KDXRIDER.NET

Just recently I completed a rebuild of my '97 KDX200, put in an '04 bottom end, top end sleeved and bored with a new piston and rings fitted. plus bearings. anyways got it all back together, kick it over and it fires seconds kick and sound nice and revvy so I let it idle to being the run in process. after 3mins of idle it dies. i kick it over and it runs again for another minute. then it dies and now im having trouble starting it. When running a quick rip on the throttle and she revs up nice and fast and clean. but now it practically wont start, and the carby is pissing fuel out the bowl over flow hose. im guessing this is an unfortunate coincidence happening at the same time as the rebuild. I can say with 100% confidence that the bike has plenty of good strong spark, and heaps of compression. at first i thought that the lube i put on the piston and bearings during rebuild was burning up and fouling the plug so i took it out to clean, also put a squirt of starting fluid in the bore and put the plug back. well it runs first kick, for about 5 secs then dies. did it a few times and same result. even got my mate to tow me round the block a few times with the bike in gear to clear out any excess fuel or oil. still no joy. must be the carb? i really dont know where to start with carbys can someone give me a few things to look at? sorry for the long post.

Cheers!

Take the carb off, disassemble it and clean it real well with carb cleaner... pull the jets and make sure they are clear. Adjust the float level and you should be good to go.....

OK thanks for that, by 'pull the jets' you mean take them out to clean them? I have never dismantled a carby before so Im not even sure what a jet looks like. Also not sure how to adjust float level but I do have a service manual, its a factory one i think but most of its procedures seem to lack enough detail to keep you wondering..

Your main jet sits on the very top when you carb is upside down... it takes a 6mm 6 sided socket to take out.... be very careful since it is brass and can strip real easy. The pilot jet sits beside it but is recessed and takes a very small flathead screwdriver to unscrew... Once they are out... spray every orifice with carb cleaner and make sure it is exiting somewhere.... Once you clean the jets and make sure they are completely clear... put them back in just a little bit past snug.
I will almost bet that the jets are plugged from sitting.... especially if you had old gas in the carb.

If you have anything there similar to this stuff I would not waste my time squirting carb cleaner

http://www.berrymanproducts.com/Default.aspx?tabid=146

Your grundgy old carb will come out looking like a new carb

Just make sure you remove all non metal parts of carb

I wasn't to happy with it last time I used it. It became like syrup almost... had to use brake cleaner to clean the carb afterwards...

I pitched it..

I've got a can I've had since '02 and it still works great

well i took the carb all apart, cleaned it with a high flash point solvent, there really wasn't much to clean it was surprisingly clean already. I unscrewed and cleaned the jets, both appear unblocked as you can see through them and blow air through them. Adjusted the float level aswell. Now it isn't leaking fuel out the overflow hose but it still wont start for me, I might try starting fluid again but its too late for that now the neighbors wont be happy!

Never seen that cleaning stuff either btw..

I wouldn't use starting fluid...

Change out the plug, fresh gas....

If you think about it... what does it need to run?

Air, Fuel and spark.... and compression of course....

yes you know despite the fact that it did run fine for a while, the fuel in there has been there since December so no doubt that could be a key factor. I will put some fresh stuff in and see how it goes. The fact that it runs for a little while on starting fluid and then dies still makes me think the carby is the one at fault but I guess I have more troubleshooting to do. New plug and fuel it is.

Unless you just have crap fuel down there, just a few months? it should be fine

If the carb is clean... jets are clear.... I don't see how it could be the carb! Maybe a restricted supply from the tank. Is the petcock on?

LOL i wont take offence to that Indawoods but obviously you had to ask. If I take the fuel hose off it runs freely..

No rag in the airbox?
Duct tape over the airbox opening?

I've done both.....

I've done the petcock thing... out in the woods after a break... Kick, kick, kick... 10 minutes later... DAMMIT! Worn out and sweating like a pig from kicking.... All someone had to do is say... "Did you check to see the petcock was turned on?"

Don't forget the pipe. Is it plugged up or does it have an old mouse nest in it? How bout the silencer, is it plugged??
Oh yeah is the piston on the rod correctly??
Please let us know what it took to get it running, inquireing minds want to know

THAT's another stupid thing I do 4 or 5 times a year... forget to take that stupid plug out of the silencer...

Harder than hell to start after it dies from that....

Re: 'Is it plugged up or does it have an old mouse nest in it?'

He's not kididng. That's happened before. It might have been elkster even..but it's happened.

Tank vent good?

The carb can LOOK clean and still have a varnish on the inlet seat that'll stick. It would be interesting to rig up a float level tube...watch it as the bike runs. If the fuel level drops..the inlet is getting stuck. That you get a free flow of fuel out of the tank doesn't tell you anything about the inlet seat.

Ah, all good points, will check them all (except rod and piston). Pulled an 18hr working day yesterday so I get to go home early today which should give me enough time to get stuck in and work out whats what! If theres something thats blocking the pipe or silencer it would have somehow dislodged, or as you say a mouse nest. Tank vent im fairly sure if adequate if i put the tank on the ground leaning forward and its full fuel comes out pretty quick.

Re: 'Tank vent im fairly sure if adequate if i put the tank on the ground leaning forward and its full fuel comes out pretty quick.

Maybe you don't have a check valve. It shouldn't leak gas OUT the tube, but let air IN (with a check valve). If you don't have a check valve..then fuel flowing out probably means air can get it.

You could just pull the tube off the cap to see if that makes any difference.

But...maybe you're talking about fuel coming out with NO tube attached. The check valve is in the tubing line.

Good luck!