johnsnownw

I'm glad to see you looked into the gas tank, as I was going to mention that you're inline fuel filter seems to have rust in it. Here is what you need to do: 1. Pull the gas tank off and clean and restore the tank. I did this by using electrolysis and the POR-15 motorcycle kit. If you search the forum you will find a discussion detailing my use of this method. 2. The part that you are describing as leaking is called the carb holder or carb boot. You should replace both carb holders. 3. Dismantle the carbs, as they are probably pretty gummed up, not to mention that there is probably rust from the tank in them, despite the fuel filter. This should be your main focus, as you probably shouldn't be riding the bike around with these issues anyway. After completing the above, you can focus on the electrical issues. I would suggest replacing your fuse box, with more up-to-date fuses, but not before checking all your wiring to see if there is an issue. Some have just upgraded their fuse boxes to a newer box that still uses glass fuses. I however replaced all mine with in-line fuse holders that use mini-blade type fuses. Either way check on the electrical system as a whole before attempting the upgrade. The bike looks pretty good, considering it's been sitting around for some time. Good Luck.

Easiest way to find out what exactly it is, would be to perform a search of the engine number. Also, that is an aftermarket paint job, as all Yamaha twins of that era came with raised yamaha emblems on the tank.

Not a problem. I'm still not entirely sure where the leak you have mentioned is, but I commend OllieB for possibly figuring it out. I will say this about carb cleaning. You will need to take the majority of the carbs apart, because there are lots of pieces that contain rubber or plastic. For instance, your butterflies have plastic and rubber, your float assembly has a plastic piece under the float needle, the choke has rubber components and their are rubber washers at the end of your mixture/pilot screws. Therefore, you should probably just do a full dismantle as it's nearly impossible to remove all of the plastic and rubber components otherwise. Because you can't explain the carb/gas issue you are having very well, which is no fault of your own, it would help us tremendously if you could take pictures of what you're talking about, and post them. Anyway, good luck.

Thanks Drewps, I know it's supposed to be LT. However, when moving from LF to LT the intake valve begins to move downward. This is why the adjuster screw on the left side had to be loosened so much more than the right side. I don't know what is causing this issue, but TDC seems to be at "LF" or slightly after. Got me, all I know is after only adjusting the left side differently the whole engine sounds better, and seems to run quite well. I was afraid that adjusting it on LF could cause the valves to be too tight, which is why I adjusted them slightly more loose than spec.

Very nice. That model has not made it to the U.S., quite a shame.

Well, I believe I have the valves figured out. After adjusting them on the LF mark, leaving them a bit loose, the bike sounds great. Well, it did after it didn't. I finished putting in the new spark plug cables, caps, and plugs, and starter her up. However, now there was a loud sound coming from the engine on the left side, almost as though exhaust was escaping. Well, it was, the left header had lost a nut and was quite loose. I was worried before I found the problem because I had just traded a clicking for a much louder pounding sound. So, I bought a new nut and tightened both headers. Problem fixed, and she runs beautifully. Hopefully that's the last of the major repairs/adjustments I will have to do this year (knocks on wood). Thanks for the suggestions everyone.

Welcome. Also, post some pics of the bike. I'll await your next reply, that hopefully has a bit more info about the issues you're facing, before offering any advice--as HoughMade has already asked and indicated the things you need to look at.

Hello, I purchased the gas cap gasket from MikesXS and it's worked very well, seems well made. If you've placed a new battery in the bike, and it won't start up, you may need to look into the cables attached to the battery. Occasionally these rot from the inside, and may be causing the smaller battery to not be able to turn the engine over. I don't think the issue lies with the starter motor, based on what you've mentioned. From your description I cannot tell exactly where the carb is leaking, so I cannot help with that. If you don't keep your air filter stock, you will have to re-jet the carbs, which is probably more work than you want to get into. However, stock filters are not cheap, and will probably cost you between $70-$80 to replace both. I've done extensive work on my XS400, and have ordered many parts from MikesXS and Bikebandit...so feel free to contact me about compatibility. You've inherited a good bike, but it may need a bit of TLC to get it running well.

If I were you I would begin by checking the connections in the headlight. On my bike there are several unused connectors there. I'm not sure that is your only problem, but seems like the best place to start.

It is not normal for your turn signals to be on unless you flip their switch. Nor should they ever stay on without blinking. Which turn signals are on, just the front, or the back or is it the ones on the right side, or the left?

Sorry to hear that, mate. Hope they catch the wanker, and find your bike in good condition.

If you haven't fiddled with the mixture screws on the carbs (top of the carbs) then I would say that is the culprit. However, checking your spark plugs is the best method to see exactly what's going on. Here's a chart to diagnose spark plug deposits: http://www.spark-plugs.co.uk/pages/technical/diagnosis.htm

How fast are you going in that picture? Your posture leads me to believe around 90 or so.

So, I installed Rizoma Zero-11's on my Triumph. Ever since I purchased the bike I have disliked the stock front signals. I know its' not a Yamaha, so many of you may not care, however, if you are looking to put new signals on your bike I would recommend the Rizoma's. They were a breeze to install, and look fantastic. They're also bright as hell, as you can see from this video: (Not my bike btw)

Are you sure you have the mixture screws adjusted properly?

No worries. When I originally tried to adjust them I had to unscrew the LH side a lot to bring it in spec when on LT. So, the fact that TDC is now slightly before LT, kind of makes sense. I still don't understand why though. *shrugs*

Tried that already. Every single time I come up to the LT mark after the LF mark, the intake rocker moves down. It does not do this for the RH side when nearing RT. So I simply turned it to the LF, where the rocker doesn't start to move down and adjusted there. I think somehow, in the 30 years of use, something has come amiss. I mean there is really only an inch between the LF mark and the LT, if that. Thanks for the reply though.

I'm going to do it, I swear! I will start this thing up, unless someone stops me. If I've done something wrong and no one tells me, I'm going to blame you all! Not really. I mean I'm going to start her up, but I won't blame anyone

The only one I find is a Clymer XS360-400 1976-78, published in 1980. http://www.amazon.com/Yamaha-XS360-400cc-Twins-1976-78/dp/0892871709/ref=sr_1_7?ie=UTF8&s=books&qid=1280981610&sr=8-7

Update: So, I decided to fool around with it. When turned to "LF" the rockers had more play in them than when it was on "LT" (Even after I adjusted them on "LT") This doesn't seem like it should happen, as there should never be more play than in TDC or "LT". I'm assuming here so feel free to tell me I'm wrong and am an idiot! So, I decided to adjust the left side on "LF" Now the screw adjusters for the right and left piston look to be at the same height. Meaning that the distance between the lock-nut and adjuster screw top seems to be equal, for both the right and the left valves. I'm going to wait until tomorrow to start her up, but if anyone has any comments on whether I'm about to destroy the engine or not, feel free to post them!

Thanks for that reminder, Bark

Alright, so I ordered a set of new adjusting screws to replace the old ones, because when I adjusted the valves before it didn't seem to work. So here are some questions. I know I'm supposed to adjust the left side valves when on the "LT" mark. However, when I reach the "LF" mark, and continue on to the "LT" mark, the left intake begins to move slightly downward, and continues to do so until I'm at the "LT" mark. When I tried this with the right side valves, the right intake did not move downward as I neared the "RT" mark. Anyone know if this is supposed to occur? Also, if I line up to the "LF" mark, there is free play in both rocker arms, after I've adjusted the valves on the "LT" mark. Is this supposed to happen? Hopefully my questions are not confusing. Edit: I should also mention that the Left intake adjuster screw seems quite a bit higher, that is there is more screw above the lock nut, than on the Right intake.

Thanks, that's what I thought. I was thinking about replacing the wires too. Edit: Just bought the XS 7mm ones. They are yellow, figured the fiance might like yellow.

Oye! I'm going to be replacing the caps when they arrive. I purchased NGK 5k resistance. Was wondering if anyone had any advice on removing the old and replacing them with the new. Are the wire's just screwed into the cap, sort of like when using electrical caps to join two wires together?