XS11 bogs down on acceleration

[wmengers]

XS11 bogs down on acceleration

Scott,

I didn't pay attention to how much I changed the floats when I adjusted them at the time and I did measure them without the gasket. I want to try setting them using a clear hose, but need to learn more about that. Thanks,
Bill

Thanks Petejw.

[bikerphil]

Make sure the petcocks are flowing good, then I'd try raising the floats 2mm and open the mixture screws up more. Sounds like she want's more gas.

[3Phase]

I want to try setting them using a clear hose, but need to learn more about that.

You're welcome, Bill, and welcome to the forum.

Here's a link to a thread about using a Zerk fitting to measure the fuel level in the float bowls:-

Not quite a carb tech tip?

[Toolmaker Tim]

Lean

Bill, simple stuff first. Have you checked to see if your fuel lines are kinked? Check the vent hole in your gas tank cap and make sure it is open. Is your bike a standard or a special? Are you running inline filters? Pull the lines off the tank and check for flow from the petcocks. If your bike is a special, do you still have the octopus installed?

Phil, when you say raise the floats are you talking about moving the floats so they are set at .986 ( plus 2mm and dropping the fuel level in the bowl) or lowering them( minus 2 mm thus raising the fuel level). The reason I ask is if I remember correctly the .906 measurement is the fuel level in reference to the gasket seat while the carbs are upright and using a clear hose to check the fuel level. The float setting method for the 80/81 bike is different in the Clymer manual. IMHO I think the problem is a fuel starvation issue. If the floats are set to .906 from the gasket seat to thebottom of the floats the setting would be approx. 23MM. If I am way off base here please correct me and I will attempt to learn something.

[Larrym]

Wholesale Substitution of Carb Bank.

And the results of swapping out the carbs were.....???

<insert audio: Extended Drum Roll>

[crazy steve]

One thing to look at when setting the floats is to make sure both sides are the same. If the float is 'twisted' a bit (and it's seldom enough that you can 'see'), your effective float height will be off. A small thing, but these carbs are really touchy...

[bikerphil]

Tim, when I said raise the floats, that would be with the carbs in their normal upright position as mounted on the bike. When flipped upside down on the bench, it would be actually lowering them. Sorry for the confusion.

[Toolmaker Tim]

Which Way is Up?

Phil, that's what I thought you meant. Some one who has worked on these bikes alot would understand what was meant, but it's easy to confuse someone (especially ME!) who is getting frustrated. I agree with you that it sounds like there is a fuel starvation issue here. On the 78/79 carbs the set height is 27mm. Bill's .906 setting should be overly rich due to the fuel level being CLOSER to the gasket level. And as Steve said, they can get twisted very easily and it does affect the fuel level. .906 translates to 23.01 which is very rich.

Bill have you checked the screens on top of the fuel petcocks? Something else I forgot to have you check. When you start moving things around on these older bikes, debris that is going to cause problems can get broken loose and cause fuel issues. Like Phil said, check fuel flow from the petcocks.

[TopCatGr58]

The float levels for the 78-79 are 25.7 +/- 1.0mm, the 80-81's used a lower 23mm setting, so that's why he set them to the 0.906 level. So....the 23mm setting is actualy essentially stock, and to richen it he would need to set it even lower(upside down) .

T.C.

[Larrym]

Float Setting= Vertigo +/- 1mm

Up...Down

Inverted...Non-Inverted...

78-79 versus 80-81...

23mm is .906 and 25.7 +/- 1.0mm is uhhh...ummm.

One way makes it Rich and the other way turns it Lean.

The room itself is leaning and I'm getting queasy......

[crazy steve]

One way makes it Rich and the other way turns it Lean.

... and the ones that mother gives you don't do anyt....

whoops, musta been the poster...

[8SpadeEpiphany]

I had a problem with similar symptoms, it started occasionally and worsened more and more as I rode it. I would drop it a gear and up the RPM's and it would fix the problem momentarily. It ended up being the fuel advancer diaphragm in the right front part of the engine (if looking at the bike head on). It may not be it, but it's close enough in symptom's to mention.

[Toolmaker Tim]

I guess I shouldn't trust my memory. Next time I start stating settings I will do it with my manual handy. Sorry

[nutwister]

wmengers,

When you cleaned the carbs did you remove ALL of the orafaces? Jets, pilot jets and emulsion tubes (needle jets)? If there is old gas, varnish, around the emulsion tubes,(needle jets) it will do just what you are talking about.

If you didn't I would almost bet that partially clogged emulsion tubes is what you are experiencing.

JAT.

[wmengers]

XS11 bogs down on acceleration

I changed the carbs and it runs better, but it basically has some of the same symptoms. Now it will start up normally with the enrichner on and then idle good when it warms up and it responds well when you open the throttle. It feels normal until you put a load on it to take off. It then chokes and sputters, so you have to rev it a little to take off to keep it from choking when taking off. Once you get it moving it will accelerate fine as long as you are accelerating at least moderately, not slowly. It will cough and sputter on no or slow acceleration below 3K. Then, between 3K and 3.5K it will start bogging unless you at least accelerate moderately, not just slowly. Once you get above 3.5K it runs normally. You can let off and re-accelerate without it bogging. If you drop below 3.5K, it will bog if you accelerate at all, whether slow or fast, but if you get down below 3K, in the sputtering range, you can get it to accelerate without bogging (or sputtering/choking) as long as you accelerate moderately, not just slowly. As long as you keep accelerating, you can accelerate through the 3K to 3.5K range without it bogging.

Another thing I did after changing the carbs and driving it was put the coils from my 78 on it, because I noticed that cylinders 3 and 4 were not affected as much as 1 and 2 when removing the plug wires one by one while it was running. And #3 and 4 are fed by two different coils. The coil swap seemed to make this go away, but it was raining and by the time I got it on the road again it seemed to come back to #'s 3 and 4. I think I have wire and or plug cap problems.

At any rate, I am going to buy new coils, wires and caps. I am still not completely convinced that it doesn't have something to do with the carbs, but is seems unlikely that the other carbs would produce the same symptoms, even though the other carbs have been sitting, inside off the bike, for quite a while, but they ran fine last time they were used. After I noticed that taking the wire off number 4 cylinder did not affect the running as much as numbers 1 and 2, I removed number 4 carb and took it apart and cleaned it and checked the float level (both sides). This didn't seem to affect how that cylinder respnded to removing the wire while it was running.

Thanks for everybody's help. I will let you know what happens after I get the new coils.

Bill