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MotoMacGyver
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2,546 Posts
Discussion Starter #1
Ok. Here's what I did today:

1. Turned the mixture screws out 2.5 turns (oddly enough, since mine was a dealer demo before I got it (only 285 miles), the EPA plugs were already taken out!)

2. Put in one 2mm washer (or maybe 1.5 mm. didn't measure, but it's the thick washers) in each needle.

3. Removed the "pre-filter" foam thingy as well as the white "thingy" at the entrance to the airbox.

That's it. Now, at anythign below 1/3 (almost 1/2) throttle, the thing lurches and shakes and nearly stalls. It's fine when you're open on the highway, but at stoplights, I looked like I did the first time on a bike. I literally had to slip the clutch all the way through the intersection to not stall. Pretty damned dangerous. What did I do wrong? Everything else on my bike is stock.

Also, and I hope I didn't mess this up, but how many lines are supposed to come off the tank (and underneath) and get routed
below the bike (like an overflow or something) and not get plugged into anything? You know, the one that is nearly straight down underneath the seat and points downwards by the swingarm? I can't remember (serves me right for not double checking) how many there were, but now there are 2. Both come off the fuel tank. One is from the right front of the tank. The other, I don't know. I was having a hard enough time trying to balance the thing and not drop it. ARRRGGGHHH! :yell:

Any suggestions?
 

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Silver Member
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207 Posts
Emrah,

Can't help you with the shims (sorry). I've got my mixture screws at 2.5 turns on otherwise stock carbs and it only helped in my case.

There are four hoses and one wire connection on the tank.

1) The fuel line comes off of the petcock.
2) The vacuum line comes off the petcock and goes to the 2nd carb.
3) The front vent line comes off of the right front of the tank and routes through the clip on the bottom of the tank along with the fuel sensor wire
4) The rear vent line on the right side of the tank is routed back by the airbox.

Both 3 and 4 eventually route inside the side cover and down to the outside of the swing arm (you'll see the retainer brackets for them).

I use a rubber mallet to hold the back end of the tank up while disconnecting hoses. Makes it a ton easier. A small piece of 2X4 would work just as well.

Hope this helps.

Craig
 

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Wheelie for Safety
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1,550 Posts
Emrah, Emrah, Emrah...

This fix is an easy one. Put it back to stock. :D

Okay. Well if you insist on trying something first, try putting the airbox back the way it was.

BTW do you have a stock slip-on and air filter?

Sounds like you got the overflow hoses correct. There are two.

Andy
 

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West Coast Moderator
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12,996 Posts
Easy, there hombre, let's break this down. Did you get all the vacuum lines back on? There's are lines on carbs #'s 1,3 &4.
 

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MotoMacGyver
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2,546 Posts
Discussion Starter #5
I never disconnected any of the vacuum lines from the carbs. I only disconnected the 2 lines for the fuel valve (is the bad word filter off so I can write "petcock" now?). Anyway, those are back on. Both "Vent" lines are also routed down by the swingarm.

Yes, I have the stock can and filter, but I can't see how removing that little foam pre-filter (or whatever it is) can make that much difference. I mean, this isn't a little hesitation. We're talking major bucking and shaking here. Even when riding past 1/2 throttle, I can feel it - like a "miss" or like when you first start to run out of gas, how you can feel mini-"surges".

I'm at a loss. I think I'm going to try putting the mixture screw back a bit and see what it does. I don't feel like messing with the whole tank removal thing if I don't have to. I don't think I messed up anything with the shims. The washers easilyn fit inside the tube, and the needle has plenty of room in the hole. In other words, I don't think the needles are getting jammed or anything.

Any other suggestions?

Emrah
 

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Wheelie for Safety
Joined
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1,550 Posts
Yes. Put the air box back to stock. It was only a couple of weeks ago that another guy had a similar problem with his air box.

One of the first things to remember when it comes to modifications is, DO ONE THING AT A TIME, then test it! You did three.

Andy
 

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West Coast Moderator
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12,996 Posts
You may wanna go back and start with the screws turned in some and then work them out from there. It's real "Boggy"? Like too much air or too much gas?
 

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MotoMacGyver
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2,546 Posts
Discussion Starter #8
Too much air and too much gas. That's not the bike, that's me! :laugh:

Anyway, I just put the screws back to 2 turns out (from 2.5). Same problem. I think I'll start with putting the airbox back the way it was in the morning. If that doesn't cure it, I'll take the shims out.

How does it feel? It feels like it's running out of gas or something. At partial throttle, it bucks and shakes and loses power. Then, if you hold the throttle exactly the way it is (no more, no less), it gets a sudden surge (enough to take you by surprise) and the bike lurches forward. It acts almost like it's starved for fuel, then gets a big shot of fuel. Although I really can't see how that can happen???

I think it's the shims, but I'll do the airbox thing first. I'm clueless right now.

Emrah
 

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West Coast Moderator
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12,996 Posts
If I said I was going riding next weekend, would you get it fixed any faster? If I go riding, I'm going Sunday. I won't know till Sunday morning. I'm going to the Supercross race Saturday and I don't usually get home from that till about midnight.

So hurry up! :laugh:
 

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The Commander
Joined
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5,020 Posts
Sure sounds like a vacuum leak to me. Particularly if it's running well at higher rpm's where there is enough vacuum to make up for the leak. I'd go over every hose on the carbs, airbox and tank and make sure they're all seated and sealed, even the one's you didn't remove. Also tap each of the plug wires down to make sure they're seated firmly on the plugs. It's definitely not the shims or screws. Could be the airbox, but that's usually pretty obvious if it's bogging when you twist the throttle wide open at lower RPM's. What did you mean by removing the "pre-filter foam thingy as well as the white thingy at the entrance of the airbox"? The pre-filter foam is wrapped around the white end cap, so I'm worried about why you mentioned those as separate items. Did you remove some other "foam thingy" that you shouldn't have removed? Please tell me you didn't remove the foam air filter from the inside of the box!:eek:
 

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The Deer Slayer
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7,382 Posts
I thought the same thing, did you remove the whole air filter element ?

More important, why were the EPA plugs out ? And if they were, what else could already been done ?

Did you turn in screws in all the way prior to backing out ? Last, those washers are super thin, You said thick.

Anyway, does sound like a vacuum thing.

Tony
 

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Registered
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1,274 Posts
hey dude :) get a mirror and make sure you've still got all your mixture screws. if the plugs were already gone and you backed them out some more one of them may have fallen out. but i'm guessing you did that already

definitely put your air restrictor back in. then check your hoses. if you don't have the manual let me know and i'll scan and send you the relavent pages.

martin, i'm going out saturday but i might be up for going sunday as well. kee me in the loop :)

scott
 

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MotoMacGyver
Joined
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2,546 Posts
Discussion Starter #13
Everything's Back to Normal

It was the shims. I went into the shop extra early this morning to work on the bike (another fun 20 miles lurch and surge session). I put the air restrictor and foam back in (and no, I didn't remove the entire air filter!!!), and no change. So I put the mixture screws to stock (1.75 turns) and no change. So it had to be the shims. I pulled the shims back out, and voila! Back to stock.

Oh, and I did try doing JUST the mixture screws with no shims, and for the life of me, I SWEAR it has MORE hesitation than stock. At the stock 1.75 turns, it's fine. At even 2.0 turns, I can feel more off-idle hesitation than before. I don't know. My bike seems to react opposite of everyone elses to mods. From this whole shim/mixture fiasco to the PVC spacer debacle a couple of months ago.

Anyway, everything's back to stock and running peach keen. The only other mod on the way is the -7S springs from Stan's (Netlore's) dearly departed bike. They should hopefully be here tomorrow.

And why were my EPA plugs out? I have no idea. Like I said, mine was a dealer demo. But it only had 285 miles on it when I bought it. Maybe they do that and fiddle with the screws to impress people on demo rides so they don't feel the hesitation and buy the bike or something??? Oh, and the first time I did it, I did NOT back them out a further 2.5 turns from stock. I screwed them all back in, then went out 2.5 turns. Either way, the bike does not like the extra richness from the screws or the shims. I'm just going to assume it's a great mystery and not mess with what works.

P.S. I just passed 8000 miles. Whoo-hoo!

P.S. #2 I'm not sure if I can make it for a Sunday ride. If the weather is as nice as it has been for the past week and half, I'm putting on another 400 some miles in the twisties in my backyard.

Thanks for all your help anyway guys,

Emrah
 

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Wheelie for Safety
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1,550 Posts
Hi Emrah,

Glad to hear you got it running good again. The next time you want to do a go-fast modification, do what I did.



Andy
 
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