mdsims

like i said before, with proper operating techniques such as turning the fuel valve to the off position when not riding the bike (just as all MSF instructors teach) there is no harm to having a manual petcock. I do agree, the danger is when people forget to turn that valve after riding the bike so it is much easier to just have the vac petcock and thus the peace of mind.

harm? not at all. extra and perhaps unnecessary work? possibly. just remember to turn it to off when the bike sits for a period of time. my vac one hasn't bothered me at all. did take some getting used to when removing the tank because the stock vac line was very short. new carb boots and vac lines about 2 months ago solved that problem. what exactly is wrong with it?

adjust your points, that may very well fix the hard to start issue. That's what was up with my 77 xs400. I also fully rebuilt my carbs and added an inline fuel filter between the tank and carbs. A little piece of mind, that way I'm sure what's going on in the carbs...nice and clean now. Post up a picture of your xs

http://slo.craigslist.org/mcy/1268834864.html ran across this gem today. Looks like a steal to me

Totally welcome! I'm pretty sure our bikes share the same wheels and thus require tubes. Hope the bike rides better after the swap!

see one of drewps previous posts, he runs the same as you, 90/90-18. That size tire will be fine for the front. I'd suggest getting new tubes every time you change tires. They are too cheap and too important not to change ($6.00/each). As for not needing to run tubes, yes you SHOULD run tubes. The tire may say tubeless but unless the wheel itself says tubeless you need to run them. Tubeless rims are made with different lip shapes to help a tire bead hold on the wheel better.

x2 on checking the bearings. Smaller tires alone won't cause a wobble but they do have an effect on performance, acceleration, rpm ranges (power band), top speed, etc. A 90/90-18 is even small as a front tire. 100/90-18 is where the front should be per spec. Running the smaller front tire is also going to cause your speedometer to be inaccurate.

hahaha, there's your problem! spec for your bike's rear is closest to 110/90-18, If my memory serves me. That is roughly a 2" difference in overall diameter. Effectively, you've changed the final drive ratio of your bike. At 70mph, what do your rpm's look like? Seems like it could be an alignment or balancing issue as well. I'd also suggest using a very small amount of rear brake to help you get out of that wobble zone safely.

Maybe you hurt the battery but I suspect everything is just fine. If the battery voltage is too low, the relays that work the turn signals won't break back and forth and thus the lights stay on full time. After you charge the battery that problem should go away.

Is this true? Something you witnessed firsthand? I haven't purchased anything directly from Mikesxs.com but I have had a decent amount of contact with Michael "Mercury" Morse over at 650central.com and that guy is pretty awesome. He's a fountain of information and more than willing to help with any of my issues. He answered all my questions until I was satisfied and knew full well I was riding an xs 400. Best part is, he's only 100 miles away. Back on topic - This is what I just did for my front brake troubles: 11mm XS Performance master cylinder (~12.1:1 ratio), slimline and lightweight Vesrah sintered pads Caliper rebuild kit New caliper piston braided stainless line Eventually I may get a nice new drilled stainless rotor, but for now this should make a world of difference for the bike. Turns out the rear disk on a 650 is the same as the front on the 400. Maybe once I strip the bike down and start chopping into the frame, rebuilding the front end and powder coating the wheels, well...maybe then I'll buy that shiny new front disc. Either that or graft a modern superbike setup onto the right side and make a custom mount for a 4 piston caliper. Endless possibilities really.

what kind of oil are u running?

who does this bike belong to? and why all the drilled out material?

The oil light will ALWAYS come on after you shut down the engine, least on my 77. It's a low oil pressure indicator and an off engine has no pressure. it's when that light turns on and the engine IS running that you start to have problems and risk seizing the engine. Either way, that sound doesn't sound very pleasant.

oh wow, that stuff is cool. worth looking into.

http://www.mikesxs.net/products-27.html#products 2nd one down, item #14-0901 Is there any reason why this wouldn't work on my 77 xs400? I sent MikesXS a couple emails and they said they have no way of knowing if it'd work. The next step would be to contact the manufacturer and ask you guys here. If the advance assemblies are the same, I think this kit should work fine. This is something I'm looking to do eventually, not immediately. matt

a clicking relay tends to be a good thing more times than not. If it's one click and then nothing I'd put money on it being a wiring short somewhere along the line. The power wires tend to fray right where they bend to go into the hollow threaded rod. The lack of a ground can happen anywhere in the circuit. I'd check the ring terminals that attach to the bolt, sometimes they can pull loose and separate. Like I said before, I rewired the whole rear end just to be sure I found all the shorts. nothing worse than fixing it now and than having to fix another spot in a week. Keep us updated.

Also, when you engage the blinkers, can you hear the relay clicking over. Maybe just one loud click?

Same thing happened to me, however only the front light would turn on, rear wouldn't, and no blinking. The problem was in the frayed wires and lack of a consistent ground. So I took the rear blinkers off, completely rewired them down to the sockets. All my connections were soldiered, wrapped, heat shrink tubed. Doing this fixed one side of the bike but the other still had issues. I traced it to the seam between the blinker housing and extension rod. It was loose and since the grounding runs through the metal housing itself, I was getting poor conductivity. A small stitch weld, on the bottom of the blinker, joining the 2 parts of the assembly fixed that right up. Cosmetically it is unnoticeable. I'm not concerned as I have bigger plans for the rear of the bike anyhow.

so I can run tubeless tires with tubes and be fine?

My bike is a 2A2...the local shop I called said that they think the cast xs wheels can be ran tubeless so they'll try it, see if they will hold air, and run my tires tubed if needed. I went with the dunlop 404's. After taxes, old tire disposal fee and everything else they will be $170 otd, free mount/balance

I searched the forum and still have a question: So it's time for new tires. I was looking at the Dunlop 404 series. My 77 xs 400 has the cast alloy wheels. By the age of the bike I'd assume they came from the factory tubed but since they are not spoked wheels can I run my tires tubeless? I found the tires I wanted to get but it seems that I'm left more confused. Here are the tires I was looking at: Rear: http://www.motorcycle-superstore.com/3/31/...-Rear-Tire.aspx Front: http://www.motorcycle-superstore.com/3/31/...Front-Tire.aspx both are bias ply tubeless. Can I run these tires as is or must I run them with tubes?

It runs!! and I rode it around the block for a bit. I adjusted the float to 26.5mm and the thing still idles very high. I used the idle adjustment screw once it was warmed up and i slowly backed it all the way out with not much change in idle speed at all. There are times where the bike will idle around 1800rpm but the second she gets any throttle, she'll rev back up north of 3500. other than that the engine sounds great, the mixture seems not too rich, not too lean, pleanty of power when you open her up. Just this darn high idle. any suggestions? and I rewired the tail light and winkers due to some frayed wiring, works wonderfully now.

In addition, sometimes the engine forces air back through the carb. I just got it to idle down to roughly 1600-2000 rpm. when I go to tun on the lights, then engine bogs down, slows, sputters a bit and tries to die. It's quite odd. the engine seems like it wants to run, but something just isnt set rightor there is something I'm missing.

So I checked the float levels. I measured and they were quite low, 24mm, so I adjusted per the haynes manual (to 32 +- 1mm) and set mine at 31mm. Now I can't even get the bike to start. Seems like I'm fighting this beast at every step.

Bike: 77 xs400 Just got the carb rebuild kits in the mail so I put everything back together, threw the tank on and she started up first kick. sounded good, even firing. was running high though, about 4500 rpm. I figured it was just blowing through some extra fuel and getting warmed up and would tame down once warm. no such luck. not sure what that means or what I could do to fix that. any opinions? also, upon reassembly of the carbs, the choke rod no longer holds in the out position. it used to have two positions, in and out. now if I pull it out and let go, it just springs back in. maybe I missed something when reassembling the carbs?