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Ninja EX500 carbs on an XS650?

Discussion in 'The Garage' started by Highside, Oct 20, 2011.

  1. highboy_coupe

    highboy_coupe XS650 Addict

    Ok with a few test runs under my belt I can summize that adding the long intakes and restricting the intakes slightly to promote constant pressure does have a positive impact, however, it is mostly felt in the midrange.
    There is a noticable smoothing of throttle transition from low to mid, and a strong (almost frantic) pull through the midrange.
    I got it up to 94mph, but I ran out of road, it was still pulling well.

    I then added 140 main jets and tried again, 96 mph on same road, so no noticable differences with a bigger main.

    I think if I went up to 32 teeth on the back I would have smashed my goal! video to follow....
    grizld1 likes this.
  2. DaveO

    DaveO XS650 Addict

    I have pods and a Motad two into one exhaust and I've done this mod with 38, 138 and JJJ needles. (I thought I'd report back here to encourage anyone contemplating this. If I can do it anyone can.) It runs fine but I've only got a few test miles on the bike as its been laid up for years.

    One problem I have is that when I start up with the enricheners (choke) on it very quickly revs high and needs a bit of finessing to bring the revs down without killing the engine. It seems a little sensitive and pernickety. Also, whilst the enrichener is on there is the occasional chuff or misfire.

    Once the bike bike is off the enrichener everything is absolutely fine and the bike runs sweet as a nut. I'm enjoying riding, so before I pull it all apart again, I but I wondered if anyone else has had this issue or if the answer might be "they all do that"?

    The brass "nail head" on the "plunger / starter" is worn so I wondered the internals are too and if the answer is simply to replace them both.

    kawasaki 16016-1061 random photo from eBay.

    gggGary likes this.
  3. gggGary

    gggGary Stop that! XS650.com Supporter Top Contributor

    The rubber on the bottom is the seal. Usually fine but.... worth checking.
    bikefreakjon likes this.
  4. bikefreakjon

    bikefreakjon XS650 Addict

    Yes, sync???

    Also if your mixture isn't dialled in good when hot your idle will be turned up too high to compensate.

    Really dial in that idle mix.

    I ended around 2.25 turns out on one and 2.75 on the other. That was with 38 pilots, uni pods.

    Remember each engine (each cylinder really) is unique!

    People who think they can set the idle mix to a specific number they found on the forum are confused. It has to be done for your engine.
    timbeck, DaveO, gggGary and 1 other person like this.
  5. DaveO

    DaveO XS650 Addict

    @bikefreakjon , that sounds exactly right. I am ashamed to say, I did have to turn up the idle quite a bit and I haven't touched the mixture screws. I was just that keen to ride it.
  6. DaveO

    DaveO XS650 Addict

    @bikefreakjon you are the "carb whisperer". You were exactly right. Thank you so much.

    I lost count of where they were to start but I'm pretty sure I had to turn one in more than the other. I backed them each out 2.5 turns. Started on the first kick with only a small amount of choke. No fiddling. Came off choke by the time I had my helmet on. Ticked over smoothly and moved off down the road. By the time I'd gone a half a mile it was fully warmed up and I had to pull over and back off the tickover screw as it was racing. But even this was completely stable, just far too high. I thought the bike was "OK" before, but it was much better. After a quick fiddle at the side of the road the tickover is probably too low now but its rock solid in comparison to what it was before. I'm years off a bike so I don't know what to expect but I can tell when things are better.

    I'll go through this properly at the weekend. I'm not happy with the choke mechanism I knocked up. It sticks out too far and I have some cap head screws for the carb tops. I've got a stumpy screwdriver which will be perfect for this and I don't use it for anything else so I'm going to pull the screws and grind the screwdriver to be a good fit. Looks like I'm going to be hitting the tech section. What I know about tuning carbs can fit on the back of a postage stamp.


    bikefreakjon and gggGary like this.
  7. I've got mine running quite nicely now. I did have issues which I put down to dirt in the carbs. They looked clean so I'd never stripped them down apart from swapping out jets and setting the float heights. So anyway I got some Seafoam additive that the Yanks go crazy about and gave her a good dose and filled her up with super unleaded. I did have a problem when cold starting. It was like the choke aka enrichener wasn't working right and it was erratic on idle. But now it fires up first kick from cold and I've had to lower the tick over. I can trash it then pull up at a junction and she just idles without fear of stalling. It's a 78 on 38s 138s JJJs Pods and straight thru pipes with VW Beetle muffler tips. Mixture screws 3.5 turns out. As being said above. You can only use forum information as a starting point. I had to drop down from 140s to 138s
  8. DirtyErnie

    DirtyErnie Renaissance Hick

    Mine's been a wild adventure, and I have a lot of needles that could be sold. Settling in in an HKF needle...
    Got close with a set of stock pipes, and then cracked a header. Back on the 2-1 setup, and starting over.
    Think I'm going to make my own exhaust and go EFI.

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