GaSo

I'd check ebay for the wheels and brake bits...I have no idea how complicated it is to change it over but it can't be that bad if you're a little handy with mechanical bits. Instead of cables and linkage, you'd just have hydraulic hosing. Actually, thinking about it, it sounds like quite a project. Maybe PM duaneage to this thread to answer some questions? I'm wondering where he picked up those handlebars from, I'm not looking forward to trying to make sure all my wires and cables fit a new set correctly, but really want to ditch my stock bars...

I ride pretty conservatively, never noticed the drum brakes being crappy. How hard was it finding a complete set to change over to the disc brakes? I'm in Williamsport, PA (middle of nowhere, PA). Might have to check out those painters if I ever decide to redo my tank, they did a mighty fine job!

Your bike looks like my bike's more beautiful sister: I was too cheap to buy new tank badges, so I just glued and painted over the old flaked chrome Also, you put a lot more effort into making the bike look brand new, holy moly nicely done!!! How do you like those handlebars? They look a little high to me, but that may just be the angle. I hate the stock swept back bars, I find them hard to use and uncomfortable.

If it does turn out to be this seal, I had the same issue and documented the process here: http://www.yamahaclub.com/forums/topic/14526-1981-yamaha-xs400-special-ii-xs400h/page__view__findpost__p__79825

I had a bad gasket under a nylon washer, under a circlip for the butterfly valve rod. Found it by dropping oil onto each of the exposed sections against the carb body, and when the RPMs dropped every time I hit that spot with oil, I knew I found my leak. I strongly agree with Runningdog, WD40 is a good choice for when you're searching all over hells half acre.

Worked a treat. Started about 6" from the top, was rock hard. took one drain screw out, put a tiny bit of weight on it and it shot some oil out, put screw back in, took other screw out, little bit of weight, shot oil, screw back in...now its got a couple inches of soft movement before firming up quickly, feels great. Thanks!

So to control dive when using the front brakes (which I have come to despise) all you have to do is fill it with 20w fork oil to about 6" from the top without following through with the other modifications listed (cause most of that was over my head).

My 81 XS400 had electronics: http://cgi.ebay.com/ebaymotors/1981-Yamaha-XS400-special-rectifier_W0QQcmdZViewItemQQhashZitem3ef97eb32cQQitemZ270473802540QQptZMotorcyclesQ5fPartsQ5fAccessories#ht_500wt_956 Mounts around/under the battery. I replaced that and my battery and I have no charging issues any longer. The holes in the diaphragm will certainly screw things up. The new diaphragms are expensive, so is gambling on whether an ebay special is going to contain a decent set. I'd go by the condition of your carbs in general whether that's a good idea or not. I haven't seen aftermarket carbs for the XS400, just her larger sisters. MikesXS has a lot of parts that will fit in our carbs without issue: http://www.mikesxs.net/products-35.html#products < was vital while I was rebuilding my carbs. EXCELLENT overview of the BS34 carbs on our bikes (while some of the specific jet sizing info may be off, in general this guide is amazing): http://drop.io/jn5sqkc

I'd say the idle screw needs adjusted on the right side. Sounds like it's too rich, so try turning it in a hair. Just my uneducated guess tho

Go to imgur.com, hit browse, select image, hit continue. Right click in the "Message Boards" box and select copy. Right click here and hit paste. Tada!

I got everything from http://www.mikesxs.net/ myself, but I have an 81 with BS34 carbs, so they had a lot of stuff that I could easily verify would work on my bike. The only thing that they didn't have a direct cross for is the needle jet and jet needle, those are slightly larger versions off the XS600. Looking at older years, it seems that they didn't have anything listed for BS34 carbs from before 1980? Maybe just because the XS600 did not use this smaller carb till after 1980? And further wild guesses, the parts listed for the 1980+ BS34 carbs would work on earlier BS34 carbs? (haha, good luck!!!!)

if you just want to get one image on the internet with a minimum of fuss, I highly recommend imgur.com. No registration necessary, free, and crazy simple/easy.

Tom, for reference (at least with my particular machine heh) it runs around 1500 RPM when cold with half-choke, around 900 RPM when cold with no choke. Once it is warmed up, with no choke it runs around 1250 RPM. Very cold (as in, needing full choke for a few seconds) it runs even higher, perhaps 2500 RPM if I remember correctly? Been a few months!

That's amazing! Both versions!!

heh...it could be so many things who knows where to start! how long ago was it last run regularly? I would first guess that you dislodged some junk and it wedged into some bit of the carbs which is essential to starting. Any difference between trying to start it with full, half and no choke? Does the engine at least try to catch on full? It wouldn't hurt to take the carbs off and give them a quick cleaning. Good excuse to begin becoming familiar with them. Also, while you have the seat off, might as well check for blown fuses and loose connections around the fusebox.

Here is a short clip I took at the beginning of the spring after doing a few small things to my bike. Took it with my Canon, it has a terrible mic so I'll take another video with my Sony tomorrow morning. The Canon really makes the highs too loud. Although with whatever muffler this is on my bike, I think it is too loud in general. UPDATE:

wow you've got your work cut out for you... I've got the same bike, thankfully in a bit better shape. All she needed was some carb work and a bit of cleaning... I like the color scheme you've got planned, sounds very sharp!!

Ahh I never came back and followed up on this! I had to find some new washers at the hardware store of an approximately correct outer diameter, and then drill the inner diameter out to fit the bolts. Then mounted them under the existing hardware (on the top side of yoke), tightened everything down and it made an AMAZING difference! Good as new! Sorry for taking so long to follow up...

lol! nice well, you have a happier engine AND now that you've found the source a quieter bike Looking at my center stand I see there isn't any rubber to prevent it from banging around, will have to do something about that myself as well.

Interesting. My bike makes a little noise around 3 to 4k as well, a light clanky noise seemingly irrespective of engine load. I'll have to check my valve clearances as well, thanks for the post and the followup information!

Alright, mine are definitely not correct then! The old rubber didn't look worn in any way. I'll try to throw another washer underneath and/or tighten them further. Calipers measured them about 31.6 mm, the new ones actually seem looser.

So I think my handlebars on my 81 XS400 are pretty sloppy. There are four rubber bushings under the handlebar clamp, and it doesn't seem to matter how tight I make the nut underneath, the handlebars wiggle front to back fairly freely. So, I figured the old rubber must be fatigued, and picked up some new mounts from mike's XS...only to find the new ones even looser...hah... I was wondering if maybe some additional washers under the nut would help tighten down more. I put a short breaker bar on the ratchet to try to get some extra torque. I really don't know what to do other than maybe glue the damn things in. I mean, I can appreciate trying to dampen some vibration, but the amount of movement just looks ridiculous to me. Anyone have any insight or thoughts they could share?

just make sure you're getting the BS34 parts from the same year and you should be fine. I've gotten the butterfly rod seals, float rebuild kits (needle, gasket, etc), jet needle and needle jet and everything fits fine. Since everything is sorta lumped together, just go slow and read the descriptions.

I've also noticed having the idle stop set too high definitely aggravates this. The RPMs don't drop down nearly as quickly when I have the throttle stop set to give me 1500+ when the bike is FULLY warmed and has a warm ambient temperature. Having the idle stop set for 1200 RPM FULLY warmed means that it runs really low on a cold morning with no choke when I first start it, but I usually only warm it up for about 15 seconds or so before driving off (4 seconds full choke, 8 seconds half choke, then no choke with a little throttle and down the driveway I go). This (from your other thread) clued me in (unless you're restarting a warm bike...): Just can't set the idle stop with anything other than a tuned, warmed up bike it seems.

mmm, if that side isn't firing, maybe oil is getting past the rings?