XR 250 R Carb issues

[Rangerfng]

So my total rebuilt 250 is great. starts right up, runs and rides great. that is until I get into the woods and start bouncing around. When I get into the woods and start banging around on the rocks. my bike start to bogg and wants to stall. to make it stop. I have to half choke it for a few seconds and then turn it off. So I have to make ir rick. Hmmmm. My thought is that I need to adjust the float level. any thoughts

[Trailryder42]

That was my first thought.

Set the floats minimum drop to the manuals spec., then set the max drop only 5mm more than that. Max drop is usually set way too much from the factory. That big range between min and max drop allows the float to flop around between float stops on rough terrain.

The theory is, when you encounter a big enough bump that would cause the float to be forced down, it momentarily displaces fuel in the bowl. The jet orifices are so small that a sudden displacement of fuel by the float causes raw fuel to be shot up thru the jets into the carb throat, causing the engine to stumble.

[Rangerfng]

Ok can someone walk me through this. It is my first time messing with the float. Can this be adjusted with out pulling it apart

[Trailryder42]

Ideally, the carb should come off, but if you want to try to do it with the carb on the bike, the float bowl has to come off, minimum.

I'm guessing this is your '86 XR270 we're talking about? Download this free shop manual to show you how to do it.

https://docs.google.com/leaf?id=0B7-qz8FhJsvFYmYyZGQ2NWMtMTI5Zi00YTQ1LTgxNGMtMWY2ZmVhZTY3MjBj&hl=en

I made this simple tool out of a piece of tin metal, scribed with lines for my min and max float levels.

[Rangerfng]

Hey Bro!

Yes it is the 86. The 91 is tore down to the frame. hahaha. theat has a pumper carb if I am not mistaken. Thank you very much. I already have the carb off and will work on it tomorrow while I wait all day for the cable guy to show up.

Ideally, the carb should come off, but if you want to try to do it with the carb on the bike, the float bowl has to come off, minimum.

I'm guessing this is your '86 XR270 we're talking about? Download this free shop manual to show you how to do it.

https://docs.google.com/leaf?id=0B7-qz8FhJsvFYmYyZGQ2NWMtMTI5Zi00YTQ1LTgxNGMtMWY2ZmVhZTY3MjBj&hl=en

I made this simple tool out of a piece of tin metal, scribed with lines for my min and max float levels.

[Rangerfng]

Ant hint to the page I need to be looking for. I must be blind

[Trailryder42]

Page 4-7 shows you where everything is at. Page 4-11 and 4-12 show setting the float level with a gauge. It's spec is 12.5mm. I would set max drop to 17.5mm. Set the gauge or your scale on the bowl rim inline with the main jet.

[Rangerfng]

Ok my lazy ass just took my carb off. now lets see If I can get this done today....

[Rangerfng]

Ok, I took the carb off this morning. Lets see If I can actually get this done sometime this year! haha

[Rangerfng]

Ok so I took the bowl off and this is where the float sits at 12.5mm

Then I made a litle tool to gauge the float

I then followed the directions that were in the book. Actually I have the book that came with the bike and the Cymers book as well. Buth give different directions.

I put the carb at a 45 angle facing down and allowed the float to rest in the down postition getting the reading you see above.

I then carefully bent the bracket till the float reached 17.5mm

I have to tell you. This does not look right to me. If the float is pushed down, wouuldnt that leave less fuel in the bowl. At 17.5mm it is quite low to the bottom of the main jet.

12.5mm

17.5mm

What do you think.

[Rangerfng]

I also noticed that I am missing that plastic dome on the bottom of my jet. could that be an issue as well. I do not have one on my XRL250 either

[Trailryder42]

No, that doesn't look right. Let me do a little photo doctoring.

This picture has nothing to do with the 12.5mm min. drop because of the way you're holding the carb. This picture shows max drop.

http://i39.photobucket.com/albums/e158/Rangerfng/XR%20250%20Carb%20mod/100_4113.jpg

These are the tangs you bend for each setting.

Edited June 25, 2011 by Trailryder42

[ramz]

You're measuring it wrong. Look at page 4-12 in the manual. Note that the carb is not held vertical; you tip the carb on it's side and lean it until the float tang just touches the float valve (the little tiny nipple part). Then you measure from the carb body machined face to the BOTTOM of the float (lowest point, but it should be fairly level, taking into consideration it's tipped on its side). ?

Please don't use the Haynes or Clymers manuals or any other besides the official Honda Service Manual; Honda designed and built the bike, after all.

One last note - the amount of gunk on the inside of the carb and on the jets is not acceptable. Remove the jets and replace them with new jets. Clean the inside of the carb until you can see bare shiny metal; don't use a wire brush, but consider using a plastic brush and carb cleaner fluid. Clean all other parts inside the float bowl; overflow tube, baffle plate, float valve, float pin, float. Do not open the air cut valve, the small chamber on the side of the carb body. Parts inside are costly and are generally ok if you don't open the chamber.

Edited June 25, 2011 by ramz

[Rangerfng]

Ok Brother! Thank you so very much for the advice! I followed the directions from the wrong book. I, this time followed the Honda manual. I had the minimum drop set at 17.5 and the max drop at god knows what. Following the correct directions I have the correct reading of 12.5/17.5