New XS400 Owner. Need Help!

markdtx

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I am a new owner of a 1980 XS400 Special and am happy to be a new member of this community. I need some help getting my bike going though...

First some background info: This is my 2nd bike but I have very little experience actually working on motorcycles because my first bike was a dead reliable Yamaha SR150 that had essentially no problems in the year that I owned and rode it. With this project I want to learn as much as I can.

About the bike: the previous owner had the bike since 1983 and said it was running fine when he last rode it about 6 years ago. After I put in a new battery and some fresh gas, it started right up at the push of the button but had problems idling. After fiddling with the throttle stop screw it idled fine right at around 1200 rpm. However, it seems to be really moody with when it wants to start up, sometimes starting on the first push and sometimes not at all.

I've taken it out for short rides twice but it seems to have some major problems. On acceleration from a dead stop in first gear, it really wants to die and I have to basically give it full throttle to keep it from dying. In every gear and at any engine speed it is massively underpowered and the highest speed I've gotten up to is probably 35mph at about 5K rpm.

I took apart the carbs yesterday to take a look inside but didn't see anything glaringly awry. Admittedly though, I don't know if I would recognize a fault if I saw one.

I changed the oil today and started it up and it seemed to be running well, but then about an hour later I wanted to take it out for a ride but it just would not start up. When I try to start it, aside from the normal sounds there is sometimes a clacking and spinning sound. Another weird thing is that about 80% of the time when it isnt running, I cant change the bike out of neutral and into any other gear.

Oh yeah and a few other things: The left side exhaust seems to be missing a piece in between the muffler and the header pipe so the connection is not airtight even when the tightener is fastened as tight as it goes. Also, I took apart the air boxes to take a look at the air filters and half of one of them has basically disentegrated. Lastly, I took a look at the sparkplugs this morning and one of them looks exactly how it should look and the other one is black and oily.

Any thoughts or suggestions would be greatly appreciated.
 

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Hey, welcome to the forum! Sounds like the side where the spark plug is black and oily is running rich and/or has a blown headgasket. Thats gathering from what I read on here. Unfortunately I dont know all that much and everytime I ask a question all I get is told to do a search. So dont expect too much help, but hopefully if youre able to figure out the terms to search you can find what youre looking for. Good luck!
 
Hi markdtx. welcome! :thumbsup:

I wish I had loads of answers for you, but I'm new on here too. I've found it super helpful and there are some great chaps on here. (and some comedians). haha.

In my experience though, i've gotten loads of help (sorry to hear your experience here liger). you might need to break down your questions into diff areas... but you'll find loads of information on here!

fun project ahead of you!

ps. the search option does seem to work well for me. if you can't find your answer... write a how to. :laugh:
 
Your bike looks like mine, First off to get the bike running "Clean your Carbs" My wifes bike was sitting from 2003 to when I finally started working on it 2010. The fuel turned into enamel on every surface of the carb, so only way to clean the carbs the best is to boil em. Look up the advise on here.
About the bike: the previous owner had the bike since 1983 and said it was running fine when he last rode it about 6 years ago. After I put in a new battery and some fresh gas, it started right up at the push of the button but had problems idling. After fiddling with the throttle stop screw it idled fine right at around 1200 rpm. However, it seems to be really moody with when it wants to start up, sometimes starting on the first push and sometimes not at all.
Screaming dirty carbs.
I've taken it out for short rides twice but it seems to have some major problems. On acceleration from a dead stop in first gear, it really wants to die and I have to basically give it full throttle to keep it from dying. In every gear and at any engine speed it is massively underpowered and the highest speed I've gotten up to is probably 35mph at about 5K rpm.
Carbs, Some of those small tubes for the choke, they just dont get clean by running commercial fuel additives. One person posted they boiled em a second time, for 2 hours and still got scum on top of the water. I was successful after doing both carbs for 20 minutes in lemon juice. Then blow em out with Air, and spray carb cleaner thou all tubes till you get 3 streams from the carb. Find the instructions, (pics and all). Sooner you get a paper inline fuel filter the sooner you count on no debries coming in from the carb, Don't forget to change the brake fluid as well. Sooner you download the manuals, and a parts manual, Listed under Tech on this page Very top bar has everything you should need to get going. Great google resources use your google, If the tech page doesn't answer your questions, All of us have asked the same questions, then another person has re-answered with pics. Soo take your time, Remember your there we cant see what you got, So a lot of us will assume your have the same problem/things as we had.
Which after 30 years, We suspect your charging system is shot, and you will find the fix here. That wont cost more than 3 spools of wire, some Heat-shrink tube, and possibly a new plastic connector, unless you don't destroy yours. New connector blades from www.mikesxs.com forum sponsor.
Lastly, I took a look at the sparkplugs this morning and one of them looks exactly how it should look and the other one is black and oily.

Sounds like you will be doing some Head work soon, I have not done this yet, This winter I am kinda planning chcking that head stuff out.

I changed the oil today and started it up and it seemed to be running well, but then about an hour later I wanted to take it out for a ride but it just would not start up. When I try to start it, aside from the normal sounds there is sometimes a clacking and spinning sound. Another weird thing is that about 80% of the time when it isnt running, I cant change the bike out of neutral and into any other gear.
I have found that changing gears is helpful to move the back tire a little bit. direction doesnt seem to matter, just to move it a little bit. The whole hour thing, is special to Carbs, (one of mine had a hole in it, and after it filled up with fuel starting sucked) so tackle one thing at a time, I enjoy buying things from
http://www.ebay.com/
http://www.powersportsplus.com/
http://www.amazon.com/
http://www.mikesxs.net/
Beyond normal consumables, Oil, filters, Rebuild kits (Carb, both brakes kits,) Take lots of Pics, Its helpful.

Well that was longer than I thought it would be, Have Fun!
 
.... Sooner you get a paper inline fuel filter the sooner you count on no debries coming in from the carb...
Hi, welcome to the Forum. I am new to all this too, but was lucky enough to find a bike which had been properly readied by the PO.
All I have done, besides oil changes and other routine checks and adjustments, is change a sprocket and ad the in-line fuel filter. After reading about boiling carbs multiple times in lemon juice, I figured the longer I could put that off the better I would like it. So far, nearly 8k kms (5k miles) since April with no fuel, carb or plug problems. It costs all of $3 and seems to have been well worth it to me - especially after reading about carbs on here.
Here's the thread I followed:
I wish I knew more and could offer help in different areas, but others do and will. Best of luck.
 
OK so I need some more help.

I took apart the carbs again and this time I got all the jets out and found 2 that were gunked up and got them cleared up with carb cleaner and got the rest of the carbs all cleaned out but now it seems I've got other problems.

Once I put it all back together and tried to start the bike up, instead of starting up, I just hear a really pathetic whirring sound. It seems to be coming from a part under the seat pan near the battery. Then about a minute later, my bike has no power at all. When I put the key in the neutral light doesnt come on or anything. Completely dead.

I tested the battery and its still good. I have no idea whats going on. Can someone please explain this?
 
First thought, Blown fuse. I haven't had a fuse blow for doing a carb cleaning, perhaps your relay got bumped while pulling the carb out. Only thing near the seat pan, is the starter solenoid, and the starter, a little further south, on the battery tray is the Voltage reg, a rectifier, and a battery, 2 relays. So power goes from the battery to the Solenoid, to the fuses. so that brings us to the other 2 things this forum tells us, after cleaning Carbs, Clean the Contacts, Gounds and the positives.

You said the battery is good, but can you tell if the Amps are there? I suspect you can have the volts, then your last bit of amps may be below the minimum amount needed. There are some really brainiacs that have answered this here, I would use my car, and connect it up to a Jumper cables and jump it. If that works then you know the problem, Bad battery, or need of maintenance, (water in the top of the lead stuff in the batteries.) Then you still need to go thou all the main connectors from the - pole on the battery, to the + pole and the main ground next to the battery left side of the battery on the frame, and look for the other ground points.
Good luck -- Tobie
 
Use anything to clean those connectors, Sandpaper, wire brush, Polish it up, and make it shiny. use the sandpaper on the frame to create a new/fresh connection point. Look for any corrosion.
 
Alright so I figured out that there were 2 problems, one was with the starter motor but that's not really a big deal because I'm going to get rid of electric start anyways, and the other problem was with the fuse box. The holders for the main fuse have broken off and right now I just have it stuck together with some clamps.

I bought a little in-line fuse holder from autozone but didnt realize that automotive fuses were larger sized than motorcycle fuses. Would it still work if I just modified the fuse holder a bit to fit the motorcycle fuse?

Anyways, with the old fuse holder jury rigged together I can kickstart the bike up real easy and it does seem to run better now than before but when I open the throttle a little the rpms will jump to about 4000 and stay there for about 3-4 seconds even after i put it back to closed throttle. I'm not really sure what the cause is. Throttle cable? Carbs? Any suggestions?
 
... I can kickstart the bike up real easy and it does seem to run better now than before but when I open the throttle a little the rpms will jump to about 4000 and stay there for about 3-4 seconds even after i put it back to closed throttle. I'm not really sure what the cause is. Throttle cable? Carbs? Any suggestions?
You didn't mention if you had confirmed that there are no leaks in the air intakes. I have read a number of threads on here where a tiny crack in the boots makes the engine run inconsistently.
Apparently, an easy way to test for one is to spray carb cleaner, quick-start or propane on them when the engine is running. If there's a leak, it will get sucked in through the crack and will change the way the bike runs. No change then no leak.
 
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