Jetting beginner

[lgr]

I've just recently purchased a 2009 ec 300 and am attempting to learn a bit about jetting, mainly by searching this forum. Now, either not many folks had this model or I don't know how to use the search function. Probably the latter.

Here is the current setup

172 main
40pilot
2 and a fuzz on air screw
N1EF clip 2. (Now I'm wondering if it n1eg as I didn't write it down)
Idle screw is nearly bottomed out

Riding is done from 700 to 1500 ft in 50 to 80 F. It seems to have good power from the start but seems to load up after slower first and second gear trails. ( lugging with the lower end a lot) If on a road rolling on the throttle slowly there is no bog, but rapid acceleration it seems to be loaded up around mid throttle. Clears up quickly but something is obviously not right.

Please be patient with me as I haven't much (any) experience with jetting and have only had this bike for two rides

Also the very edges of two of the reed petals are starting to look chipped. There is still full contact with the cage though.

 

[Elvis74]

Check Out this Thread

http://www.gasgasrider.org/forum/showthread.php?t=2162

 

[Jakobi]

Double check which carb you have. AS1 is the deep bowl, 16mm float height, and round threaded cap. The AS2 is shorter, 6.5mm float height. and has a flat steel cap retained by 2 screws.

2007-2011 is very similar with exception to some plastics and the frame material. The carb model will have a more profound difference on the specs than the engine.

 

[lgr]

The top of the carb has two small screws. Remove them to remove the slide assembly.

 

[Jakobi]

AS2, just double check the number stamped on the top of the cap. It'll likely be a 38.

Lots of useful info, you want the float heights to be set around 7.5-8mm to limit overflow and overfuelling on downhills. The 300's generally like a J diameter needle with a 42 pilot. Depending on your preferences you may like a N3EJ/N3CJ available through both KTM and Yamaha dealers (shop for best prices) with a 178 main, or an NEDJ/NECJ Suzuki needle, with 172 main.

A quick search in the 2T carb and jetting section will give you more info on what you're after.

 

[lgr]

Got the nedj what needle position should be used? And will it work with 40 pilot?

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[n_green]

Got the nedj what needle position should be used? And will it work with 40 pilot?

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Try 40pilot NEDJ clip 2 175 main. Should be ok for your temps and elevations. You may even be able to step down one on the main but start there to be safe.

 

[lgr]

Set the NEDJ on the second position, with 40 pilot and a 180 main for safety, air screw 2. Runs nice. Still loads up some after lugging but nothing like before.

Still waiting on new reed petals, hoping that cures the last of my bog in the low/mid transition.

I also checked my float level. With the carb level the needle just closes as the float seam disappears from view.

Can anyone offer further advice? And thank you for advice already offered.

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[n_green]

180 is too rich for that needle unless you ride at sea level on 5deg C days with 10% humidity
Step it down to 175 and be amazed at the extra over rev you get. You could probably go down so far as 172/170 depending on where you ride and at what temps.

Air screw set at 2, is that where it needs to be set as per this advice http://youtu.be/zVzqqpgviyI

Set it as per the video if you haven't already. It could/should prevent some of the bogging/ loading up.

Float height refers to the distance from the top of the floats to the seam of the bowl when the float valve shuts off. Stock is 6.5mm you want it to be about 7.5mm. Easier way to measure is connect a hose to fuel inlet, blow through it and slowly shut off the valve (push the floats up into the carb body). When the valve closes (you can't blow through the hose anymore) measure the distance between the top of the floats to the bowl seam.
If that's too difficult just make sure it passes the 45 degree test (tilt bike over 45 degrees and make sure fuel doesn't leak out the overflow).

 

[lgr]

I'll double check my air screw tomorrow with slavens method but its pretty good on that initial crack from idle. Also idles very nice. I don't as yet have a very wide selection of mains, although it had a 172 in it.

What is the downside of being a little fat on the main? Almost none of my riding uses the last eighth to full throttle, and when on a long road run I never hold it pinned ever.

Also I tried the needle in the third position for fun and it was horrible.




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[lgr]

Fresh plug after a short ride behind the house

 

[lgr]

Ok I'm off for a ride with 172 main. Its pushing ninety and humid so well see how it goes.

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[Jakobi]

I think you'll find the 172 is about right. A 180 was way too big with that particular needle. Even though the main supplys fuel mostly at WOT (where it is the primary circuit) it will have a lesser effect through the rest of the rev range too.

 

[lgr]

I am pretty satisfied with the way it ran.

The next problem I need to address. It will suddenly load up and nearly stall after steep decent or steep ascent under low rpm heavy load. I'm thinking this is probably due to my float level being off and over fueling?

Fuel consumption was much better than before and it pulls like a freight train down low.

Also I'm using a non resistor plug (b8egv) so it may be messing up the ignition.

Perfection is so close I can taste it

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[Jakobi]

Did you check the float height? Recommended details back in my first post.

 

[lgr]

Well, I looked at the float height but I can't say I checked it, since I had no small measuring tool. It will be done tomorrow.

I appreciate the help and input very much

 

[Jakobi]

Sounds like you're pretty close now too! Good work mate!

 

[n_green]

Well, I looked at the float height but I can't say I checked it, since I had no small measuring tool. It will be done tomorrow.

I appreciate the help and input very much

Make something like this:

I used an old plastic card and the stuck the paper to it and laminated it. I clamp it in the vice level and then lower the floats onto it whilst blowing air through the inlet hose til the valve shuts off. Then you eyeball the measurement and adjust to suit from there.

 

[lgr]

Well I took everyone's advice to the best of my abilities, ending up here
172 main
NEDJ needle clip 2
40 pilot
Airscrew 1.25 turns out

New reeds installed and it runs so so nice. Super smooth lots of bottom with really no transitions or steps in power. No loading up on the test ride either
Made a tool as per ngreen's pic to set my floats. They were almost dead on.

Thanks a bunch folks