Author Topic: Carb problems  (Read 1451 times)

Tim B.

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Carb problems
« on: September 25, 2003, 07:26:04 AM »
I cleaned my carbs (tried anyway). The problem is when I open the throttle wide the engine boggs down big time. On my other Vision even if if bogged a little, when the throttle was wide open it would "catch up" and rev to redline. I'm thinking maybe the accelerator pump? When you twist the throttle you get a stream from both nozzles but not a "cone" shape as indicated in the manual. Also I don't see any place on these carbs (82's) to adjust the fuel/air mixture as mentioned by others on the forum.

I'm supposed to go on a ride next week and don't want to be the junk bike on the trip- I'm getting desparate! ???
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Lucky

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Re: Carb problems
« Reply #1 on: September 25, 2003, 10:23:33 AM »
on the nozzles, first, they may be a little dirty, & the trick to cleaning them is to get yourself some of the stranded wire used to hang pictures.  useONE strand in the nozzle to scrap away the carbon that may be built up in there, you'll have to take the carbs apart  to reach them, & possably pull the nozzles out.  email me for this procedure, it's delicate.

second, be sure that when they spray, the spray goes IN BETWEEN the throttle plate & sidewall of the carb, if it hits either, the fuel comming out won't atomize properly.  CAREFULLY bend those nozzles from underneath with a screwdriver, a little at a time, some times the solder connection comes loose & they'll have to be resoldered.

the pilot screw adjustments are on the left side of the carbs, (sitting on the bike) just above the intake boots. you'll need a long skinny screwdriver to adjust them.  It may be that the factory plug covers over the screws are still intact, in which case, you'll need to carefully drill a small hole in the aluminum plug, screw in a sheet metal or sheetrock screw & pull them out. they do not need to be replaced.

If the plugs are still intact, PLEASE PLEASE count & record the number of turns in untill lightly seated.  this is valuable info on the never published factory settings, & i'm keeping track of them when it happens, so we can give a reccomended "initial" setting.  email me these numbers, or post them here.

Thanks! --Lucky
1982/3 XZ550 Touring Vison, Gold on Black

admin

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Re: Carb problems
« Reply #2 on: September 25, 2003, 07:15:36 PM »
just to clarify that Tim, if it's bogging down at wot while you're riding it, there is probably something plugged up,
or it's starving for fuel (same problem) check your fuel filter,
(if you have one) pull the hose from the petcock and run it into a bucket,
you should get a good steady stream of fuel, if not then
possibly the screen is plugged in the tank or restricted in the petcock itself. lastly, there is probably still some gunk in the carbs.

along with checking the things Lucky suggests, you should be able to get it straightened out...

-Ron



Tim B.

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Re: Carb problems
« Reply #3 on: September 26, 2003, 10:44:36 AM »
I did re-aim the nozzles and that helped. I think you are right, it acts like it is starved for fuel. But I'm thinking accelerator pump. When you open the throttle, a stream flows from both nozzles. The rear carb peters out first. Is the "stream" supposed to be a spray? Under more pressure from the pump? What it's doing now is that it's pretty smooth acceleration up to 4k RPMs (if you don't nail the throttle wide open) then starts bogging out, then starts to catch up. At about 7k it seems like one of the carbs is running dry (feels like it's running on one cylinder). BTW the air/fuel screws were exposed I just never noticed them. The front one was set at 5 turns, the rear is too chewed up to turn with a screwdriver so I don't know about that one.

I think I'm going to pick up a second set of carbs and start from scratch. My buddy I traded my other Vision to is going to let me borrow his carbs for my trip so I've got some time to figure this thing out.  Thanks guys.
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Walt_M.

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Re: Carb problems
« Reply #4 on: September 26, 2003, 05:19:05 PM »
Have you disconnected the rev limiter? It is the black wire with yellow tracer, cut it or disconnect it at the plug. It can surely cause you some grief if you don't. It can fail and cut out the front cylinder for no reason and just make you wonder why. If the carbs are right, it will run great, if not, it won't.
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Lucky

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Re: Carb problems
« Reply #5 on: September 26, 2003, 06:04:18 PM »
It's not a big long shot from the accelerator pumps, a steady stream is fine, it'll atomize at speed.one petering out a tiny bit before the other is fine.  your big problem is going to be that chewed up pilot screw.  I'll sell you one if it's that bad $10.  You need to be able to adjust it.  as for the bog, it sounds like sounds like sever, but classic "vision Stumble. Cleaning & adusting should cure it. (including syncronization)

The rev limiter wire is located on the TCI 6 plug connector, btw.

--Lucky
1982/3 XZ550 Touring Vison, Gold on Black

Tim B.

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Re: Carb problems
« Reply #6 on: September 28, 2003, 08:07:41 AM »
I was thinking maybe the rev limiter too, so I had already snipped it.
The reason I think I need to just start fresh is that messed-up pilot screw and broken float mount on the other carb. I broke that mount (the tip just past where the pin goes through) when trying to drive the pin out. What's the trick for removing the float pins? Most of my carb experience has been with Keihin slide-type carbs on Hondas. Those pins are pretty easy to remove.

This problem is definitely a carb problem. I put my buddy's carbs on and it runs fine.
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Lucky

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Re: Carb problems
« Reply #7 on: September 28, 2003, 10:01:39 AM »
the tip for getting the float pins out are patience, care & prayer...

The way I do it is twofold.  first, what holds the pin in is that the side with the head has a slightly larger diameter, so it really doesn't matter which post you put it in.  if the head of the pin is tight up against the post, I use a small set of vice grips or chanel locks to push the pin end flush against the post.

then I use a small screwdriver that I have ground a groove into to slip under the head & pry it out.  this works 90% of the time.  sometimes I have to grasp the head of the pin with the vice grips and twist it out.

sometimes they break, and sometimes I get one that's been repaired already.  the thing is that if they break right at the hole, then it can be a problem because one side of the float has a metal tab on it that hits the post.  this tab keeps the float from flopping all the way down into the bowl & allowing the needle to fall out.  This wouldn't be a problem normally with fuel in the bow, but if you need to drain the bowls the needle will fall out.

I haven't had great luck with epoxy, sometimes, but not often.  I have pinned them back in, tapped them & used a small 4/40 screw (found at r/c car hobby shops) through the top of the carb, and even used a bent paper clip mounted under the inlet retaining screw and going up thru the hole in the metal float pivot (to keep the float from dropping)

82 carbs aren't much of a problem because I have several spare parts carbs, but 83's are a different story. I've never had one i'd even consider using for parts...too rare.

I'm thinking of taking a dremil to the jaws of a small pair of vice grips & creating a tool that will slide under the head of the pin & clamp on the head to remove it... we'll see...

--Lucky
1982/3 XZ550 Touring Vison, Gold on Black

Lucky

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Re: Carb problems
« Reply #8 on: September 28, 2003, 06:55:28 PM »
Hey Tim, Are you still doing those Vision logo's? I'm getting to that point on my fairing.  I tried looking on your site (you had posted some there a long time ago) but the link was dead....
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Walt_M.

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Re: Carb problems
« Reply #9 on: September 29, 2003, 06:29:27 AM »
It is beginning to look to me like carburetors are going to be the one thing that finally stops the Vision. Has anybody tried to find out if there is a Japanese car (or truck) that uses this carb? They are after all described as automotive type and I would be surprised if this is their only application.
I did some checking around for other type carbs, Keihin FCRs to be specific and, aside from the trouble of adapting them to fit, they cost $600 aftermarket each!
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Silver_Bullet

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Re: Carb problems
« Reply #10 on: September 29, 2003, 12:13:27 PM »
Walt,

I emailed Mikuni some months ago and they had no idea that these carbs existed.  Probably no one old enough still working there that remembers anything about them.  They could not give any info on parts,etc.  Makes me beleive that we are on our own!

Mark
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RobTx

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Re: Carb problems
« Reply #11 on: September 29, 2003, 12:57:18 PM »
Silver Bullet, someone mentioned the Dellorto's.  Something similar to this maybe.  http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=2434039145&category=33550
You'd have to fab some kind of manifold though.  You could also experiment with regular side draft motorcycle carbs, you'd have to fabricate intakes and use a dual throttle cable.  This wouldn't be too hard if you were really into trying something else.  Carbs from a early 80's XS650 might be a start, they're available on ebay for a reasonable price.  Just some suggestions.
Rob