04 250F carb problems

I have a like new 04 250f that had sat for a long time and had some varnish in the carbs. The bike has less than 20 minutes of run time on it. I have cleaned the carb on the bike multiple times by removing the float bowl and clearing all visible passages/jets with carb cleaner. I also replaced the AP diaphram since it was corroded and cleaned and lubed the hot start since it was corroded as well, plus cleaned where the cables goes into the carb and one of the screws in there was corroded as well. The bike will run with the choke on high rpm but not with it off. If I leave the choke on and start off and get going I can turn it off and keep the bike running if I keep it in the upper RPMS but if it goes down to a lower rpm it will pop and stall or back fire if you try and get back on the gas with the choke off. I heard if the piltot or the main ever gets clogged/corroded no matter how much you clean it they still need to be replaced. The bike is 100% stock but it does have a 42-45 leak jet I forget what it is but its the recommended one and it has a zip tye fuel screw. This carb is way more complicated than the two strokes carbs I am used to and its obviously not getting gas threw some passage way/circuit. Any ideas what I need to do or passages I need to clean?

Thanks

The pilot circuit must be very clean since the passages are small. You need to shoot with carb cleaner and blow out with air. Make sure the throttle slide plate is not on upside down(fits both ways), the concave end down and tapered end up. Hope this helps.

Make sure you shoot the air passages located on the intake side of the carb . You've got to remove the carb from both boots to get to them .

Check for a vacuum leak around the carb boot .

You might want to check the float height .

Sounds stupid , but make sure you have a clean air filter .

Here's some good info ... http://www.thumperfaq.com/sitemap.htm

You've got a great bike ... it'll come around ! :thumbsup:

DO NOT USE CARB CLEANER!!!!

There are internal rubber parts that are not replacable. If the carb cleaner attacks them, your carb will become a paper weight. Use a weaker solvent like brake or contact cleaner. If in doubt, saturate a paper towel with the solvent you want to try and lay a rubber oring on it. IF the oring feels funny after a few minutes, do not use that solvent.

ZipTy and most other fuel screws are poorly machined. They tend to make the pilot circuit too rich, requiring a very small (#38 or less) pilot jet. Kientech Stainless Steeel or Kouba Brass are the only good ones.

Replace the pilot jet, do not bother trying to clean it. Each time you have pulled the bowl off, was it clean inside or did debris migrate from the tank? All passageways are clear?

You can send the carb off to a company like ZipTy, they can get it perfectly clean. I thnik Merge Racing also provides this service if you just cannot get it right.

Thanks for all the help. The bike literally has less than 20 minutes on it but when I got it had been sitting 2-3 years with CA gas in it which goes bad very quickly. The AP cover and gasket were corroded and the hot start forzen with corrosion up into the hot start cable. IF carb cleaner ruins internal parts that aren't replaceable then I guess its a paper weight because I have sprayed all passage ways with it. These carbs are so much more complex in design than the two stroke carbs. I guess I will clean it again with contact cleaner, check the throttle slide plate, replace the pilot and if that doesn't work send it to Zip tye

Thanks again

redlines i have sprayed carb cleaner in hundreds of carbs and none of them are on my desk or anyone else's, just don't submerge. On nasty fcr's i will submerge in carb cleaner about halfway-remove rubber parts for this. Stay with stock size pilot jet , do not go down(get it running/tweak later). Jets should probably be replaced with new if they were really gummed up. You can look into the body of carb when it's off and tell if slide plate is upside down. Move the throttle and look , both sides of slide should look about the same on bottom. It will run exactly like yours does if the plate is on wrong.

redlines i have sprayed carb cleaner in hundreds of carbs and none of them are on my desk or anyone else's, just don't submerge. On nasty fcr's i will submerge in carb cleaner about halfway-remove rubber parts for this. Stay with stock size pilot jet , do not go down(get it running/tweak later). Jets should probably be replaced with new if they were really gummed up. You can look into the body of carb when it's off and tell if slide plate is upside down. Move the throttle and look , both sides of slide should look about the same on bottom. It will run exactly like yours does if the plate is on wrong.

There are internal rubber parts that you cannot access without take the carb body apart. Most of the time, you cannot put it back together. You can soak it want to gamble. A famous man once said "Do you feel lucky? Well, do ya, punk?" Too many times I have heard the tales of woe of someone who soaked a FCR and was never able to get it running right ever again. For five plus bills, I'd rather be careful than lucky.

What about the GYTR fuel screw?

DO NOT USE CARB CLEANER!!!!

There are internal rubber parts that are not replacable. If the carb cleaner attacks them, your carb will become a paper weight. Use a weaker solvent like brake or contact cleaner. If in doubt, saturate a paper towel with the solvent you want to try and lay a rubber oring on it. IF the oring feels funny after a few minutes, do not use that solvent.

ZipTy and most other fuel screws are poorly machined. They tend to make the pilot circuit too rich, requiring a very small (#38 or less) pilot jet. Kientech Stainless Steeel or Kouba Brass are the only good ones.

Replace the pilot jet, do not bother trying to clean it. Each time you have pulled the bowl off, was it clean inside or did debris migrate from the tank? All passageways are clear?

You can send the carb off to a company like ZipTy, they can get it perfectly clean. I thnik Merge Racing also provides this service if you just cannot get it right.

What about the GYTR fuel screw?

It should be fine. But I still prefer the SS or brass ones.

Ok thanks EVERYONE its good to know I might not have ruined my carb, I am ripping it off the bike now, checking the slide plate

Took the carb off/apart again and finally got the other section of the carb apart that has those safety torqz screws. It runs way better and with the choke off now but still back fires and misses at lower rpms, higher rpms are almost perfect now. I have the fuel screw set at about one turn out with a 42 leak jet. The rest of the jets are stock and so is the bike. I think its need all new internal gaskets and all new jets. Also I think the float bowl needs to be replaced since I can't seem to clean it good enough, maybe I need to soak it in some parts cleaner. I realize I have never even taken the slide out so I guess I couldn't have put the slide plate on wrong. Anyone have any ideas where I can get all new OEM gaskets for it for a good price if I can even buy them?

Thanks

The internal rubber gasksts are not available. The reason those screws are safety screws is because you are never supposed to take it apart. This is why I was saying no carb cleaner.

I have nearly the same problem. Mine is an '06 YZ250f that pretty much sat since the original owner bought it. On my first ride the fuel screw fell out and needless to say wouldn't stay running. I replaced the fuel screw with an OEM one since the aftermarket ones don't come with the spring and the o-ring. I set the screw to 2.5 turns out and it was very lean. Turning it out makes it run a little better. Problem is that if I continue to turn it out (past 3 to 4 turns) I run the risk of losing another fuel screw. It seems to me that my pilot jet must be partially clogged with old gas (varnish). My next step is to pull the pilot jet, clean it in a parts washer and hit it with compressed air. I guess if that doesn't work I'll move up to the next size pilot jet so I can set the fuel screw in further. Does anyone know how far you can turn the pilot screw out before its likely to fall out? William1: Why not clean the pilot jet? Also, if aftermarket fuel screws tend to make the pilot circuit too rich, then perhaps that's just what I need. What do you think?

No more than 3 turns, max. I put a second oring on the screw shaft to provide additional friction.

The jet is so tiny, that cleaning sometimes does not get it all out. You cannot safely poke at it as any scratches inside will affect it. For the five bucks, I replace. You can try real strong carb cleaner too, if you like, it is all brass and therefore will survive fine.

Aftermarket screws do not all make it too rich, just the poorly machined ones. The Kientech Stainless and Kouba brass work identical to stock and are the ones to get. If you order from James Dean, he can hook you up with whatever carb parts you want, like the second oring.

It runs way better and with the choke off now but still back fires and misses at lower rpms, higher rpms are almost perfect now

Alrighty ... now we have a ball game . :thumbsup:

Use the sticky at the top of the Jetting forum to get the pilot circuit right .

Once you get that done . Move on to the needle position . This will control jetting from 1/8th to 3/4 throttle position . See : Jetting the Needle Circuit and also Here

Hang in there ... your almost home .:ride: Once you get the the jetting solid , you should usually only have to fine tune through the fuel screw .

GASKET, FLOAT CHAMBE (float bowl)

5JG-14984-00-00 1 $13.52

gasket (top, slide roller cover)

5JG-14959-00-00 1 $10.42

GASKET (looks to be the AP one)

3TJ-14536-40-00 1 $0.50

GASKET, FLOAT CHAMBE (float bowl)

5JG-14984-00-00 1 $13.52

gasket (top, slide roller cover)

5JG-14959-00-00 1 $10.42

GASKET (looks to be the AP one)

3TJ-14536-40-00 1 $0.50

Those are not the internal gaskets, O-Rings. There was a company selling them at one time but they stopped doing so, I suspect because so many were unable to properly get the body sections back together without issue.

For those with doubts, ask Eddie.

I just copied and pasted all the gaskets from a parts finder, I didn't say those were all of them.

those are just all the ones i could find because I didn't know which one he wanted. I though he was asking about the float bowl to be honest

For those with doubts, ask Eddie.

Daaayum ! ... no need to bring out the Big Guns , we believe you

:thumbsup::ride::rant::lol::mad::o:D;):bonk::eek::p :p :p

There is just 4 safety torqzs screws holding the main body of the carb on and only one big gasket underneath it. There was all kind of varnish in there and the jet that squirts gas into the motor was clogged as well. It went off and on like butter. If they don't sell that gasket I am screwed since it and almost all of the gaskets are weak. Thanks for EVERYONES help. I am calling Zip Tye tomorrow and ask if there $100 carb mod includes all new gaskets, then I know I can at least get it. I really can't believe no one has taken those 4 torqzs screws out before on badly gummed up carbs.

Thanks

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