350X With TRX250 Engine - Carb Problem, Studdering really bad! Help!

[3wheelers]

I have a 350X with a TRX250 engine. I'm having some trouble with the Carb. First, it was running great. Then I let it sit for a while, and it kept dying after I burnt up all the gas in the carb. Then it would slowly leak gas into the carb from the gas tank untill it was full. Then you could ride it for a while untill it all burnt up. And that cycle would continue. I took the carb off to clean it assuming it was clogged somewhere. Then I got it back on, and it would rev really high when started. Then I figured out that the idol screw was in between the float inside the carb. I loosened that 1 and 1/2 turns. Then I put the barb back on and it ran fine, and Idoled fine. So it took it for a ride and it started stuttering really bad. It stutters, then takes off like a 2 stroke. (It's a 4 stroke). That is my problem now.

It stutters really bad and doesn't want to take off quickly. Then at higher RMP it takes off. It doesn't idol either, maybe I have the idol screw out too much. But before I pull the carb again, I want to find out how to fix the stuttering. What could it be causing it to stutter? I've messed with the fuel mixture screw. I've cleaned the carb. It doesn't have any air leaks. What could it be?

Thanks for reading the whole thing. Let me know what you guys think the problem is.

[cwolfe]

pretty sure the pilot adjusting screw is on the bottom on the outside of the carb bowl below the front opening. I think you may have backed the main jet out if i understand you correctly on the adjustment inside the carb bowl.

[6speedthumper]

Are you sure that your tank is clean? No crud in it? Is the fuel line clean? Is it still in good condition otherwise? If it is collasped then it will pinch off the flow of fuel. Also, check the "sock" on the petcock (inside the tank) to see if it is gummed up.

It does sound like to did something with the main jet. That needs to be tight. How well did you clean it? What did you use? Did you blow out all the passages with compressed air? It may be that you need to get a carb rebuild kit. Many times they need all new jets and needle jet tube after they get gummed up. I have an 84 200m in the shop now that I cleaned the carb on, but, it needs a kit.

[Poco Loco]

Make sure that tank is vented too. There is an arrow on the gas cap. When its pointed forward the vent is open. When its pointed to the back the vent is closed.

[Poco Loco]

Did you check to see if the gas flows outta the petcock? Pull off the fuel line and see. If it not flowing good you have a problem. If you pull of the petcock theres a fuel filter inside the tank. Make sure its not all dicked up. Most are so old they tear when removing. Be careful when touching them. They are still in stock so you can get another. Make sure you have a good fuel supply to the carb 1st. then work down from there.

[dougspcs]

Make sure that tank is vented too. There is an arrow on the gas cap. When its pointed forward the vent is open. When its pointed to the back the vent is closed.

350x doesn't have that style cap Loco..direct vented cap with rubber hose

[Poco Loco]

If it doesnt have an arrow, then dont worry about the arrow...duh.
350x doesn't have that style cap Loco..direct vented cap with rubber hose

[barnett468]

Hello



I would check the things suggested above and if that doesn’t fix it try the following.


If gas is a year old or more change it.

Install new std plug, no fancy tips.

Make sure air filter is clean.



GAS LEVEL TEST – Take a 12” clear tube and attach it to the float drain fitting, turn the gas on, hold the clear hose next to the carb with the open even with the top of the carb. Open float bowl drain screw and check gas level. It should be from even with the bottom of the carb body to around 3/16” below it.

If float level is incorrect then fix it and try again.

If it still runs poorly check the following.



NEEDLE POSITION - Test with needle lowered all the way [lean position] then raised all the way [rich position]. Make notes of the results then put needle clip in center position and proceed to next step.

If it burbles/sputters/misses upon acceleration it is rich so drop the main two sizes and try again.

If it does NOT burble/sputter or miss upon acceleration but simply fails to accelerate it is lean so raise main jet 2 sizes and try again.



PILOT JET – With the fuel mix screw properly set if the bike starts easily when the engine is cold and the air temp is around 58-68 degrees and it starts EASILY with 0- 1/4 choke, the pilot is too large and should be reduced 1 size.

If it requires full choke to start and is difficult to start the pilot is likely too small and should be increased by 1 size.

If it starts easily with full choke at 58-68 degrees the pilot jet size is anywhere from very close to perfect.

[Poco Loco]

350x doesn't have that style cap Loco..direct vented cap with rubber hoseThats funny, both my 350x's Ive owned have an arrow on the cap to let you know if the vent is open or closed. I guess you dont have a 350x gas cap or maybe you just confused. Or both...

[jb2wheels]

My TRX70(125) was stuttering bad at part throttle. It was because I had raised the needle to max height while troubleshooting what turned out to be an air leak on the intake. Once I fixed the leak, I forgot to set the needle back to normal/middle and it was running rich at part throttle.

[Jason125m]

Thats funny, both my 350x's Ive owned have an arrow on the cap to let you know if the vent is open or closed. I guess you dont have a 350x gas cap or maybe you just confused. Or both...

The arrow on the 350x cap has nothing to do with venting... The arrow in there strictly to let you know the cap is on properly. It is a fulltime vented cap, with a rubber hose that goes into the top triple tree.

Think twice before " duh " ing an experienced member....

[barnett468]

Hello



The OEM Honda fiche shows 2 different gas caps and two different steering stem nuts for both 85 and 86 ATC 350X. Unfortunately there is only a photo of a gas cap with a hose in the fiche and a black steering nut with a hole for the gas cap vent in the fiche under the p/n. The nut with the hole is the later part number which the earlier p/n was superseded to. One of the things this suggests is that it is possible the early p/n gas cap had a vent knob instead of a hose in which case the early steering stem nut would NOT have a hole in it. Another thing it could mean is that they were both different colors, like they were chrome instead of black etc.



cap 17620ha5003

cap 17620hc0003

http://www.cmsnl.com/honda-atc350x-1985-usa_model968/partslist/F++14.html#results




nut 90304ha5000

nut 90304ha5670

http://www.cmsnl.com/honda-atc350x-1985-usa_model968/partslist/F++04.html#results

[dougspcs]

The arrow on the 350x cap has nothing to do with venting... The arrow in there strictly to let you know the cap is on properly. It is a fulltime vented cap, with a rubber hose that goes into the top triple tree.

Think twice before " duh " ing an experienced member....

Bah, ha, ha..newb got owned!

[Poco Loco]

The arrow on the 350x cap has nothing to do with venting... The arrow in there strictly to let you know the cap is on properly. It is a fulltime vented cap, with a rubber hose that goes into the top triple tree.

Think twice before " duh " ing an experienced member....You guys should read the owners guide. Point the arrow to the rear and the vent is closed. You know like when your gonna store the bike. Point it forward and the cap vents. I guess both you guys dont know why Honda put that on the cap for. Do you think they put it on there because it looks cool???.....Schools in session boys. Who owns who?....Duh. Do your research, or pull more unaccurate facts outta the air.

[dougspcs]

You guys should read the owners guide. Point the arrow to the rear and the vent is closed. You know like when your gonna store the bike. Point it forward and the cap vents. I guess both you guys dont know why Honda put that on the cap for. Do you think they put it on there because it looks cool???.....Schools in session boys. Who owns who?....Duh. Do your research, or pull more unaccurate facts outta the air.

I don't mind learning something new and have no problem even if it's from a new guy..but where did you read this fact?

Just read my owners guide for my 86 350x and it make no such reference..can you direct me to where you found it.?

[Poco Loco]

The manual only says to run with the arrow pointing forward. Its common knowledge with old school wheelers like myself that Honda has employed at switchable cap vent for years. Have you ever seen the older version? Its a "t" switch. it say on and off. You just turn the vent on or off as needed. Honda later upgraded this to the "triangle arrow". Point it to the back and the vent is closed. Point to the front then its open. Early XR's also had the "t" switch. Hondas vent switch has been around longer than most of the people on 3 ww have been alive. I didnt just buy a 3 wheeler and jump on this forum and start blasting out garbage, Ive been on 3 wheels for about 40 yrs. Im an active racer, quads and wheelers. I rebuild my own motors 2 and 4 stroke and have for years and I build for others. The arrow referance will be in the fuel section of the manual. Like i said It only mentions it must be pointing forward. (so the vent will be open) . Point it backwards and pull off the fuel line open the petcock and see how long it takes for the tank to start gulping for air.

[dougspcs]

The manual only says to run with the arrow pointing forward. Its common knowledge with old school wheelers like myself that Honda has employed at switchable cap vent for years. Have you ever seen the older version? Its a "t" switch. it say on and off. You just turn the vent on or off as needed. Honda later upgraded this to the "triangle arrow". Point it to the back and the vent is closed. Point to the front then its open. Early XR's also had the "t" switch. Hondas vent switch has been around longer than most of the people on 3 ww have been alive. I didnt just buy a 3 wheeler and jump on this forum and start blasting out garbage, Ive been on 3 wheels for about 40 yrs. Im an active racer, quads and wheelers. I rebuild my own morors 2 and 4 stroke and have for years and I build for others. The arrow referance will be in the fuel section of the manual. Like i said It only mentions it must be pointing forward. (so the vent will be open) . Point it backwards and pull off the fuel line open the petcock and see how long it takes for the tank to start gulping for air.

We are going from 'consult your manual' and get educated to 'its common knowledge'??

I think if Mythbusters were to take this one on your theory would be busted a Loco!

Until then, I'll wait to stand corrected!

Pretty sure the only reason there is an arrow is to indicate where on the cap the vent hole is..this way you keep the hole on the top and prevent fuel from burping up the hose when on bumpy terrain.

Not to get in a credentials match with you, but isn't my 1st rodeo either!

[Poco Loco]

Oh your the guy that said the 350x cap doesnt have an arrow on it...So now you think the arrow is so you know if the vent is on top??? Oh genius, the mystery has been solved. What ever you need to make you and your friends happy, I'll go along with that. I know who I am.

[dougspcs]

Oh your the guy that said the 350x cap doesnt have an arrow on it...So now you think the arrow is so you know if the vent is on top??? Oh genius, the mystery has been solved. What ever you need to make you and your friends happy, I'll go along with that. I know who I am.

I didn't say it didn't have an arrow on it nor that it didn't have a purpose..where did you read that??

Just that the 350X doesn't have the style of cap where by the vent has an on/off function..

Properly read others posts before correcting them perhaps..


You guys should read the owners guide. Point the arrow to the rear and the vent is closed. You know like when your gonna store the bike. Point it forward and the cap vents. I guess both you guys dont know why Honda put that on the cap for. Do you think they put it on there because it looks cool???.....Schools in session boys. Who owns who?....Duh. Do your research, or pull more unaccurate facts outta the air.

And if you are going to take us to school, which by the way I have no problem with since I love learning new stuff, then at least bring the text book.

Especially if you are gonna call me out as the 'genius'!

BTW, I'm still locating and checking my older owners guides to verify this information you have provided. I will stand corrected to my claim that the cap doesn't operate this way..but to this point none have stated this.

Until then perhaps we should discontinue this conversation as it is garbaging up the posters thread without purpose.

[Poco Loco]

350x doesn't have that style cap Loco..direct vented cap with rubber hoseWell I would think this is where you said it doesnt have an arrow. Thats what I gather from your quote. but you can put down whatever you like to make yourself feel superior.

[mudmike]

Im not getting in the middle of "if the arrow is important" because I don't own a 350 and never have. But the OP was right it sounds like a vent problem. Just find a smooth area and loosen the cap a bit and ride it if it doesn't die in a a couple minutes you have a vent problem. Remove the vent hose and make sure that the nipple it is attached to isn't plugged with dirt also blow through the hose and make sure it is clear as well.

[3wheelers]

Thanks for all the replies! I will try all the things you guys suggested. And my gas cap doesn't have the thing you can turn the vent on and off with. Gas flows right through my petcock and my gas tank is almost rustless.