Won't run over 1k rpm

[bowerbird100]

Hi,
I'm having a bit of an issue.
My 1990 gpx250 is being quite temperamental.
Over the last two days it has started to not want to run, it will start and either die straight away or will run at 1-1.5k rpm even with wide open throttle.
And then if you come back in an hour some times i will start straight up and other times it will continue with the use.

The bike hasn't idled since owning it but it has run fine for the last month (I've owned it a month).

What could be a possible problem?

Could it be the clutch switch? The bike used to refuse to kick over when the clutch was pulled in in neutral but now it doesn't mind.

[jkv45]

Doesn't sound like it would be a switch problem to me.

Have you looked at the plugs? They may tell you something. Is the air filter good and the intake snorkel clear? Something could be blocking the intake.

I would also drain the tank completely and refill with fresh gas and a fuel system cleaner (just the proper amount - not too much). Drain the float bowls first and look at what comes out - does it look like fresh clean gas? Is the tank free of rust? If not, you may need to clean the filters/screens.

Chances are if that doesn't do it you'll need to remove the carbs and clean them carefully. Do some research into what needs to be done first, or you'll need to pull them and do it all over again.

[bowerbird100]

Originally Posted by jkv45

Doesn't sound like it would be a switch problem to me.

Have you looked at the plugs? They may tell you something. Is the air filter good and the intake snorkel clear? Something could be blocking the intake.

I would also drain the tank completely and refill with fresh gas and a fuel system cleaner (just the proper amount - not too much). Drain the float bowls first and look at what comes out - does it look like fresh clean gas? Is the tank free of rust? If not, you may need to clean the filters/screens.

Chances are if that doesn't do it you'll need to remove the carbs and clean them carefully. Do some research into what needs to be done first, or you'll need to pull them and do it all over again.

Well I spent several hours with the help of my father to stip down the bike enought to be able to move the airbox and release the carbs

The float bowls were drained until they ran clear fuel, when they first started to drain they both looked a rusty colour.
The fuel coming out of the tank is clear And it had a filter in the fuel line to the carbs.

It still didnt run properly if at all.

We pulled the airbox back till it was off the carbs and then ran the bike, it was great ran well.

I sprayed the very gunky mesh in the airbox with carb cleaner till it was clean and washed the foam component of the filter in filter cleaner

Ran alright.

Put Everything back together and its back to its same old antics of not running

Is it the filters? Or the airbox? Would pod filters fix it? Are pod fitlers available?

[alex.s]

clogged main jets. pull the carbs again and do a more thorough cleaning. ie take off the bottom bowls, and poke wire through the main jets

[bowerbird100]

Originally Posted by alex.s

clogged main jets. pull the carbs again and do a more thorough cleaning. ie take off the bottom bowls, and poke wire through the main jets

Sounds like a plan

I'll drain the tank as well.

Just a few questions.
I also have another ex250 that was allegedly running alright when it was still in pieces, it is now a parts bike.

Is there any variation with the carbs over the difference models of ex250's?
I have the carb off the other bike so can I clean and use it instead, it looks cleaner.

Can you recommend a source that I will be able to follow to clean the carbs?
Will I need to sync the carbs?

[Ninjinsky]

yes it makes no sense
process of elimination needed
First take out the air filter and check there isn't anything blocking the intake rubbers, you should be able to get your hand in far enough to poke your finger in the rubbers and tell.
Then try with the airbox connected but the filter out and the snorkel off
Then snorkel in and still no filter
If that runs okay get new filter foam $10 a square foot off ebay
I wouldn't recommend pods right now because you will need to rejet the carbs which is major league

This is probably it v
What may have happened is that someone cut any old piece of foam to fit in the filter but most general foam passes much less air than filter foam so with it in you are running very rich.
That's my best guess

[alex.s]

there are variations. i couldn't tell you exactly what they are. mostly the throttle linkage and choke

step 1:
locate carbs


step 2:
take the carbs out and remember where everything came from and what hoses you took off





step 3:
take off the bowls




step 4:
remove the main jet and spray it with carb cleaner and poke it out
here's an example from another type of jet:


step 5: put it all back together

step 6: have a beer

[Ninjinsky]

^^^ This is good but please first try the filter foam as I mentioned in my post above. If that is all it is then the carb strip will be wasted effort.

[bowerbird100]

Originally Posted by Ninjinsky

^^^ This is good but please first try the filter foam as I mentioned in my post above. If that is all it is then the carb strip will be wasted effort.

I have attempted to run the bike without the foam to no prevail so i assume that means the foam won't help?

[bowerbird100]

Originally Posted by alex.s

step 6: have a beer

Sounds good, only problem is that I am 16
And don't like beer

Thanks heaps for the help.

I'll tell you in a couple days when I've gotten around to striping the bike again how it has all gone

[jkv45]

If you got odd looking gas out of the floatbowls I would completely drain the tank (remove it and dump it upside down while shaking it vigorously into a pan so you can see what comes out) and refill with fresh gas before tearing into it too far. I would also add 1 oz per gal of Techron Concentrate fuel system cleaner to the fresh gas. Use 87 octane without ethanol if you can get it, or the lowest grade that's available without ethanol - sometimes that is Premium.

Have you looked at the plugs?

[bowerbird100]

Originally Posted by jkv45

If you got odd looking gas out of the floatbowls I would completely drain the tank (remove it and dump it upside down while shaking it vigorously into a pan so you can see what comes out) and refill with fresh gas before tearing into it too far. I would also add 1 oz per gal of Techron Concentrate fuel system cleaner to the fresh gas. Use 87 octane without ethanol if you can get it, or the lowest grade that's available without ethanol - sometimes that is Premium.

Have you looked at the plugs?

I have not looked at the plugs mainly because I don't know how to

The bike get 95 octane (RON)
Which is the aus octane measure system.
91 is almost always with 10% ethanol
Then 95
Then 98

[DaBlue1]

Originally Posted by bowerbird100

.....We pulled the airbox back till it was off the carbs and then ran the bike, it was great ran well.

....Put Everything back together and its back to its same old antics of not running

What is the size of your main jets and how does your airbox look? (post pics)

Originally Posted by bowerbird100

I have not looked at the plugs mainly because I don't know how to

FAQ Reading Spark Plugs


How to Read Your Spark Plug

[flitecontrol]

This shows various spark plug conditions: http://www.dansmc.com

This computer won't let me link directly to the site, so you may have to look around to find the spark plug pics.

[bowerbird100]

Originally Posted by DaBlue1

What is the size of your main jets and how does your airbox look? (post pics)

Airbox was damp, black and oily.
No idea of what size the main jets are because Ive had the bike 4-5 weeks, was running fine except for refusing to idle until one day it wouldn't run over 1k and then an hour alter it was fine, I went for an hour ride and the next day it did it again except it hasn't run right again since except when the airbox was disconnected from the carbs.

I will look over it again when I get home and may be able to get some pics.

[bowerbird100]

Originally Posted by DaBlue1

What is the size of your main jets and how does your airbox look? (post pics)

Airbox was damp, black and oily.
No idea of what size the main jets are because Ive had the bike 4-5 weeks, was running fine except for refusing to idle until one day it wouldn't run over 1k and then an hour alter it was fine, I went for an hour ride and the next day it did it again except it hasn't run right again since except when the airbox was disconnected from the carbs.

I will look over it again when I get home and may be able to get some pics.

[DaBlue1]

Originally Posted by bowerbird100

...Airbox was damp, black and oily.

That's either a sign your filter has too much oil on it or your crankcase is spewing oil into the airbox via the crankcase breather tube. Too much oil on the filter will disrupt airflowand cause the engine to breath poorly. This may also explain the gunk on the mesh.

I'd have a look at the carb boots and airbox cap to make sure they are clean and unobstructed. There's no reason why the bike should not be able to run with the airbox on and the filter removed.

[bowerbird100]

well i cleaned the jets out using peice of brass wire and 60psi of air.
all of them excpet the left pilot jet.
it woudlnt come out
it was unscrewed off the thread but refuesed to come out.
only 3 milimeters and it would have been free but nope, not happening so i soaked it with carb cleaner while the carb was upright several times and then blew the air through another hole that exited the pilot jet so i hope that is enough.

i may put the carb back in tonight if dads feel like it after work or i may have to wait till tomorrow. ill keep you posted on how it goes.
i will also keep an eye on the bottom of the air box now that i have cleaned it and see if any more black oily residue appears

[Midnight_tinkerer]

Where in N.S.W are you? I'm in Taree.

Check your oil level to make sure it is not over full. It can become over full from the carbs flooding, leaking fuel into the sump & diluting the oil. They usually don't run right with fuel in the sump. Carbs could be flooding intermittently. Could also be intermittent electrical fault, dropping spark on a cylinder. You really do need to get those plugs out for inspection.

[bowerbird100]

I think all i want to do is die at the moment.
the oil level is weird looking through the sight glass.
we just spent two hours trying to get the airbox back on the carbs.
the bike worked without the airbox and ran fine

i need sleep for school tommorow and i am in menangle so taree is a bloody long way

going to sleep and try again tomorrow :'(

[Ninjinsky]

Originally Posted by bowerbird100

we just spent two hours trying to get the airbox back on the carbs.
'(

That's the same for everyone, the rubber connectors are complete pigs, especially when old and hardened.
I have made a tool by bending the last cm of an electricians screwdriver at 90 degrees to run round the rubber a bit like those power machines in tire depots that ease them onto the rim. Get the inside half over then use this around the outside section
Looks a bit like this

Image cedit pelicanparts.com

Ideally you could get the Kawasaki designer round at gunpoint and not release him until he has done it, but that is probably illegal, even in Menangle

[Midnight_tinkerer]

Originally Posted by Ninjinsky

That's the same for everyone, the rubber connectors are complete pigs, especially when old and hardened.
I have made a tool by bending the last cm of an electricians screwdriver at 90 degrees to run round the rubber a bit like those power machines in tire depots that ease them onto the rim. Get the inside half over then use this around the outside section
Looks a bit like this

Ideally you could get the Kawasaki designer round at gunpoint and not release him until he has done it, but that is probably illegal, even in Menangle

If the rubbers have shrunk & gone hard, then ideally they should be replaced with new ones. But as a temporary measure you can heat them with a hair dryer or heat gun to soften them for easier fitting and using your tool as well would make it even easier. In the past I've just used a long thin flat blade screwdriver to assist fitting, but your tool idea looks like it would work even better.

I too have often wanted to get the designers to work on the products they have made. In the heat of the moment have also wanted to threaten violence against them, or get a bill passed which mandates engineers to perform every job in the repair manual, before the model is released for sale.