Just about given up

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Marcfab33

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I've been reading this forum for about a month now. I've tried just about everything on this site so far but my bike still won't work.

I have a 1979 xs400e (I think). All original everything. It was given to me after sitting for almost a year in the sun. I had ridden it and it ran great before it sat. I cleaned out all the crappy gas and changed the oil and battery. Put new spark plugs. Cleaned the oil screen and took the carbs apart and cleaned them well. I honestly have now cleaned them 7 times. Once boiled in vinegar. Compressed air blasted every bit. Checked every hole and needle. The diaphragms were in great shape. And nothing leaks. I readjusted the valves. Re-gapped the pionts. Set the timing, static and by light. Synced the carbs with a home made manometer(Gatorade bottles and blue water). I started it many times and it idled great but at 4000 rpm it collapsed and came back to idle.

I re checked everything. Someone blamed it on the float height. I had them both set at 27mm(brass floats) I tried to check those with hoses from the bowl and they were both below the seam by more than 3mm. I adjusted them as close as I could to 1mm and tried again. Now I can't touch the throttle without it stalling. Also now it seems to idle super low. I raised the idle a lot and it won't go over 1500 rpm. I'm about to re set the float heights to 27mm and try all over again.
I am extremely frustrated. Any help would be greatly appreciated.
 
I had one experience, I hope its where your at, because I don't remember what else was going on, when this happened.

I remember the bike was running dodgy, I don't remember all the symptoms, but back of my head, the "Italian tune up" was ring thou it. I got it on the side streets, and I don't remember if it was backfiring previous to this trip, but once I got it onto the highway, there a backfire, and it stared running right. and wide open throttle (WOT). If you can post a Youtube video, and give us something to work with.

One of my earlier follies also included the brass floats, and I had one with a hole in it. What was happening then, was I would spend all day getting it to run, put it together, at night, run it, it would test fine, since its night time. I would postpone any other tests, then the next morning, I would not be able to start it. eventually I would hear fluid rattling around the float. I think the Album if you interested shows pics of me testing, and various other issues I have to overcome.
 
Update.
I got new float needles and set the float heights properly. While I was waiting for the float needles to arriveI took the points off and took the timing advance off. Cleaned it well, made sure it worked and put it back on. I put the points back on and re gapped, re timed and put the new needles on. I put the bike back together an voila!! It never started again. How does this happen, it gets a great spark and it gets tons of gas, even floods after trying to start it too long. Is there something I am missing. What moronic thing did I do that I am over looking. I really want to ride this bike but at this point parking it in the middle of traffic sounds more fun.

Please help.
 
Id double check the timing.. What about your battery? Mine went dead on me when I first got my bike started after doing a full rebuild and was messing with the timing and carbs..
 
NewHavenMike said:
Id double check the timing.. What about your battery? Mine went dead on me when I first got my bike started after doing a full rebuild and was messing with the timing and carbs..
Click to expand...
Battery is brand new and I keep it on a trickle when I'm not around. I am checking compression again today. I can't think of anything else. Could it be possible to be "180 out" from when I took the timing advance off? I want to blame it on a timing issue since the carbs worked when I changed the float needles. The spring was dead on the needles hence the revving problems.
 
I can't remember exactly, but there's two wires coming from the points right? One for left and one for right... maybe they're reversed. Even if it was the carbs, you should still be able to get it to kick over if you sprayed some me fluid in the spark plug holes.

That timing unit with the points confused me at first. Because you could move the points and turn the base plate. A lot of room for error but very simple design.
 
yup, that is a common possibility. look at the diagram, at the coils. one will have a different color on the left, compared to right. that is one way to verify that the coils are backwards. or not.
 
arfstrom said:
yup, that is a common possibility. look at the diagram, at the coils. one will have a different color on the left, compared to right. that is one way to verify that the coils are backwards. or not.
Click to expand...
Ok, I'll verify. I dont remember unplugging the points. I think I just let them hang while I did the points advance.
 
Points plugged in correctly, compression is at 132 left and 140 right. Re gapped the sparlk plughs and one was almost touching the tip. I don't know how that happened but I regapped and tested to make sure the piston wasn't hitting for some odd reason. Going to take apart the carbs again just for SERIOUS redundancy. Checking valve clearances today. I think I should check to see the output of the coils also. I took them off and cleaned every connection. Also plan on checking all the grounds and wires on the entire thing.
 
Plugs could just be very old? What do the sparks look like? If the sparks are brown/orange and small then I'd start with getting new, correct plugs.
 
Everyone with these old bikes have re-done the carbs minimum of 3 times before its good to run. I did the vinegar boiling method. some who have done it in one shot, cheated and had it ultrasonically cleaned, (I am just jealous).

So Compression is fine, which means you valves should be fine, Always start with the pilot jet to 3 turns. once its running, you can choke it down if need be. (I suspect for elevation consideration) Remember that is the one jet that can break off if you tighten it down too much. so don't.

Double check for leaks in your floats. you can have a leak soo small, you will never see it. So take it in to the kitchen, and hold under some water. Have a maker handy to mark the hole. A cheap way to fix it, is to put solder on it. I didn't do that right. so I went to the bone yard near me. (sportswheels.com) i think jordan MN.
in the manual it talks about the float height, and using plastic tubes from the fuel bowl drain, and verify that the height is right,(see pic in Manual) download from the Garage forum (one of the sticky top 3 threads)
 
I need to make a correction to the last post. He states turning the pilot jets 3 turns out. You actually turn the idle mix screws 3 turns out. The jets should be snug tight. I say this because people in the past have loosened the jets because of these type statements. How about a few pics of this bike. Seeing what you are working with may help us.
 
My first start only happened after I blocked the air intake with my hand. I had podfilters, but they fell off and for some reason I thought that would work. Maybe if your airfilters are custom they are not providing enough resistance?
It only ran on one cylinder so I cleaned my carbs over and over, and I finally found that in one of the jets (I think the main jet) I missed a tiny hole in the end which was corroded shut, that did the trick.
 
Marcfab33 said:
Update.
I got new float needles and set the float heights properly. While I was waiting for the float needles to arriveI took the points off and took the timing advance off. Cleaned it well, made sure it worked and put it back on. I put the points back on and re gapped, re timed and put the new needles on. I put the bike back together an voila!! It never started again. How does this happen, it gets a great spark and it gets tons of gas, even floods after trying to start it too long. Is there something I am missing. What moronic thing did I do that I am over looking. I really want to ride this bike but at this point parking it in the middle of traffic sounds more fun.

Please help.
Click to expand...
Are you sure that you wired the point's to the correct ignition coil's, it's easily done, as I've done it a few times myself, then kicked my own ass, for such a simple mistake!

Merlin
 
I have new plugs in. Now I re did the valve heights. Left piston( lower compression) had super tight valves. That was fixed. Had to drill and tap the oil drain plug. Oil had gas in it. Guessing the constant trying to start it caused this. I did the float check with the hoses on the floats. Tomorrow I will re do the carbs. I have the original airboxes. I will be careful with the mix screws, I've noticed this comment over and over on this forum. I'm guessing this is a common mistake. Maybe I'm dumb but how would I make sure the points are wired correctly?
 
What air filters did you have? You should post a few pics of your bike. This can help us see what you are working with.
 

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