(TL;DR on bottom)
First of all, I popped the tops off of my carbs today to check my needle shims. I found out that I had NO idea what I was doing when I first rejetted. So, I re-shimmed and went on my way. I also found out that I'm missing the little o-rings on each side of my carb tops.
With that information in hand, I have an afterfiring problem. Well, maybe not necessarily a problem, which is why I'm asking. I have a Jardine and pods, and my exhaust pops quite a bit on deceleration. I've jetted according to the matrix, and have played around with the mixture screws (2 to 3 turns in .25 increments). 2.5 seems to be where I get the least popping. I have also triple checked my header bolts, so I think I can rule out an exhaust leak. It also idles fine and runs like a dream, so I don't think I have a vacuum leak, either. Carbs have been synced, and valves were within spec as of spring.
TL;DR: Will a performance aftermarket exhaust pop a lot on deceleration if properly tuned? Will those little o-rings cause this issue if they're missing?
I believe I have read that on this forum... answering being yes, especially if the pair system is intact. Maybe some others can say why or add info to that to confirm? ... but I really don't know if its true, but I've read it on here before and I'm not sure I remember the source :dunno_black:
- Bboy
My hd did. my gs' not so much one had a vance an dhines, other one was punched. ( stock)
Quote from: BockinBboy on October 02, 2013, 09:41:22 AM
I believe I have read that on this forum... answering being yes, especially if the pair system is intact. Maybe some others can say why or add info to that to confirm? ... but I really don't know if its true, but I've read it on here before and I'm not sure I remember the source :dunno_black:
- Bboy
That's another puzzling point. I supposedly have a 2004, according to the VIN. But I have no PAIR system of which to speak. There aren't even block-off plates; they're sealed on the block itself. Perhaps the PO swapped motors or something. Not that it really matters. That's just one less thing to worry about lol.
As far as the exhaust goes, it's not really bothersome. I just want to make sure I have it tuned properly. I have severe OCD when it comes to my vehicles. They HAVE to be in top shape, or it really bothers me. (I have a 2005 Stratus 2.7L sludge machine with 108k that runs like new.)
You need to replace the O Rings on top. That can make it misfire.
Cool.
Buddha.
Awesome-sauce. Know where I can find some of those little guys?
Quote from: JAS6377 on October 02, 2013, 01:37:21 PM
Awesome-sauce. Know where I can find some of those little guys?
Take the carbs and match it @ autoparts store. Buy neoprene/BUNA O rings, not rubber.
Cool.
Buddha.
Alright. How big are they supposed to be? Just big enough to fit around that little post thing on each corner of the carb cap?
Quote from: JAS6377 on October 02, 2013, 05:00:18 PM
Alright. How big are they supposed to be? Just big enough to fit around that little post thing on each corner of the carb cap?
They should leave that air hole open, the rest they should seal up against the top. I use pretty fat ones, stock is rather thin. The smallest in a 432 piece kit from harbor freight works fine. Auto shops have those kits but never use the tiny ones. They may give you some.
Cool.
Buddha.
I just took a look at the parts list and pictures for the K4 carburetors, and it shows no o-rings under the caps... So,I guess I'm not missing any o-rings, as I didn't have them to begin with..?
Alright... In light of recent events, I just need something to do to take my mind off of things.
I have found that I have 3 lines that are questionable under my gas tank. My valve cover hose is currently unfiltered, which I should probably fix ASAP. The hose connected to the top "T" (that rubber connection between the carbs) has a small breather filter on it. The lower "T" hose is currently connected to what I believe used to be the airbox drain hose (the one that has that little rubber cap on it). Should I be looking to do anything else with these hoses that may help alleviate some of this afterfiring? I may also, if I can get the time this week, do another valve check and carb sync, just to double check everything if no solutions come up.
OK 01+ bike has no Orings on top.
So that not your problem.
Hoses ... valve cover vent could be open, ot fitted with K&N type filter ... Or fitted with PCV valve.
The top T should be relatively open to atmosphere. Filter may be OK, but it should flow air in.
Bottom carb T ... should get fuel from the petcock.
Cool.
Buddha.
I was slightly mistaken when I said the lower "T". The fuel line is obviously hooked up correctly, as the bike has been running strong. There is a second rubber T connector between the two carbs that I believe used to be connected to the airbox, but I'm not sure.
The "Ts" that I'm talking about are numbers 48 and 50 in this diagram:
(http://i1338.photobucket.com/albums/o681/JAS6377/k4_Carbs_zps50ebfe07.jpg)
48 is vacuum, had to go to petcock.
50 is the vent and I think its just filtering the air coming in.
Cool.
Buddha.
Quote from: The Buddha on October 07, 2013, 03:52:35 PM
48 is vacuum, had to go to petcock.
50 is the vent and I think its just filtering the air coming in.
Cool.
Buddha.
Maybe not, the 50 T thing is to the rollover valve whatever that is, not vacuum.
Looks like vacuum comes off the right carb - 44 goes to it.
Cool.
Buddha.
I'm thinking that rollover valve is probably something like a PCV valve to help keep proper vacuum pressure..? Idk. The valve is there lol. I'll play around with 48, plugging it and whatnot, and tinker with that filter doohickey. You've piqued my curiosity now lol.
Edit: It seems as though I was halfway right on that valve. It's to prevent excessive fuel leakage, apparently. So, it is a one way filter. Who knew?
Quote from: JAS6377 on October 07, 2013, 05:07:03 PM
I'm thinking that rollover valve is probably something like a PCV valve to help keep proper vacuum pressure..? Idk. The valve is there lol. I'll play around with 48, plugging it and whatnot, and tinker with that filter doohickey. You've piqued my curiosity now lol.
Dude PCV valve belongs on an engine vent ... not on a carb vent.
The Rollover valve, essentially is like marvel mystery oil. What it does is the mystery.
Cool.
Buddha.
Quote from: The Buddha on October 07, 2013, 05:09:31 PM
Quote from: JAS6377 on October 07, 2013, 05:07:03 PM
I'm thinking that rollover valve is probably something like a PCV valve to help keep proper vacuum pressure..? Idk. The valve is there lol. I'll play around with 48, plugging it and whatnot, and tinker with that filter doohickey. You've piqued my curiosity now lol.
Dude PCV valve belongs on an engine vent ... not on a carb vent.
The Rollover valve, essentially is like marvel mystery oil. What it does is the mystery.
Cool.
Buddha.
I'm well aware of what a PCV valve is... I was just noting a similarity in the fact that they both are one way valve devices. The PCV valve only vents, but doesn't allow intake. A rollover valve does the opposite, and with fuel, not crank case gases.
Oh. And :mad:
:cheers:
Another edit (I seem to be doing this a lot): From the parts diagram that I'm looking at on BikeBandit, it looks like that doohickey really is just a filter. It lists the part as FILTER,2ND AIR.
Did some more research. I found this post (http://gstwins.com/gsboard/index.php?topic=52921.0), and this how-to (http://gstwin.com/fuel_hose_routing.htm) from, believe it or not, GSTwins! Go figure. It seems as though my hoses are not the issue here. Both top Ts are air-related. The topmost has the filter, the lower is just left open, and the bottom T is for fuel, as you said, Buddha.
So, onward. I'm at a loss. I guess I'll just take it apart, do a valve check, sync the carbs, and put everything back together. Perhaps I did something wrong the last time. :dunno_black:
A rollover valve does somehting ... danggit ... there is like 300 in the ravine across the street form me ... they must be up to something, Lately I've seen big dogs go down there ... and never be seen again. :D
Cool.
Buddha.
Just got done with shimming my valves. I haven't had a chance to test ride it because it's been raining all day. However, it did develop a ticking noise at idle when warmed up... The shop I got my shims at didn't have the 255 that I need for the intakes (they were both below .038mm), so I got 250 instead. I'm thinking the ticking is excessive valve clearance on the intakes. Good news is the exhaust valves are both at around .1mm. The left was tight at just barely .038mm.
So, main question now is, will higher valve clearance on the intakes cause ticking?
Clacking is more like it. Ticking is for tappets, we get a noise so deafening you cant hear other sheite blowing up, that's how bad it can be.
Cool.
Buddha.
Yeah, you could call it clacking, too lol. I'm not a fan of valve noise at all. I'm used to hydraulic lifters, so I get the willies every time I hear valves. I think I'm just going to swap my shims back for now until I can get 2.55s.
Clacking is a bit annoying, and too loud clacking will make you not hear other problems ... true, But TBH it doesn't hurt 1 bit.
The other thing is the yamaha shim over bucket 2 valve motors - FJ600, maxim, radian etc etc - essentially the exact same as the GS specify to run their valves much much looser ... 1-3 thou is GS intake or exhaust, the yamaha is 3-5 intake and 5-7 exhaust.
I guess we could do that too if needed. Just that the racket will be deafening. I suspect that is why they even put that tight spec in there.
Cool.
Buddha.
Alright. The clacking was the intake valves. I swapped shims back. Glad I did, too. Now it's making a sound like the cam chain is smacking the case. It's only when warm, and only at idle. Still valve chatter?
It cranks fine, idles fine, and rides fine. Once I heard the noise start, though, I pulled it back into the driveway.
Cam chain - OK try this. Turning the motor over in the correct direction, keep an eye on the section between the sprokets.
If it ever sags from being taut, that = CCT is bad.
Cool.
Buddha.
Awesome... I guess I'll crack it open again lol. Just to be clear, correct direction is spinning the rotor clockwise?
Ooohhh crap... Let me ask this: do you check the clearances on all of the valves with the R-T mark lined up, or with the cam lobes normal to the bucket? I just checked them all at the same time just lining up the R-T mark.
Quote from: JAS6377 on October 12, 2013, 05:12:08 PM
Ooohhh crap... Let me ask this: do you check the clearances on all of the valves with the R-T mark lined up, or with the cam lobes normal to the bucket? I just checked them all at the same time just lining up the R-T mark.
I'm pretty sure you check the clearances in two different cam positions, but I don't know which position for which valves. If you don't have one, its worthwhile to invest in a Clymer or Haynes manual if you are working on the bike yourself.
I dont think I've checked valves or the cam chain ever by pulling the right side round cover.
I put it in 6th, take out spark plugs and spin the back wheel.
Cool.
Buddha.
Alright... So, correct direction IS clockwise around the rotor. And you're right Drt. The cam notches should be facing one another for RI, LI, and RE valves, with the R-T mark lined up on the pick-up. You then turn the rotor (or back wheel) until the cam notches are facing AWAY from one another, with the R-T mark lined up, to check the LE valve.
With that said and done, I swapped out some shims, and checked the cam chain. The chain is fine. The issue was that my LE valve was at about .15 when warm, causing some valve noise. I swapped it out from a 255 to a 260, and all is well. I still need another 255 for my intakes, as they're still at minimum, but it rides fine and purrs like a baby Nittany lion.
Back to the original issue, it still has a slight afterfire lol. Next up is a proper carb sync, I guess?
If it purrs watch out ... maybe someone put a GSXR motor in it ...
If it clacks softly then congrads, you've done a good job of a valve adjustment and have had a good slice of luck.
Cool.
Buddha.
Oh, you didn't know that it's a GSXR 500? Lol. Yeah, purring may not be the appropriate word. It happily clacks along, as a proper GS should.
Quote from: JAS6377 on October 12, 2013, 06:49:51 PM
Alright... So, correct direction IS clockwise around the rotor. And you're right Drt. The cam notches should be facing one another for RI, LI, and RE valves, with the R-T mark lined up on the pick-up. You then turn the rotor (or back wheel) until the cam notches are facing AWAY from one another, with the R-T mark lined up, to check the LE valve.
With that said and done, I swapped out some shims, and checked the cam chain. The chain is fine. The issue was that my LE valve was at about .15 when warm, causing some valve noise. I swapped it out from a 255 to a 260, and all is well. I still need another 255 for my intakes, as they're still at minimum, but it rides fine and purrs like a baby Nittany lion.
Back to the original issue, it still has a slight afterfire lol. Next up is a proper carb sync, I guess?
Definitely do a carb sync, but it probably won't cure your popping on deceleration. My GS did that ever since I installed the cobra slip on. It ran fine, just always popped when I closed the throttle. I tried different jetting and air screw settings, and it never went away. I think my slip on let some air into the exhaust. I don't know if your Jardine system has a removable muffler. If it's welded, then that it likely not the issue. I read somewhere that a properly tuned engine can pop on deceleration. I think it was on the internet though, so it's probably not accurate.
Nah. If it's on the internet it has to be true lol. But yes, the Jardine does have a removable muffler held on to the pipe by two springs. That could be it. It could also be the band clamp on the midpipe, but I re-torqued everything before I even did the valve check. I guess I'll just maintain it and double check everything again. If it goes away with the carb sync, awesome. If not, oh well lol. I'll post an update after the sync later this week.
Popping on deeceleration is because when you shut the throttle the air flow is cut off, but the engine speed doesn't drop that quick.
So you get a lot of suction and it sucks fuel through a closed butterfly (as in it only gets gasoline let in by the air screw) so it is very lean, and that will not burn with spark, but when it gets in the exhaust it is in a thin tube that is bloody hot. Poof it burns and makes a pop.
It has started doing it with the addition of pipe cos - well when it burns, the pipe will let it escape quick and you hear that pop.
The stock pipe also has so much pressure, the shutting of throttle results in the exhaust gas still sitting in the chamber, so it doesn't suck as much from the carb, and since it has the 3 convoluted chambers will make no audible noise.
Singles are a lot worse ,and 4's a a lot better @ this. Though with unequal length headers my eliminator 1000 let off the most unbelivable staccato AK 47 gun fire ... I highly recomend it.
Cool.
Buddha.
Okay... So, the bike has now developed an odd surging, like it's running out of fuel. It doesn't happen a lot. Only at mid-full throttle at lower RPM. I'm thinking it's either the carbs being out of sync because of the valve adjustment, or the really tight intake valves. I'm getting the proper intake shims tomorrow, and I'll be doing a carb sync after that. We'll see how it goes.
Quote from: JAS6377 on October 15, 2013, 12:57:31 PM
Okay... So, the bike has now developed an odd surging, like it's running out of fuel. It doesn't happen a lot. Only at mid-full throttle at lower RPM. I'm thinking it's either the carbs being out of sync because of the valve adjustment, or the really tight intake valves. I'm getting the proper intake shims tomorrow, and I'll be doing a carb sync after that. We'll see how it goes.
Mid to full throttle @ low rpm ? Like when you open throttle when you're under load @ say 2500 rpm ...
Yea set the valves and synch it ... you need to do both ... but wont do squat to your situation.
You're likely having the slide lift too fast. The fix was the PITA od plugging 1 hole in the slide ...
Is it better if you gradually open throttle ? If yes, I'll train your right hand to open slow.
Cool.
Buddha.
Yeah, it's under load at 3500 and under, sometimes in the higher revs. It's only slightly better if I roll on slowly. The only way to avoid it is to slip the clutch quite a bit. Could the carbs being out of sync possibly be causing just one slide to have more vacuum, thus raising it faster?
Quote from: The Buddha on October 13, 2013, 06:12:37 AM
Singles are a lot worse ,and 4's a a lot better @ this. Though with unequal length headers my eliminator 1000 let off the most unbelivable staccato AK 47 gun fire ... I highly recomend it.
That would be a performance :D
I forgot about this thread in the midst of my clutch issues, and waiting for Suzuki to quit screwing up. The warehouse sent the dealer 2.50 shims in 2.55 packaging. So I had to wait another week to get my intake shims in. They're here, finally. Looks like I'll be popping the new shims in tomorrow morning and syncing the carbs. Then I get to ride it and see how she runs. I hope the sync gets rid of that surging.
Update: The shims are in and the carbs are synced. It felt really good seeing the neighborhood, so I'm going to take it to school today and see how it goes.
Update 2: Woohoo! She runs like new! Thank you everyone for your help. She still has an afterfire, but I'm going to just say it's the exhaust. Everything else is in perfect shape.