250x running problem

[efilnicafesin]

I went out riding today, and after about 10 min, my baby started acting up. I thought it may have been fuel related, but I have pretty much eliminated that. I was running a bit of octane boost mixed with VP4 (I think--the oxygenated stuff). The bike ran great last time out. Before going out this morning, I topped the tank with AV gas 100LL. I have never run it before. Got to riding a bit this morning, and all seemed fine. After about 10 min or so, it felt like I was running out of fuel. I checked the switch and it was on. I pulled the main jet, and it was clear. We thought it was the messed up mix of fuel, so I dumped the tank and put straight gas in it. No difference at all. So I packed it in and took it home. I took the tank off and completely drained it. I pulled the carb and pulled the needle jet out. That looked fine, but I blew it out with air. Float level looked good. I put it back together, and put fresh gas in it. Started it up and same problem. The plug was a bit black, but I cleaned it and put it back in. The main jet I changed from a 130- 135 and didn't make a difference. THe pilot jet is a 35. This is almost identical to right when my valve train let go, so I checked the valves, and they are good. My car compression gauge kit doesn't go small enough to screw into the spark plug hole, so I don't know what the compression is. I've got a 400ex carb sitting here, but I don't want to put it on until I get it back running right with this carb. When I pulled the float bowl off, I didn't see this needle jet that everyone is talking about, so I don't know what that setting is, but it hasn't changed since I've had the bike.

What can cause an immediate change in performance? Should I still look at fuel side? I don't want to rip into the engine yet if I don't have to. This is driving me nuts.....

[honda250xrider]

could be your stator going out

[mojoe2878]

try a brand new plug, make sure that nothing is in the muffler that would be closing it up. need to find a compression tester that fits and check that, the head gasket may be blown.

[Aceman]

Replace your plug first. Then check the spark, should be a nice fat blue spark. If it's good, now is the time to check compression.
Like mojoe said you could have a bad head gasket, especially since your running a 12-1 piston.

[honda250xrider]

water in the airbox, what about the airboot is that tight on your carb, make sure there are no holes in your airboot.

[efilnicafesin]

The airbox is dry, and the boot is tight on both sides of the carb.... It really acts like a plugged up carb. It will not idle at all, and the only way to keep it running is at WOT, and that keeps the rpms at just above idle.

As far as a blown head gasket--- Would there be any other signs? Fuel in the oil? blow by on the outside of the case? Where does the compression go? There is no fuel smell in the oil, and the mix I had in the tank stunk and would be obvious... There is no oil on the outside of the head that would show a leak and there is no air leaking around the head gasket... When I pulled the carb off, there was raw fuel in the intake boot. not alot, but enough that I noticed it.

As far as the compression gauge goes... Does anyone off hand know what the thread specs are for the adapter?

[honda250xrider]

does it stutter quite a bit whenever you get on the gas.... mine did this and it turned out that the stator was bad. also take off the carb and you should see the top cover take the gold top cover off and make sure that the needle is still in tact and make sure everything is fine in there.

[efilnicafesin]

Originally posted by honda250xrider
does it stutter quite a bit whenever you get on the gas.... mine did this and it turned out that the stator was bad. also take off the carb and you should see the top cover take the gold top cover off and make sure that the needle is still in tact and make sure everything is fine in there.

It will not even consider idleing. At WOT, it barely gave enough to motor back to the truck without getting off to push.. Now that I know where the needle is, I'll have a look at it.

[efilnicafesin]

Well, I have eliminated the carb/fuel system, cdi and coil.... I put a 400ex carb on it, and it ran the same way... I'm still in search of a compression gauge to fit... I'm gonna swap the stator tommorow, but I don't think thats gonna do it.........

[440exwlspankyou]

check the plug also, make sure it is not fouled and see if you ran it lean.