grusvag

Progress Report: Bike now starts on first kick! (electric starter needs to be replaced) and idles not horribly. Here's what I did: 1. New battery 2. New plugs 3. Fresh 93 octane fuel 4. Rudimentary cleaning of carburetor (not sure this was really necessary) 5. Set electronic ignition timing 6. Adjusted valves (I think this was the real key and I noticed a big improvement after I did this) So now it starts, dare I say, easily and idles without fear of stalling around 1,500 (I know that's still a little high but I'm still a little gun shy). Still feels like it has no power (it is, after all only a 400cc and I'm a big guy) which I'm attributing to the carburetors. It hesitates at certain throttle openings and just feels "flat". Still planning on rebuilding the carbs but I also suspect that they might not be perfectly balanced. Not sure that's ever been done since I've had it. So there you go. Lessons learned: 1. A fresh battery is a great thing. 2. Set timing. 3. Adjust valves. All for now.

Thanks for your patience. Ran positive power to the big lead going to the starter and negative to a fin on the engine. Nothing. Dead as a doorknob. Looks like I need a starter. Will post my results.

Clip what to an engine fin? What does the other end of the lead go to? Directly to the starter after I take the cover off?

Forgive me for being dense... I ran a jumper from the battery positive terminal to the post on the solenoid that also has the fat black wire going to the starter - so I assume I'm sending positive current directly to the starter. Nothing happened. I also assume from what you're saying that I also need to run another jumper from either any ground on the bike or the frame or from the negative terminal on the battery also directly to the starter? Where do I make the negative attachment on the starter? Do I have to take the cover off the starter and find a negative terminal on the starter? By the way drewpy, your XS400 looks gorgeous! Wow - looks absolutely perfect! Very nice.

From the wiring diagram it appears as if the fat black lead to the starter supplies positive power and the starter is grounded probably from it's mounting on the engine. I ran a jumper from ground to the post on the solenoid that the fat black wire going to the starter is attached. Nothing. My guess is that this wire needs to be energized with positive power in order for the starter to turn but I wanted to double-check here before trying that and possibly frying something. I think I need to run the jumper from the positive battery post to the post on the solenoid that goes to the starter. Am I correct?

Thanks everyone. Will let you all know how it goes when I get this done. Will probably be a few weeks and I might have a few questions once I get into it. Wish me luck!

I'm going to clean the bits using carburetor cleaner. Probably the same stuff over there, but here it comes in a gallon can with a strainer. Cheap. Put the parts in the basket and let them soak. Has always done a great job for me in the past! Since I've never completely disassembled carburetors before I'll have to go slowly, take good notes and maybe even photograph the process so I can put the thing back together the same way they came apart! Thanks drewpy.

The solenoid clicks when the starter button is pressed. I assume that means the solenoid is good. If the solenoid is good do I then need to remove the starter motor itself and check brush lengths as you suggest?

1979 XS400 Working through a bunch of issues on this bike that's been sitting for about a year and a half and would love to get the electric starter working again. Can anyone suggest a troubleshooting checklist? 1. New battery. Check. 2. ?

Looks like I have a different carb than the one illustrated. Here's a shot of a pair identical to the ones on my bike. I bought these to rebuild - do you like all the overspray on them?! Kind of hard to screw up the routing on the carb on on mine. I think I like yoda's idea best. Just lean! ;-)

Progress Report: -checked and cleaned petcock filter (a few flakes of tank paint on it but otherwise clean) -adjusted valves. One makes noise now so I need to recheck them but it seems to run smoother now. -reset electronic ignition timing. Definitely runs more smoothly and dare I say, even starts easier?! Still won't start without taking the air filters off and shooting some starting fluid in there but on the whole it does seem to start more easily. Idles better too. Once it was warmed up I pulled the choke in and out and didn't notice a difference which leads me to suspect they're not working or doing what they're supposed to. So a carb rebuild is definitely needed. Drewpy, I have a compressor. Are you simply suggesting I use compressed air to blow out and clean various parts of the carburetor? Maybe I'll look into having the parts cleaned ultrasonically though I'm not really familiar with who would do something like that. A machine shop? Next will be trying to diagnose the electric starter and get that working too. After watching "The Long Way Round" my wife now wants to go for her license!

Routed it as suggested. Didn't fix it completely, revs still climb slightly when bars are at full lock to the right but it's good enough that I think I'm not going to worry about. Got enough other tasks to keep me occupied for now. PS: What do you mean Goff that "it could be on the wrong way round INSIDE the switchgear"? Do you mean wrong way round on the bar end or the carb end? Not sure what you mean. Anyway, here's how it's routed now which is much better:

Yea, I was afraid someone was going to say that. Oh well, I actually just picked up a pair of spare carbs so guess I'll buy a rebuild kit and have a go at it! Might use a can of dip-and-dunk carb cleaner instead of the ultrasonic method.

Don't know how much you'll be able to see from these but here you go. I can take the tank off to show you where that end goes too. http://www.wynnphoto.com/Images/Yam3833.JPG Revs don't go to redline but from idle (1500 - 2000) when bars are turned to full lock (right only) they climb to about 5000. Revs climb only in one direction, to the right.

Ok gang, I'm trying to get my 1979 XS400SG running again and here's one of the things I need to sort out: I recently installed a new battery and cleaned the carbs out. I need to check / reset the basic idle but that being said, the bike is very hard to start when cold. So far, the only way I can get it started is to squirt copius amounts of starting fluid in the carbs with the air cleaners removed. Once the engine fires I have to keep the revs up fairly high or it will stall. After letting it warm up for a while I can very gradually drop the revs down, by a combination of putting the choke back in and turning in the throttle adjuster near the hand control. Even then it's somewhat erratic and won't hold a steady idle too well. Part of my problem seems to be with the cable itself but this is not the cause of the problem, only something else I have to solve. Tank has fresh 93 octane fuel in it and new spark plugs. Can anyone recommend a troubleshooting checklist for me to work through to try to figure this out? I wonder if the carbs need to be cleaned better or more thoroughly. I'm not too familiar with the inner workings of carburetors and had a friend help me partially disassemble mine. He thought the insides looked pretty clean but I'm sure we took out all of the jets. -John.

Couldn't find any good diagrams or photos in either of my manuals showing exactly where the throttle cable should be routed. Can I post a picture of how mine is routed for you to see? Also, I replaced the bars with flatter ones along with replacing the throttle cable. If anything it looks too long, but I just don't know.

1979 XS400SG, new throttle cable. Problem is that when the bike is turned the revs climb! Not good. It's worse in one direction and at full lock. I think it's a modern cable with a plastic sheath inside so I understand it's not a good idea to lubricate inside those. Not sure if the cable needs to be clamped or secured somewhere in the middle. Any ideas?

Thanks man.

Once you take the cover off is that where the cam marks are? It's all in the same area? And finally, is there any problem with oil flying out of there while the bike's running?

Can anyone tell me the procedure for setting the ignition timing on a 79 XS400SG with electronic ignition? Thanks.