KTM Forums banner

1 - 20 of 37 Posts

·
Registered
Joined
·
21 Posts
Discussion Starter #1
I have a 2003 625 sxc with the bst40-266 mikuni carb in it. It ran, and then sat in the garage for a couple years. Now it will turn over but won't start. Battery has been charged. New spark plug. It will start and run for a few seconds with starter fluid, which leaves me to think that it is the carb. I have meticulously cleaned it, with no result. I am starting to think that there is too much wear on some of the parts (slide, slide guide, float needle), but if that were the case then it wouldn't have ran before it sat, right?.

Any thoughts?

Thanks
 

·
Registered
Joined
·
271 Posts
:cool: You need to clean or replace the piolet jet , check the fuel valve on tank for good flow into cup , when you have the carb opened up clean all the rest other jets, you should be able to see light through them, hope that helps ya...
 

·
Registered
Joined
·
21 Posts
Discussion Starter #3
:cool: You need to clean or replace the piolet jet , check the fuel valve on tank for good flow into cup , when you have the carb opened up clean all the rest other jets, you should be able to see light through them, hope that helps ya...
Thanks for the help.
I already tried cleaning everything and can see the light through all the jets. I also know that there is a good flow of gas to the carb because I can immediately drain it from the float bowl... by the way the gas is new.
Thanks
 

·
Premium Member
Joined
·
1,978 Posts
It would seem your artificially fueling the motor allowing it to start briefly would indicate a fuel system problem. Hopefully you checked the airbox for rat/mouse nesting? I would expect a plugged pilot jet to cause problem but a non squirting accelerator pump or plugged starting circuit will cause it to refuse to start. I would have another careful inspection of that carburetor if it were my bike. If it were any other mechanical defect in your engine I would expect it not to start on spray ether. Good luck
 

·
Registered
Joined
·
21 Posts
Discussion Starter #5
Airbox is clean. I just kind of assumed it was a carb problem since we have compression and spark. Since it's a 2003 with a cv carb, I didnt think it had an accelerator pump... the carb is the only part of the fuel system I thought it could be.
Thanks for the input!
 

·
Premium Member
Joined
·
1,978 Posts
Wasn't sure which size or model bike was involved. Or which carburetor was fitted. Suggestions were more generic without specific model information.
 

·
Registered
Joined
·
21 Posts
Discussion Starter #7
Sorry for not being more clear, I really appreciate your input. The bike is a 2003 ktm 625 sxc with a mikuni bst40-266 in it.
 

·
Registered
Joined
·
271 Posts
If all seems ok then try to start as normal and after a few long cranks and nothing then try full throttle while cranking to see if it will clear up and run...:cool:
 

·
Registered
Joined
·
21 Posts
Discussion Starter #11
Quick update
After cleaning the carb again I hooked it back up and tried starting it. It just cranked and then nothing. I think the carb is working since there was a little gas on the inside of the cylinder entrance afterwards. Any new ideas? I think I am going to try with starter fluid again to make sure I still have good enough compression and spark.

*just to make sure, it should still start without an air filter connected, right? It isn't going to allow in too much airflow?

Thanks again
 

·
Registered
Joined
·
271 Posts
:cool:Ok, I need to know when you put it away ,was it running good?What happened that you would let it set for 2 yrs? I know -none of my biss, I just don't understand, during winter time I have to gander, clean more, sit on after uncovering, I have 3 bikes and I'm always thinking about and wanting to get back out there in the garage to tinker, sorry,back to your bike,Did you do a valve check?,any engine work that requires anything other than the carb to be taken apart?If it runs on start fluid then it HAS to be carb related,start at the tank and check everything through the carb to the intake,check intake runner for cracks,Try unhooking the kill switch?Are the vent hoses all open and not plugged?
 

·
Registered
Joined
·
271 Posts
Where was the bike stored? any chance mice chewed some wires? might have to pull the bike apart to check the wires,check battery terminals for good clean connections and a good ground, Do you have a service manual? If you do and have the specs, might want to start checking out the electrics of the bike,coil,plug wire,pulse trigger,:cool:
 

·
Registered
Joined
·
21 Posts
Discussion Starter #14
I'll do that next :)
As to why I let it sit: the bike is actually my dad's, and he bought it and rode it like 3 times. By the time I got to it wasn't running. As far as I know he just parked it, turned off the key, and left it.
Thanks
 

·
Premium Member
Joined
·
1,978 Posts
If she starts on spray ether I would continue to check fuel system. If motor cranks strong and starts running on starting spray fluid it would seem logical to expect it to start with wiring and other things as found. If you find your spark plug is not getting wet during start attempts it would indicate fuel is not reaching it. You mention fresh fuel. Was tank emptied and cleaned before fuel was added? Adding fresh fuel on top of 2 year old stale fuel will only dilute your stale fuel/sludge. All residual fuel and sludge/varnishes fuel has to be cleaned out first. After cleaning tank and strainer the carburetor should be cleaned and checked. Fuel systems are sensitive to varnished fuel. Motors will sometimes refuse to start or run poorly on stale fuel. Have to recheck system properly to ensure proper fueling
 

·
Premium Member
Joined
·
1,978 Posts
Just keep in mind how relieved you're going to be once this monster is running. Keep up the good work
 

·
Registered
Joined
·
21 Posts
Discussion Starter #19
I'd like to thank you all for your help through this. I'd like to report that I got it running! I'm not exactly sure what changed, but I cleaned the cab again, put it back, adjusted the idle a couple times, and it started after a few times. After that, I just had to put in more fluid and bleed the clutch. I then proceeded to ride it around a bit.
Couldn't have done it without y'all.
 

·
Registered
Joined
·
271 Posts
:cool:Glad to hear she lives, so do you think you mist some grub in the fuel system ? or just tried to start it with longer atempts ? Either way congrats on getting her going.:D(y) If you need a ridding bud, I'm in Syracuse ...
 
1 - 20 of 37 Posts
Top