Ktm 300 jetting help needed

[Luke CharlesworthMember]

Hey Guys

I have gone through the jetting thread on OBT but would like to possibly get a second opinion. I ride mainly Nundle, Attunga and around Tamworth etc

The last two weekends I have been riding at Attunga and have fouled plugs both times (first plug was black with carbon and the 2nd was black with less carbon and maybe a bit oily – so bike must be rich). The is no spooge/oil on exhaust tip, its very clean for a 2 stroke. I have had my current jetting for over a year and have ridden this area before with no problems. The only changes would be it has gotten hotter and I have been riding a trail that looks to have been put in by some Trials riders (tight, rock step ups and drop offs etc – bike boiled several times as I can’t ride for shit)

My current set up is
Pilot Jet 35
Main Jet 170
Needle – Unsure what type as no markings but set at 3rd clip position
Air screw 1.5 turns out
Plug BR8ES – I have a BR7ES as spare now.
Premix Bel Ray Si7 at 33:1 and run with 95 petrol – always fresh fuel.
FMF Gnarly with a shorty pipe – but I would like to put the standard pipe back on if it would quiet it down.

The bike revs, rides and idles fine with no hesitation. Replaced the top end 45ish hours ago.

Any help is appreciated.

Cheers

[alanMember]

mines an 09 model and i think the br7es is the standard plug try that its a bit hotter.i also found the standard silenser goes better than a shorty in my opinion defenently worth trying anyway

[DeanMember]

hard to determine but it might be worth trying a leaner pilot jet, your right in saying as it warms up the mixture needs leaning off,maybe half a turn out on the air screw. Its just trial and error take some jets out with you and have a play. Is your air filter clean ? When was the last time you re-packed your silencer?

Rockets point on a hotter plug has merit as well,also 2 strokes can be fussy my GG only likes NGK B8EGV’s anything else and its not happy Jan :laugh:

Good luck with it,let us know how it goes

Ollie

[Luke CharlesworthMember]

Thanks for the replies guys. Looks like its just going to have to be a day spent testing. I will be putting the standard exhaust back on which has fresh packing in it, the br7es plug will go in and I will try the following: Pilot 38, Main 162, red JD needle on clip 3 and play with the air screw. This seems to be the combo recommended in the JD jetting kit. Cheers

[DeanMember]

Luke Charlesworth wrote:

Thanks for the replies guys. Looks like its just going to have to be a day spent testing. I will be putting the standard exhaust back on which has fresh packing in it, the br7es plug will go in and I will try the following: Pilot 38, Main 162, red JD needle on clip 3 and play with the air screw. This seems to be the combo recommended in the JD jetting kit. Cheers

Luke, write down all your settings and comment on what you feel the bike is doing for each change. I would only change one thing at a time otherwise it might be a longer process. Also remember that a richer oil/fuel ratio actually leans off the mixture going to the engine. I run 40 to 1 with semi synthetic and 50 to 1 when using fully synthetic. Not sure of the Belray oil.

Ollie

[Luke CharlesworthMember]

Thanks Ollie
It’s a good point to make small changes one at a time rather then changing the whole setup all at once like I was going to. After a night of reading good old google I had convinced myself I was way off in my Jetting. Some people talking that they get 130km out of a tank and I was getting 90kms and others say that their jetting has their bike pulling 4th/5th gear power wheelies – I would need to give my bars a fair tug to do that. I just though if the bike went well and no spooge running down my silencer that I must have been close to OK jetting.
I wasn’t aware that more oil would lean the mixture off. I just thought more oil would be better for the bottom end etc Bel Ray si7 is fully synthetic that can be mixed between 20:1 to 50:1 – I might give 40:1 a shot. Cheers

[alanMember]

i just had another look at your set up i reckon your problem is the 33 to 1 oil and the br8es plug change those and it should be close stop fouling plugs anyway

[DeanMember]

yep what i reckon as well rocket + only 1 1/2 turns out on the air screw (should be 1 3/4 to 2 1/2) if outside that range look at changing pilot jet

Ollie

[Adrian SnowdenMember]

Save the hassle – ditch the outboard motor and buy a four stroke !

[nathan steeleMember]

changing you fuel mix sounds like a possible win in itself, 40:1 is where i’m running my 300 and its great. Does get a wee bit boggy after a long time spent in the tight stuff but a quick squirt clears its throat.
5th-6th gear wheelies aren’t out of the question on these things

[Luke CharlesworthMember]

Thanks again to all the replies. Except Snowy, I know he secretly loves the headache that the smell and sound of a 2 stroke gives him. Find me a 4 stroke that has as much grin factor and I will gladly make the change.
I will push the oil ratio out to 40:1 meaning 70ml less oil per tank = more beer money
I will use the BR7ES plug as I never fouled a plug when using these – although they were pretty rich looking when I did the regular swap one out for a new which I do every 10 hours for no other reason than spark plugs are cheap and I like the idea of a reliable bike.
I though it odd that the JD kit recommends going to a larger pilot jet (38) as a first step of improving jetting when I am already clearly running too rich. But I will give all options a go and make notes of any improvements etc.
Cheers again

[murph the surfMember]

I’m surprised the Dude hasn’t chimed in on this thread.
He has just changed the standard jetting on his Husky/KTM 300
I don’t know what he changed it to but he said he was much happier with the power delivery

Tim has always run 40:1 fuel oil mixture on his 200
First piston/ring change at about 7000kms
Can’t complain about that
The bore was fine as well

Good luck with it
Cheers
Murph

[xr torcherMember]

dust run the spark plug that is recommend in the spares kit you have 4 needles to pic from you need to find out what power delivery you wont i run 50/1 ktm husky recommend 60/1 i run 50/1

[DudeMember]

Greetings sir Luke

my 5 cents worth

So the bike was going good then it boiled and fouled the spark plug.

Replace spark plug and rev the bejesus out of it after a downhill. :huh: :dry:

I have the 15 model 300 husky and the set is as follows

necj #3 (suzuki needle)
165mj
38 pj
as 2
red spring

but been 600m up the settings should be a bit different.

just rev it to blow out the oil, my son wouldn’t rev the stuff out of his rm80 and he was always fouling plugs. :huh: :dry:

If the set up you were using was a good thing……. something has changed :ohmy: :ohmy: :ohmy: :ohmy:

[AlexMember]

Dude is making sense here.
These 300s just work now days. Mucking around to solve a fouling issue is rare.
Fouling is most likely due to bad fuel, too much 2T oil and bad plugs.
2014/2015 jetting is not necessarily suited to 2003-2013 (or whenever the 36mm carb came in).
Always aim for 1.5 turns out on the pilot. Anything more than 1 turn either way and jet change 35/38/40.
Dude’s needle is a good choice – I run it too now on #3.
I used to run (and Rocket runs now I think): 35 pilot, 165 main, N3CJ #3 . (2008 300EXC)
Now I run: 38 pilot, 165 main, NECJ #3.
BR7ES is for Europe and cold climates. BR8ES or BR8ECM is what you probably should run – shiney new one. If your running a 7 to fix a fouling issue, I think you’re masking the issue.
Just about everyone I know run 50:1 fully synthetic. 40:1 if you like wasting money and like buying oil more often. Manual recommends 60:1 which is probably not a great idea.
Start with the plug and 2T mix, make sure the pipe has been burned out of carbon and muffler repacked (plus all the other assumed stuff – clean filter, no air leaks). Hopefully the piston and rings aren’t stuffed too (>200hrs)? Then play with jetting.

[Author]

Posts