Carb Tuning Help

[D0wn5h1ft]

Slow pullin on the top-end is my first clue to too rich in the mains, float levels too high, or metering rods set in higher clip position. Looks to be the same effect at the lower end too by what you are reporting. BTW, no points in these bikes. They're a bit old, but not ancient. The plugs show normal for their location. Two center cyl. run a bit hotter, and plugs show that based on location. The good news is the two outer plugs are identical and the two center are identical. That tells me float levels are pretty dead-on all the same and firing of plugs is all good. For not actually having done a CORRECT sync, pretty good I must say, even though a bit rich (which could be from idle circuit cruisin back to house). That possibly being the case, not being there not knowing exactly how and where ridin before plug removal, and if having the matching year early carbs, I'd suggest removing the slides(under chrome carb top covers), remove the needles(read tech tips on procedure of removal and installation), RAISE the clip on the metering rods one position which drops the needles. Pay special attention and keep each slide with THAT carb it came from. Porclien looks good as if was run at high enough rpm in the main circuit, but at the lower rpm, maybe towards end of ride in the lower rpm range metal threaded ring all the way down to inside base was blackening up. One change at a time IS critical to start eliminating the problem! No offense intended, but the points question tells me your not very savvy at this point, so don't be afraid to ask. The only dumb question is the one not asked here FIRST, before proceeding!

I misspoke about the points, I meant to say PU coils. I'm working on an XS400 right now and its having issues with the ignition system... But yes, I'm still cutting my teeth on this bike.

I'll clean the plugs thoroughly take her out for a ride today and post new pictures of the plugs. If the plugs still look rich I will adjust the needle to make the mixture more lean.

I have the 3ohm coils, btw, and I have removed the ballast resistor.

[IanDMacDonald]

Even though Motoman is better than this over me, one thing I'd suggest before u play with the needle clip position (very involved without the right snapring pliers), is to tell everyone on here what you have for jets, float settings, and air pods. Junk? K&N? Motoman'a advice may change as soon as he learns of what you have going on.

At the least, reset your mixture screws to 3 turns out and THEN clean ur plugs and go.for a ride before you mess with the needle clip position

[DGXSER]

TADRacer is on to something regarding your ballast resistor. Definitely make sure it is bypassed (simply remove it and plug the two wires directly together).

Now before we go off on a goose chase on jetting, do check your mounting of those POD filters. As TC mentioned I believe, the cheaper ones can block off the air jets in the inlet bell. As for jet sizes, if you look at the pilot air jet (roughly 10 o-clock position on the inlet bell) it has its size printed on the face of the jet. Probably a 180-185 range number. Same for the main jets for location. On the pilot jets, you have to remove it and look at the side of the jet for the size, should be in the 42.5 to 45 range. It is important to know where your at now on jet sizes before we make suggestions on where you should go. If you have say 145 mains and 47.5 pilots with 150 pilot air jets, then you do not need bigger mains, and pilots, probably smaller and a bigger pilot air jet. If you have stock jetting, and your that rich, then most likely it is float level or needle valve position. So it will all depend where your at for us to suggest a path to improvement.

[motoman]

Even though Motoman is better than this over me, one thing I'd suggest before u play with the needle clip position (very involved without the right snapring pliers), is to tell everyone on here what you have for jets, float settings, and air pods. Junk? K&N? Motoman'a advice may change as soon as he learns of what you have going on.

At the least, reset your mixture screws to 3 turns out and THEN clean ur plugs and go.for a ride before you mess with the needle clip position

Three turns out on the early carbs for starting point IMO is gonna be too far.......although a decent starting point goin back in with them slowly in gradual steps while idleing till that slight change is heard, then backout an 1/8 to 1/4 turn at the most. BTW, never have needed snap ring pliers to pop that clip out myself. He just has to be sure and get spring top-side not under washer. Have heard of that happening here holding those metering rods up and not down. As stated a little more info jetting wise and such is always good for helping in the right direction.

[IanDMacDonald]

Three turns out on the early carbs for starting point IMO is gonna be too far.......

Yeah, I was going to suggest the standard 2 1/2 turns out, but I'd rather lead someone astray going too rich over too lean and have something (possibly) go bad.

Advice on here can go bad, and if someone takes a novice's advice like mine and runs with it, and things go bad, I feel bad, and the receiver of advice gets pissed and points fingers. A few of you have taught me a lot very quickly in my young age to SLOW DOWN, and just take everything in. I see myself a few months ago in some of these posts, and it's nice to pass-on the advice I was given.

[motoman]

Yeah, I was going to suggest the standard 2 1/2 turns out, but I'd rather lead someone astray going too rich over too lean and have something (possibly) go bad.

Advice on here can go bad, and if someone takes a novice's advice like mine and runs with it, and things go bad, I feel bad, and the receiver of advice gets pissed and points fingers. A few of you have taught me a lot very quickly in my young age to SLOW DOWN, and just take everything in. I see myself a few months ago in some of these posts, and it's nice to pass-on the advice I was given.

Point taken Ian. Was just looking at in the sense that if he were gonna try and set mixtures running as should be done anyways, at an idle, just was trying to avoid having some plugs go black mis-firing before mixture setting process got started. On the later carbs having basicly a seperated circuit, the 3-4turns out for starters doesn't seem to create that issue.

[TopCatGr58]

The tech tips regarding the Pod filters are in the MODS section, carbs.

http://www.xs11.com/forum/showthread.php?t=8269

http://www.xs11.com/forum/showthread.php?t=35425

T.C.

[donebysunday]

T.C. mentioned he saw pics of your bike with those emgo pods. Pull them off and try it on a clean road where your not going to pick up any dust debris that could get sucked into the carbs and ruin your day not to mention your engine. I threw those emgos in the trash. IMO UNI or K&N are the best and work about the same.

[TopCatGr58]

Hey Done,

The XS brand Mikes.net and PNM sell, or K&N are good because they don't have the prominent mounting lip that can interfere with the intake bell ports, HOWEVER, the air is still coming into the carb from a sideways direction with those short mounts of the filters. The fine Yamaha Engineers also knew that the air flow into the CV carbs was important to be coming in STRAIGHT into the inlet bell without turbulence....and so that's why they put the VELOCITY STACKS INSIDE the OEM airbox.

SO...thru accidental discovery having to fix the EMGO mounting lip problems, we learned to mount them onto some form of VELOCITY stack type mount, and it solved a couple of problems. 1, cured the mounting lip restriction/interference, but also provided the smoother straighter airflow path from the filter into the carbs...which seems to have improved the low rpm throttle response since the air is moving straighter and smoother, no or very little turbulence!

SO...even though the XS and K&N filters will mount directly to the carbs without an interfering LIP, it is still advised to install some form of Velocity stack type mount for the Pods....moving the pods a few inches away from the carbs. Ever since I installed the Lowes Plumbing style velocity stacks for my EMGO pods...I've had no problems in both tuning my bike and having very good throttle response and power thru the full rpm band, etc.!

T.C.

[donebysunday]

Hi T.C. !

I've always tested (when having troubles) by taking the filters off to see what changes in the way it's running.
With the XS650 I had enough trial and error that when I got one of them ready to ride and it stumbled and coughed I knew it was the exhaust. Even though the pipes and muffs were stock and in really nice shape on the outside there was something really wrong on the inside. Had another exhaust so I put it on and all was fine. Later I cut the muffs off that bad set and found that water (I think) must have gone into the 2 walled pipe on one side, froze and expanded the inner wall almost closed, that side was junk. Years later, matched up the good side to another nice looking head pipe, after market muffs and all was fine on another bike.
To bad we don't have a known good set of exhausts that could be tried when all else fails.

Done };~)

[D0wn5h1ft]

So I just got back into town and I took off the air filters and went out for a ride. I noticed something coming back out of the carbs and realized it was atomized gas. It was a gas/air mixture coming back out of it, not liquid gas overflowing from the float bowls. Not sure if it is supposed to be doing that.

There was a slight increase in low end performance (as should be seen with no air flow restriction with a rich mixture) but nothing that would make me think that air jets are getting blocked off.

I'm going to try adjust the float levels next and getting you guys some numbers on those jet sizes but the gas mixture coming out of the carbs might be a clue to what is going on?

[motoman]

So I just got back into town and I took off the air filters and went out for a ride. I noticed something coming back out of the carbs and realized it was atomized gas. It was a gas/air mixture coming back out of it, not liquid gas overflowing from the float bowls. Not sure if it is supposed to be doing that.

There was a slight increase in low end performance (as should be seen with no air flow restriction with a rich mixture) but nothing that would make me think that air jets are getting blocked off.

I'm going to try adjust the float levels next and getting you guys some numbers on those jet sizes but the gas mixture coming out of the carbs might be a clue to what is going on?

That turbulance goin on thru the intake bell is normal, and is what the stock airbox helps eliminate and keeps a smooth intake flow.