1980 XS400 SG Firing on one cylinder.

[jacjr]

First off i would like to say hello to you all.

I have a 1980 XS400 SG its been sitting for about 4 years untouched in a shed. last week i tried to start it up and it was dumping gas out of the carb so i had a friend check it out and pressure test it, and fix the leaking issue. he replaced a needle, adjusted the float level to standard and i believe he said he replaced an o-ring. Today i got the carb back hooked it all back up and fired the bike up. At first it didn't want to stay running but after awhile it was fine until you tried to ride it. i put it in first and go to let out the clutch and just cut out. the left side was warmer that cold but barely and the exhaust was ice cold. I don't want to take it back to my friend if i don't absolutely need to he has his own shop and is slammed with work.

I got spark from the plug but i am no good with carburetors so i was wonder what steps I should take so I don't wind up doing something COMPLETELY unnecessary, all help is welcome and appreciated!


Thanks - John

 

[willem]

Sounds like your floats were stuck due to very dirty carbs. Yes your friend probably replaced the float needle O rings, these get a bit tight over time. It does sound like the carbs need to come apart again to get them fully cleaned, your friend probably missed some small passages in there. I think nearly all of us did that when cleaning our carbs at one point.

But first, check your air filter. Then try to idle the bike for a while, sometimes just running the bike for a while beats the spiders out the engine. Check your petcock and install an inline fuel filter.

If you've done all that, and it's not running well yet, open up the carbs and clean, clean, clean. Boil them in lemon juice or vinegar, or ultrasonic clean them. Then probe through all the passages with very fine wire or guitar string (seriously, get REALLY thin wire). Make sure you get all the passages, also the ones on the air intake side. Check all openings with compressed air, or blow WD40 through them. Check your diaphragms for tears.

Good luck

 

[arfstrom]

I got spark from the plug

I know you said that you had spark, I found that a set of new wires, plugs, and caps fixed my problem, This is the plug the site has been promoting, with a NGK cap, and new wires.
http://www.oreillyauto.com/site/c/detail/NGK1/5534.oap
look up 5534 on one of the search bars, or spark, and you will get hundred or more possible suggestions.

 

[jacjr]

Sounds like your floats were stuck due to very dirty carbs. Yes your friend probably replaced the float needle O rings, these get a bit tight over time. It does sound like the carbs need to come apart again to get them fully cleaned, your friend probably missed some small passages in there. I think nearly all of us did that when cleaning our carbs at one point.

But first, check your air filter. Then try to idle the bike for a while, sometimes just running the bike for a while beats the spiders out the engine. Check your petcock and install an inline fuel filter.

If you've done all that, and it's not running well yet, open up the carbs and clean, clean, clean. Boil them in lemon juice or vinegar, or ultrasonic clean them. Then probe through all the passages with very fine wire or guitar string (seriously, get REALLY thin wire). Make sure you get all the passages, also the ones on the air intake side. Check all openings with compressed air, or blow WD40 through them. Check your diaphragms for tears.

Good luck

Thanks willem. I'll start with the air filters, I'm probably to do away with the P.O.S. at this point they are probably in terrible condition anyway so I'll see what i can do. honestly im just trying to get the bike rideable so i can sell it.

not trying to give to much info here but I'm having a rough go money wise, and the bike has been sitting and theres no point in wasting something that someone else might love ya know.

 

[willem]

Well, cleaning carbs is free And air filters can often be salvaged by cleaning them out with some hot water and soap.

Good luck, and don't forget to put it up in the classifieds here as well when you get it running. You're right about not wasting a good XS.

 

[jacjr]

So after talking to me dad about my money trouble... i show him this website and he starts looking at the Yamaha customs forum so now he wants to make a bobber out of the bike so were not gonna sell it but when we get out fund up together were going to do a father son project! so watch out for my thread when we finally start getting some parts together

 

[willem]

awesome! have fun with father son bonding times