Throttle Response UNDER 4k RPM's - Page 3
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Thread: Throttle Response UNDER 4k RPM's

  1. #21
    GP Champ rxf610's Avatar
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    Quote Originally Posted by malenurse13 View Post
    The cracks don't seem to be long enough to leak.
    Well an oxygen molecule is 1.55 × 10^-7 mm wide.... how wide is the crack?

  2. #22
    GP Champ rxf610's Avatar
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    Maybe use a small propane torch around the intake vacuum lines and listen for a surge in idle?

  3. #23
    Evil Twin malenurse13's Avatar
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    Quote Originally Posted by rxf610 View Post
    Maybe use a small propane torch around the intake vacuum lines and listen for a surge in idle?
    If it's that important, I'll just try to get my hands on a new hose. I figured the hoses with clips on them were a little more important than some of the others. But I'm still not sure what this hose does. Other than allow an oily residue into my airbox.

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  5. #24
    Evil Twin malenurse13's Avatar
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    What I meant by the crack not being long enough was that the crack does not pass the metal clip or the raised area on the nipple. But your point about the size of an oxygen molecule is a good point. If I had any extra slack with this hose I might cut a half inch off. But this one is pretty short.

  6. #25
    Evil Twin malenurse13's Avatar
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    While having the throttle cables and all exposed, I checked to see if there was any mechanical issues preventing my fast idle cable from raising RPM's like it's supposed to. However, there's no rust, nothing broken. All seems to be connected and working right. But all the fast idle cable does is cause give me more problems keeping a steady idle.
    WITHOUT the fast idle cable on and with idle set to around 1200 RPM's here's what happens when I slowly roll on the throttle. AS SOON as I open the throttle the slightest bit, the RPM's actually drop. Then after just a bit more throttle, the RPM's surge up to nearly 4000 RPM's. After that, throttle response is smooth and appropriate.
    Again, there are no cracks in any vac lines (except that big one I just posted on the bottom of the airbox). TPS seems to be set right. I haven't done the TB sync yet. And I haven't gotten my hands on a Yosh box yet. But is there anything else I'm missing that could cause this? How difficult is it to clean out the jets myself? I'm much more familiar with carbureted motors than FI. I may be getting in over my head...

  7. #26
    GP Champ rxf610's Avatar
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    Quote Originally Posted by malenurse13 View Post
    While having the throttle cables and all exposed, I checked to see if there was any mechanical issues preventing my fast idle cable from raising RPM's like it's supposed to. However, there's no rust, nothing broken. All seems to be connected and working right. But all the fast idle cable does is cause give me more problems keeping a steady idle.
    WITHOUT the fast idle cable on and with idle set to around 1200 RPM's here's what happens when I slowly roll on the throttle. AS SOON as I open the throttle the slightest bit, the RPM's actually drop. Then after just a bit more throttle, the RPM's surge up to nearly 4000 RPM's. After that, throttle response is smooth and appropriate.
    Again, there are no cracks in any vac lines (except that big one I just posted on the bottom of the airbox). TPS seems to be set right. I haven't done the TB sync yet. And I haven't gotten my hands on a Yosh box yet. But is there anything else I'm missing that could cause this? How difficult is it to clean out the jets myself? I'm much more familiar with carbureted motors than FI. I may be getting in over my head...
    There are no jets in a fuel injected system. If rolling onto the throttle immediately drops the rpms, that says to me vacuum issue or a fuel delivery issue. Either bad sync (which you said you handled) or an air leak or weak fuel pressure. The ecm is calling for a certain fuel to air level and that is being altered. Either clogged primary injectors, vacuum leak, or fuel pump/filter... a yosh box WILL NOT fix your issue...

    You don't actually need the fast idle cable at all. It could be removed and the bike would run fine... try re seating the air box and tightening the boots. They can cause headaches if they aren't seated fully...

  8. #27
    Evil Twin malenurse13's Avatar
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    I guess I meant injectors when I said jets. How difficult is it to clean the injectors myself? My fuel treatments don't seem to be working.

  9. #28
    Evil Twin malenurse13's Avatar
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    I haven't done the TB sync yet. I've got to get the right tubing and find out exactly which nipples to connect to. Once I get the TB sync and TPS done, I'll put it back together and see what she runs like. But I just don't feel like the sync will help. I agree with you it's either fuel or vacuum related. Especially with bike running perfect over 4000 RPM's. With the cylinder intakes exposed, I would get a small flame out of the front cylinder nearly every time before the RPM surge when slowly rolling on the throttle. I just don't think TB sync or putting the airbox back on there would fix that. Forgive me... what do you mean by "tightening the boots?"

  10. #29
    AMA Pit Boss Six5's Avatar
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    Quote Originally Posted by malenurse13 View Post
    While having the throttle cables and all exposed, I checked to see if there was any mechanical issues preventing my fast idle cable from raising RPM's like it's supposed to. However, there's no rust, nothing broken. All seems to be connected and working right. But all the fast idle cable does is cause give me more problems keeping a steady idle.
    If the fast idle cable is not moving the cam lever up to engage the throttle linkage, it simply needs to be adjusted. There is a procedure in the manual for that.


    Quote Originally Posted by malenurse13 View Post
    WITHOUT the fast idle cable on and with idle set to around 1200 RPM's here's what happens when I slowly roll on the throttle. AS SOON as I open the throttle the slightest bit, the RPM's actually drop. Then after just a bit more throttle, the RPM's surge up to nearly 4000 RPM's. After that, throttle response is smooth and appropriate.
    ......
    This makes me think of two things - neither one is for certain. Just thinking out loud....

    1) A Bad Throttle Position Sensor (TPS). There may be a bad spot in the resistor/wiper contact. If it is as drastic as the symptoms suggest, you will be able to see it glitch on a meter when you do the test outlined in the manual.

    2) A Bad IAP sensor. This sensor detects the vacuum in the intake manifold and the ECM uses that information to add fuel in the proper amounts - especially at lower rpms. I forget the correct terminology, but the fuel injection method used by the TL employs two separate modes to determine the fuel mix. In the lower revs, it primarily uses the IAP sensor and TPS info up to about 3700~4000 rpm. After that rpm, it switches to a different mode where the primary sensors are the TPS and the Crankshaft speed (RPM). A faulty IAP sensor or circuit could explain why it smoothes out above 4000 rpm.




    Quote Originally Posted by malenurse13 View Post
    I haven't done the TB sync yet. ....... But I just don't feel like the sync will help. I agree with you it's either fuel or vacuum related. Especially with bike running perfect over 4000 RPM's. ....."
    The TB balance really needs to be done (if it will idle) before you get too involved in pursuing other fixes. The vacuum balance has a large impact on how it runs with small throttle openings. Once the butterflies are opened substantially, any variance between the two TBs doesn't really affect the performance, because now the engine in just sucking air in through two large openings. It doesn't care if one is a few thousandths less than the other.
    January 2012 TLOTM & BBOTM


  11. #30
    Evil Twin malenurse13's Avatar
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    As for the fast idle cable... it doesn't move the TB at all. So I'll make those adjustments tomorrow.
    I believe my tubing is ready for TB sync. However, I've gotten no responses in my other post about how to do the TB sync properly. I need to know if antifreeze or 2-cycle oil will be ok to use in the tubing. And I need to know which nipple to connect to on the rear air intake. Then I'll get the TB sync done. I'll do the TPS adjustment as well. I'm not really anticipating any improvement with either of these adjustments. But I'm a nurse... not a mechanic. I'm hoping for the best.

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