Robert Barr is the guy who sells the O-ring kits....and they're very good. Berryman's carb dip is great stuff.....as long as you don't buy it in California.:?

[txironhead]

These carbs have to have some restriction on the intake side for some reason. If you do run pods, you'll have to rejet the carbs. I honestly prefer pods, I like the look and ease of installation, but I'm also running a 4-1 exhaust and a stage 3 jet kit.

The bike should start without the air filter on, but don't expect it to run very well. I think there's still something iffy with the carbs. A complete teardown, dip and 0-ring replacement will probably do wonders. Just remember that you'll need to to a running carb synch to make it run correctly.

[tomm]

Few other suggestions, based on a rebuild I recently did on my 78 GS750E. Not sure how they relate to the 81, but I assume they are fairly close.
Do a compression check, just to make sure you don't have any problems there. Minimum I believe is 100 psi, but they should all be within around 5 psi of each other.
Also, changing the carburetor boots (both sides) can make a huge difference. I read somewhere on this web site that after 20 years, they just need to be replaced. Period. I did it, and it was like night and day. You can forget about ever getting it to run right if they are leaking.
I also had problems with clogged pilot air and fuel passages, and it took a lot of trial and error to get the pilot fuel screws correct, but it eventually paid off. Started at 1 turn out. I believe 1 and 4 ended up at about 1-1/2 out, 2 at about 1-3/4 out, and 3 just a little more than that. Just kept pulling the plugs and adjusting based on that.
I also swapped out the coils and wires, and put in a Dyna ignition. Spark just seemed weak to me before that.

I'm a little intrigued by your comment that the wires to the starter relay get hot after just five seconds. The starter motor does pull a bit of current, but I wouldn't expect the wires to get hot. Sounds like you're sinking a lot of current someplace or you have some bad connections, maybe even enough to dull the spark enough to keep it from starting. This would be line with the horn problem as well. Suggest you take a voltmeter, measure at the battery, and then measure somewhere else on the harness. Start turning things on and see if you get a voltage drop on the harness from what you read at the battery. If you do, you're dropping voltage somewhere between the battery and the the rest of the bike, and the more current you draw, the bigger the drop. Drops too low, and you're bike won't start.

I think you've got carburetor tuning issues, but I think you have an electrical problem first. Check simple stuff too. I've seen a main fuse fail mechanically that was still partially connected and that caused some pretty weird symptoms.

[txironhead]

Hadn't thought of the starter issue, could be the starter's dragging. That would make the wire heat up AND make the bike harder to start. You might consider taking the starter apart and inspecting the parts. Rebuild kits are pretty cheap at www.stockers.com.

[keeena]

Well, I have the carbs separated. The fuel and vent passages look good, no residue buildup, no cracks, O-rings look good. I'll still be doing another cleaning while they are separated as well as replace those o-rings , but I just have a suspicion that the carbs are not the culprit. Boots all look fairly good, not a hint of rot or cracking... But I'll keep those in mind too.

Yeah, the main 12v wires (battery, starter relay) get fairly hot pretty quickly. Can still touch them by hand, but definitely hot. The main bundle near the battery (the slide connections that supply main harness?) don't get hot.

The starter's strength seems inconsistent...sometimes it seems strong, other times it hiccups or goes slower than I would expect. The battery is known good, and battery connections are solid. Looks like I will have to search GSR for info on inspecting/testing a starter (if anyone has good links off the top of their head, please post).

While I'm here - is there a company/web site that sells float bowl gaskets? I just need the gaskets themselves, not entire rebuild kit.

No end in sight... :?

[Nessism]

My guess is you have a fuel supply issue. Fuel should flow out of the petcock when the lever is turned to the Prime position - easy to check with the fuel line off. After you get the bike back together, turn the petcock to Prime and fill the float bowls. If the engine craps out again, open some of the float bowl drains and see if you have fuel in there.

Good luck.

[txironhead]

I agree that it's probably fuel related, but from the sounds of it you need to rebuild the starter, or at least clean it. It's fairly straightforward, just a simple two-brush system.

[keeena]

The bowls are filling nicely - definitely no problem there. Petcock working 100%. Tested operation w/ vacuum gauge.

I haven't found detailed info on cleaning the starter. All I found was vague info indicating to "clean it" (bushing dust/junk accumulation and sanding/polishing some part down?). I found a user who stated that have numerous detailed posts on the subject (nabrams), but failed to find cleaning details (searched for keyword "starter" and user name "nabrams"). Just tough piecing the info together.

[Fare]

While I'm here - is there a company/web site that sells float bowl gaskets? I just need the gaskets themselves, not entire rebuild kit.

http://www.z1enterprises.com/detail.aspx?ID=47

[txironhead]

It's pretty straightforward, just take the two long screws out, take everything apart, keep track of which washer/spacer/bushing goes where (simple), clean everything with electrical parts cleaner. The armature (long round cylinder that turns in the center) should not be worn badly. If it's very worn, get a rebuilt starter. If it's just discolored or slightly worn where the brushes rub against it, you can sand it down a bit with emery cloth. Make sure everything's nice and smooth. I'd probably go ahead and order a new brush plate from www.stockers.com. If the brushes are still okay, which is unlikely if it's dragging, you can clean them up and use them. I highly recommend replacing the whole plate unless you're really good at soldering. The hardest part is getting the armature between the brushes during reassembly, but with the use of some small drill bits or something similar to hold them back while you insert the armature it's not that bad. Reassemble everything, making sure the seals are in properly and everything is clean and voila! you've got a rebuilt starter.