running out of fuel?

[cchracer77]

Hello everyone.
This weekend I went and did some dune riding for the first time on my 2010 ec300. I encountered an issue I have never had on my normal singletrack trails. The bike runs great, plug reads good, float level is perfect. However at the end of a long wot pull the bike will lay down and lean out like it was running out of fuel. Two buddies on ktm 300's were also having this problem. The only idea we could come up with is that the bikes were "sucking the float bowl dry." Anyone else ever experience this sort of issue or have any other ideas?

[gasser]

Are you running much lower altitudes in the dunes? High altitudes require less fuel so you might not recognize a slightly low float setting until you put the motor under max load for longer periods of time at lower altitudes. Sounds like you need to readjust for the dunes. One thing you might want to do first is to check for good fuel flow from your tank and clean the fuel filters if needed.

[Jakobi]

Did anyone try going up a size or two on the main? The sand will put a bigger load on the engine plus as stated if you'd dropped alititude the bike will require more fuel also.

Is it one big surge as you come off WOT? A surging idle once stoping your long run? Or surging at part throttle after a WOT run??

[cchracer77]

That's why I'm confused. I jetted for altitude, the tank will drain quickly, float needle and seat are clear. I run the floats as high as possible without a continual dribble from the overflow. The bike will pull strong banging gears on the flats. On the long hill climbs it will pull hard through the top of third gear and hold good strong power there for about 45 seconds, then it gets about three good sputters and falls on its face, downshift to second without lifting and no change. Dump the throttle to turn out and within 1-2 seconds it will wind out again. As a test I got on the flat highway and let it pull in 6th for about 45 second and it does the same thing, dump the throttle and pin it again and it will pull. As stated the 2 ktm 300's were having the same problem. Altitude was around 5000 ft, 55 degrees f. I have a 40 pilot, N3CG needle middle clip, 165 main. Normally run a 38 pilot, same needle on second clip from top, and a 162 main at 6500ft +. Running Sunoco 100 octane and Motul 800 at 50:1. The ktm's were running 91 pump on junk oil, and Sunoco 118 with Bellray H1-R respectively. Second ktm running a 35 pilot, jd red needle, and a 162 main. It was jetted on a dyno at 5000ft.

[Jakobi]

Is that with a 38mm carb?? Thats a hella small main for a dual taper n3xx needle.

I personally run a 42P N3CJ#2 172/175 main in my 2010 EC300 with a high comp head. 98RON 300M 30+C (1000ft 86F). Jeffs runs 40 N3CH#2 with a 172 not sure on his temps or altitude. Considering you are running richer than us both on the pilot and the needle with that setup also makes me wonder why your bike would need 4 sizes smaller than us on the main.

Does sound like you're running out of fuel considering its running for around 45 seconds before cutting. I'd suggest throwing a fat main in just to check.

[cchracer77]

Dealer recommended a 158 main. The 40 pilot is rich on the air screw, but it gives better "pop" off the bottom. After fully warm, 30 min of hard riding to clean it out, a 20 second wot plug chop looks fat to me:

[Jakobi]

Yep yep

I run the leaner needle diameter with a bigger pilot. Its not as punchy but I prefer the cleaner smoother delivery of if. Still pleanty of torque for lugging hills.

Can't argue with your plug chop either. Is it a 38mm PWK?

With all bikes displaying the same symptoms perhaps you blokes just need to lay off the gas a little!

[cchracer77]

I assume its a 38mm. Its the carb it came out of the shipping crate with. It has no p#'s or markings at all other than the "Keihin" logo. Not an asII. Looks like a classic pwk. Of course I have come to realize that my bike must have been built on an overtime sunday! It has a combination of parts that the importer says didn't exist here in the U.S. The combination is closest to what everyone refers to as a "euro." These things have the consistency of Mona Lisa knock off's. As for "us blokes" I can't help it if i ride too hard!

[rgranger]

look on the top of the carb, should be a circle with a 38 or 36. my 2011 300 came with a 36mm.

[Jakobi]

Originally Posted by rgranger

look on the top of the carb, should be a circle with a 38 or 36. my 2011 300 came with a 36mm.

I believe the classic PWK has a plastic screw top cap. I've never owned one so have no idea how to verify sizes.

Heres a consideration though.. Still thinking about main jets here and maybe a little off topic.. You realise if you do have a 38mm carb that you are running the same size main as the ktm with a 36mm carb. Here in Australia the KTMs all run same as you described. 35/38 pilot. 158-165 mains. The gassers require 38-42 pilots and 170-178 mains simply because the smaller carbs have a higher velocity of air pulling more fuel through the same sized jets.

The 'Euro' model was marketted to Australia as a limited edition. Essentially it is a US EC300R with everything to be road reg (blinkers etc), which is what I have. White and black plastics. We all ended up with the ASII 38mm.