Bike won't drop revs??

[ForceofWill]

So I put some gas in the bike and wanted to see how it ran after I put everything back together. I got her started and she will idle fine with no choke after a few seconds. The issue I'm having is that if I give it gas, it will rev up but then STAY at that RPM. Say it's idling at 1500, I rev a little to 2500 then let off the throttle, the bike will stay at 2500. Little more gas to 3500, bike will stay at 3500.

At first I thought maybe the return cable on the throttle wasn't attached, but when I move the throttle, it will open and close it fine. I can see it use the range of motion. I'm not familiar with these bikes operation and am stumped as of now.

The bike has all the stock air stuff removed with a K&N filter and a small breather put on. Using dynajet 108's 2.75 turns out on the screws and it has the full race exhaust from Area P.


Sidenote: Is the neutral light supposed to come on when I'm in neutral? I would think so lol. It's yet to come on for me, so I've held the clutch all the way in the whole time. I went down until it wouldn't let me anymore, which should be first, then one up from there should be neutral right? I don't get any light. With just the key turned on or even with the bike running.

[ForceofWill]

Don't know if this matters but when I was putting everything back together, I was pretty sure that this hose didn't go anywhere. So the left side of it is attached to the carbs like that but the right side isn't attached to anything.

[Boosted139]

Pretty sure that just hangs out there. As far as the RPMs not dropping, do they just hover at a RPM range for a bit and then drop or literally not come down at all? I would adjust your mixture screws...sounds lean (which is strange with 2.75 turns out).

[Momaru]

Mine was doing that sometime last year. After giving the carb internals a good cleaning, it stopped.
Couple other things to check:
-Vacuum leaks
-Settings of your idle adjustment screw
-Throttle tube (the handlebar grip) is snapping back to 'closed' position after you release it

And that tube is a vent tube; it shouldn't be hooked up to anything on the non-carb end, so you're good.

[setasai]

If you play w/ the choke, does it make it better or worse?

Have you done anything w/ the needles?

Have you carb synced?

You said that the throttle return/push cable is fine. That also means that the throttle pull cable isnt binding, correct? It sounds to me like a carb issue if you didnt mess w/ anything else and the throttle is smooth.

I would start with checking all your tubes to make sure they are connected correctly and then troubleshoot the carb mixtures and see if that changes anything.

[alex.s]

if you turn the bike off then back on it returns to normal until you give it gas again?

sounds like a vacuum valve issue?

maybe check the butterfly valves inside the carbs to make sure they aren't binding?

[ForceofWill]

Originally Posted by alex.s

if you turn the bike off then back on it returns to normal until you give it gas again?

sounds like a vacuum valve issue?

maybe check the butterfly valves inside the carbs to make sure they aren't binding?

Yeah, when I turn it off at say 4k rpm. It's back to normal idle when I start it. And I can see the throttle open and close with the cable, no sticking there.

I put new needles that came with my kit in, on the 3rd notch like it recommended. I'm not sure why the internals of the carbs would be sticking now, when the guy rode it over here it didn't do that.

I took the tops off the carb and replaced the needles. The the bottoms off and put the jets in there. Then I set the screws to where it said. The way to set those screws isn't very precise though.

Also, the knob on the left side of the bike, it's black plastic. I think it's the idle knob? When I turn that, it doesn't seem like it's turning. In either direction it just seems like it's twisting the whole cable around. It doesn't turn much and is really hard to turn.

[ForceofWill]

Also, is it normal on these bikes for the throttle to lag? When I crack back on it, it doesn't rev immediately. Not sure if that's normal.

[alex.s]

that usually means its not jetted properly. if you have it in gear and hold the front brake and use the clutch to put a little bit of friction on the engine to drop the revs, then pull the clutch all the way back in, do the revs go back to where they were stuck? or do they stay where you dropped them to with the clutch

check all your vacuum hoses and make sure they are sealed. also is that hose capped with a screw-driver bit? lol.

[ForceofWill]

Originally Posted by alex.s

that usually means its not jetted properly. if you have it in gear and hold the front brake and use the clutch to put a little bit of friction on the engine to drop the revs, then pull the clutch all the way back in, do the revs go back to where they were stuck? or do they stay where you dropped them to with the clutch

check all your vacuum hoses and make sure they are sealed. also is that hose capped with a screw-driver bit? lol.

Lol yea, just used it to stop fuel leaking while working on it. I'll run through all the lines. Is there a way to tune these screws on the carbs without a wideband? Also, area p said they had the best results with 106 or 108 jets. I went with 108. Would this be a symptom of going to big and needing to go down to 106?

[Boosted139]

The main jet should really only affect your top end. The needle height will be your mid range and the mixture screws your low end. So in other words, no it shouldn't be the reason you're seeing the RPMs hang.

[ForceofWill]

Originally Posted by Boosted139

The main jet should really only affect your top end. The needle height will be your mid range and the mixture screws your low end. So in other words, no it shouldn't be the reason you're seeing the RPMs hang.

Ok thanks. Just read the DIY on how to adjust the screws while bike is running too. Gonna try that and see if I can fix it.

[choneofakind]

Originally Posted by ForceofWill

The issue I'm having is that if I give it gas, it will rev up but then STAY at that RPM. Say it's idling at 1500, I rev a little to 2500 then let off the throttle, the bike will stay at 2500. Little more gas to 3500, bike will stay at 3500.

Using dynajet 108's 2.75 turns out on the screws and it has the full race exhaust from Area P.

Originally Posted by ForceofWill

Also, is it normal on these bikes for the throttle to lag? When I crack back on it, it doesn't rev immediately. Not sure if that's normal.

sounds to me like you have the idle mix too lean. adjust those screws until it's right

here's the jetting database, just for an idea of what others have done to their bikes. look for someone with a similar intake and exhaust setup and similar elevation just to see what they and you have done differently.

here's some tips for jetting
notice the tips for getting the idle mix right. yours appears to be hanging, which is a symptom of being too lean at idle

[ForceofWill]

Ok, quick question about the needles. I don't think I fully understood how it was supposed to work, so mine might be F'ed up.

Here's a pic of what I did. I wanted them on the 3rd notch, so I put the little clip thing on the 3rd notch. But then there were two washers and another clip in the bag. So I put the two washers over that clip and sandwiched them with another clip on top. Is that right? Or should there only be 1 clip on the third notch and the other stuff was extra.

Pardon my ghetto paint skillz

[Boosted139]

I didn't sandwich the washers like you did, but it shouldn't matter. The needle is still at the same height with or without the sandwiching.

I would double check your mixture screws. The screws actually on the carb (actually beind a cap which you have to drill out), not the black nob thingy (the idle adjuster).

[ForceofWill]

So I took everything back apart. Took the carbs apart and cleaned everything with carb cleaner. I took the washers and other clip off my needles, so now it's just the 1 clip on the 3rd notch. The screws are at about 2.8 turns out.

This seems ok to me, this is about what my cars do when revving. Should it be dropping faster than this, or you think I'm ok?

http://youtu.be/olXhy-MEuRE

[setasai]

Looks pretty good to me. Take it out for a spin and see if it pulls nicely all through out the range and you're good to go.

[ForceofWill]

Originally Posted by setasai

Looks pretty good to me. Take it out for a spin and see if it pulls nicely all through out the range and you're good to go.

No license yet and the bike has no wheels on it lol

[Boosted139]

Looks fine to me. Like Setasai says now you just have to take her out and tune the mid range and top end. After you get a license and it has wheels of course... lol

[ForceofWill]

Also, I fixed my sidenote about the neutral light lol. I took the cover off the front sprocket and that little plug for the neutral light had fallen off. Put it back on and bingo!

[ForceofWill]

Right now it's more of a speeder from star wars.

Vroom Vroom.

[choneofakind]

Originally Posted by ForceofWill

This seems ok to me, this is about what my cars do when revving. Should it be dropping faster than this, or you think I'm ok?

looks about right to me. Only way you're going to know is by going rich until it bogs, then turn the mix screws in a bit. You can really only adjust the needles and mains based on how it rides and feels. worry about the mains first by doing WOT tests, then once those are right, play with the needles based on how it feels with partial on/off the gas in rolling smoothly out of the turns (not WOT). Then play with the mix screws a little more to get the combination of needles and mix screws right so that it's smooth in that barely off idle smoothness. jetting is all about trial and error and getting what feels best. we can give you advise, but we can't tell you what's best for your bike in your location in your climate. it's different for everyone

[setasai]

It just occurred to me that you're doing all this before even riding it. That could be problematic later down the line since you'll have no idea how it felt before making all these adjustments.

Typically, it is never wise to do so many mods at the same time. Hope it all comes together without too much trouble.

[ForceofWill]

Originally Posted by setasai

It just occurred to me that you're doing all this before even riding it. That could be problematic later down the line since you'll have no idea how it felt before making all these adjustments.

Typically, it is never wise to do so many mods at the same time. Hope it all comes together without too much trouble.

I'm not too worried about it. I think I can get a pretty good baseline down even being a new rider, and just fine tune it as I go. If for some reason I just can't get it right, I'll try and get some dyno pulls and adjust accordingly.

It's not like I'm piecing together a turbo kit and trying to tune from scratch. It's just 2 bolt ons.

[choneofakind]

Originally Posted by ForceofWill

It's not like I'm piecing together a turbo kit and trying to tune from scratch. It's just 2 bolt ons.

yes and no. The bike changes tons when you alter the intake/exhaust and jetting. he does bring up a good point that you won't know what feels good vs what feels like the bike is holding back. The lean surging is easy to pick out, but sometimes a slightly rich slowness can be hard to pick out, even for someone who's accustomed to what the bike feels like.