|
|
Post by lain on Mar 25, 2015 13:23:25 GMT -5
So I just checked my plug, looks pretty light brown/white-ish. I think this means I'm probably running lean. Also, I notice when I go full throttle for a long time on a ride, afterwards my oil level has gone down a little bit (I've been adding oil every 2 weeks), but if I ride mostly at low RPM, and half throttle I do not lose oil it seems. It also smells like I am burning something when I stop after going WOT. I mostly ride half to 3/4 throttle so I feel this is a sign I need to tune the main jet. I am currently running #  main jet, I have #  ,  , 80 jets in my toolbox. When I first tried to use the # jet it sputtered and bogged like crazy when accelerating, making me believe it was too much, but now I have a little bit more understanding I think maybe I have to just raise the clip on the needle to drop it to essentially lean the middle end a little bit to fix that? What do you guys think? I am still new to carb tuning and want to understand more so I can tune it right. |
|
|
|
Post by lain on Mar 25, 2015 15:04:26 GMT -5
So I have the # in there now. I had to raise the needle up to the top to get it to idle properly. I then tuned the mix screw on the lean side which made the idle even better (its 50 degrees right now). The bogging during acceleration was horrible when at the clip position under the top, it is still sort of bad on the top clip position but not horrible. I also noticed after accelerating when I let go of the throttle it slows down to 2500rpm, then over a minute slows down to 2000 and stays there, is that too lean or just right? Also at the same time, when I accelerate it feels like it revs up really fast as compared to with the # , it goes from 3000-6000rpm in less than a second while on the stand. Going to go out for a test ride in the next 20 minutes or so to see how it works under loads. |
|
|
|
Post by lain on Mar 25, 2015 16:02:52 GMT -5
So I went for a ride. It seems like it bogs at about 1/4 to 1/2 throttle then picks up after half throttle. When I start it up if I apply 1/4 throttle then let go it will die as soon as I let go, same goes for when I come to a stop at a light.. Am I still too rich somehow? Maybe # is too much for my setup? Maybe I need a different low jet? It seems like my idle is lean since it idles at about 3000rpm at stop lights then slowly goes to 2000 and has trouble staying alive. Maybe I need a different air intake? I could really use some input guys. I've been reading the guides and whatnot but this still confuses me. |
|
|
|
Post by JerryScript on Mar 25, 2015 17:53:51 GMT -5
If your idle drops, it means you are rich. Perhaps your setup would be best with a 92 main. I'm not convinced your idle jet is the wrong size.
What happens at cruising speed if you let off the throttle 1/8 turn and hold it there? If it speeds up you are lean, if it settles down you are rich.
The bogging at 1/4-1/2 throttle could be your accelerator pump is either to rich or too lean, I would first try increasing the bend in the spring, then go way the other way decreasing the bend, testing after each change to determine which way you need to fine tune it.
|
|
|
|
Post by lain on Mar 26, 2015 0:17:11 GMT -5
If your idle drops, it means you are rich. Perhaps your setup would be best with a 92 main. I'm not convinced your idle jet is the wrong size. What happens at cruising speed if you let off the throttle 1/8 turn and hold it there? If it speeds up you are lean, if it settles down you are rich. The bogging at 1/4-1/2 throttle could be your accelerator pump is either to rich or too lean, I would first try increasing the bend in the spring, then go way the other way decreasing the bend, testing after each change to determine which way you need to fine tune it. I'm not sure what you mean by changing the bend in the spring. |
|
|
|
Post by JerryScript on Mar 26, 2015 0:43:02 GMT -5
Bending it more will give more fuel sooner via the accelerator pump, less bend will give the fuel later, and a lot less bend will make the amount of fuel delivered less. Here is a good explanation of how an accelerator pump works: www.thumpertalk.com/wiki/_/tuning-the-keihin-accelerator-pump-r173What I am referring to as the spring is a thin piece of metal in a curved "C" shape on the throttle linkage side. When you twist the throttle, and the linkage gets turned, this "spring" gets pushed against the accelerator pump actuator, which compresses a diaphragm inside. This squirts a bit of extra fuel needed when the butterfly first opens, since the vacuum instantly drops for a moment when the opening enlarges, meaning less fuel is drawn through the jets for a moment. |
|
|
|
Post by lain on Mar 26, 2015 11:51:47 GMT -5
Bending it more will give more fuel sooner via the accelerator pump, less bend will give the fuel later, and a lot less bend will make the amount of fuel delivered less. Here is a good explanation of how an accelerator pump works: www.thumpertalk.com/wiki/_/tuning-the-keihin-accelerator-pump-r173What I am referring to as the spring is a thin piece of metal in a curved "C" shape on the throttle linkage side. When you twist the throttle, and the linkage gets turned, this "spring" gets pushed against the accelerator pump actuator, which compresses a diaphragm inside. This squirts a bit of extra fuel needed when the butterfly first opens, since the vacuum instantly drops for a moment when the opening enlarges, meaning less fuel is drawn through the jets for a moment. The piece of metal by the throttle wheel? So what I am understanding is that I can turn down the fuel mix the accel pump gives by moving it away from the wheel? Lol I didn't realize that thing did anything, I thought it was a guard of some sort. |
|
|
|
Post by lain on Mar 26, 2015 13:14:45 GMT -5
Is it better to have a lean or a rich idle? I'm just thinking, I turned the idle mix to 1 1/2 out, wondering if I should change it.
|
|
|
|
Post by JerryScript on Mar 26, 2015 13:26:01 GMT -5
It's an often overlooked part of carb tuning. Many issues people call bogging and think are related to their a/f screw adjustment are in fact related to the change in vacuum when the throttle is turned more opening up the butterfly and momentarily decreasing the vacuum. For the beginning of the throttle range, that is a tuned via the accelerator pump. If the condition exists later in the throttle range, it is addressed by the needle, either clip height or taper.
You want quick response to quick twist of the throttle, both up and down in rpms from idle to 3k.
|
|
|
|
Post by lain on Mar 27, 2015 9:36:36 GMT -5
I'm still trying to get this # jet to work properly. I am mostly having issues with idling now. I thought the main jet didn't influence the idling though, but it seems to be clearly the opposite with my scoot. When I first changed to # from # without changing anything else it would not star or idle. After dropping the needle all the way down and adjusting the mix screw to very lean it idles but after about a minute or so seems to bog down really slow like it's about to die, and if I push it off the stand it does die... The high end is however amazing now, I was going 50 uphill! Before I only did 35 uphill at most on the same hill! |
|
|
|
Post by lain on Mar 27, 2015 10:52:24 GMT -5
So I changed the main jet back to # and put the needle back where it was before I started messing with it and adjusted the mix to where it was before I was messing with it as well. I started it up and it started having issues idling as well. I turned it off and then put the metal slide thing back to where that was before i was messing with it, or as close to it as I think it was. Then I turned the scoot back on, it started up fine, no throttle twist or anything, but then it was idling at 3k and it wasn't even doing that before. When it sounds like the enricher has kicked in totally the engine is only down to 2500. I then tried to turn the idle speed down, each turn down did nothing. I unscrewed it all the way out and it was still idling at 2500 and would go back to 2500 even after twisting the throttle. Did I break something when I was messing with the metal slide thing? I bent it by hand. I didn't see anything that I could have broke when I was bending the metal thing. Is there something in the pump that might have gotten damaged when I bent the metal slide? |
|
|
|
Post by JerryScript on Mar 27, 2015 15:02:13 GMT -5
The accelerator pump only squirts a bit of fuel in via a diaphragm, it will not affect your idle speed when not twisting the throttle. After you changed back to the main jet, did you go thru the carb tuning procedures again? |
|
|
|
Post by lain on Mar 27, 2015 15:32:28 GMT -5
The accelerator pump only squirts a bit of fuel in via a diaphragm, it will not affect your idle speed when not twisting the throttle. After you changed back to the main jet, did you go thru the carb tuning procedures again? Yeah, I tuned it on the rich side. I'm really starting to believe my CDI or coil may be at fault. Nomatter how good the mix is I always seem to have slight starting issues that require me to rev it so it goes higher than 2k at starts and if i let it idle under 2k it seems to have trouble or just die. I'm also starting to have irradic rpm rates when on the road at any and all throttle ranges. It sounded like my engine was fluctuating in rpm as it rose whenever I accelerated. And it would not hold a steady sped, I would have to keep adding more or less throttle. It sounds like wa-oh-wa-oh-waaahhh as it accelerates or if I hold it at any speed before it reaches top speed. At top speed it will stay steady for the most part. |
|
|
|
Post by lain on Mar 27, 2015 15:46:57 GMT -5
The weird thing is the high idle and the erratic rpms didn't happen until I bent the metal thing for the accelerator pump. Could be entirely coincidental though, that seems to be my luck. Whenever I tweak or fix one thing something else, sometimes totally unrelated, pops up.
|
|
New Rider
Currently Offline
Posts: 44
Likes: 3
Joined: Sept 20, 2014 16:24:02 GMT -5
|
Post by blue on Mar 27, 2015 16:34:29 GMT -5
I would go down to a main jet. Then raise the needle to let more gas in.you should be fin. |
|
main jet, I have #
, 
, 80 jets in my toolbox. 
