Fuel problem.....I think...

[Zuma-Zuma]

The last couple of rides, it seems after a few minutes of hard throttle, it feels like its running out of fuel. A couple times, I had to give it WOT just to hear it fire!! Once its below 35, it seems to run fine. And little runs are fine. Since I haven't messed with the fuel system, I'm thinking something new is happening. I checked the fuel valve, and it seems to flow LOTS of gas. Do the Arreche carbs have low vacuum at hi throttle? If this isn't the problem, I must be sucking the bowl dry. I'm afraid that if thats the case, I'm going to smoke my motor. Plug checks always look good. I've heard of by-passing the fuel valve, but it seems to work fine. Any idea's??? Could it be I'm losing ignition under certain conditions?

[Zuma-Zuma]

I must also add, this started happening AFTER installing the overrange. So if that helps. Different characteristics require different tuning??

[speedy_scooter]

Well you said that the plug looks good so maybe your vac line has a bit of a leak. Try putting a zip tie around the vac line hookup.

[Zuma-Zuma]

I zipped both the fuel line and vacuum line already. I'm thinking either the fuel cap vent is plugged, or I blew a crank seal. I'm still on vacation, so tomorrow I'll be screaming around doing test runs.

[speedy_scooter]

If you blew a crank seal the motor wouldnt run much more than at idle. The compression would start building up and then not be able to hold it in. I highly doubt that this has happened. I would try and see if the gas cap is properly venting.

[Zuma-Zuma]

I just changed crank seals on a jog that had a hi end bog. It had similiar symptoms, but not quite the same as mine. But it did run, and idle fine. It was the top end that acted up. You can check them with a little carb spray on the seal while idling. If the engine rpm changes, seal is bad.

I'm hoping its the fuel cap, or something simple

[pinkymingeo]

A lot of guys have thought they had fuel delivery problems. Never is, though. It's never the crank seals, either. Air leaks can kill you, but don't normally require the engine to heat up before they become apparent. Focus on jetting. Assuming you're running an open filter (95 is way, way too big for the stock airbox) try 100 or 105.

[Zuma-Zuma]

I'm runnng the uni-filter that came with the stage 2. I agree with the jetting, I have the jets, just never had the problem like this with my set up. I am HOPING ITS NOT BECAUSE OF THE WEATHER. If this thing is going to be that picky, I may have lots of parts for sale!!

[Lennox]

start selling...... this is one of the reasons Jered went back to stock. This is also a reason I took out my stroker, and run my MILD70cc. Weather reeks havoc on these things.... start playing and see.........

[Zuma-Zuma]

LOL @ Lennox. What exactly is a "mild" 70cc. I was hoping thats what my end result would be. I didn't get the polini evo for just that reason. Please tell me the T-6 isn't a high end jug. I was shooting for middle of the road. I like aluminum, nikisil and the single ring, but never planned on going above the 8k rpm's the stock ignition puts out. Torque and gearing was the ultimate plan. OOOOPS.

[XPS1210]

a mild 70...

70cc cylinder, 19mm carb, variator and mild pipe...


but you have to remember that much of my riding is sub 40 degrees... which is hard on a 2 stroke motor going from some 70 degree days to 30 degree... the choke freaks out and such...

[florida derbi rocket]

The Cylinder both Zombie and I have, is considered "Mild"..the Polini Contessa is below the Corsa...and of course the mighty EVO.

[zuma ned]

are you serious, your rev limiter cuts out at 8k RPM...lol, mine revs all the way to 10600 before its starts cutting the spark.

[speedy_scooter]

then you must not have the newer ignition. I think that on the prebugs there isnt a rev limiter.

[zuma ned]

oh ok, cool. the highest i have reved to while riding is 9900, 10600 was acheived with it on the stand. what will a Ixil sport pipe allow me to rev to.

[pinkymingeo]

The stock bugeye CDI isn't limited. Doesn't need to be. The torque driver will keep you from revving.

[speedy_scooter]

Those Ixil pipes are just for looks as far as I'm concerned.

[Zuma-Zuma]

Problem solved (I think). I removed the carb, and was about to change the slow jet. Something made me take the mixture screw out. And something was in there, that shouldn't have been.It must have been there since new, I don't know how something could get between the end of the needle, and the housing. Anyway, I opened it up a few turns, and got TONS more top end, motor sounds better, and isn't babbline at midrange anymore!! Of course, it was another hot day out, so I'll let you know when its cool again.

[speedy_scooter]

What was it? some kinda metal?

[Zuma-Zuma]

It almost looked like casting flash, but I don't think it was metal. It fell on my hand, then fuel ended up washing it away, so I couldn't really inspect it. But it didn't pass through the jet, or the needle and seat. Like a big flake of something. Anywho, it runs much better, and reacts well to mixture adjustments.

[speedy_scooter]

Good. I hate when its little things killing performance.