1986 Big Red Carb Replacement

[Swany10]

So I bought a pretty clean 1986 250es about two months ago and I just noticed it has an 85 carb on it. It's disappointing, I was looking forward to easier cold weather starts. I should have looked closer when I bought it, but it was so clean it didn't occur to me. Anyway, I want to make it right and I'm looking for some guidance. I don't really want a clone carb, I'd rather buy an original one off eBay if I could find one. There's someone near me parting out an 86 fourtrax 250, is that the same carb?

[MrConcdid]

Id recommend a 300ex carb from www.223cycles.net put MRCBUILDS in the promo at checkout for 10% off.
its a much better carb than factory.
MrC.

[Swany10]

See, that's the kind of thing I'm looking for here haha. I had no idea that existed, and my search skills on this site are not great, so I probably wouldn't have found it on my own. It's a little pricey, but is it a "drop in" replacement? Why is it better than the oem carb? How's the cold weather performance on it? I use my bike for ice fishing, so that's an important factor.

On another note, I found someone parting out an 86 250es, and they still had the carb! Perfect. Except when I asked for pictures of the carb, it was definitely an 85 carb. Does anyone know if the early 86's had 85 carbs, or was I just unlucky enough to run into two 86 machines that had 85 carbs put on them?

[Swany10]

I can see from this thread that an 86 fourtrax carb at least has a different part number, probably not the best option. According to this thread I have an 85 SX carb, and so does the guy parting out another 86 250ES, so that's weird.

http://www.3wheelerworld.com/showthread.php/161746-ES-SX-350X-Carb-rebuild-Tutoral

[Flyingw]

Any ES or SX carb will work. The same hold true for a properly operating TRX carb. The difference between the ES and SX carbs is a hole in the butterfly on the SX carb while the ES does not have that hole and to be truthful, I have no idea what the hole does. The jetting is the same for both carbs, the venturi is the same size, the slide is the same size. As far as the cold start issue goes, I drill the stock startup jet with a .80mm micro drill bit. The stock jetting for the startup jet is a .70mm. Back in the day, a mod kit could be bought and it came with a new startup jet that had a .80mm hole in it so drilling it does the same thing

[Swany10]

I'll go with the .80 mm drill out. I need to do a rebuild on the carb I have anyway, it's leaking fuel from somewhere, and after the bike gets warmed up from a 5-10 minute ride, it starts to idle fast. My guess was a hardened float valve until I noticed the high idle. With that thrown in, I figured I'd stop guessing and do a rebuild.