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Bike won't rev....at all..I've read the thread(s) still nothing.

Discussion in 'The Garage' started by Jbrum, May 13, 2017.

  1. Jbrum

    Jbrum XS400 Member

    So I put my engine back in ( i recently had a guy replace all of the gaskets in it) and hooked everything up. I welded the dime city shorty slash cut mufflers to my headers repacked the baffle and wrapped the pipes. bike started up wonderfully...well much faster than I expected but it had an issue, bike won't rev at all. I have to completely have the throttle open just to almost make it go up...almost. every couple of secs it sounds like it wants to go up but doesn't. I can have it completely open and it doesn't make a difference in sound
    So after reading some threads on here I've tried:
    Checking the cable. definitely working the way it should.
    I've checked to make sure the butterflies open and close when i'm hitting the throttle and off the bike they are. I've tried taking the air boxes off and seeing it the slides are moving at all when I throttle....They aren't. I tried using a screw driver and lifting them up and the engine starts to die. I tried spraying starter fluid with the air box off and I see flames shoot out but the bike doesn't rev at all.
    I adjusted the floats (brass floats at 26mm) i've cleaned the jets/carb now for the third time and soaked them in seafoam using carb brushes and copper wire to make sure they're not blocked in anyway.
    So I'm going to try to adjust the valves tomorrow, Also switching plug wires around. is there anything else I can try?!?
    The only thing different now is exhaust is welded where as before they were just clamped on and I didn't have any packing in the baffle before. Jets worked fine before, is it too much back pressure now so I have to re-jet? I should at least get some kind of indication of rev'ing if its the wrong jets now for my set up shouldn't I? if its valves ( ive had them for sure wrong before and i at least got it to rev it did so crappy but it still worked) same lash/clearance as the manual states?
    All of my mechanical experience is from this site and youtube. So far so good but I've exhausted my wealth of knowledge on this one.
    Thanks in advance .
     
  2. NewHavenMike

    NewHavenMike 1976 XS360C Top Contributor

    The slide dont move up when you give it gas?? Im not sure how much they actually move when you have the filters off but they should move freely. Does it sound like the diaphragms are sealed when you slide them up by hand? If you push a slide all the way open, you should be able to put your finger over the vent hole and the slide will stay in place. Take your finger off and the slide should return to closed. This means that everything is sealed.

    I was going to say that your timing must be way off until you mention this about the slides....
    Checking the static timing is very easy and I bet if you had someone else change the gaskets, the points plate was moved and not adjusted properly.
     
  3. Jbrum

    Jbrum XS400 Member

    Ill check the timing. Ive already watched a video on here how to do it. But the slides aren't moving at all when I throttle. Ive cleaned the carb and I know the needles and slides are good. The rubber diaphrams dont have any holes in it and when I test the speed of their decent its uniform and quick.
     
  4. Jeff0133

    Jeff0133 XS400 Junkie Top Contributor

    Did you do a compression test?
     
  5. xschris

    xschris XS400 Guru Top Contributor

    Did the bike run fine before the muffler change? Did you have the bike's battery hooked up when you welded it? You may have fried the TCI box or another component.
     
  6. 16VGTIDave

    16VGTIDave XS400 Guru Top Contributor

    Seafoam won't clean the carbs other than helping degrease them. You need to remove corrosion and debris from the tiny internal passages. Use Vinegar or lemon juice and simmer the carbs before running a fine wire through the passages. In particular the pilot jet passages that are exposed by the throttle plates. Then simmer them again.
     
  7. new kid on the brat

    new kid on the brat new kid on the brat

    When you say flames shoot out,do you mean out the exhaust or out the carburetors?
     
  8. Jbrum

    Jbrum XS400 Member

    bike ran fine with the old exhaust (again same headers and same muffler just welded so i didn't have leaks). I welded them on the headers off the bike so I didn't hurt anything of that nature. And yeah when I spray starter fluid with the air boxes out flames shoot out of the carb. I'll do a compression test on it after I adjust the valves. I'll get some carb cleaner and pop them off again.
     
  9. Jbrum

    Jbrum XS400 Member

    Valves checked. Carbs clean spent hours scrubbing and spraying . New plugs gapped. Still won't rev. The gas is a couple of weeks old but had seafoam in it. Could that be the issue? The only thing I can think of is static timing so im gonna do that next. Then bigger set of jets. Anyone have any other ideas to try?! My car died so im walking to work until I get this fixed. Im fat I don't like to walk haha
     
  10. new kid on the brat

    new kid on the brat new kid on the brat

    When you get it running. Hold your fingers flat together and slowly slide your hand over the carb intake while revving the throttle.Try and find a position where the engine will rev. This will work on one carb at a time. If you can make it rev doing this then you are defineatly to lean.
     
  11. NewHavenMike

    NewHavenMike 1976 XS360C Top Contributor

    As i said, static timing. Its too easy to verify not to check it first...
     
  12. Jbrum

    Jbrum XS400 Member

    Yeah looking up how to check static timing now. Gonna go out and test the carb again now.
     
  13. Jbrum

    Jbrum XS400 Member

    Alright. So I made a timing light tester with a 9v battery. And watched videos and read most of the threads on. Static timing. BUT mine looks like this and everyone has a different set up. So I didn't really understand where to clip and test and the manuals aren't really clear on it. BUT I could see where the plate used to be by marks on it. So I loosed the screws and moved it to its original location. 20170517_181240.jpg DSC02149.jpg
     
  14. Jbrum

    Jbrum XS400 Member

    Could someone give me a brief break down on static testing with this set up. I get the LF and RF part I just basically need to know where to clip my tester to see how far off i am. Thanks
     
  15. NewHavenMike

    NewHavenMike 1976 XS360C Top Contributor

    My bike has points, but it shouldnt be too different.
    Did you remove the round side cover to turn the crank? You need do do this turning one way ONLY and without spark plugs to make it easy

    Once you get to the LF mark, you will have a look at the timing unit and see that something there should be lined up. It looks like there is a dot marking on the timing thing where you are point to in the pic.

    That should get you close enough to where it will run and then you need a timing light to fine adjust. BUT the static timing should get it to run.
     
  16. xschris

    xschris XS400 Guru Top Contributor

    You need a timing light for a TCI bike. There is a test for it in the manual at the back of the book. Pg. 133 of the haynes.
     
  17. Jbrum

    Jbrum XS400 Member

    Excellent. Im gonna test it out tomorrow. What I did was turned it to get the LF and saw where that lined up at and then turned and looked at where it was at RF and then tried to get the plate back to the old spot to see where it lined up at hopefully thug will get me in the ball park to pin down this revving issue. Ill look at my haynes manual on that page to further fine tune it. These bikes are a love hate relationship. Damn
     
  18. Any updates on this? My guess is that your cam-crank timing is off when he rebuilt it, not the ignition timing. In my experience, that timing plate in your picture can not be thrown off so much that is does not let the bike rev at all.
     
  19. xschris

    xschris XS400 Guru Top Contributor

    The dot point on the rotor will point to the magnetic poles on the ignition pickup at RF and LF on the fly wheel. This is kind of a "static" timing for a TCI bike. But like I said a timing light will make it perfect.
     
  20. Jbrum

    Jbrum XS400 Member

    Well fellas the old girl is running again. It must have been the ignition timing. (I was afraid to check it at first because of lack of experience) but new plugs clean carb and fresh gas will never hurt. Valve lash is on point everything seems to be good to go. Thank you again for the help.all of what I know now is from this site. 20170523_170254.jpg 20170523_170254.jpg 20170523_170303.jpg
     
    Jeff0133 likes this.

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