SPITTIN CARBS

MYYAMAHOG · Full Member Joined: Jul 23, 2005 Posts: 19 Location: TEXAS

I'VE GOT A 80 MODEL XS650SG, THE RIGHT SIDE CARB SPITS GAS OUT OF IT WHILE RUNNING AND THE MORE THROTTLE YOU GIVE IT THE MORE IT SPITS, JUST WONDERING IF THAT WOULD BE A SPECIFIC PROBLEM OR IF I JUST NEED TO GET A KIT AND ATTEMPT TO REBUILD THE WHOLE THING(NEVER WORKED ON A CARB BEFORE,BUT YA GOTTA LEARN SOMETIME)ANY ADVICE GREATLY APPRECIATED.

grizld1 · Posted: July 23, 2005, 8:04 pm Post subject: Re: SPITTIN CARBS

The best way to go is to identify the problem before you throw money at parts. When you say it's "spitting" gas, where is the gas coming from? If it's coming from the overflow port that's more likely than not a float problem. The plastic floats in your carbs don't hole as readily as the copper floats on earlier machines, but it happens; fuel gets into the float, the float don't float, and overflow results. A malfunctioning float needle can also do that deed. But that problem should cause less fuel to flow out when you give 'er the wick, not more. If fuel's being ejected under pressure somewhere, that's another issue entirely. Where's the fuel coming from, and what kind of "spit" is occurring? Are we talking a flow, a pressured mist, or what? Was the bike running well before this happened and does it behave now? Are both vacuum plugs in place and secure? Don't fear--these are pretty simple units.

MYYAMAHOG · Full Member Joined: Jul 23, 2005 Posts: 19 Location: TEXAS

BEST I CAN TELL IT'S COMING OUT OF THE THROTTLE BODY, I GUESS THAT'S THE TERM IT'S THE CARB ITSELF WHERE THE SLIDE IS NOT ONE OF THE LITTLE JETS, AND BY SPIT I MEAN A PRESSURIZED MIST THAT INCREASES WITH THROTTLE. SORRY IF MY TERMINOLOGY IS HARD TO UNDERSTAND, I AM IGNORANT WHEN IT COMES TO CARBS. THANX ALOT FOR YOUR HELP

MYYAMAHOG · Full Member Joined: Jul 23, 2005 Posts: 19 Location: TEXAS

SORRY FORGOT TO SAY THE MOTOR IS ONE I PICKED UP FROM SOMEONE ELSE DON'T REALLY KNOW HOW IT RAN BEFORE BUT HE SAID IT RAN GREAT, AND ONCE I FINALLY FIGURED OUT THE WIRING IT FIRED ON THE THIRD KICK JUST THE RIGHT SIDE CARB ALWAYS WAS A PROB, IF IT HELPS ANY WHEN YOU PUT YOUR HAND BEHIND THE EXHAUST THE LEFT SIDE IS HITTING GOOD BUT THE RIGHT SIDE ISN'T HITTING HARD AT ALL JUST SPUTTERING PERIODICALLY AND VERY WEAK, I DID DO A COMPRESSION CHECK AND IT WAS AROUND 130 WITH BUTTERFLY AND SLIDE WIDE OPEN SO I THINK I'M OKAY THERE.
ONCE AGAIN THANX

grizld1 · Posted: July 24, 2005, 12:44 pm Post subject: Re: SPITTIN CARBS

OK, now we have somewhere to start. First thing: on both carbs there should be a threaded plug (short bolt with a head for a 10mm wrench) that covers a threaded hole near the throttle (butterfly) shaft. The hole takes the nozzles for synchronizer lines when you're balancing the carbs. Is the one on the right side in place, sealed, and secure, and is that where the fuel mist is coming from? If the plug is in place and secure, remove the right-hand throttle slide and tell me if the top of the diaphragm has a lot of raw fuel on it.

Hey, don't worry about terminology. We're here to help, and asking questions is part of the process. I'd just rather make sure I understand what's happening and work toward a fix than try to flash my knowledge by throwing out a dozen or so WAG's. Everybody starts somewhere. Maybe some folks were born with a wrench in one hand and a dial caliper in the other, but I'm not one of 'em!

MYYAMAHOG · Full Member Joined: Jul 23, 2005 Posts: 19 Location: TEXAS

screw is in place and diaphram was dry, i might have stumbled on something by accident, i was running the bike to get a better idea where exactly the gas was shooting out of, and it seems to be where the needle goes into the "jet"?? but when i killed the bike i forgot to turn the petcock off and a while later i was outside and could smell gas, when i looked at the bike it was running out of the bad carb, killed the petcock and the flow stopped, is that a sign of a bad float, needle and seat, anything else???
once again thanx for all your help

grizld1 · Posted: July 24, 2005, 10:45 pm Post subject: Re: SPITTIN CARBS

You betcha! First off, you're gonna have a crankcase full of fuel, so don't fire that beast till you've changed the oil. When you say fuel was coming from where the needle goes into the jet, were you looking into the carb with the slide out and one cylinder running? If so you were seeing a normal condition. If not, I'm not sure what you're describing. Now, we have two issues in front of us. Your bike in stock form has a diaphragm petcock which has no "off" position, but does have a "Prime" position which lets fuel flow without vacuum action on the diaphragm. If your petcock has an "Off" position, it's either a custom-fit or an aftermarket unit. Let me know what you have. In either case, you do indeed have a float issue (and maybe more, but we'll keep on doin' till we get it right). There are several possibilities here. Unfortunately, your carbs have to come off.

The carbs are a tight fit; so after you have the air intake tubes to the breather box or pod filters, whichever you have, out of the way, it helps to remove the cam chain adjuster cover, the throttle perch on the left carb, and the carb bridge. You can get 'em out with those things in place, but it's less like a Chinese puzzle if you give yourself some room. Now you want to check the floats. Remove the float bowl, tease the float pin out with a probe, and give the floats a shake. If you hear fuel sloshing in them, replace them with new ones. Repairs are usually not reliable (expect half a dozen methods of sealing floats to be posted in response to this!) Also, be sure the internal surfaces of the gasket are in good shape. If not, replace it.

While you're in there, check the float level, referring to a manual. If you have to adjust the float tab (you'll have to do this regardless if you need new floats), be gentle. A little change there goes a long way. If I were doing it, I'd install a new float needle and seat while I was in there, just to be on the safe side. As long as the carbs are off, be sure everything is garf-and-varnish free.

ike's XS is the best source I know of for parts. You get the float needle and seat as well as a new carb gasket and other stuff you may need sooner or later in his kits, and it's a smaller buck than buying the pieces one at a time.

Your carbs should be resynched when you put 'em back on, but that has to wait 'till you get that right carb working normally. One more thing: if the petcocks have been replaced with a manual nonvacuum unit, be sure the vacuum nipples on the boots are well blocked off.

MYYAMAHOG · Full Member Joined: Jul 23, 2005 Posts: 19 Location: TEXAS

petcocks have been replacd with non vacum, the bike has a sporster tank on it now, gotta pull two double shifts today and tomorrow but i'm off wed. gonna order the kit today and hopefully it'll be here then and i can pull em off and check it out, also thanx for the info about the oil change never woulda thought of that. thanx again for all your help i'll let you know what happens wed.oh yeah the vac nipples are in place.

grizld1 · Posted: July 25, 2005, 9:40 am Post subject: Re: SPITTIN CARBS

Cool. manual petcocks are the way to go, and if you didn't have them already I'd recommend them. Just be sure to turn off every time you shut down; even with a good float system there's a bit of seep that'll contaminate your oil if you don't. Be sure to use motorcycle oil--the stuff for cars will get your clutch slipping like a hog on ice.

MYYAMAHOG · Full Member Joined: Jul 23, 2005 Posts: 19 Location: TEXAS

got the kits this afternoon, already had a few so not gonna touch the carbs till in the morning. got new needle and seats for both sides and new floats for both, since the left side is working fine do you think i should change it too while i have it off or "if it ain't broke don't fix it" and just shelf the carb kit and extra float for future use. gonna tear into it in the mornin i'll let you know what happens. sure hope to see you at a run somewhere in the near future, the drinks are on me if i do!!!!!

grizld1 · Posted: July 27, 2005, 6:38 pm Post subject: Re: SPITTIN CARBS

It's always a judgement call, but I don't replace needles and seats unless there's a problem. If you get up this way (Southern IL, Southeast MO, Western KY), holler at me. I may do the Yamaha 650 Society Smoky Mountain run in September. Ever run Deal's Gap? Pure carnage--log trucks, Goldwings and Harleys all over both lanes.

MYYAMAHOG · Full Member Joined: Jul 23, 2005 Posts: 19 Location: TEXAS

good news/bad news... replaced needle,seat, and installed the new float, took a little playin with but got the float set per manual i believe, good news is that stopped the gas from free flowing, so i believe the float issue is good now. bad news is once i got everything back together and fired it up i'm still getting the mist spitting out of the center of the carb, i had someone tell me that the valves were probably warped yesterday. you think it could be somethin that serious, i,ve got good compression and the more i tinker with the carb i can see and hear a little difference in the exhaust on that side. you used to feel hardly anything if you put your hand behind it, now it is popping and you can feel it stronger just nothing like the other side and the carb is still spitting.

grizld1 · Posted: July 28, 2005, 8:11 pm Post subject: Re: SPITTIN CARBS

OK, we're getting somewhere! With 130 lbs. of compression you're a little shy of the 145 lbs. your unit should have (Yamaha went back to 8.7:1 compression in 1980 from the previous drop to 8.5:1), but most of us don't have precision equipment lyin' around the garage; so check the compression on the good side too and let me know how they compare. If you haven't done it yet, adjust the valves and cam chain first. 130 lbs. on an engine that's been sitting awhile ain't bad, and it'll probably come up as the rings get worked a little. I really doubt the bent valve idea; but hey, valves have to be right to get the carbs dialed in anyway.

I'm still not sure just where the fuel mist is shooting out. The fuel screws controlling the pilot circuit on your scoot are hidden under plugs that have to be drilled out for access. There's another thread in the forum on this. Try to describe the fuel geyser for me with reference to the fuel screw plugs (the writer calls 'em idle screws, but that's the Yamaha term for the throttle stop screw), throttle shafts, starter (choke) assemblies, air intake, mounting boot, slide body, inside/outside, and so on. You metioned it was in the center of the carb, and where the needle enters the jet. Were you looking at the back of the carb with the airbox/filters pulled, with the slide high enough to see the needle and top of the atomizer jet? Sorry to be so dense; word-pictures are tough to draw, but we'll get there! While we're at it--what does the sparkplug on the missing side look like?

MYYAMAHOG · Full Member Joined: Jul 23, 2005 Posts: 19 Location: TEXAS

read through my manual this morning and tried the adjustments on the cam chain and the valves, cam chain seemed fine, on the valves i was a littla lost. i pulled the side cover and lined up the marks for top dead center, and then pulled the covers to check for valve clearence with my feeler gaps. this is where i got a little out of my leauge, i assumed you would check the clearence between where the set screw on the rocker arm starts to touch the spring, but at top dead center there is no clearence there on either my intake or exhaust side they are both touching and the feeler gap will not go in between. for fear of not knowing what i was doing i did not try to adjust because i did not know if i could do more harm than good, but my manual shows to have a clearance on intake and exhaust both. does it sound like i am checking the right spot. if so i will adjust and see what happens. as far as the mist goes sorry i can't seem to explain it right i know it is hard to visualize without actually seeing, but yes i am talking about the carb with the airboxes off, with the needle all the way up. the plug looks fine. sorry to be such a bother, i really appreciate all the help you've given me i'm gettin there slowly but surely.

grizld1 · Posted: July 28, 2005, 11:07 pm Post subject: Re: SPITTIN CARBS

Great! I got the picture now on the fuel.

You're checking valve clearance in the right place. Take both sets of valve covers off. When the TDC marks are lined up, one cylinder should have slack at the tappets (you should be able to move the rockers a little) and the other should be tight. Rotate the engine 360 degrees, and the tight tappets should now have slack, and the ones on the other side should be tight.

So: move that motor by the ignition rotor nut on the crank (easier if you pull the spark plugs) until the TDC mark is lined up, find out which cylinder has loose tappets, and set them. Then rotate 360 and do the other side. If you don't find any slack in either of them, go to the thinnest blade on your feeler gauges till you find some slack on the working cylinder and put the clearances where they should be, then rotate 360 and do the other side. If you can't find any slack at all, let me know.

Hey, you're no bother--this is what the forum's for.

I'm more used to the earlier Mikuni CV carbs, but I've got two sets of the later ones in my stash. I'm gonna pull 'em off the shelf tomorrow and review a few things.

grizld1 · Posted: August 3, 2005, 10:47 am Post subject: Re: SPITTIN CARBS

Went back over some old notes and broke down a pair of '82 carbs, just to freshen the memory. If you've got the valves adjusted and the problem is still there, you may want to have a look at two more possibilities;but the thing I find worrying is that these conditions should be causing one seriously rich mixture, and you've said the right-hand plug isn't fuel fouled or blackened. It sounds from that as though fuel isn't getting pulled into the engine, but valves that badly warped shouldn't leave you with 130 pounds of compression!

I had a problem similar to yours around 12 years back. It was caused by a pilot jet that had vibrated loose. Those are under the black plugs near your main jets. Pull the plug in the right-hand carb and see if the pilot's firmly seated. But as I indicated, this should show up on the spark plug.

Another possible problem is the fuel screw in your right carb. There's a long vertical tubular casting on the front end of each carb, and the fuel screw lives at the bottom of it. The casting is plugged, unless a prior owner's opened it up already. The plug usually has to be drilled for removal. When you get the plug out, run the screw in until it bottoms gently, counting the turns you take. Then remove it, and inspect it for damage. At this point, just to eliminate a possible problem, I'd advise you to replace the O-ring that lives under the washer at the bottom of the tube. You'll need to order a new fuel screw plug from Mike's anyway, and maybe a new pilot jet plug as well. Don't install the fuel screw plug till things get dialed in, as follows. When you remount the carbs, set the right-hand fuel screw at an initial setting of 2 turns out. Give it a quarter turn each way. Set it where it runs better and do quarter turns again. If you start to get a strong idle and the spittin' stops, reinstall your air filters and continue the tweaking till you can get the scoot to run on the right cylinder only; you may have to bump the throttle stop up for this. Go for the highest idle speed you can get from the fuel screw setting, backing down the throttle stop as the idle gets stronger. Keep a strong fan on the engine, and take it in small sessions--don't want to overheat.

MYYAMAHOG · Full Member Joined: Jul 23, 2005 Posts: 19 Location: TEXAS

sounds like i might be getting somewhere thanx to you, i work shift work and have been working nights and overtime due to someone being on vacation but i finally get another off day on friday the fifth, gonna try the fuel screw only problem is that whoever had the bike first must have messed with the fuel screw because when i got it the plug was gone and the screw is stripped. any suggestions as to how to get it out, if i have to i will buy an easy out.thanx again and i'll let you know what happens friday once i finally get a day off.

grizld1 · Posted: August 3, 2005, 9:38 pm Post subject: Re: SPITTIN CARBS

Ouch! When you say it's stripped, I hope you mean the slot's fouled up, not the threads! If there's any slot left at all in a little brass fitting, I try to dress the edges a bit with a small, sharp screwdriver, using it like a chisel. Then I use a blunted screwdriver, one I've run down on the grinder to thicken the blade for widened slots. I set it to the workpiece (usually a jet somebody's screwed up) and give it a rap. Then do a sharp push-and twist, and see if the rascal breaks loose. Now we need to wonder why Og the Neolithic Wrench tried to solve a problem by driving the fuel screw down hard into the seat....

MYYAMAHOG · Full Member Joined: Jul 23, 2005 Posts: 19 Location: TEXAS

UH OH!!! I'VE BEEN TOLD A HUNDRED TIMES I'M TO HEAVY HANDED. I SHOULDA LISTNED. I TRIED TO HAMMER THE SMALL SGREWDRIVER INTO THE SCREW AND BROKE THE ALUMINUM HOUSING, PROBABLY SHOULDA LEFT THE HAMMER OUT OF THE EQUATION, CAUSE NOW I'M SURE THA CARB IS SCREWED, YOU MENTIONED YOU HAD A COUPLE PAIR ON HAND WOULD YOU BE INTERESTED IN MAKIN SOME $$$ FOR A SET, IF NOT NO BIGGIE I'LL CHECK OUT EBAY, I HAVE A SET OF THE OLDER ONES IN THE WORKSHOP BUT HAVE NO USE FOR THEM THEY ARE DIFFERENT THAN THE ONES I HAVE NOW SO I GUESS I'LL NEED ANOTHER SET. EVER WANNA KICK YOURSELF IN THE A**???

grizld1 · Posted: August 5, 2005, 11:23 pm Post subject: Re: SPITTIN CARBS

No problem. I'll send you a pm, we can swap contact data, and I'll get a
carb to you. Hey, I'll tell you about some of my better moments sometime--like dropping a bike off the center stand 'cause I thought I could get away with a shock swap without blocking the engine and trashing a bullet fairing I'd spent a bunch of time filling, painting and polishing. Oh, yeah, I've wanted to do that!

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