On my last ride the 97 KDX220 was occasionally dying completely (like it ran out of gas). Came home and found the carb bowl with a huge glob of dirt/clay that must have been wedging the float. Had been meaning to do a full rebuild anyhow, measure float height, jetting ,etc.... but question is.... HOW does this much dirt get in the bowl? Does it come in through the airbox end or from the gas tank fuel line? I've been given conflicting opinions on this.
I had cleaned and oiled the filter, and rode twice in an area with a bunch of coal. Maybe the air filter wasn't seated right?
I have not been running an in-line fuel filter. Does not seem like much room between tank and carb to squeeze one in. Do you guys run in-line fuel filters?
Almost all contamination comes in through your fuel. You can get a little from the air filter but it would take a really long time to accumulate that much crud in your float bowl. I'd be more worried about the engine than the carb if that much could get through! Of course, it could be a combination of things
Check to make sure everything is right just to make sure though. Air filter properly oiled and seated, carb cap gasket good and on tight, bowl gasket good and not leaking/weeping, all carb body/bowl vent hoses are on and in good shape. I would also probably drain the tank via the petcock in to a jug but filtering it through a clean white coffee filter to see if there are any contaminates. Once drained you can also remove the petcock to see what condition the internal screen tubes look like and clean/repair/replace as necessary. I would also do a thorough cleaning of that carb. Beware not to soak it or you risk damaging the jet block gasket. If you're replacing it as well, disregard and clean it with brake clean.
Have you checked your petcock screens? Could be torn allowing junk to get through, or that could be parts of your screens right there, lol. Or if you're running the black rubber fuel line and it's got some age, it could be pieces of that flaking off. I know my petcock screens are torn, so I always just run an inline filter (which I would run anyways, even if they weren't). The little right angle ones fit pretty good, along with some good flexible Tygon fuel line
New jet block o-ring was ordered just to play it safe
While I am at it, maybe I should replace those three small-ish diameter hoses coming out of the carb (overflow, vaccuum?)
Mine are pretty stiff and cruddy.
What inside diameter hose do I need, and is there a recommended material (rubber, vinyl, etc.)??
I used to get vent hoses from ace hardware. They have huge spools of it and it's cheap, fuel safe, clear, 1/8" inner diameter. 20 cents or so per foot. Even with vent line kits you buy you may have to heat the end of the hose with a hair dryer or heat gun the first time you slide them on. I've busted my fingers up trying to get those things started without heat.
Thanks to the tips here I was clued-in to investigating the bottom of tank. Looks like petcock screens are in good shape. Just some crap in the bottom of the tank that I need to flush out ~!
Not sure if that is where the heavy gunk got into the carb, but step by step I am learning the bike and restoring it to tip-top shape. Carb was rebuilt with a new jet block gasket, new Keilhin jets (40/150 to start) and a CEL needle at 2nd clip from top. Float was high at 22mm so brought it down to 18mm.
Also bought a pro-circuit pipe and will being the jetting process per the guide here to tune to that.
Took a few tries, but eventually got the smart phone to peer into the tank with its flash perfectly!
I have been running ethanol free, but who knows what the guy before me ran.
There is still a good chance I didn't put an air boot or filter on correctly for those two rides, and sucked the dirt in that way. But learning its often a process of elimination, and fixing every link in the chain. Thanks all !!
