Is there a rev limiter on the 250x? I have an '87 that I just bought and am trying to get it to run right. When I hold it at WOT, it acts like it's hitting a rev limiter. I've been having all kinds of carb problems with it, and am trying to get it dialed in. I just put a 400ex carb on it. It has a 150 main jet in it right now. It runs decent, but I think that 150 jet may be a little rich for it. It has a Uni filter on it, and I took the airbox lid off. The idle is fine on it, just a bit high. Any suggestions?

 

yes there is a rev limiter be careful and dont blow it up.

 

Anyone else have any experience with the 400ex carb on a 250x or 300ex? I'm just wondering what I should jet it to. Any other suggestions on what may be causing it to run bad? It seems to bog in mid throttle, and do that surging at full throttle.

 

I think the rev limitter on the 250x is 9100 or 9200.

We have a 400 carb on a 300. It is built so my jetting isn't gona work on yours most likly. From what you desribed though, I would think you are lean on the needle and rich on the main. Raise the needle one clip and drop a main and giver' a try.

 

Why would u want a 400ex carb? Do u have a big bore kit or a cam? Just wondering. If not than the 400ex carb would be too much gas for a 246cc. Try using a smaller jet if it dosent have mods.

 

Well it does have a .020 12:1 piston and a web cam. For now, I'm running it with the airbox lid off. Still has stock exhaust though.

 

i was going to say if u wernt. i run a uni filter no lid and a supper trapp pipe with the stock carb with like a 155 dont quote me (i dont fell like pulling it tonight) u shouldent be getting to much gas if thats the stock jetting for a 400.

 

Well I think stock is 148, so this is one above stock. I think I'm gonna drop it down to at least a 148, maybe a 145.

 

Thats what i would do and check your plug every once and a while to see how it is running. coffe brown is good black is too rich and white is too lean.

 

Yeah hopefully that change will help. It seems to pull strong when I get on it, but when i let off, it seems to fall flat on it's face. It may just be the compression though.