What Fuel Problem Could This Be?

[AngusJustice]

When I Put Fuel down My Cylinder My Trike starts And Idles But It Will Not Run At All When The Carb Is On! Do I Have A Carb Prob Or A Reed Prob Or What Any Help Would Be Great! Thanks A.J.

[Rustytinhorn]

Do you have a manual? If not, I would suggest buying one.

I'm assuming this is for your 1985 Atc250r.
There are lots of reasons that could cause this problem. First off I would eliminate the possibility of any other problems by pretty much doing a full system sweep. This includes:
Exhaust pipe and silencer-inspect and clean
Air filter element-inpect, clean, replace, etc...
Check reeds and intake boot**
Check all electrical connections
Perform Compression Test (177-199 psi)
(this will check for possible leaky headgasket as well, but not always)
Check for good spark
Check Timing
Check Radiator fluid (Loosing any?)
new gas/oil
new spark plug
Good fuel line/clean petcock
Also wouldn't hurt to check your throttle cable to signs of wear.

If everything checks out to this point, then you are ready to start inspect/clean/rebuild/tune of your carbeurator.
For this you will want to completely dissasemble it to clean it. I suggest soaking it in a carb-cleaning solution. For this you will want to completely disassemble it. Remove any rubber or plastic from the carb. (O-rings, seals, floats, float needle). If there is any noticable build up, carefully try to remove what you can before soaking the carb. After you soak the carb you will want to thoroughly rinse it out, and thoroughly dry it with compressed air. If there is a lot of build-up, this process may need to be repeated several times. Make sure the jets are not plugged up. Also while you are at it, check the float, needle and seat, for signs of wear. At this point you should have a clean carb that is ready to be reassembled and installed.
If your bike does still not run, by this point we have atleast narrowed the problem down to most likely be caused by the jetting.
Jetting can get complicated and frusterating very quickly. There is a sticky at the top of the forums that has jetting info in it.
I would suggest purchasing a manual though, as it will explain how to do all these diagnostics step by step, and it will have tuning information in it. It probably will also cover things I may have left out of my comments to aid in the repair of your 250r.


** I saw your reeds in your other post, and from what I can see because the picture is fuzzy, they appear to be in good shape.


Rusty

P.S. Most of this is probably not necessary to perform, because chances are is that your carb is causing the problem. However, it is something that should be done regurarily, and since the bike does not run, now would be a good time to eliminate other contributing factors. I'm sure I've missed stuff to check too.

[AngusJustice]

The funny thing is i've owned honda cr's my whole life and never had this problem before I don't see why i'm having all these problems with my 250R atc! I've never owned a two stroke that gave me this much trouble must have been made on a friday!@ lol! They either start on 2-3 kicks or they don't start at all but this thing is just ******* me off! I've Got Two 250R's and no matter what parts I interchange it just wont run! The Other One runs Like A top! It used to run great then it would only run for say a hour then only 15 min then only a minute now nothing the only other thing I can think of is to buy a brand new carb! Cause the one on it has been cleaned 4-5 times now with no luck! Like I said if I put fuel down the cylinder it starts right up so i know its not a electrical prob checked the spark last night big blue spark! I'ts got great compression so i'm stumped! WOW!

[Rustytinhorn]

Hhhmmmm.....Beats me.
Good luck with it though.

[boosted96cobra]

Are you getting fuel in the bowl? Sounds to me like the problem. First make sure it is running out of the petcock, then make sure it is filling the bowl in the carb by undoing the bowl drain. If it is not filling the bowl I'd bet the flaot is mis installed or the stopper is gummed up.

[Erics350x]

Do a compression test.

[300rman]

this sounds like a carb problem to me.

check the fuel comin gout of the petcock, check to see if the bowl fills, and CHECK AND SEE IF YOUR GAS CAP IS VENTING!

if all goes well and your bowl fills up, the carb is probably just all gummed up with crap.

try tossing a different carb on there off a diff. machine. if it fires, its the carb.

[Russell 350X]

Deffinetly sounds like the carb. Pull it off, clean it as stated above, and see what happens. Mabey even check your fuel filter, and the petcock, both could be clogged.

[Erics350x]

If it has weak compression, it won't pull fuel from the carb.

[300rman]

If it has weak compression, it won't pull fuel from the carb.

true, but if it fires right away with fuel in the cylinder, this is unlikely.

How well does the bike run with the fuel in the cylinder?

[Erics350x]

Remove the carb and the intake tube and slide the reed cage out and look at em