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My 2 steps forward 1 step back bike build

Discussion in 'The Garage' started by short1, Jun 24, 2018.

  1. short1

    short1 XS400 Addict

    They head pipes aren't stock and weren't cut. I don't see any steam buildup on the pipe where the mufflers join, but an air leak could always be a possibility. I think I'm gonna do like you say, ride it and see how things go. How often should I check the plugs? After every ride or after a certain amount of miles?
     
  2. xschris

    xschris XS400 Guru Top Contributor

    Google plug chops that will give you a better tell on reading plugs.
     
  3. short1 likes this.
  4. short1

    short1 XS400 Addict

    Gassed up, finally gonna take it for the first test ride
    20180818_114647.jpg 20180818_114608.jpg
     
  5. short1

    short1 XS400 Addict

    OK, first impression, ran pretty good. Doesn't pull as good as I'd hoped but that could be the nature of these bikes? I've never ridden a stock 400 so idk. Seems like it might bog a tad when on the throttle but it's not jerky. I backed the mixture screws out to 4 turns and adjusted the idle, didn't notice any difference under throttle. Rpms don't hang Shifts are super smooth. Brakes definitely need adjustment. Only got it up to 50 and only rode a few miles as I'm waiting on plates.
     
  6. NewHavenMike

    NewHavenMike 1976 XS360C Top Contributor

    A lot of people always assume that they need more fuel to run better. This is not always true. With main jets that large, you should be able to just look at the plug and tell youre way too rich. You should be able to give it full throttle from 3k to redline and not have any hesitation, and the engine should be screaming by 6k. If the plug is black and sooty, youre too rich. Getting the valves adjusted and the carbs synced is a must before you start tuning. You should also only tune when the bike is in its final state. Even if the timing is off, you can get weird backfiring and all sorts of issues.

    Ill say it again, I put an aftermarket exhaust on my bike, stock air filters, and I had to go down 2 jet sizes from stock. I run 130 mains and 17.5 pilots.

    Get pics of the plugs, then chop them and get pics of those.
     
    short1 likes this.
  7. xschris

    xschris XS400 Guru Top Contributor

    Are those single wall pipes? The one is very blue.( running hot) The tip of the plug is pilot circuit ( idle to 1/4 throttle) middle of the plugs porcelain would be 1/4-3/4 throttle which is the jet needle, and 3/4- full is your main jet and the bottom of the plug all the way into in. That part is hard to see and why people cut the threaded part off to get a better look. Plug cop. Running your bike at different parts of the throttle range then shutting it off cooling it down and checking plugs is how most do it.

    Your setup is not the most optimal way to run these bikes. A well tuned stock setup will give you the best overall performance. I have run all sets of pods and pipes over the years and have found the setup that the yamaha engineers came up with seem to work the best. I have put a few bike together that where total crap heaps and using stock parts and setups got a fully tuned and running excellent bike in just a few minutes. Using pods and aftermarket systems I always seemed to be looking for that sweet spot when I should be just riding.
     
    Last edited: Aug 18, 2018
    buztabuzt and short1 like this.
  8. Petew

    Petew XS400 True Believer Top Contributor

    A quick question that can sound stupid, what oil are you using? I had been using regular auto oil and the additives caused some slippage under hard acceleration. It felt like a bog though, and the engine ran perfectly. I took out the clutches, drained the oil and replaced it with a diesel oil, cleaned the clutches, and my sluggish and underpowered 1980 400G woke right up. I have also found that doing the simple checks first are seldom a waste of more than a few minutes and often cure problems. I hope it is something simple, the bikes that I have are certainly not underpowered and I am a 220 pound man. Have fun!
     
    short1 likes this.
  9. short1

    short1 XS400 Addict

    Heres the plugs after my first couple test rides, i haven't chopped them yet. Look pretty rich eh!
    20180818_171401.jpg
    The pipes are single walled, the blueing happened the first time I fired it a couple months or so ago, way before syncing the carbs or making any adjustments.

    Diesel oil huh? I don't recall what I used for oil..I'm pretty sure it was at least motorcycle oil, i wanna say 30w, I'll check

    Sluggish could be a good word for it but it ran ok, like I said though I don't know how these 400's are supposed to perform.

    Lol all this because I wasn't sure if idle rpm sounded right. I do appreciate everyones input and guidance, wouldn't be anywhere near where I am without it!
     
  10. Use rotella t4 15-40. Power loss is bad AFR. even when my 400 isn’t running the best, still wants to pull the wheel in first. If you’re bogging, something isn’t right
     
  11. NewHavenMike

    NewHavenMike 1976 XS360C Top Contributor

    Try going down about 8 or 10 steps in jet sizes. This is pretty much what I did when I was jetting. I have a small collection of jets now! Im not sure what your factory jet size is, but get one or two sizes smaller than that. Idle jet and needle also factory setting.
     
  12. short1

    short1 XS400 Addict

    Checked and I'm using regular 20w50 motor oil. It's definitely not anywhere near wanting to pull the wheel lol The stock jets were 42.5 and 135, I may toss those back in and see what I get
     
  13. Petew

    Petew XS400 True Believer Top Contributor

    Regular motor oil has additives that can cause clutch slippage. The shift feels ok but until you bring the revs up it seems to stumble and bog on acceleration. Mine feel like they can slide you off the seat in 1st!
     
  14. Has to be JASO MA rated oil
     
    buztabuzt likes this.
  15. NewHavenMike

    NewHavenMike 1976 XS360C Top Contributor

    The engine should stall if you screw the idle mix screws in all the way. If it doesn't, they are too big. Its probably best to just start with main jet sizes before you get into the finer end of the tuning. My carbs are slightly different from yours too, my idle jet is a 17.5 and 135 main stock.

    Get 132.5 and 137.5 jets. Maybe a set of 130s. See what jet works best and then try dropping/raising the needle jet. Or, you can go back to stock jets and just try raising/dropping the needle one notch. Im running 132.5 mains and stock idle jet with the needle dropped one notch. Get a bunch of spark plugs too because youll need fresh plugs for every test. The plugs you have now are no good. Pick up 2 boxes of plugs, that will give you enough plugs for 4 jet size changes.
     
  16. short1

    short1 XS400 Addict

    I'll start with changing the oil, what's the consensus on oil weight? Is removing and cleaning the clutch plates necessary? What should I use to clean them? I'll check what happens when I put the mixture screws in but I may swap to the stock jets to be at a baseline with new plugs. Like I said before the needles seem to be unadjustable unless someone can point me to a way to do it, everything I've seen has been needles with notches which mine don't have
     
  17. Lowest cost and you can look it up but rotella.
    Or 10-40 motorcycle specific oil
     
  18. NewHavenMike

    NewHavenMike 1976 XS360C Top Contributor

    I guess oil depends on your climate. But ive only used Valvoline and Castrol, both 20w50 motorcycle blends. I used 10w40 when i was riding in 40-50 degree weather. I can get Castrol for under $5/quart so im probably picking up a case today.
     
  19. xschris

    xschris XS400 Guru Top Contributor

    20w-50 wet clutch bike oil. 10w-40 for cold temps under 50*f but still wet clutch bike oil. Walmart sell it for around $4.50 a quart. $6.50 for full synth at least my local one does. I do also use Lucas oil stabilizer in my bikes but that's me. Your plugs are wayyyy rich!! Your right to start with stock sizes and go from there. I would set you pilot mix screws to 3 turns out to start with but no more the 4. If you need more go up a size in jet.
     
  20. Petew

    Petew XS400 True Believer Top Contributor

    I cleaned the clutches on mine with brake clean and a soft shop towel.
     

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