Newbie Problem

[topherbarnett]

Hey gang, just wanted to thank you for the fantastic site and all the info I've already learned. I am new to bikes and just got my 1978 GS-550 the other day. I had a '76 Honda CB750 that I worked on before, but never got to ride, so I'm not a complete moron when it comes to mechanics, but it's still pretty fresh.

With that said...I have a problem and cannot seem to find anything quite like it on the boards.

I bought the bike 3 days ago. It ran well with no apparent problems. Yesterday I go to fire it up and it really does not want to. I give it full choke and it cranks fine, but a few seconds later it putters and stalls. After a while of doing the same thing, I finally get her to run but the revs would jump pretty high, drop, and the bike would die. I assumed that was the choke, but turning it off just a little would make it die. this went on for maybe 30 minutes. Then one of the times (maybe because it had warmed up) I finally got the choke off and she ran, but started backfiring like crazy out the exhaust. I know it is running very rich because I can smell it out the exhaust and the plugs are dark.

I know it didn't get ridden all that often and it probably needs the carbs adjusted. I have the manual, so I guess I can start there. What I'm so perplexed about is why it ran fine one day and wouldn't the next.

Thanks in advance and let me know if I need to include more info.

[hampshirehog]

Hi and welcome to the nuthouse (?).
There are 2 must do jobs on any new GS - check / re-set the valve clearances and strip and clean (completely strip and clean) the carbs and replace the rubber o rings between the carbs and the head.

If you don't do both you'll sure as eggs end up chasing your tail. There are good tutorials on Basscliff's site - he'll be along for your official welcome I'm sure and will point you in the right direction.

Great bike the 8V 550 by the way - when it's sorted rev the pants off it, that's what they thrive on.

[topherbarnett]

Thanks for the welcome. While I'm at it, I have another probably really dumb question:

Is gas going to spill everywhere when I pull the fuel line off the gas tank? Is there a proper order to take off the vacuum line/fuel line/carb drain?

[waterman]

Welcome to the GSR. As for the gas lines, shouldn't matter which way they come off, the vacuum will disapear after motor quits spinning. The gasoline should not be flowing from the tank unless the petcock is in the prime position. If it is still flowing with petcock on or in reserve, then the petcock needs attention (replacement). You should only encounter the gas that is in the lines. I will warn you that when you remove carbs, the gas will flow out of vent lines and everywhere else when turning them over. Please consider this if working in a nonventilated space.

[nisom512]

Thanks for the welcome. While I'm at it, I have another probably really dumb question:

Is gas going to spill everywhere when I pull the fuel line off the gas tank? Is there a proper order to take off the vacuum line/fuel line/carb drain?

That is really funny because the EXACT same thing happened to me when I got mine back home. I had my buddy drive it back for me(I had no permit) and once he got it back it would start but later that night once it cooled off the thing wouldnt start for the life of me. it would do the same thing rev all funny and not run.

So with the help from the forums I got my carbs off and took them apart to find a broken float post(yippy!!!) i didnt know what to do I knew the JB weld that was on it would not work a second time if it didnt work the first so I went on Fleebay and bought another set for $50 then cleaned thos and put them on.

then after a season of riding it still seamed that I the bike didnt run right so I cleaned them again and found a bunch more stuff to clean that I missed.

Finally after a second season this winter I have them off again and found this great link http://www.thegsresources.com/gs_carbrebuild.htm that helped me a lot seeing as how I tought me self how to clean them out and thought I did a good job......what a joke.
I also ordered these finally this year. http://cycleorings.com/

I would suggest the same. and I know lots of people say "look at bass cliffs website" But please actually scan over his site with a fine come cause there is a lot of good info on there that would have answered a lot of questions.

Also Find Steve(actual user name) on here for a spead sheet on doing valve clearances.

Good luck
Jake

[drhach]

Welcome to the board. Just to clarify, you said, "it ran well, with no apparent problems". Does that mean that everything was fine three days ago and that this just popped up, or that you didn't catch the problems in the first place? The solution is probably the same but I was just wondering.

One theory I've developed is that these bikes get "parked" because they start to run poorly due to the need for regular valve adjustment. Most people don't realize that regular maintenance is not just necessary but mandatory. They ride the bikes for a while and slowly the bike gets harder to start and just doesn't run as well as it did. so they park it rather than trying to fix it. Or, they try to fix it and make it worse (usually they go right for the carburettors). Once the bikes sit for a while, the carburettors get gummed and rubber seals deteriorate making it even worse for the next guy. It's funny but regular use seems to be the thing makes these bikes last even longer. The valves get adjusted, circulating oil keeps the seals swollen and sealed, gas doesn't turn to gummy varnish etc. Just theory.

[Steve]

Also Find Steve(actual user name) on here for a spead sheet on doing valve clearances.

Good luck
Jake

Here, I'll make it easy to find me.

Toss an e-mail my way (click on my name for the address) and I'll send you a spreadsheet.

.

[topherbarnett]

Well, I must have missed something. The guy I bought it from said that the carbs needed to be adjusted (which I took to mean synch'd) and that it would backfire every now and then (also sync or valve adjust).

He cranked it cold right in front of me and on the second kick it fired right up. I gave it a thorough check and he gave it a spin up and down the road and I didn't catch anything that was alarming. It did the same later that day when I got it home and was toying around on it. Come to think of it...I'm not sure the choke was ever disengaged though...maybe that's why I never heard the backfire until day 2 when I had to release the choke??

Thanks again fellas.

[BassCliff]

Greetings and Salutations!

Hi Mr. topherbarnett,

Please click here for your mega-welcome, chock full of tips, suggestions, links to vendors, and other information. Then feel free to visit my little BikeCliff website where I've been collecting the wisdom of this generous community. Don't forget, we like pictures! Not you, your bike!


Thank you for your indulgence,

BassCliff

[nisom512]

Here, I'll make it easy to find me.

Toss an e-mail my way (click on my name for the address) and I'll send you a spreadsheet.

.

Man your a funny guy.