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78 XS400 Mach1 Cafe Build

Discussion in 'The Garage' started by Spitfire_X24, Oct 30, 2020.

  1. Since introducing myself in the Lounge, I've made some progress, and figured I'd start a build thread where it belongs, not in the Lounge so here goes...
    This is the bike as I got it.
    Doesn't run, hasn't run in several years, but stored indoors, so it shouldn't be too bad right?
    PO put a set of grips and bar end mirrors on it, cut the rear frame off, bought a seat for it, got rid of the air box and side covers, wrapped the pipes, and lost the key.
    As such this will not be a restoration, my goal is to get it running, get it safe, and get it ride-able, all for under $1000. I paid $400 for it, so buying big fancy "high end" parts for it are off the table with only $600 left to go. I feel like the $600 will go fast, so keeping things simple and minimalist will be key, if it doesn't need it to be running, safe, or ride-able it won't happen. And when I say "ride-able" that is a subjective term. What one person would ride is different from the next.

    The Mach1 in the title refers to my 2003 Mach1. I plan to use it as inspiration for the color scheme and use styling cues from that car.

    Wish me luck.


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  2. The first thing I wanted to know is if it would fire, so I bypassed the ignition switch and sprayed a bit of carb cleaner in the carbs and kicked it over. It fired right up and ran for 3 seconds or so. It's got spark.
    The fuel tank was disconnected and I want to clean the carbs before I get too carried away anyways, so I removed the fuel tank and gave it a shake...full of rust...so I tossed a couple of 3/4" nuts in the tank and kept shaking it to break as much of the loose stuff out before I hit it with the white vinegar, and then the pin holes began to appear. It's full of holes. Looks like I'll need to find another tank...
  3. Went to the the local motorcycle salvage and found a tank in decent shape with no rust in it and only one small dent in it. So I figured I'd mock up the look I'm somewhat going for to get the creative juices flowing. I also dropped the front end a bit and flipped the handlebars over to get a rough visual of the stance with the lines on the tank.
    $400+$60=$460.....$540 left...

    18.jpg 19.jpg
    motoTrooper likes this.
  4. I removed the Carbs and disassembled them. Everything looked to be in nice shape with no broken damaged parts. Gave everything a good cleaning with carb cleaner and made sure all the ports, passages and orifices were clear and reassembled.
    17.jpg 16.jpg 15.jpg
  5. Next up I pulled the harness off and removed the rear wheel assembly, and pulled the engine for cleaning and detailing, and an eventual paint job. 20.jpg 13.jpg 14.jpg
  6. Well, can of worms #2 just showed up...it looked like it was sorta on there good...I mean it didn't fall off previous, as soon as I grabbed it to see how solid it was it came off in my hand. I'm torn about what to do with this, I'd love to fix it properly, as in get a new housing, but that may be cost prohibitive with my budget goals. So, it's nothing structural, it only keeps the end of the housing covering the sprocket from vibrating. If I can do a good job with JB Weld or some other epoxy, I think I'll go that route, as long as it doesn't leak...
    12.jpg 11.jpg
  7. xschris

    xschris XS400 Guru Top Contributor

    Make sure you remove the emulsion tubes (needle jets) and clean them also. New shaft seals? Those need to be replaced. Bad place to have a hole in the case but the oil is not under pressure at that place. Not sure epoxy is going to do it but as long as the oil stays in it you should be ok. I would look for another set of matched cases.
    Last edited: Oct 30, 2020
  8. I pulled the emulsion tubes and cleaned them, there was a lot of crusties in between the tube and the bore so I’m glad I did that. And the shaft seals were nice and soft so I reused them.
    Getting another matched set of cases is not an option at this point with my budget. What epoxy would you recommend? JB Weld?
  9. JPaganel

    JPaganel XS400 Addict

    Looks like a really good place for a TIG weld...

    I'd look around for a welding shop and get a quote. If they weld, and you do the cleanup yourself, might be cheaper than you think.
  10. amc49

    amc49 XS400 Junkie

    X2, oil will eventually leach under the epoxy and why your piece came off in your hand.

    You need a good heliarc guy there, and skills making sure the resulting flat is still flat when done. Gluing that is hack work.
  11. Dang it! Y’all are telling me $h!t I don’t want to hear.
  12. spectra

    spectra XS400 Junkie Top Contributor

    Agree on the welding part.........

    And not trying to be a debbie downer but how is the rear master cylinder? the 78 I had was junk and the rebuild kit for them was a waste of money......
  13. I really didn’t want to split the housings, but I’m starting to think I’m left with little choice. I think I’ll start by taking the whole assembly to a shop and asking for a quote if I disassembled the whole bit and once I have that nailed down, I’ll decide what to do. Leaning toward getting it welded properly. Although it only takes an hour to pull this engine, so if I do epoxy it and it developed a leak this summer depending on how much I use the bike I could just yank it next fall and do it. It’s almost a challenge now to find something that works.

    As far as the rear master cylinder, I haven’t got that far yet. I know the front master cylinder reservoir is junk but the rear one seemed to have fluid in it still, and when I applied the rear brake it actually worked. The front not so much...
  14. spectra

    spectra XS400 Junkie Top Contributor

    Thats good the front is an easy re place as there are tons of options out there....
  15. JPaganel

    JPaganel XS400 Addict

    Given how much work you are putting into the rest of it... Yeah.

    Good plan.

    Unless that leak happened to be the whole thing falling out, and you dumped your oil, and trashed the motor completely.

    Shortcuts in things like this always make for more work down the road.
  16. But then what am I going to do all of next winter? Lol

    I’m not too worried about it puking oil all over the place to the extent that it damages the engine. It’s well above the oil line and would get splash lubrication in that area at the most. Also the housing that bolts to this broken tab would at least hold it in place so at no point would there ever be a gaping hole. To be honest the easiest and most leakproof way to do it would just be to use some good gasket maker and it would never leak. It has little to no structural impact at all.
    I think what I’m going to do is leave this decision for last and see what I have left over in my budget once the tank is painted and any other parts I need to make it safe are purchased. Things like brakes and tires. If I have enough left over I may just replace the housing. I’ll keep you in the loop. Thanks for the input guys.
    All that being said, when it comes to epoxy repairs, what have you all had the most success with if I do decide to go that route in the end.
  17. amc49

    amc49 XS400 Junkie

    Yours and do as you will. BUT.............

    'It has little to no structural impact at all.'

    Maybe not. If I'm looking at the pic of the broken piece right it's clear the bolt that 'keeps the piece from falling off' is also at the end of a lever (cover casting extension) to vibrate at the broken part. Why the epoxy came loose along with exposure to petroleum distillates. Look at the clarity of the break and how it's semi-smoothed/blurred to not have razor sharp nooks and crannies as reflected by the light on a fresh clean break. The part has already been slightly vibrating to move break to break and fuzzing the break contact area up to make the piece no longer fit and register as tight as it did before, crucial if you ever hope to replicate the exact points in space at the gasket line to not leak after a possible weld job there. That gasket mating surface on broken part is a high squeeze pressure point to have some crush to seal properly.

    So, the bolt holding part in place is both a help and a curse. It helps because nobody has thought yet to connect the broken piece falling off (no bolt) to lock in chain/sprocket to lock up rear wheel and accident. It hurts by vibrating the part to wear the break contact point and slowly degrade any sealing achieved there. Gasket maker? They commonly fail when vibration attacks the seal. What do we think epoxy is?

    You have as good a chance as any using J&B weld, the most important thing will be getting the surfaces there 100% bone dry to guarantee the full locking down of the epoxy. You see where the thinner outlying epoxy layers chip off easily due to the smoothness of the outside casting, no bite there. Take some like 220 or 320 sandpaper to the smooth and rough it up to get more bite, the epoxy will stay locked on better. You want deep scratches there but CLEAN when you throwdown the glue on it.

    I see several bolts holding back of case together there and one shorter thing with a cover around it looks like. Is that top case cracked at that one hole too?, sure looks like it.
  18. JPaganel

    JPaganel XS400 Addict

    Polish nooks and crannies with a q-tip? :laugh2:
    Spitfire_X24 likes this.
  19. Thanks for the reply man.
    So as far as I can see there are no other cracks anywhere. After cleaning up that part of the case all looks good. It appears to be isolated to that one boss. There are marks on it from where it looks like a loose chain may have slapped it and been the cause of it breaking loose in the first place. Thanks for that suggestion. I’m a big believer in failure analysis and used it extensively in a prior role as a shop supervisor at a Caterpillar Dealership. If I go down the road of JB Weld or another aluminum epoxy, I’ll be sure to use some blue loktite on the bolt to prevent it from coming loose and ending up in the rear sprocket.
  20. Well, this is where I went with it. Permatex Steel Weld Epoxy. It got really good feedback on a number of sites so I figured I would give it a shot.
    I ground out a bit of a gap and roughed things up with my Dremel to give it something to bite to, cleaned and dried it and set it in. Once it cured I filed it flush and cleaned up any excess. We’ll see how it stands up.

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