XT Stumbling and Cutting Out

[jeffrow68]

This is the second time I have experienced this issue with my XT. It will cut out, stumble, and sometimes die. It happens under load, usually when I need the power, such as going uphill. The first time it happened, I removed the check valve in the fuel cap vent. This seemed to help, as it seemed to be starving for gas. I have since removed the carb, cleaned it, and installed a JD Jet kit. I raced a hare scramble last weekend with no issues at all. Today, every hill climb was a stumbling, cutting out adventure. It seems to be a fuel issue, but I can't pinpoint it. I checked the float level and it is good, I checked all the carb vent hoses and they are clear. I tried going to reserve but that didn't help. Anyone else experiencing this issue or have any suggestions?

[hawaiidirtrider]

This is the second time I have experienced this issue with my XT. It will cut out, stumble, and sometimes die. It happens under load, usually when I need the power, such as going uphill. The first time it happened, I removed the check valve in the fuel cap vent. This seemed to help, as it seemed to be starving for gas. I have since removed the carb, cleaned it, and installed a JD Jet kit. I raced a hare scramble last weekend with no issues at all. Today, every hill climb was a stumbling, cutting out adventure. It seems to be a fuel issue, but I can't pinpoint it. I checked the float level and it is good, I checked all the carb vent hoses and they are clear. I tried going to reserve but that didn't help. Anyone else experiencing this issue or have any suggestions?

Did you check the petcock? Did you put an inline fuel filter?..did you check if there is rubbish in the tank? ..sometimes crap moves around in the tank..too..idk.. just something else to check that has screwed up for me in the past.

 

How about electrical..check connections? ..dialectic grease.. idk..just throwing stuff out..

Edited February 7, 2016 by hawaiidirtrider

[jwdub1]

I'd also consider checking the float level and that the float hasn't absorbed fuel.

[jeffrow68]

When I first got my XT, I had fuel coming out of the overflow tube on the carb when I leaned it. I pulled the carb and checked the float level,everything was fine and this problem fixed itself. I have pulled the carb several times to change jets and needle, etc. and I usually check the float. This problem with the stumbling has happened about two months ago, but when I pulled the fuel cap vent check valve it cleared up and it's been great for several rides. Yesterday, it came back with a passion. I was curious if anyone else had had similar issues. It sounds like it's starving for fuel, maybe running out during high loads. I'm going to pull the tank and look for trash as HDR suggested, sounds like this could be a solution.

[marty725g]

My 300rr was cutting out very badly under load. Ran fine up to 1/2 throttle and free revved normally. After pulling carb apart, pulling petcock and finding nothing wrong I replaced the spark plug. Bingo, good as new.

[borgwarner]

Check your killswitch too.

[Roon]

When I first got my XT, I had fuel coming out of the overflow tube on the carb when I leaned it. I pulled the carb and checked the float level,everything was fine and this problem fixed itself. I have pulled the carb several times to change jets and needle, etc. and I usually check the float. This problem with the stumbling has happened about two months ago, but when I pulled the fuel cap vent check valve it cleared up and it's been great for several rides. Yesterday, it came back with a passion. I was curious if anyone else had had similar issues. It sounds like it's starving for fuel, maybe running out during high loads. I'm going to pull the tank and look for trash as HDR suggested, sounds like this could be a solution.

 

I suggest you look very closely at the check valve in the gas tank breather. it has a tiny arrow cast on it (very hard to see with my 53 yo eyes) these valves have been known to be fitted arse backwards at production.....and causing a whole lot of grief diagnosing the problem.....

if in doubt, chuck it out....

[Marco the Pool Boy]

You already know that the Beta check valves are garbage funny thing is sometimes they work, and sometimes they do not.

But always make sure there is no blockage in the vent line. 

 

Funny thing about the float level. I had the same issue with my Beta, checked the level and it was on the heavy side (stupid line idea), I dropped it 1mm, made all the difference, never in 1200 miles since have I ever felt that it was starving and it does not puke or run like its loaded up as it did before (when new).

Slightly lower float and JD jetting make my Beta rock!!

But on a side note if I get fuel at certain stations, alcohol and these carbs do not like each another.

[jeffrow68]

Thanks for the advice guys, at least now I have a plan of attack. I completely removed the inline check valve on the fuel cap vent hose so I know this is not the issue. Are there any other check valves in this system?

MarkB, I sent you a pm to get some details on how you set your float height.

I also plan to remove the tank and clean it out and check the petcock. I'm also going to drain the gas and go back with non ethanol as I have been using ethanol treated gas.

[rhale]

Check the float setting screw and pin for malfunction

[Bedunjgi]

Coil bolts.

[Marco the Pool Boy]

Oh yeah, ethanol fuel and my beta carburetor do NOT mix well, especially when it sits for a few weeks.

 

I now have a habit if it sits and I've had ethanol fuel in it from the last ride is to open the bottom of the float bowl, drain bowl and turn on the petcock to drain a little from the line. Only then does it start nicely on the choke. 

Otherwise it runs and then won't run off the choke and runs like sh*t, till I return to the garage to pull the carb, blow out the jets 

[Thewegian]

Ethanol blended gas sucks!  I'm from Iowa and they make it hard to buy normal gas, but we do have it.  The only problem is that some stations mislabel non-ethanol fuel.  If you are not sure, dump it out and start over.  The only thing this crap does is make farmers and ethanol plant owners rich, not much else. If you put the suspect gas in something clear, you can normally see the crap at the bottom of the receptacle.

[jeffrow68]

OK, so here is what I have done so far to attempt to solve the stumbling issues with my XT:

I pulled the tank, checked the petcock (OK), and cleaned the tank out. I did find a little bit of trash but not much.

I pulled the carb, it was spotless clean, no water or trash in the bowl or jets. I lowered the float level to make it shut off sooner and stop overflowing.

I put in a new plug, the one I removed looked great.

I cleaned the air filter and air box, but they were clean also.

I cleaned all the electrical connections and added dielectric grease.

It seems to run better so far, but I will know better tomorrow after a thorough shakedown.

I also have a fatty (tire) that I am trying tomorrow, I will provide a ride report soon.