2001 Raptor 660 - completely stock - only has about 10 miles on it.

I rebuilt the carbs completely and it went great. It runs but has a hard time pulling up RPMs past half throttle. The jets are in the right spots, the slides are in OEM adjustment, the airbox is tight, valves are adjusted within spec, and the tubes are connected to the diaphragms of the carbs. The plug is dry black and both carbs were leaking out the overflows. My thought is float adjustment needed, no problem.

I bet I've had these carbs off 10 times or so to adjust them and even try to verify with the clear tube method. No matter which way I adjust it and how much, they still overflow. I can put them at 5mm up to 25mm and nothing will stop it from overflowing. I figured the needle and seat were leaking for some reason.

Here's where it gets weird. I checked the needle valve and seats for leaks by leaving the bowls off and installing the carbs on the bike. I attach the fuel tank and fuel flows fine. I close the floats to right where they should be adjusted and the fuel flow stops. They act completely normal and do what they are supposed to do. I put the bowls on and bam... out the overflows.

The only thing I can think of now is the gas might be old and the floats aren't floating enough even with max adjustment? I'm losing my mind with this one.

Anyone have any more ideas?

 

What you're able to do with your finger on closing the float arm may not be what's happening when fuel is in the bowl. It's worth the trouble to always replace the needle and seats because even a small amount of wear on the tips and fuel may not not able to shut off in time. With a kit even if the jets supplied are the wrong size,the price you'd pay for new bowl gaskets and oem needle and seats would be triple what this kit costs at 45 bucks.http://www.ebay.com/itm/NEW-YAMAHA-RAPTOR-660-CARB-KIT-YFM660R-2001-2005-CARBURETOR-REPAIR-REBUILD-KITS-/331537259297?hash=item4d31291b21&vxp=mtr Plus a lot of times fuel can seep past the seat o rings over the years bypassing the needle valve entirely.

 

Thats the exact kit I used to rebuild them in the first place. The needle and seat are new.

 

What shape is the float arms and pins in? They don't come with carb kits and most people over look them. If wobbly and loose,I'd replace them. Plus you can always check floats to see if they're gas saturated..

 

Float arm is great. Which pins do you mean? The floats are in great shape no holes. They float great. Is there any other way to check them?

 

Float pin that holds the arm. If it's grooved or worn down replace it as it can in itself cause a float arm to stick.Items #29,36. Dirt Cheap Yamaha, Polaris, Suzuki & Kawasaki OEM Parts & Accessories – Cycle Parts Warehouse Plus don't know if you've seen this video or not on setting float level. Shows for a 2003 model.

 

The float pin will fall out if Im not paying attention. Thats how smooth and new it is.

Yea, I watched that. He doesn't know much about adjusting them. The clear tube method works great and I've bent the tangs about every position imaginable without any difference. Fuel is getting in somewhere and I can't figure out where.

 

If the float level is set correctly, the needle is shutting off the fuel ok then the only other way for fuel to get in is seeping around the o-ring bypassing the needle and seat. You might try slightly larger metric o rings from a good hardware store and see if that solves the problem.I had a drawer full of these at the shop for this same reason when I got a hold of a leaking carb.

 

Thats kind of where Im headed next. Although with the bowl off nothing leaks when the fuel is turned on. It really acts like the floats arent raising to shut the fuel off.

 

Are you using regular gas (with ethenol)?
Many problems from ethenol.