Theres my first thought. What if the fuel Im checking with isn't dense enough to float the floats. But I can't imagine it would make that much of a difference. I think its 87 blend right out of the pump. What should I try?

 

Then try adjusting float height to 14-15 mm instead of the 13 mm the book calls for so it might shut off the float needle a tad quicker and see how it does.Sometimes you have to throw the book away.

 

Yea I bet I went from 5mm all the way up to 25mm in small increments. No change no matter where.

 

Then there's only three things left that I can think of. Either a bad float assy as you've mentioned,fuel leaking past the needle valve body o-ring or a leaking or split overflow tube in the carb bowl. That's easily checked by filling the bowl up with fuel.

 

I have banged my head against the wall in the same fashion regarding the float valves on the 660. I had the same issue.. I rebuilt the carbs TWICE, used new float arms, float valve seats, the whole 9 yards.

What I found to be the issue was the carb body, where the float seat resides. The body gets worn, and leaks around the float seat. The only way I ever got mine to stop overflowing was to go with a slightly larger o-ring for the valve seat. Afterward I had to go through the clear tube method of adjusting the floats all over again, but after that it cleared the problem.

In all, the 660 carbs are a huge pain to keep from leaking, and to get dialed in perfectly after mods. I would buy a set of FCRs if you plan to keep the 660 long term. I have a 700 now, with the 660 being an extra ride, so not a huge deal for me anymore.

 

Im with you ob, but if I sell it, Im going back to a Pred 500 and turboing it. I loved that thing until I flipped it up and hill climb and totaled it. Im regretting that now.


I finally figured out the solution to this overflow problem and I hope some people can learn from this.

I tore them apart again to compare to the OEM parts I tore out. Most of the OEM parts were destroyed in the teardown due to being seized. When I compared what I had put in to what was OEM, I found a minor difference with the floats - the float needle clips. Check the pic - left is aftermarket rebuild, right is OEM.

The problem is the rebuild kit has weak clips that bend and move with pressure on them. The OEM style is a better design and holds the float down which closes the needle valve. The aftermarket rebuild was flexing and would never actually close the needle valves so fuel would alwasys flow.

Swapped clips and problem solved. No more overflow. I used the offroadparts kit on eBay for future reference. I have never had a problem with them before until now.

Lesson learned, buy a higher quality rebuild kit! Or at least use OEM stuff in combination with a rebuild kit.

 

Good catch! I would bet that most people who are rebuilding these carbs get their parts on ebay. I have to pull my carbs off to clean them, I think it would be wise to dig out my old needle clips.

 

Strange problem,but I can see why you had problems. Two kit brands that I've never had problems with over the years is Shindy and Keyster. Shindy kits are still made in Japan,Keyster kits are still made there too last I checked.Shindy Products, Inc. - ATV Replacement Parts Keyster Carb Kits