Carb issue or perhaps even more...

[kaic]

Hi guys,

I'm in help needing some guru's advise...

I recently bought my first bike, which is a 2002 Ex250. It looks good and everything, never dropped, with roughly 3650 miles on it. :ride

The problem is the bike has been sitting in the guys garage for a long time (it was last registered in 2005...), and it intermittently has starting problem, even with the engine warmed up. It has new battery, and the engine turns just fine.

When it started up, it runs fine when idling, but when i give it a little throttle, it dies. It died couple times when i ride the bike home, all of which were when i cranked up the throttle 1/4 of a turn from 1st gear, and it bogged... I notice the guy turned the throttle cable adjuster all the way out, and also adjust the idle throttle. so my idle rpm is higher at about 2.5K.

I pull one of the hosts from the diphragm, and saw some gunk, Would this be a carb problem, with gunk inside?

I read some threads about draining the tank, replace the fuel lines and clean the carb. I'm not sure what to start and honestly how to start. Could anyone give me some pointers?

[Stormdragon]

If you're not familiar with carbs, it might be best to have someone do it for you. If you really, really want to DIY, I's suggest taking the carbs off carefully, making note of which cable/hose goes where, and only take off one float bowl at a time. If you take off the float, and clean the valve underneath, then take the jets out one at a time and clean both them and the passages they go into, you probably have a decent chance of fixing the problem. Wear some safety glasses when you're playing with the spray carb cleaner. That stuff hurts.

And I'd suggest a valve check, and a carb synch after you're done since the caarbs are likely to be out of synch when you're done fiddling with everything.

[supertireguy]

Gunk in the carb is bad.

You can take a chance cleaning the carbs yourself (what could possibly go wrong?) or...

If you honestly don't know where to start then have a recommended shop do the carb clean and save yourself the time/effort. On the plus side if the bike has other hidden issues the shop should be able to identify/correct them for you.

[kaic]

Thanks for all the advices! really appreciate them!! I think I'd try not to open up the carb in the mean time, and get some maintenance done first. ie: oil change, check airbox and lube cables

One of my coworkers told me to try a gas additive called Sea Foam, into a fresh tank of premium gas. It's supposed to be a gas treatment + carb cleaner... Does anyone has any experience with it, or should I not even bother?

[kaic]

oh, and how much does carb cleaning cost in a shop?

[elskipador]

i've never had good luck with seafoam. persoanlly i'd just remove the carbs and clean them with a good, low POV, carb cleaner. be very careful when using and solvent on the rubber parts or gaskets of the carb. many cleaners/solvents can cause them to deform.

oh, and how much does carb cleaning cost in a shop?

3 hours labor is usally fair. might include a carb sync as well.

[ST Guy]

Sometimes SeaFoam can work. But you're really much better off pulling the carbs, disassembling them, cleaning them, putting them back together properly with float levels checked, and then syncronizing them and tuning them. If you've never done it before, it may or may not be something you want to try. You'll also need some sort of syncronizing tool. Maybe, if you do it right, you might get the bike roadworthy without a sync so you could then ride it to a shop where they could do it. But maybe not. What I think you need to chew on is how confident are you that you can disassemble and reassemble the carbs properly and get it running good enough to at least ride it to a shop for the final tune. If you don't think you'll be able to get it back together so it will run and that the shop doing the final tune won't have to go back into the carbs to fix something you did, you might be best off letting a pro do the work. Otherwise the work may get repeated (though there's nothing wrong with a learning experience) and you may even find yourself in the position of having to get the bike to a shop with it in pieces and not running.

Good luck.

[altomista]

PM me if you don't want to do the carb cleaning and sync yourself and don't want to take it to a shop.

[Uridian]

http://faq.ninja250.org/wiki/Cleaning_the_carbs_2

and for any other problems you may come across:

http://faq.ninja250.org/wiki/Main_Page

EXCELLENT resource for your wee Ninja. With no prior carb experience at all, using that FAQ I removed, thoroughly cleaned and replaced my carbs, did a valve adjustment and carb balance. Bike ran like a gem after that.

[kaic]

So after 2 weeks i've finally took the carb out and cleaned it. To my surprise, there isn't any gunk in the carb, I drained the float bowl, and no water, and gasoline is in golden color, the pilot and main jet didn't get clogged or anything. I used half can of those carb cleaning spray, and seem like the cleaner was coming out of those tiny holes where it supposed to be.

Now the problem is i can only start and run the bike with my choke on, if i turn the choke off, then the engine dies. After the bike is warm up, and adjust the choke to half open, RPM approx @2500, if i give a little throttle, then the rpm would dip and engine dies..

I've adjusted the idle mixture screws and also changed the spark plugs.

Any idea? Should i clean the pilot jet (and port) again?

[Stormdragon]

What did you adjust the idle mix screws to, and what are the factory suggested settings for them? Is the engine running smoothly when it's on the choke, or is it a bit rough? If so, it might be time to adjust the valves and synch the carbs before assuming that the carbs are still the main culprit. Did you also examine the CV diaphragms in the tops of the carbs to make sure there weren't any pinholes or tears when the carbs were off?

[ST Guy]

Hmmm.....sounds like something else is going on.

First, when you cleaned the carbs, did you remove all the jets and the mix screws as well?

Second, are there any hoses unplugged? Like vacuum lines?

The rubber boots or connectors between the engine and the carbs, what kind of condition are they in? Soft? Hard, brittle, or cracked?

It's kinda sounding like you've got a vacuum leak somewhere and too much air is getting into the engine. Or, you think you cleaned out all the fuel passages and jets in the carbs but somethings still plugged up.

In any case, the choke is really a fuel enrichening circuit which dumps extra fuel into the motor to aid in cold starting. (Effect is the same as using a choke on the air inlet.) So, that indicates your fuel/air mix is too lean if adding fuel with the enrichener makes it run a bit better. So, you are either still starved for fuel, or the engine is getting too much air somehow.

[jacksingh]

Bud, I have the same issues going on see the thread below ...
http://www.bayarearidersforum.com/forums/showthread.php?t=227295

[kaic]

What did you adjust the idle mix screws to, and what are the factory suggested settings for them? Is the engine running smoothly when it's on the choke, or is it a bit rough? If so, it might be time to adjust the valves and synch the carbs before assuming that the carbs are still the main culprit. Did you also examine the CV diaphragms in the tops of the carbs to make sure there weren't any pinholes or tears when the carbs were off?

The idle mixture screw is 2.5 turn from fully seated, this is the base setting everyone recommend. The original factory is about 1.7 turn from fully seated.
when on choke, the rev hike to 4-5Krpm, and if i put it on 1st, it will dip to like 1.5 - 2k when warm. The diaphragms are OK, no tear or crack, i use warm water to clean it. Thanks for the advise!

First, when you cleaned the carbs, did you remove all the jets and the mix screws as well?

Second, are there any hoses unplugged? Like vacuum lines?

The rubber boots or connectors between the engine and the carbs, what kind of condition are they in? Soft? Hard, brittle, or cracked?

yes i did remove all jet and screws, they were OK, no blockage or clog. The only thing i can think of is the internal pilot passage which is inside the carb body. But i did spray lots of cleaner and they run out clean from the small holes.

i also think it might be a leak somewhere... when i give a little throttle, (and if it didn't dip and die), it will take a good 2 - 3 second for the throttle to respond. It's like "turn throttle" "wait" "wait" "rpm revs up" Closing the throttle is OK though.

If there's a leak, it has to be between the engine and the carb right? anywhere i should check for leak?

[kaic]

Bud, I have the same issues going on see the thread below ...
http://www.bayarearidersforum.com/forums/showthread.php?t=227295

subscribed!!

man... it makes my heart break when i can smell the gasoline on a rev engine and not able to ride it. Good Luck!

[jacksingh]

i just have my fingers crossed that Ironbutt helps me out this saturday so that I can make it for sunday ride !

[altomista]

Sounds like valve adjustment time. I do those too.

[QuaiChangKane]

Sunds like a vacuum leak somewhere....

It starts and warms on full choke, but won't idle once warm unless you use partial choke?


Check your intake boots and o-rings. With the bike running, use a spray bottle and mist water around the carb-to-engine rubber boots and listen for a change in your idle. IF the idle gets rough when you spray water on the boots, your boots are sucking air - this could either bee cracked boots or sloppy connections at the carb or head.


-Q!

[kaic]

It starts and warms on full choke, but won't idle once warm unless you use partial choke?

yes! i can idle the bike with about half choke, anything less the bike will dip and die.

I checked the carb/head boots and they seems fine and tight, water mist didn't get suck in as far as i can tell.


would the vacuum diaphram contribute to this problem (Fuel starvation and slow throttle response?) i mean there's obviously fuel in the float bowl, but i read somewhere here if the vacuum diaphram was somehow rigged up, then it might not give enough pressure for the tank to flow? At some points, i thought the vacuum diaphram thingie is only for the emission control...

[kaic]

Sounds like valve adjustment time. I do those too.

LOL thanks Al! will definitely keep u posted. I'm a bit short in $$ thanks to the x'mas shopping and girlfriend, so i'm now spending my own effort and trying to learn couple things along the way :nerd:p

[QuaiChangKane]

yes! i can idle the bike with about half choke, anything less the bike will dip and die.

I checked the carb/head boots and they seems fine and tight, water mist didn't get suck in as far as i can tell.


would the vacuum diaphram contribute to this problem (Fuel starvation and slow throttle response?) i mean there's obviously fuel in the float bowl, but i read somewhere here if the vacuum diaphram was somehow rigged up, then it might not give enough pressure for the tank to flow? At some points, i thought the vacuum diaphram thingie is only for the emission control...



Are you talking about the petcock diaphragm or the carburetor diaphragms?

It doesn't sound like your symptoms could be attributed to a faulty petcock. Your carbs are filling properly - implies a working petcock, and the bike runs better when the mixture is richened up - implies a lean mixture, indicating a vacuum leak since the symptom came on suddenly.

(FWIW -The symptoms I've encountered for faulty petcocks are carbs overflowing when bike is sitting or high-speed fuel starvation due to the petcock being partially clogged.)


On my Suzuki, the o-rings on the coupling tubes between the carburetors were cracked, and it caused symptoms very similiar to yours. Also, if your intake manifolds have o-rings between the boot and the head, these can go bad as well - but both of these things should have been noticeable when you used the water bottle trick.

I'm thinking it's time to check the valves, as well.

EDIT - does the idle smooth out once the bike is fully warmed up? A slight vacuum leak can cause the bike to be hard to start and rough idling when cold, as the vacuum leak makes the mixture slightly lean. Once fully warmed up, the heat of the engine causes the intake air to heat up and expand, causing the mixture to richen itself a bit - sometimes enough to completely eliminate the previous symptoms.

This is also why a lot of older bikes become really cold-blooded in the winter time - hard as hell to start, needs to idle forever on the choke before it warms up, but runs noticeable better once fully warmed than it did during warmer weather....

Valves that don't seat properly can cause a lean mixture, as well - among other things.

-Q!