Stumped, Puzzled & Confused

[WBD]

To start with I am a new bike owner so I'm fairly ignorant but the man that is helping with my bike has been working on motorcycles for years. That stated I have a 78' GS550 that was given to me at Thanksgiving. It only has 12,000 miles on it and was running when it was parked 2 years ago. It was stored outside under a tarp. We can't get it started.

Here is what has been done. It has a new battery. New gas. The tank is clean and gas is getting to the carbs. The carbs have been apart twice, by me & then by the fellow helping me. We found that the condensors weren't keeping the spark long so I got new condensors and points. The plugs then kept spark fine but didn't really burn hot enough to even burn off either sprayed on them. So we got plugs rated one stage hotter. Now they burn good. We have set the timing around 5 times and are convinced it is right. We did a compression test and all 4 were good. I believe at 120 each. The last thing we did was pull it with a 4-wheeler to jump it. Nothing. It is making a lot more noise then when I 1st got it but still wont start at all.

When we try to start it, it will pop and puff smoke out the back of both mufflers. Every now and again we get a loud backfire. The thing that is really puzzling is that it will make small pop backfires into the airbox.
Another question we have is when we were cleaning the carbs we saw that there is the factory screw for the jets that isn't suposed to be messed with but I'm wondering if those could be an issue.

Any suggestions will help. [-o< We have even talked to the local shop mechanics and they say we are doing everything they would do.

 

[Dink]

Got a manual??? Got the plug wires on correctly?? One coil goes to numbers 1&4 the other to 2&3.

Dink

 

[49er]

Bikes are often parked up by their PO because they become hard to start.
Your compression figures are good as the engine was cold. This eliminates badly worn bores, piston rings and burnt or tight valves.
Your valve timing should be ok also. Re-check your ignition timing as those backfires through the airbox can be a pointer to incorrect timing. Another cause of carb backfires can be a very lean fuel mixture. Is the airbox sealed properly as any leaks will cause a lean condition.
Try cranking the engine over and then check the spark plugs to see if they are getting wet with fuel. If they aren't, you need to check the fuel line again for flow. You may need to service/replace your petcock. If you have a prime positon on your petcock, try starting it in this position.
Those screws that the factory says shouldn't be tampered with are your fuel mixture screws. If you don't remove them you can't check that the passages are free of rust/dirt particles when you clean your carbs. These will affect your idle and bottom end rpm performance and starting.
When cleaning your carbs you should remove these screws. Screw them in gently and count the number of turns until they seat. Do this with all the carbs and write this down so you can reset them correctly. They should be in the 1-1 +1/2 turns range when set corectly. If they vary greatly from that this will cause some of your problems. After removal, the passages should be blown out with compressed air. This is assuming that you soaked your carbs in carb cleaner previously. If not, you need to do this and blow out all of the passages.
Good Luck

 

[tomo]

This might seem a daft suggestion, but it has always worked for me if the bike has been stood and won`t start. Take the two carb breather tubes (one connects between each pair of carbs) and with choke on, blow a few times into them. The bike should fire up. Give it a try anyway, it has surprised a lot of people including myself when I was first shown this trick !.

 

[bradleymaynar]

My 1100 was a two year parked bike when I first bought it from the PO. He did a good job of going out and cranking the bike once or twic a month. He had drained the gas from the tank, but neglected to do the same for the carbs. That being said, when I left his house, it only seemed to run on 2, if not 3 cylinders. The only way I was able to get it firing properly on all 4 was to do a complete tear-down of the carbs. It included dipping each body in carb dip.

What I found in the tear-down was that one carb was completely "gunked up" from old gas turning bad in the float bowl chamber. I think this may be your problem. While you may have had the carb bodies apart, you may not have properly cleaned them out and cleared the passages. My suggestion is to go to a local parts store (Auto Zone etc,...) and pick up a gallon of carb dip. Their are different brands to choose from. I used Gunk, but others here might suggest Berryman's. Then follow the carb rebuild section here (found on the homepage) and follow it. Once you've accomplished that, and it's more intimidating than it appears, you'll need to sync the carbs. This should help your problems.

Brad bt

 

[Guy]

If it's popping and backfiring it sounds to me more like an ignition issue. Are you certain the coils, leads and points are all connected the right way round? Are the condensers the same value as the ones they replaced? Keep at it, you'll get there!

 

[WBD]

Thanks

Thanks

Thanks all for the quick responses. I'll let you know how things work out. I do have a manual and the plugs are in the right order. The plugs are getting a little wet but we actually think maybe it is in the fuel mixture. We took out a plug and burnt all the fuel that was in there with a blow torch and then cranked it over with the torch there and at first it would flame a little but then not at all which seems like the mixture isn't getting there huh.

49er, thanks for the info on the screws. I'm always afraid to move something thinking that I might make a bigger problem but it did seem like it might be gunked since I couldn't take them off.

Tomo, I want to try your suggestion but don't quite understand it. What will I be accomplishing since that is a breather tube. I'm willing to try though.

As far as a carb dip. I thought I read that that would destroy the o rings in there. I was only using a spray cleaner on all the areas and holes. It looks clean as new on the inside of all them. I will pull them again and dip them and try all your suggestions. Sounds like everyone has gone through this from time to time so thanks so much.

 

[Steve]

Before you dip your carbs, make sure you have them COMPLETELY disassembled. Take out ALL the screws (lightly seat them first, counting the turns and record the number of turns for EACH carb), jets, plugs, anything you can find that can be taken off the main body. Remove all the o-rings from the jets and other brass pieces, dip them along with the carb body. I do the carbs one at at time, and tend to leave each carb in the dip for a full day. I will disassemble one and dip it one evening, the second carb the next evening, and so on. Sure it takes longer, but I am reasonably certain that everything is clean when it comes out.

It helps to have new o-rings and gaskets ready to put it all back together. As others have mentioned, it might also be wise to replace the o-rings on the intake runners.


.

 

[KEITH KRAUSE]

Good advice above. One thing I don't agree with is going to hotter plugs, unless the plugs that were in it were colder than stock. Non-starting spark performance wouldn't be effected by the heat range anyway. You COULD see spark improvement because the hotter plugs were new. What plugs are in it now? What gap? I suggest going back to stock.
This spark improvement also makes me question the rest of the electrical system. You say the points/condensors are new and dwell/timing set, but are all the connections cleaned, including the plug caps and coil terminals? Dirty connections add up to weak spark. The random backfiring may be raw fuel collecting in the cylinders and header caused by poor combustion/weak spark. Bikes that sit awhile can have these electrical related problems.
They can also have carb problems from sitting but I thought I'd mention the above.
I also wonder about the manifolds and especially the manifold o-rings. Sitting a couple years is especially hard on the o-rings. Replacing at least the o-rings should be automatic in this case.
The carb o-rings can get brittle too if the bike sits that long. Robert Barr sells a VM o-ring kit.
Sounds like the carbs could use a better cleaning. Special attention to cleaning the tiny pilot circuit holes at the bottom of the carb throat. Also, clean the air jets you see from the filter side. Check float levels.
Is the bike stock? Stock jetting? If any changes, what are they?

 

[gs425e]

hi i have had exactly the same proplem with my 83 gsx550 the proplem was the choke enrichment circuit the tube from the carb bowl to the plungers must must be completly clear i had to clean the carbs 3 times before the thing ran propely poke fine wire right the way up the channel until it come out of the top and keep spraying carb clean through it it is most likely to be this cheers happy chappie andy

 

[WBD]

Wow, you guys know your stuff. I definately have plenty to try this week. The dip is something I will definately work on this weekend. I am a little nervous about taking each completely apart but I'll trust you guys and go for it. I'm pretty sure all is stock on the settings but I'll check in my manual. Who is this Robert Barr and how expensive are the kits? We have cleaned alot of the connections to make sure we were getting good connection. What do you use to clean the plug caps? May go back to new stock plugs. I'm not completly certain about what the choke enrichment circuit is but I'm sure it is in the carb diagrams on this web site. Thanks all for your help. I'll let ya know where I'm at.

 

[nabrams]

Yeah, for a carb that's been sitting for two years there's just no choice: A complete disassembly is required.
Sometimes, pushing a wire (of appropriate diameter) through the jets is the only way to completely clear them (see other posts).
Then there's a whole litany of other stuff for carbs (leaking floats, leaking float needle, torn diaphragms, etc.) and for other areas (electrics, air leaks, exhaust leaks). They ALL need to be verified. Otherwise, you're just playing guessing games. See other posts about restoring bikes that have been dormant.
The vast majority of the time, these dormant bikes have at least carb and air leak issues. Electrical issues are almost a certainty as well.

 

[bradleymaynar]

Wow, you guys know your stuff. I definately have plenty to try this week. The dip is something I will definately work on this weekend. I am a little nervous about taking each completely apart but I'll trust you guys and go for it. I'm pretty sure all is stock on the settings but I'll check in my manual. Who is this Robert Barr and how expensive are the kits? We have cleaned alot of the connections to make sure we were getting good connection. What do you use to clean the plug caps? May go back to new stock plugs. I'm not completly certain about what the choke enrichment circuit is but I'm sure it is in the carb diagrams on this web site. Thanks all for your help. I'll let ya know where I'm at.

Robert Barr is a member of this site. Someone may have a link, or you can just hunt him down here. He's a fairly regular poster (screen name's robertbarr).

As for worrying about tearing down the carbs, do one at a time. As you disassemble the second one, rebuild the first. My 1100 was the first time I had ever rebuilt any carbs. I was nervous as heck, but that quickly disappeared when the bike started up after putting them back in. It's definitely easier than it appears.

The biggest thing is to have a decent container for the small parts. And, as stated, since you're removing the O-rings, you might as well replace them with new upon reassembly.

When you're done with this you'll be glad you'd done it, and it will make tackling other issues a lot easier. This is a plus, since most shops don't like dealing with our older bikes anyway.

Brad bt

 

[GS850_Coug]

I agree with everything said here, except there has still been an omission. You should check your coils also. If they are not getting/producing enough voltage at the coils, you will have similar issues.

Again, get the orings from Barr, best deal in US that I know of. Replace orings on intake tubes. Make sure intake tubes are soft and pliable, no cracks at all, replace if hard or ANY cracks. Make sure airbox is sealed properly with filter in place. Replace your petcock....you'll read of horror stories from many who've tried to rebuild them. Soak and reassemble the carbs. Bench sync the carbs. Check and adjust valve shims. Clean and clean again all electrical connections, repair any that are corroded. RESISTANCE/continuity check all fuses off the bike. Check plug wires for proper resistance. Make sure coil wires go to correct cylinders. Then try to start the bike. Once it runs, you will want to use the carb sticks for a vacuum sync, along with all other carb adjustments.

That should be a decent check list engine-wise to get up and running. Just remember to check your brakes, clutch, and tires before you take it for a spin on the highway! Good luck!

Torry

 

[WBD]

Wow, It turned cold here in WV overnight. Now it's snowing too:-D . Fortunately the good Lord has provided me with a shop that I can keep warm and tear these carbs apart. Thanks for all the great advice. Keep it coming. I did get the chance to try blowing through those vent tubes. Now what happened confused me a little. Gas started running out the air box vent off the bottom. That didn't make any sense to me, but I don't know engines. All the advice about the gaskets and o rings seems like I should replace almost any that I come in contact with as they may wear out shortly even if their not bad now. Sad thing is, I wanted to spend this winter working on the appearance of the bike, but no use working on that if it's not even running. Thanks again for all the advice .

 

[tomo]

Shame that little trick did`nt work, though in hindsight I missed the fact the bike had been stood a couple of years. If there was petrol in the bowls chances are the carbs are gummed up and need a good clean out. Most of the bikes I`ve got going this way have only been stood a couple of days. Still, worth remembering though, I have no idea why it works but it usually has for me, and has helped another guy on this forum too !. Check out my posting in technical tips. Best of luck anyway, hope you get it started. Oh, one of the other guys mentioned checking the power to the coils, I back that up !. My own GS750 decided one day it was not going to start. The breather trick did`nt work, I stripped the carbs, checked out the ignition, was getting fuel and spark at the plugs but still no luck. Going back to basics, tried wiring the coils direct to the battery and hey presto, she fired up and ran great !. Best of luck !.

 

[t3rmin]

Wow, It turned cold here in WV overnight. Now it's snowing too:-D . Fortunately the good Lord has provided me with a shop that I can keep warm and tear these carbs apart. Thanks for all the great advice. Keep it coming. I did get the chance to try blowing through those vent tubes. Now what happened confused me a little. Gas started running out the air box vent off the bottom. That didn't make any sense to me, but I don't know engines. All the advice about the gaskets and o rings seems like I should replace almost any that I come in contact with as they may wear out shortly even if their not bad now. Sad thing is, I wanted to spend this winter working on the appearance of the bike, but no use working on that if it's not even running. Thanks again for all the advice .

Those hoses vent into the float bowls AFAIK. Blow hard enough and gas will probably come out somewhere. ;-)

 

[t3rmin]

Also, to add to previously-given advice, I use an old egg carton to keep the little carb parts organized as I'm rebuilding. Much better than lumping everything in a jar or something.

Just get an o-ring kit from Robert Barr:
http://www.cycleorings.com/

Some float bowl gaskets from z1enterprises.com (if you need them)...

Lots of spray carb cleaner, a bucket of dip, etc...

and go to town. Rebuilding carbs is not all that hard -- putting them back on the bike is the hard part...

 

[salty_monk]

Take lots of digital pictures as you pull it apart... v useful on re-assembly.

Dan

 

[Poot]

egg cartons are a must! so useful and cheap too. robert barr is the way to go.


once you clean your carbs, and and are about to put the airbox back on, suck on the vacuum line on the petcock (the thin one) to fill your bowls. then use a mister to spray one or two shots (misted shots...) of gas into each carb tunnel, as it will make the bike turn over. if fuels in the bowls, then it should work.

helped me at least


POOT