I was able to find some similar topics to this but no follow ups on resolution. Bought a used bike recently. Ran fine for about 30 mins, then it bogged for a minute. I sat there then got goin again and it was fine. Checked the gas tank, it was low, I topped it off and it ran without issue for 2 days. Today, it had a rough start. It had been firing up immediately previously, this start took a few tries for some reason. Didn't think much of it, then it started bogging again, almost stalling out. The idle was kinda of all over the place but it never really gained full power for more than a few seconds after that. Got dark out so I just parked it. The carb is supposedly brand new and it looks it, not to say somethings not wrong with it but seams unlikely. Also, I noticed some black oil dripped out of the bottom of the exhaust. Any suggestions as to where you would start here? I pulled off the air filter since its quick but it looked great.

 

Found a thread that’s pointing to the clutches as the issue. If that were the issue, would it be more consistent or could it still run find for a couple days?

 

One more thing I just noticed, the inlet from the carb to the air box doesn’t sit flush, it’s nice and tight but it’s crooked, there’s two plastic tabs preventing it from sitting flush. I can take pics if needed. New to this bike so not sure if that’s normal.

 

Might need pic but I’m sure it’s the plastic isolator between carb and reed cage. Your probably getting fuel past the float needle filling the crankcase with fuel, which is why it’s recommended to put an inline manual fuel cutoff between petcock and carb along with a inline filter. The old petcocks go bad on run allowing fuel to overflow the carb and into crankcase. The black oil is a byproduct of 2 stroke fuel (gas/oil mixed) burn off . You might try standing up on back wheels and turn over a few times and see if you have fuel come out the exhaust. That’ll tell you if you have a fuel flooded crankcase.

 

Are you referring to the black piece here? If it’s a bad Petcock would it still run fine for a few minutes after it sits for a bit? Or Is that more of a recommendation than a fix for this issue?

 

How does the insulator prevent fuel getting into the crank case? Just trying to decide if I should put a new one in or try adjusting the carb needle.

 

That is the isolator, not sure why the white stuff is smooshed out the .seam, unless the rubber seal on the reed valve is bad. The extra fuel cutoff and filter is a high recommendation for these quads. On the hard start after setting couple days once it started was it bogging down and having to quickly stab the throttle to keep running. If so that was letting enough air in to match the extra fuel in crankcase until all the excess is burned off and back to regular flow through carb

 

On the hard start it was only sitting for a couple hours. Ran for a solid hour or so earlier in the day. I haven’t had it long and I’m new to all of this so my troubleshooting may not be up to par just yet. I’ll def add the fuel shutoff. After the hard start it ran for maybe 10 minutes then had almost full loss of power. Fired it up today and same exact thing. Ran fine for a few then would barely move.

 

Also. Not sure if it sheds any more light. But I had it fully stall on me today for the first time. It will fire right back up but just no power. It needs to sit for a while before it will run normal for any amount of time.

 

Are you running with choke on continually, it’s on in the pic. If not try running and when it bogs down pull choke and see if that corrects it if it does you have trash in carb and will need cleaned. I would put both 1/4 shutoff and inline filter in (you can find at autozone or such) to decrease need for carb cleanings. You may pull fuel line off petcock and check for steady fuel flow. You may also when it loses power jack the back wheels off the ground and see if you can give throttle and run right, that might indicate clutch issues.