Before i finally drive this ****** f.. stubborn beast off a cliff i would be very grateful of some help here.

History
KLF300b age im guessing early 90s.
Last compression test 120psi

Was running ok until left out in the rain for a while then wouldn't start, and starter motor failed. Replaced starter motor and in process pinched the blue wire pair when i removed and refitted the stator cover, symtpoms were no spark, so i removed the cover found one of the wires was pinched enough for the insulation to be cut and was grounding. Taped up the wire and refitted in the proper channel, bike started ok but ran like a dog. I had already fitted a carb service kit at the same time, and wasn't sure i had fucked it up somewhere. I then replace the ignition coil and spark plug in case ht or plug were failing. Still no good.

Next i bought a chinese klf300 carb off ebay and fitted that as i was convinced the old carb was knackered. But its barely improved i would say.

Symptoms are it starts and runs ok for about 30 secs and pulls ok from cold but then about 30 secs later it hardly gets out of 2nd gear and just has no power. Seems to run really hot quickly hotter it gets the less power, then can't even pull away at lows revs without cutting out especially any uphill and need lots of revs to pull away.

I then pulled out the fuel tap from the tank was a bit dirty, blew out with compressed air refitted, drained the tank and filled with fresh petrol (or gasoline if you're reading from the USA!)

Oh as above i checked the inlet exhaust valve clearances and measured a 120psi on a cold engine.

I am going to upload a youtube clip shortly but i just dont know what else it could be, is it the cdi or have i damaged the pickup coil or CDI when the wires were shorting?

Here is a youtube upload im trying to ride it up a bit of a hill then have to turn down but still struggles unless i rev alot finally get it pointing down hill where it manages to run but still bogs down easy and no power. As stated seems to run perfect for first 30secs from cold.


Also the bike is smoking not sure if its blue or black smoke. Thanks again for looking and any advice appreciated.

 

Have you checked to see if muffler or air intake is clogged?

 

Hi it seems to run same with or without muffler (air filter element) Also replace it back in summer last year so a fairly new sponge element.

 

 

Yes, indeed, go back to the OEM carb as MRSUMMIT says.

Fuel starvation could cause this problem, but if the new carb gave similar results, that is helpful.

I would check to see you get unimpeded fuel flow thru the petcock. If your KLF300 is '88 or older, you will have a
steel tank, which is probably very rusty.

 

Thanks for advice as above that was my initial thought also to do with fuel starvation.
Hence removing the fuel tap and clearing with compressed air and flushing tank with fresh fuel before refitting. The tank is plastic so I guess a bit newer than 88. But made no difference.

 

I saw in your first post that you cleaned the petcock and flushed the tank. That is a lot of debris on the filters, tho not rust, since you have the plastic tank. I suspect you still have debris in your tank and it is re-fouling the filters.

I am a huge fan of plastic tanks, but flushing them is not always easy. Lots of nooks and crannies in there. If your filters continue to collect crap, try cleaning the tank with hot water, soap, and some small bolts & nuts. Shake well, and rinse plenty.

Test the flow with actual clean gas with everything installed, except the hose-to-carb connection.

 

Thanks mate will give it a total wash out tonight with pressure nozel etc.

 

Also, you have the rebuildable petcock, with the screws holding the lever mechanism. Some use rivets. Take that all apart and clean it. If the internal rubber seal is bad, buy another, or get the aftermarket petcock. The aftermarket petcocks are quite good, and bolt up to the same holes.

 

Hi yes i already cleaned that out last night took the screws off rubber o ring gasket thing looked ok hasn't been leaking anyway. Tank cleaned and left to dry will test tom night after work.