Educate and then help me with my Jetting please

[n_green]

Hi all,

Recently got an '11 EC300 E start and I'm loving it, though the jetting currently in it sucks and needs changing.
Its a 36mm PWK carb. There is a reed block spacer fitted. Currently inside the carb:
6.5 notched slide, 38 pilot, 178 main, N1EG 1st clip down from top of needle. No idea what the float height is, air screw currently set to 2 and 1/4 turns out.

Feels ok off the bottom, maybe a bit doughy and rich. Mid is awesome, nice and crisp though a bit explosive. Top is DEAD. Drowns itself in fuel its so rich and just refuses to make power or continue to rev.

I ride in NSW Australia at mainly sea level to 500m (0-1500ft) sometimes up to 1000m (3000ft). Usually 10-25 degrees C (50-77 deg F). I like strong torquey linear power that continues to build and build, without any explosions of power during the rev range.

Ive already been given some jetting specs to try - 40p, 172m, JD Blue #3 or 45p, 165m, NEDW #2.

I will be adjusting to float to about 8 - 8.5mm. I previously had a KTM300 with the same carb and this float level worked well.

A few questions:

1) The reed block spacer:
a) what is it exactly
b) does it really do anything on the 300
c) does it affect jetting
d) is it worth taking off/leaving on.

2) The slide: I dont really understand the numbers apart from the lower numbers are richer then the higher numbers. And then the notched slides are richer then their non-notched counterparts?
a) Is a notched 6.5 slide too rich?
b) I understand they are expensive but is it worth buying a leaner slide and if so which one works best in a 300?
c) If I purchase a leaner slide will that affect the jetting dramatically?

3) Oval Bored carb mod:
a) If I get this mod done what jetting changes are usually required?

Side note) Why does the GasGas require such rich jetting. Well compared to a KTM anyway. KTM's riding in the same conditions running the same 36mm carb I have will run 35 to 40 pilots, 158 - 165 mains. Why does the Gasser need such a richer main?

Okay so there are a few more then a 'few' questions

Thanks to anyone who takes the time to actually read through all this, let alone reply.

[Jakobi]

Reed block spacer just adds extrra crank case volume. Changes the dynamics of the engine and produces more of a smooth torquey feel as opposed to a snappy one. Same reason the Gasser has different fuelling requirements to the KTM. Yep they have the same carb, but they have completely different engines. Same reason why the EXC and SX come jetted differently too. Same way a pipe can require different jetting. Same reason why everyones is a little different. You may find you can run a nice lean setup with the 36mm carb too, but I'd suggest you work down towards it.

Simmo has given you some good starting points with jets. You may find the slide too rich for a 300, particularly with the 300. Only time will tell though.

[Simmo737]

With a stock engine I'd do exactly as jd says, 38 jd blue 3 170, and also try red clip 4, maybe 168 main at a pinch. I wouldn't bother even buying an nedw, I'll send you mine if you want. I use a 172 main due to the high compression s3 head. I had problems with idle with a 38 until I changed my throttle cable, but you may well get the throttle adjusted and it idling with the stock cable, you will need to fiddle and see.

As an aside Jap 250 2ts use even larger pilots, it's all in the design differences in the engines make to make.

I ride a mates 2010 exc300 with the red spring in and the bolt flush, it has more bottom end, similiar transition onto the pipe and similiar top end, ( the kato will pull a bike length on me through the gears till you pop into 6) I changed to a 50 tooth rear and it really helps. This is with the s3 head and black insert).

If you can find someone to do the squish, it is the cheapest and best mod for this bike.

Cheers

[Jakobi]

Double that!! I did some measuring today and there is very little difference between a JD Red and N3EW. Same straight diameter, very similar straight length. The JD richens up a bit between 1/2 and 3/4 throttle, and then leans off again from 3/4 to WOT.

I'm going to give your JD red a go next ride Simmo to see how the figures translate into feeling. Probably 40 JD Red#3 180.

For you Greeny, I'd imagine you'll like something around the 38/40 pilot and 168/170 main with whichever needle you decide works best. The red needle has a leaner diameter so will probably be easier to set the idle up than the blue. Especially since you have a rich slide.

[Simmo737]

Hmm that sounds like your gonna miss the big hit in the midrange jake, might be that perfect jetting where you can sit just on the hit and murder the clutch all day, I'm just not fit enough to do it on anything but a 125.....

[fasteddy]

Originally Posted by Jakobi

Double that!! I did some measuring today and there is very little difference between a JD Red and N3EW. Same straight diameter, very similar straight length. The JD richens up a bit between 1/2 and 3/4 throttle, and then leans off again from 3/4 to WOT.

I'm going to give your JD red a go next ride Simmo to see how the figures translate into feeling. Probably 40 JD Red#3 180.

For you Greeny, I'd imagine you'll like something around the 38/40 pilot and 168/170 main with whichever needle you decide works best. The red needle has a leaner diameter so will probably be easier to set the idle up than the blue. Especially since you have a rich slide.

I'm using the jd red at 2 from the bottom to start, 40 pilot, 180 main, 2011 250 38. Carb...about 500 ft elevation... So far seems ok..>

[andoman]

I have a little info on question #3:

The Oval Bore carb mod works well on a 36mm if you need low end grunt and still have to rev to the moon. I have the mod on an orange '10 300 XC.
As for jetting: That bike also has a Dial-a-Jet that I really, really like for its clean, no fuss jetting. But there is a bit of a hit when it comes on the pipe. Throttle control is more critical than on my Gasser.

My '11 EC 300 Gasser has a 38mm carb and revs all I need. I have my EC jetted so it has very rideable tractable, linear power with virtually no hit. I prefer the power deliver of the GG hands down. But the oval-bore carb works. And the Dial-a-Jet makes it work even better. Especially if riding at lots of spots with different altitude/temps. Sea level to the top of the mountain at 11K feet + and the jetting stays crisp and clean.

[Jakobi]

Originally Posted by fasteddy

I'm using the jd red at 2 from the bottom to start, 40 pilot, 180 main, 2011 250 38. Carb...about 500 ft elevation... So far seems ok..>

Temps? ....

[n_green]

Thanks for the replies. So basically the reed spacer smooths out / increases bottom end. I'm happy with that. As much as I love the grin factor of the old school 2 stroke power delivery I'm too unfit to put up with that all day, so I like my power silky smooth.

How much difference will the slide make and what area in particular does it make a difference to? I have a mates KTM at my place at the moment, I think they have a #7 slide, I may 'borrow' it to see if it makes any difference

If I wanted to buy a leaner one what would people recommend? A number 7, 7.5, 8? Also where can I get the slides from?

I already have the NEC/NED W/J needles as they were good in the Kato.
I have 35, 38, 40, 42, 45 pilots and 170, 172, 175, 180 mains. If I wanted to improve the jetting, even as a band aid until I can get some smaller mains or a JD red or blue any recommendations on what I should go with?

Cheers guys.

[Jakobi]

Sure thing. I'd suggest trying the slide for sure while you have one on hand. You can have your 6.5 cut to a #7 if you feel the need.

I'd start with 42 NEDJ#3 162/165. You might be able to drop to a 40P on the 36mm carb. Probably not much different than how you had the kato set up.