Ktm 300 jetting help needed

[Shane CosgroveMember]

My two cents worth, just about to buy my third one of these awesome machines.

The needles etc that come with bike give you all the configuration you could want. Dont be afraid to play, see the manual for where to get started.

GAP YOUR PLUGS. Heaps of blokes with 2 strokes don’t do this and wonder why new plugs only seem to last a few rides. Put the standard plug in and just give the ground electrode a couple of light taps until the gap is closed by about a third. I used feeler guages once upon a time but now the care factor has lessened

Its a simple fix but incredibly common, hope its your problem. 1 plug lasts me about a year or so, I always carry a spare though and have given a few away Running 50:1 Btw with no probs at all but did play with needles and clips to improve fuel economy to get 110 ks or so out of a tank

[Luke CharlesworthMember]

Just thought I would post an update on how the Jetting/plug fouling problem is going.
First I put the standard exhaust silencer back on and took it for a spin to see the difference between it and the FMF shorty. Notice that the bike is quieter at idle and low revs, but seems almost as loud when giving it wide open throttle. Bike doesn’t have as much bottom end punch but seems to rev out better with more over rev and doesn’t seem to sign off as early. Just seat of the pants feeling.
Next I left the Jetting as was and simply mixed fuel/oil at 50:1 instead of my usual 33:1. I put a new BR8ES plug and gapped it per the manual. Fouled the plug after 3/4 tank. which was a bit better than previously.
Next I put a new BR7ES plug and gapped it per my manual (it was pretty much spot on). I then started with the JD jetting kit which recommend for my riding elevation 38PJ 162main and Needle 3rd clip. Originally I had 35pj 170main and Needle 3rd clip. I played with the air screw and ended up at 1.5 turns out. No bogging when snapping the throttle open and idle was good. Fuel 50:1, clean air filter. I then rode the same tracks (Attunga) and did close to a full tank without fouling a plug. :woohoo:
Later I took the plug out as I was lead to believe that the plug should be a chocolate brown colour if jetting is correct. The plug still looked a bit rich but nowhere near as oily as prior. Put the plug back in and this past weekend I did 85km at Nundle and still no plug problems.
Fingers crossed that this continues.
One thing to note though was that my fuel consumption didn’t improve. I still hit reserve at 82km?? Stuffed if I know, but topping up the tank is quicker than seat off and plug out.
Thanks to everyone for their help on this. Cheers.

[AlexMember]

I still think something is not right. 82km is very ordinary unless you ride on the main jet all day. 100-130Km is more the norm.
What about float bowl fuel level height? If fuel leak out the drain hose (too) easily you might have fuel wastage here.
Also another overlooked issue is reed petals. I have heard and seen of them loose, missing or chipped.
Your jetting looks reasonable. As it gets hotter your jetting will get richer so you may see more fouling.

[Adrian SnowdenMember]

Have you tried jacking up the number plate and replacing the motorbike?

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