double trouble 250sx bog down

[gladiator mice]

been riding my 85 250sx couple times a week. ran fine. now when i start it up i can get it to idle nicely. once the choke is off and warmed up off we go. thing is i cant gun it full throttle or it bogs down and then revs up once you let go and then it comes back to idle. its a delayed reaction. the only way i can get on it is to ease into the throttle and then it will rev up on the dot. i just got a hold of another 85 250sx mint condition, one owner, used it for yard work and nothing else. this new one has never been serviced, at all. changed the oil and filter cleaned the air ways with some carb cleaner spray, and had it running nicely. go to get on and i get the same reaction with the throttle as my other one did.

a couple things came up yesterday night when i went through possible reasons. first, dirty gas. need to empty and clean out the tank and clean the fuel filter screen in the on off valve. second, tear down the carb and clean the entire thing. and last post in this forum and see if someone else has had this issue or knows how to cure it.

[Thorpe]

Rebuild the carb....

[fabiodriven]

I know you did say in your post that the trike is warmed up, but I just wanted to make sure the trike is actually warm when you're getting this bog.

The SX is a cold-blooded creature. It takes a long time to warm up and once shut down, it cools off quickly. If you're adjusting your carb when the bike is cold, you're doing it wrong. You need to adjust the idle once the bike is completely warmed up, and that can take 15 minutes or more depending on the climate and how you ride. It won't always idle perfectly or at all when the bike is cold, that doesn't matter. The SX will bog when not completely warm, they all do that.

Other than that, rebuild the carb.

[gladiator mice]

I know you did say in your post that the trike is warmed up, but I just wanted to make sure the trike is actually warm when you're getting this bog.

The SX is a cold-blooded creature. It takes a long time to warm up and once shut down, it cools off quickly. If you're adjusting your carb when the bike is cold, you're doing it wrong. You need to adjust the idle once the bike is completely warmed up, and that can take 15 minutes or more depending on the climate and how you ride. The SX will bog when not completely warm, they all do that.

Other than that, rebuild the carb.

when i said warmed up i meant warm to get on and ride. while riding the recent one about 15 min in the throttle became seemed to not work all the time and then it just stalled, tried to crank it and got nothing, choke on and off and still no firing. two minutes later started up little sluggish and off we went again. happened again 5 min later same process. its not a spark issue for sure because it idles fine and runs steady. im back to dirty filter and screen inside valve.

[fabiodriven]

im back to dirty filter and screen inside valve.

That is going to be the first thing to check, yes.

[Dirtcrasher]

1st of all, unless those tank filters are spotless, I tear them out and run an inline filter; otherwise you'll have the same issue later on.

I had a damn backhoe always running out of fuel, it would only run for 5 minutes; I'm no diesel mechanic so I bought a book and rebuilt everything and it still did it. Guess what; at the bottom of the fuel tank were a ton of pine needles jammed in an elbow (part of the plumbing) because the prior owner/moron would take off the fuel cap and leave it open for hours.

"its not a spark issue for sure because it idles fine and runs steady"

Probably not but don't discount it. I've had wires break right at my CDI and I just kept thinking CARB CARB CARB!!

It sputtered and bogged down constantly.

[gladiator mice]

in line filter seems like a good choice. might go and pick one up down at tractor supply. as for the CDI, ill check them tonight and see whos cracked or hanging by a thread.

[Thorpe]

Hmm... Never knew those tank filters were such an issue... Perhaps I will tear them out of my ES and SX and pop inline filters on them both...

[Dirtcrasher]

The nice thing is you can keep an eye on them and they're cheap.

[gladiator mice]

ok, i put an inline filter on and cleaned out the on/off valve. started it up and let it run some. had no issues, but didnt have time to ride it. will be testing it tonight though.

if it occures again im checking the cdi next along with rebuilding both carbs. second thought was maybe the air vent on the tank is bad. not letting the gas flow steady. when i was emptying the tank i had the vent on and the valve open (not reserve) and hardly anything came out, so i put it on reserve and some dribbled out and then nothing. when i took the cap all the way off they both worked correctly with constant flow. does anyone think this is an issue?

[Flyingw]

You already answered your own question about the vent. Cap on, low flow. Cap off good flow. The vent is plugged. You can still get new caps from Honda for about 35.00 plus the seal. Get one now before they are all gone. Get it from Service Honda. I suggest getting a new one because if you put on another old one, it may work but for how long. just replace it.

[gladiator mice]

i just realized what i had written and didnt put the pieces together. sometimes if you just write or think out things the answer is right in front of you.

[fabiodriven]

I'm sorry none of us suggested that in the first place. It's usually one of the first things you check.

[gladiator mice]

no need to apollogize fabio, its not a common part to check when the motor doesnt respond right. most everyone knows the first things like air spark and fuel. then if you got spark and clean air then what people think next is carburetor issues, which is usually correct in most cases. you just have to make sure gas is getting to the carb first. my issue would have been discovered sooner or later when i cleaned out the tank while using the valve as an easier and cleaner way to empty it.

[tri again]

I'm sorry none of us suggested that in the first place. It's usually one of the first things you check.

One of my all time favorite problems.

They sound like they're running out of gas so we pop the cap for the hundreth time and make sure there' gas in the tank, it lets enough air in so it will run for a little while and it happens again.

[gladiator mice]

well i switched the gas cap with my big red (which runs like a champ). switching the caps took care of the frequent stalling on the most recent 250sx. warmed it up, took it slow for 10 min then tried to hammer on it here and there. still bogs down when gunning the throttle. even though the fuel flows nicely to the carb. i guess now would be to rebuild both carbs. and see how well they respond with clean parts and new gas caps

[slaughter]

im having the same problem with my sx even when im idling and i hit the gas it bogs out i did a little search and some people said its the air screw i haven't messed with it cuz its in such an awkward spot and once its warm my fat hands get burned up trying to reach it

[Flyingw]

I have rebuilt and tested SX carbs on my shelf for sale if you're interested. 125.00 ready to go.