300EC/GP/Jetting

[Doc Brown]

Today I was riding very slow, technical stuff, most of the time in second gear with a quarter to half throttle.

Few days ago I replaced the 172 main jet with a 170, opened the air screw further (now 2,75 turns out). I guess the 42 pilot is too rich. We had about 30? celsius (I think thats 86F) and the bike blubbered, didnt run clean with low throttle openings. Had lots of spooge on the exhaust although I run 80:1...

Any hints?

 

[(F5)]

For a start put more oil in there man!
Then change the needle. Been covered before more than once and I can't see it being different for the 18.

 

[Jakobi]

Copied straight from a response to another thread..


The pilot jet isn't your problem.

The stock needle, its short straight section and the rich F diameter of said straight section is the rich condition you are feeling. Odds are that the idle screw is wound in so far that the pilot and airscrew are just about being bypassed.

 

[Doc Brown]

For a start put more oil in there man!
Then change the needle. Been covered before more than once and I can't see it being different for the 18.

Many thanks. I will try a different needle or get a JD kit with which I have very positive experiences.
Dont worry, I run all my twostrokes (I had 3 300's and one 250) with 80:1 and no problems so far, but I dont want to start an oil thread here

Copied straight from a response to another thread..


The pilot jet isn't your problem.

The stock needle, its short straight section and the rich F diameter of said straight section is the rich condition you are feeling. Odds are that the idle screw is wound in so far that the pilot and airscrew are just about being bypassed.

That is indeed interesting as I thought the pilot jet is the problem as it was the problem on my Kato. But what you say sounds very plausible, I just didnt take that into account. Is there a needle you can recommend os should I see if I can get a needle chart and see which needle has a longer straight section and bigger diameter?

The problem with the too high idle and hence bypassed idle circuit is quite common but thats ok on my bike.

Many thanks for the help, most appreciated.

Doc

 

[Jakobi]

Ktm/Yamaha series needles work a treat. NR8/N2Z/N3C/N3E/etc
So do Suzuki OEM needles NED/NEC series.

Usually around a W-H diameter. Sometimes down to a J depending on the conditions.

The N1E series that comes OEM in the gassers is the same taper you find in KTM SX models.

Have a search. Topics been covered for years!

 

[Neil E.]

Using 80:1 makes your engine run richer compounding the already poor N1EF needle. Less oil = more gas per unit of fuel, thus richer. We're not talikng huge differences but it all adds up.

 

[Doc Brown]

Using 80:1 makes your engine run richer compounding the already poor N1EF needle. Less oil = more gas per unit of fuel, thus richer. We're not talikng huge differences but it all adds up.

Yes, I am aware of that. But as you say the difference is minor.

Ktm/Yamaha series needles work a treat. NR8/N2Z/N3C/N3E/etc
So do Suzuki OEM needles NED/NEC series.

Usually around a W-H diameter. Sometimes down to a J depending on the conditions.

The N1E series that comes OEM in the gassers is the same taper you find in KTM SX models.

Have a search. Topics been covered for years!

Thank you, I will get some Sozooky needles and play around with jets and needles. As said in the other thread I have ordered a JD kit too, let's see what works best.

Appreciate your help!

 

[thumperrider1]

Yes, I am aware of that. But as you say the difference is minor.



Thank you, I will get some Sozooky needles and play around with jets and needles. As said in the other thread I have ordered a JD kit too, let's see what works best.

Appreciate your help!

Try the NEDW to start. NECJ is WAY too lean.