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New guy, new build

Discussion in 'The Garage' started by sandmanred, Oct 30, 2018.

  1. sandmanred

    sandmanred XS400 Enthusiast

    Just picked up a 78 XS400. Wasn't running when I got but but has been inside most of its life so everything is pretty clean for a 40 year old machine. The carb rebuild section in tech was extremely helpful getting through the carbs. It took a few tries but I finally got them cleaned up and mostly dialed in. Points were badly worn so at first only the left cylinder fired. I ordered new ones but cleaned up the old ones good enough to get back into to time.

    The PO thought the clutch cable was shot. After popping the cover off it just appeared to badly out of adjustment. So I adjusted and went for test ride. 3 minutes into the ride the clutch started slipping so bad I barely made it home. I'd changed oil due to all the gas from the bad carbs and I first blamed the slip on modern oil so i decided to change to the Rotella T6 (thanks again for the tip forum) and figure as long as the oil was out I take a peek at the clutch.

    About 1/5 of all the friction pads have fallen off. Looks like it sat dry for a long time and blew up when the bike got moved for the first time in a long time. Once all the flakes the cleared I was able to adjust the clutch cable back to where it started. I cleaned the flakes out of the areas I can see from right cover off and in the sump. I also removed and checked the oil pump inlet. One chip had actually made it through the sump and was lodged in the inlet to the oil pump due to the sump screen sagging over time enough to let one pass. According to dash oil pressure light I never lost pressure. I just hope I found them all. I've reassembled the sump with the screen in the correct position and will check it for position after the clutch is re-assembled but before I refill with oil. The screen had lost it's shape a bit and created a gap that allowed a chip to pass.

    Anyone ever see the same sag in the sump screen? Or figure out where to find a replacement? I got a feeling the rubber in the rim of the screen didn't agree with all the gas in the oil from the leaky carb so I'm hoping as the gas dries out that it will hold it's shape better.

    The steel clutch plates clean up pretty good by lapping on a plate of glass with mineral oil and sheet of 600 grit sandpaper. The friction plates are on order from MikesXS. The bike had only 11,000 miles clocked and I had some doubts about that but where the friction pads are still intact the caliper is exactly 3.0 mm so I'm more inclined to believe the odometer.

    Anyways once it's all running good I plan to make a cafe racer. Plan is to put a loop on the end of the frame and fab a new tank, seat, side covers and tail cone.

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  2. xschris

    xschris a lifestyle not a trend

    The later 81-82 sohc xs400 bikes used the upgraded sump filter which seals much better then the old rubber peg type. I run them on all my bikes. Your bike looks like it would make a nice resto project. Not many people doing that with these bikes.
     

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    sandmanred likes this.
  3. BBS360

    BBS360 XS400 Guru

    Welcome to the forum.
    Looks like a nice machine. Good work on the clutch.
    Looking forward to seeing whatever you do with it.
     
  4. sandmanred

    sandmanred XS400 Enthusiast

    Good to know, thanks. Is there a parts house that sells them? I checked Bikebandit and Yamaha Parts Nation but they don't sell them.
     
  5. sandmanred

    sandmanred XS400 Enthusiast

    Thanks. From the few minutes I got to ride I think it's going to be a fun bike.
     
  6. Frankie

    Frankie XS400 Member

    Nice bike, by the way do you know the maximum width for the front tire for that bike?
     
  7. xschris

    xschris a lifestyle not a trend

    I have one one in the pic for sale if you want. I will send you a p.m. on info.
     
  8. spectra

    spectra XS400 Junkie

    Nice and glad you found one with a working rear master..............thats like gold there..........every 78 I see they need a new one and well there obtonium.......
     
  9. sandmanred

    sandmanred XS400 Enthusiast

    I fit a small support for the sagging sump screen. The sag was along the long edge so this should keep it in place.

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  10. xschris

    xschris a lifestyle not a trend

    Be careful as the side facing the front of the motor is where the flow of the oil comes from. With your design it will be restricted. Look up in the sump hole and you will see. These motors run high pressure oil to the shell bearings. Also make sure to replace your gasket and use a bit of grease on each side so when you have to remove it at another time it will come off easy.
     
    sandmanred likes this.
  11. sandmanred

    sandmanred XS400 Enthusiast

    Thanks, I have a whole set of gaskets coming so that one should get replaced soon. I might make a few relief holes in the legs of the support but there are quite a number of large inlets around the perimeter of sump that add up to at least 10x the area of the pump inlet tube that are not being restricted by the support legs. I'm more worried about passing one of the loose friction pads into the oil intake. I found one in throat of the channel that runs to the pump inlet, it somehow got past the sump screen probably due to the sag. I may have missed a chip that I can't see on the other side of the engine case.
     
    Last edited: Nov 1, 2018
  12. sandmanred

    sandmanred XS400 Enthusiast

    How are the brakes on these bikes? For the short rides I took I only applied front brake and it seemed a bit anemic. Of course it hasn't been on the road since 2014 and probably not much from 2010 on. The brake pads are still thick. The rotor looks a little beat up on the inner edge of the outer face. It doesn't have enough miles on it to have gone through a set of pads? I've never had it done but can the rotors be turned to clean them up? Suggestions?

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  13. spectra

    spectra XS400 Junkie

    Well depends if your going to keep the bike or sell it........I just got on ebay and bought 2 new drilled rotors for my 78. you may be able to clean them up but fopr the price new ones are not bad unless your on a budget.
     
    sandmanred likes this.
  14. sandmanred

    sandmanred XS400 Enthusiast

    I'm willing to adjust my budget to provide stopping power. I checked ebay and see after market rotors range wildly in price. Which ones did you get and did you like them?
     
  15. xschris

    xschris a lifestyle not a trend

    Check for thickness of the rotor. New is 5mm. A stainless braided hose will make a big difference in the feel and pressure of your brakes. So getting one would be a must over a 40 year old rubber hose. New pads also would help. Unless your going to race the bike or drive like a crazy person the stock setup will work fine.
     
  16. spectra

    spectra XS400 Junkie


    I have something like this on the 78 front and rear. Also put one on the 81 I am just finishing. Also new pads and also new lines on everything.

    https://www.ebay.com/itm/267mm-Rear...h=item3cfa86350d:g:NSEAAOSweqJbIbpO:rk:7:pf:0
     
  17. xschris

    xschris a lifestyle not a trend

    Keep in mind more holes = less surface area for the brakes to grab. They do weigh less and will cool down faster under greater load but that is for race conditions. I have a cross drilled rotor off a 82 xv 920 and it doesn't work any better than a stock one. Maybe a little worse. I have seen a few of these warp when they get hot as the 5mm thick rotor has been weakened by the drilling. Just some food for thought.
     

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  18. sandmanred

    sandmanred XS400 Enthusiast

    The front fender was cracked beyond repair due to engine vibration. Turns out I had one I fabbed up for a different bike that fit the tire perfectly. It only needed holes re-drilled to hit the mounting bolts on the fork. It's 5052 aluminum polished out. That's the direction I'm headed for the tank and tail cone so why not? Looking at the handle bars next.

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    xschris, motoTrooper and spectra like this.
  19. spectra

    spectra XS400 Junkie

    Sweet but keeping that thing shiny is going to be fun.............
     
  20. motoTrooper

    motoTrooper XS400 Addict

    Nice shaping craft on that fender!
     
    Pettsson likes this.

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