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What is the best way to determine if I am getting gas into my cylinder? I cannot get my bike started (the KX250, not the KDX220) and it is really pissing me off. New plug, clean air filter, new silencer packing (not that it matters) and I am definitely getting a spark. I have not yet checked compression and will do that tomorrow but it feels as though there is plenty. When I had the plug off and could see the top of the piston it looked like there was some carbon built up on it but this should not keep the bike from starting should it? So my next step is to make sure its getting gas so I was just wondering what is the best way to do this.

Also, when you are first starting a bike with the choke open, where is the gas coming from? Is it being supplied from the pilot jet?

If you are getting gas to the cyl and it is not firing, your plug will be wet.
The pilot jet is the fuel source at closed throttle and is affected by the pilot air screw.

If it hasn't run in a while and you've been kicking it a lot it may just be badly flooded.
I would try cleaning the carb and while it is off pull the plug and kick it over a bunch more times to get some air through the crankcase area. Try not to let any dried mud fall in/get sucked in anywhere.

I've also dropped about a tablespoon of raw gas in the plug hole and gotten 'em started and over the flooded situation that way. I've also burnt a bike to ground doing that, so be wary of all advice.

How long since it last ran?
How long since it ran on THAT gas?

It was just running the day before. What happened was this: The bike wouldn't start so I went ahead and changed the plug. The bike started up and I rode it around the storage place for about 3 minutes and stopped. I then tried to start it up again and it would not start. So I cleaned the air filter (it was pretty dirty) repacked the silincer, drained the float bowl and checked the jets (48 pilot and 158 main) put a brand new plug in it (BR8EG) and the damn thing would not start. It did at one point sound like it was going to start but then died. So I then put another new plug in (same kind) and kicked and kicked and kicked until I was completey saturated in sweat and gave up for the night.

KarlP wrote:
I've also dropped about a tablespoon of raw gas in the plug hole and gotten 'em started and over the flooded situation that way. I've also burnt a bike to ground doing that, so be wary of all advice.

I shot water out of my nose when I read that last sentence.

KarlP wrote: I've also dropped about a tablespoon of raw gas in the plug hole and gotten 'em started and over the flooded situation that way. I've also burnt a bike to ground doing that, so be wary of all advice.

heh,
I burned a car (a corvair convertable to be exact) to the ground in a similar fashion, had dual carbs that melted into shiney blobs I later made pendants out of. But nothing beats checking to see if an AFB carb secondaries are opening visually from above, then the damned thing righteously backfires....no eyebrows, no eyelashes and that "deer in the headlites" look for about 2 months.... ah, the learning curve of the shadetree mechanic....glad to see I'm not alone....

Damn AFB's

Check to see if gas is getting to the carb when the petcock is open(take fuel line off and see if gas comes out). Could've gotten gunk in it.

Use ether for testing.

All else fails, take the carb off and have a look. Something could be stuck.

Thanks for all of the advice. I plan on going there tonight to do a compression test. After that I am going to try and start and then pull the plug to see if it is wet. I may even change the pilot to bigger size. I'll let you know what happens. If nothing works then I'll just have to take the KDX to TNT tomorrow instead of the KX. The KDX is not as sensitive, I just hope its not mad at me for paying so much attention to the KX.

Well I went to the storage unit prepared for the worst, but before I started messing with everything I decided to give it one more shot. So I hopped aboard turned the fuel on, pulled the choke and started kicking and nothing. So then I held the throttle wide open (which I had done before) and womp, a sign of life. The arch in my foot was about broke so I put on my right boot and started kicking again with the throttle wide open. Then suddenly a miricle occurred and the bike came to life. I let off to half throttle and she was running but holy cow was she smokin, I closed the choke and she kept on runnin si I just held the throttle and let her smoke like a mother. Finally the smoking calmed down and it was rsponding well to throttle so I took off and road up and down the entrance road as fast as I could going through the gears and winding it out. It was running good!

So was that it ? Was it just flooded and now no worries?

Apparently. It must have been from sitting in storage???

Did you leave the gas on maybe? That in conjunction with a not-so-good needle/seat will fill your crankcase with gas. Too bad you re-packed BEFORE you got it running as your packing is probably soaked now.

Johny,

Since the bike was in storage, it's not a bad idea to take the carb off and clean out the jets / orifices with some carb cleaner even if you got 'her started.

Sounds good. How about brake parts cleaner instead? That stuff seems to clean everything and leaves no residue.

Johnny wrote:Sounds good. How about brake parts cleaner instead? That stuff seems to clean everything and leaves no residue.

I'm not sure about the brake parts cleaner - perhaps someone else can chime in on that one. I can, however, tell you that a can of carb cleaner is very cheap . . .

Re: 'Also, when you are first starting a bike with the choke open, where is the gas coming from? Is it being supplied from the pilot jet?'

'A' bike? Depends on the choke type. Not all are the same.

The KDX uses an enrichening circuit. Pulling the lever up opens a passage (normally closed) that allows more fuel to enter the airstream. I don't know where that fuel comes from jet-wise. I would suspect it to be unmetered (not through a jet). It's not a jetted situation..it's just 'more fuel'.

**edit**
Mr. Black was kind enough to give me some learnin'.

Basically: The brass tube that extends from the carb body into the fuel bowl is the fuel source for the choke circuit. I used to know that at one time..fergot it. It is a 'jet' in that the tube is sized differently in different carbs. There IS a separate air passage for the Keihin choke circuit (the choke is NOT just 'more fuel'). I didn't know that.

Ron said you can see the choke air passage at about 8:00 on the upstream end of the carb.

Information is good...correct information is even better!!

Thanks Ron!!

**edit**


BraKleen specifically cautions against contact with 'rubber' parts. Get a can of Berrymans..take the carb apart...soak it...blow out the passages with compressed air. No spray is going to get done what a good soak will. It's not the parts you see that matter in regard to carb performance.