New carb for 2510?

[farmer_74]

Hello all,
I am at my wits end on trying to get my 1999 2510 to idle in the specified range. I went to the local dealer (Castle Powersports) to ask about bigger jets and they only wanted to talk about selling me a new carb. I had rather try the jets before spending $200.00+ for a new carb.

Does anyone (RCW maybe? ) know the part number for the size jet that I should try?

Thanks,
Kevin

Also, I have cleaned the carb, adjusted valves, and cleaned out with Seafoam

[RCW]

Describe your idle problem. Is it high or low, stumble, run away, or what?

These use pretty simple carbs, and they can usually be adjusted to achieve the correct idle. But I first need to know what it is actually doing.

[farmer_74]

There is such a fine line between no idle and fast idle that it seems that I have to choose one or the other. I can pull the choke out a little bit and it will idle. Does that mean it's running too lean? I can also close the pilot needle all of the way and it doesn't kill it. Should it?

Maybe this will help you understand a little more about what it's doing. Please feel free to ask more questions.
Thanks,
Kevin

[RCW]

Ok, now I understand the problem.

The pilot adjustment controls the flow that regulates the engine vacuum through the pilot jet. It should be approximately 1 and 3/4 turns from lightly seated.

But, with the symptoms you have the problem is either a poorly adjusted governor control (or missing springs), worn out throttle shaft bushings, a plugged pilot circuit or a very low float level.

I would first suspect that no fuel is getting to the pilot jet for the pilot air screw to worry about, or there is so much air leakage around the throttle shaft that the pilot jet cannot keep up with the demand. If someone strong armed the pilot adjustment and cinched it into the throttle body too deeply, then it will no longer adjust properly and could also be the problem. If that happens a new carburetor will be required.

If it runs at high speed fine, then the float level is likely just fine.

I would concentrate on the parts diagram for the governor control assembly and make sure everything is present and accounted on the Mule.

If that is good, then move to disassembly of the carburetor and cleaning of the carburetor body and the pilot jet. Running SeaFoam through the fuel on a plugged carburetor is akin to facing the wind when evacuating your bladder - a complete waste of time with rather adverse results.

You will need a good liquid spray carburetor cleaner, not the foaming type, and one with the fine tube that fits the nozzle. Once the carburetor body is stripped of the jets and the pilot adjustment screw, you will need to blast the cleaner through each of the small holes and make sure the cleaner comes out the other side.

Check your throttle shaft for side play and looseness in the bushings. If they are loose, install new bushings.

Once the carburetor is really squeaky clean, wash it out with a bit of starting fluid. Then after it is dry inspect it closely with a bright light and make sure all the little passages are really open, including those that dump into the throttle bore itself. Once that is good to go, then reinstall all the jets, put the carburetor back together, and set the pilot adjustment between 1 and 3/4 and 2 turns counterclockwise from lightly bottomed.

It should start right up and run at idle. Once the engine is fully warmed you can adjust the pilot screw for the smoothest idle. I generally remove the drive belt to adjust the pilot to avoid problems with the clutch trying to engage while adjusting the pilot, and then run the idle to approximately 1,400 rpm and set the pilot for the best sounding engine exhaust note. Then back the idle screw (not the pilot screw) back down to the specified level, and the pilot will be perfectly adjusted.

Also check the flange that mounts to the gasket on the engine side. Some of these carbs have an air bleed that has to be open to the atmosphere on the flange side. So, never use RTV to seal the gasket to the carb, or you can be forever trying to sort out why it does not run correctly.

Be sure the gaskets from the intake manifold to the heads are good, and the bolts are properly torqued. Leakage there can also cause an idle problem.

[farmer_74]

Thanks RCW.

I will try all of these steps (some for the 2nd time). I have taken the carb apart and cleaned it. The previous owner had used RTV instead of a gasket. I made a gasket but didn't realize that there might be a bleeder hole that needed to remain open.

When I said that I used Seafoam I meant that I had decarbonized the cylinders with it. I am always a bit skeptical about product claims but it sure did make it run smoother (and quieter).

I will report back after I follow your tips. Thanks again

[farmer_74]

I've cleaned the carb as best I can and checked and oiled the govenor. I checked and tightened the intake bolts. It is still doing the same thing.

I did notice that when I removed the air intake hose that it stumbled and ran rough.

The throttle shaft has some play in it so I will order some bushings for it.

After running it at constant higher RPM's for a few minutes the exhaust pipes were glowing cherry red. Is this an indication of something (other than not to touch them ) ?

Thanks
Kevin

[RCW]

I presume you have checked the valve adjustment and compression to know you have good compression.

Check your float level, the red exhaust on a Mule sounds lean, as does stumbling when you remove the intake hose.

If it is not the float level, then take some spray oil, WD-40 works, and spray around the intake manifold and heads as it is running. If the engine speed changes you have a vacuum leak.

[farmer_74]

How can I check the float level? I didn't think it was adjustable on these carbs. Am I wrong?

I bought a compression gauge today and I will also try the WD40.

Thanks,
Kevin

[RCW]

They are a pain without the float gauge that comes with the float needle kit.

But, if you are real careful you can put a transparent glass cup under the carb and open the drain on the float bowl. Keep the cup up so the cup edge is higher than the gasket to the bowl, and watch the fuel level. If it stops about 1 mm below the bowl gasket seam, that is about right.

Kind of messy, and definitely something you do away from any gas water heaters because gas runs everywhere.

[farmer_74]

I adjusted the valves again and WOW! I'm not sure what I was doing the first time because the back cylinders valves were way loose. It sounds and runs like a different machine now that I have them set at .010".

I still don't have it idling low enough yet but I am certainly alot closer than before. I tried the WD40 and didn't discover any vacuums. I forgot to spray around the throttle shaft though. I will try that tomorrow.

The cylinders both had about 175psi ea. According to the shop manual that is in usable range.

I will try the float level check tomorrow also. I am guessing that it will have to be running for the pump to fill the bowl and glass. Right?

Thanks again for your help RCW,

Kevin