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HoughMade

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About HoughMade

  • Rank
    Member
  • Birthday 02/18/1971

Previous Fields

  • Current Bike(s)
    1979 XS400

Profile Information

  • Gender
    Male
  • Location
    Valparaiso, Indiana
  1. There should be a fitting on the top of each carb holder.
  2. I put a manual petcock from this website on my XS400. I used the universal petcock and the 46mm plate. Measure yours to be sure. http://www.partsnmore.com/parts/yamaha/xs400f/?filters[category]=carb
  3. Makes things easy on yourself on the ignition. Set the points gap exactly the way it says in the manual. Then set the static timing the way it says here: Now, once you get the thing idling on both cylinders (I have some thoughts about that, back to that in a minute) and after the static timing is set, with the points cover off, advance the timing slowly turning the points plate clockwise and the idle speed should increase. if it decreases, turn it the other way. When the idle speed is as fast as it gets, back it off a bit and tighten the plate. An engine with some wear will run better with a little bit more advance than stock. Based on your compression numbers, you have enough wear to benefit from this. After you set the timing this way, ride to make sure it is not pinging and check the plugs to make sure there is not too much heat. If there is, back the advance off a bit and ride again. As for cleaning the carbs, if they are like those used on the XS400, the idle circuit passages can be finicky. Here's how I clean them (this is for BS34s, hopefully yours are similar). With the carbs off (you can leave them attached to each other) take carb cleaner and spray it through the air jet at the mouth of the carb. With the idle mixture screw in, but at the setting for running (try 3 turns out to start) a strong stream should spray out from the hole beneath the idle mixture screw. Turn the carb over and take the idle jet out and clean it and shoot carb cleaner up through where the jet was. You should have a strong stream out the same hole. Then screw the idle mixture screw in and lightly seat it. Spray the carb cleaner in the air jet while holding the carb butterfly open. You should see 3 strong streams coming out of 3 small holes just above where the butterfly rests. Turn the carb over and spray carb cleaner up the idle jet from below and you should see the same thing. Spray until you can see the carb cleaner flowing in strong streams as noted above. If you can't see that, you may need to strip and boil the carbs (my preference...'cause it's cheap) or have them ultrasonically cleaned. If you can see the carb cleaner spraying out basically unimpeded, then the idle circuit is clean because you have cleaned it from both directions.
  4. I'm with drewpy- sounds like timing. Mine did almost exactly the same thing and after i re-gapped the points and static timed it, it started running great at just as high an RPM as I dared go. I static timed mine, which, if there is no mechanical problem with the ignition and advance, should be fine. I followed these instructions. I just found it with a search.
  5. That's pretty interesting...and kind of sad as motorcycles are built to be ridden. As popular as XS400s are, they aren't really collectible. They are popular because they are a inexpensive, simple to work on and a blank slate for modification. When set up right, they run pretty well. In this context, a 42 mile "survivor", especially one from the 'ugly' years isn't as big a deal as it could be. There isn't much of an incentive to keep it stock...I kind of doubt it will ever appreciate very much. At the same time, it would be a bit of a shame to modify it very much because it is so unmolested. That being said, at around $2,000 it's not too outrageous. It's more than most other XS400s I've seen, but at 42 miles, that makes sense.
  6. I'm on board with another cleaning of the carbs. How they look means squat unless you have the ability to see inside all the passages. My bet is that the idle circuit is clogged. However, if the bike idled at 1200rpm on full choke (enrichener) why did you take it off choke? It's supposed to idle at 1200rpm. Until the engine speed starts to increase from 1200rpm on its own to close to 200rpm, it's not time for half choke. Until it rises to close to 2000rpm on half choke, it's not time for no choke. Then, when fully warm, it should be set to idle at 1200rpm with no choke. Unless its very warm out or the engine is warm, it should not idle very well (or at all) from a cold start with no choke.
  7. Adjust the idle speed to begin with. That's the knob between the carbs shown below. as Drewpy said, 1200rpm
  8. Go ahead and check for the intake leak as above. Both the symptoms you have indicate a very lean condition. That results from either too much air- hence checking for the intake leaks, or too little fuel. the first thing I would do is set the idle mixture screws to about 3 to 3.5 turns out, adjust the idle to 1200 rpm and see if it hangs when revved. If not and the backfiring stopped, you're good. If not, check the float level and consider cleaning the carbs again...and again....and again. These CV carbs must be very clean to work correctly.
  9. HoughMade

    petcock

    With an oil change interval of no more than 2000 miles, I can't believe that I would see much benefit from synthetics...but who knows. Stick with what you know.
  10. HoughMade

    petcock

    I use Yamaha filters, Shell Rotella T 15w40 (diesel engine) oil. Works great and costs $11.50 a gallon.
  11. First thing I would try is richening the idle mixture.
  12. In the shop manual I have, it says to drain the oil before removing the alternator cover....because oil is supposed to be behind the cover. Less comes out when it is on the center stand, but nothing is wrong, nothing is amiss, nothing is leaking if there is oil behind the alternator cover.
  13. HoughMade

    Keihin Carbs

    I have not used those carbs, but honestly, the price looks good and Keihn carbs are top notch. If I ever need to replace my Mikunis, I will take a long hard look at that kit. As Yamaha used the Mikuni BS34 on both 400s and 650s, I don't see why those 32s would not work on the 400. As for the brake calipers, everything looks similar to the calipers on my '79 XS400, but I couldn't guarantee anything.
  14. HoughMade

    Keihin Carbs

    You would have to play with the jetting. I would want to know what "extra jets" are included. It would have to be jetted differently from the 650. If it were me and I were making the change, I would compare the stock jets in the BS34 in the XS400 to The stock jets in the BS34 in the XS650. I would then start tuning the Keihin by using jets in the same proportion smaller that the BS34 jets are from the 650 to the 400.
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