2014 Gas Gas 300 - Jetting

[n_green]

For background readthis but to sum it up, the 2014 bikes seem to require richer jetting then the '13's.
The '14 bikes have different reed valves (V-Force4 vs Vforce 3)
Redesign of the crankshaft
New Ignition
New crankcase design
New cylinder head
Uses the same barrel as the '13.

After my brief play with the jetting in the backyard the other day during which I learnt that the new bike did not like a jetting setting used by Simmo click I started a test ride today with 40p, N3CH #3, 178m. AS 1.5 turns out.
The day was 20deg C, 50-60% humidity, sea level.
After warming the bike up by riding for 15 mins I stopped to make changes. The bike was very rich off idle and was a blubbering mess at 1/8 throttle and loaded up and took time to clear its throat when riding at low throttle openings.

I threw in a N3CW #3, immediately there was a large lean bog when cracking the throttle that only went away with the AS at 1/4 turns out. As I was on a ride at the time I didn't want to stuff round too much so just changed to an N3EH #2. To get good response when cracking the throttle I has to set it at 1 turn out.

The idle seemed ok, was a bit low and stalled on me down hills but that may just be the idle setting so I'll check that again later. It was still rich and blubbery at 1/8 throttle and loaded up slightly but not too much. As the day wore on and I got tired the transition from rich to lean when it came onto the taper got annoying. I rode the ride with this needle for the day. Covered 62k's and used 7.1L.

I want to try and jet the rich blubber out but maintain the torque and also smooth out the transition onto the taper. This is where I struggle a bit to understand this part of jetting.

The N3xx needles all require the same size main right? Lets say 178, which means the needle tip diameter of all needles is the same right?

Second, they all have the same taper, which means they all share the same taper angle, therefore the different diameters must each have a different straight section?

So we use these different length straight sections to jet out the blubber at 1/8 throttle?

In my case the H diameter needle is rich with a 40 pilot, but the W diameter with the 40 pilot is too lean. The W diameter should also have a longer straight section so will be less likely to blubber at 1/8 throttle, but I'll need to throw in a 42 pilot to work with it.

Does it sound like I'm on the right track?

 

[Jakobi]

You like to challenge the brain in the morning, but I think you are correct. Due to the taper angles/profiles being the same, when working back from the pointy end the diameter will also have an effect on the length of the straight section and where it comes into the taper. From there however, the thicker needle is also tapering where the other needle is still straight and due to being such a small area its near impossible to measure in any accuracy.

A much larger variable is the diameter itself as it occurs over the entire straight section (closed until when it picks up the taper). That means as the slide lifts for that entire duration the fuel mix will be leaning off until it comes into fuel (the taper). Lifting the clip increases the straight section that is in effect which is why I noticed it most in that 1/4 throttle range (although it does effect the whole of the range).

Then you introduce the pilot and (air screw) which overlaps the straight section. I use this soley to set up the idle in conjunction with the needle diameter, and the air screw in the sweet spot 1.5-2 turns out.

Soo....

From what you have determined
1) N3Ex #2 is too lean on the needle (too snappy)
2) H diameter and 40 pilot is too rich (blubbers down low - small openings but idles - idle mix seems OK but rich on the needle)
3) W diameter and 40 pilot is too lean (hestiates when cracking - how'd it run at part throttle?)

My next step is exactly as you suggested, work with the 42 pilot and W diameter. You may find yourself jumping one further and even going 45/J for the best repsonse.

Interestingly though, you're going through a similar process I did on my 2013R after the head mods. No cracking issues on the pilot for me though as even a 40/W combo has me running 2.5 turns out on the AS (on a 250!!).. But the N3Exx was too flat/flat out transitionish at clip 2, and just too rich at clip 3. I moved back to the Suzuki needles, and ran it in clip 2. Gave a similar off the bottom as the N3Ex#2 with a mid to top similar to a N3Cx#3.. Kind of best of both worlds.

 

[n_green]

You like to challenge the brain in the morning, but I think you are correct. Due to the taper angles/profiles being the same, when working back from the pointy end the diameter will also have an effect on the length of the straight section and where it comes into the taper. From there however, the thicker needle is also tapering where the other needle is still straight and due to being such a small area its near impossible to measure in any accuracy.



A much larger variable is the diameter itself as it occurs over the entire straight section (closed until when it picks up the taper). That means as the slide lifts for that entire duration the fuel mix will be leaning off until it comes into fuel (the taper). Lifting the clip increases the straight section that is in effect which is why I noticed it most in that 1/4 throttle range (although it does effect the whole of the range).



Then you introduce the pilot and (air screw) which overlaps the straight section. I use this soley to set up the idle in conjunction with the needle diameter, and the air screw in the sweet spot 1.5-2 turns out.



Soo....



From what you have determined

1) N3Ex #2 is too lean on the needle (too snappy)

2) H diameter and 40 pilot is too rich (blubbers down low - small openings but idles - idle mix seems OK but rich on the needle)

3) W diameter and 40 pilot is too lean (hestiates when cracking - how'd it run at part throttle?)



My next step is exactly as you suggested, work with the 42 pilot and W diameter. You may find yourself jumping one further and even going 45/J for the best repsonse.



Interestingly though, you're going through a similar process I did on my 2013R after the head mods. No cracking issues on the pilot for me though as even a 40/W combo has me running 2.5 turns out on the AS (on a 250!!).. But the N3Exx was too flat/flat out transitionish at clip 2, and just too rich at clip 3. I moved back to the Suzuki needles, and ran it in clip 2. Gave a similar off the bottom as the N3Ex#2 with a mid to top similar to a N3Cx#3.. Kind of best of both worlds.

Thanks for mate I was hoping you'd chime in and steer me in the right direction.

You are correct on all three points. I didn't run it with the W diameter as when rolling the throttle on slowly with the bike on the stand it started getting too tinny sounding for my liking. Maybe a 42 will solve that.

I'll probably jump back to the Suzuki needles too, whilst not as 'fun' they just seem less prone to whiskey throttling and as I get tired that happens more then it should

 

[Jakobi]

Note, my current setup is AS2.5 40 NEDW#2 172..Good fuel economy, good power, good grunt, a little spooge, and occassionally hard to start cold (strange - as it comes off the choke really quickly).

Things I still want to check on mine are the powervalve tension and the reeds. I had a corner frey on the previous bike (so you did).

 

[n_green]

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

42p, 178m, N3CW#3. AS 1.5.
Well close anyway. Fuel economy is promising at 8.1l per 100k's and there is still room for improvement as it's still pretty blubbery and rich just off idle and especially at 1/8 throttle.

Today was pretty much all high speed large throttle openings along sandy twin trail. The main is spot on and the taper fueling is close to perfect.

On the way home along the tar I played with the choke a bit to confirm things.

Choke on max speed was 129k's and pulled pretty average. Could feel it choking on fuel a bit especially at the mid range. Choke off it pulled hard once on the taper to 132k's.

At 1/8 throttle under load it felt pretty good but was still a bit blubbery. on the flats or downhill it was blubbery and 4 stroking. Pulling the choke on made things a lot worse and sapped the power from the motor so that confirmed I'm slightly rich at 1/8 throttle.

At 1/4 throttle the engine changes note, almost sounds like a swarm of bees are inside the pipe and that's where it starts going into band. I was worried I may have been slightly lean, pulling the choke on made it start blubbering and sapped the power so I'm pretty confident 1/4 throttle is pretty much spot on. The fueling feels great from 1/4 on. Wheelie machine

I'm not sure if ill chase the blubber just yet, no doubt it'll annoy the hell out of me in the singles when I'm between 1/8 and 1/4 throttle all the time but I think first port of call is to send the head off and get that done. Then if it's still blubbering I may try a J diameter with a 45 pilot.

 

[Jakobi]

Nice one bruvva! Sounds somewhat similar to my 2013 after all. You should bang a 42 NEDW#2 175 in for giggles. I think it will be EXACTLY what you want.

I'm still trying to work out how the leak jet effects things and to what extent. I have a feeling its vastly improved the idle, but perhaps is also contributing to some of the lower blubber.

If I was riding on the pipe everywhere the 40 N3CW#3 175 would have smashed it in my bike. Probably even a 178, but as you said, in the tighter stuff it blubbed too much and contributed a load of spooge.

 

[n_green]

One thing I've noticed is even when the pilot circuit has been obviously lean - (big lean bog on cracking the throttle) the bike won't idle high and settles down at the same speed it usually would. I'm wondering if the leak jet prevents the carb from starving itself at low throttle openings.

 

[n_green]

And I may just try the NEDW, although wouldn't that only need a 172.

As I said, head is getting done first. My mind is made up

 

[Jakobi]

A size here or there mate!

I read on DBW that the leak jet may tap into the choke circuit adding extra fuel.. but I think it may work in that lower area as you've said. I've had a bit of hard starting cold with mine, but the bike comes off the choke really quickly. If I keep it on choke it really loads up and takes quite a bit to clear out.

I'm somewhat interested in doing a carb swap between my bikes to gauge the differences.

 

[n_green]

Bike year & model = 2014 EC300R E-start

Carb: 38mm PWK ASII carb and reed block spacer

Engine: Stock

Temperature (degC) = 10 - 25 degC,

70% - 90% humidity

Elevation (feet) = 1100f, or 350m.

Main jet = 172

Pilot jet = 42

Leak jet = 85

Needle & notch = NEDW #2

Air screw setting = 1.5 turns out

Throttle valve/slide = 7 non-notched


Results:


Great idle with awesome torquey power, can lug around a gear high without a problem, rolls on smoothly into a very strong mid and top end. Wheelie machine in 2nd 3rd and 4th rolling on and will easily bounce up in 5th.


I covered 240k's in 2 days with this jetting, 50% twin trail, 50% single trail. Some of the biggest longest hills I have ever seen, they never seemed to end and they were slippery so I was forced to labour the motor in 3rd gear to get traction up them. When we were on a flat section it got treated like a race track and the engine was screaming like a banshee. The motor got worked hard this weekend

This jetting is bloody brilliant, it is so torquey off the bottom, then comes alive with a nice linear hit of power all the way to the end. There is still the slightest hint of a burble at 1/8 throttle but it seems to go away under load. By the end of the second day my filter must have been getting pretty dirty as the idle dropped low and the bike started stalling on slow downhill descents and the burble got worse. The fact I could notice that tells me this jetting is pretty darn close.

Fuel economy was good - 240k's - 19l used = 8l per 100k's.

Quick check of the porcelain on the spark plug and its a lovely caramel colour.
--------------------------------------------------------------------------------------------------------------------

Engine: Modified head running 1.2mm squish, 1 x .3mm base gasket. CR unknown but higher then stock.

Temperature (degC) = 10 - 18 degC,

70% humidity

Elevation (feet) = 1100f, or 350m.

Main jet = 172

Pilot jet = 42

Leak jet = 85

Needle & notch = NEDW #2

Air screw setting = 1.5 turns out

Throttle valve/slide = 7 non-notched



Results:


Has awesome torquey power, can lug around a gear high without a problem. It's rich off the bottom and this cause a very low idle/stalling down hills along with a super annoying burble at anything below 1/8 throttle. As soon as the needle was on the taper the jetting was spot on. Super responsive and crisp with that super smooth power delivery the Suzuki needles are known for.

I was slightly concerned that by lowering the jug (went from stock .5mm base basket to .3mm) I'd lose some top end. If I did I can't tell. If anything the mid range and top end is better and stronger then ever. The bottom is also very strong, just blubbery at the moment.

Interesting is that I didn't change a single thing for this new head, the jetting is identical to what I used on the previous ride with stock head and stock port timing. On that ride which was similar temps/elevation/humidity the bottom end was close to perfect and the mid and top were spot on too. Now whilst the mid and top are still spot on (and possibly stronger) the bottom is a blubbery mess. Could this be due to the modified head burning the fuel more efficiently so it now needs less in there? Dunno next ride I'll play with the air screw and maybe even drop the pilot size down one to see.

Fuel economy was ok - 7.7l used for 74k's = just over 10l / 100ks. Pre modified head with this jetting I was getting 8l/100ks.

Edit: Swapped the NEDW#2 for NECJ#3, left the pilot and main jet the same. AS is right on 1.5 where it seems to have the best off idle response. 1.75 turns is a nicer idle and not quite as blubbery but cracking the throttle from idle results in a lean hesitation and the idle hangs for a slight amount of time just before settling again. Again once on the needle taper and main jet fuelling felt perfect. Below 1/4 though and its still a blubbering mess, its better then it was with the W dia but still needs leaning off a tad. I'll try an NEDJ#2 to see if things improve but the rich burble seems to be present all the way from 0 to just before 1/4 throttle so I doubt a half clip leaner will do too much.

Fuel use = 4.7l for 45ks = 10l / 100ks.
----------------------------------------------------------------------------------------------------------------

Engine: Modified head running 1.2mm squish, 1 x .3mm base gasket. CR unknown but higher then stock.

Temperature (degC) = 2 - 4 degC / 37 deg F

80% humidity

Elevation (feet) = 3500f, or 1100m.

Main jet = 172

Pilot jet = 42

Leak jet = 85

Needle & notch = NECJ #2

Air screw setting = 1 and 5/8 turns out

Throttle valve/slide = 7 non-notched



Results:


The pilot/diameter is correct. 1/4 turn on the air screw either way makes a noticeable difference. Where the AS is set is perfect, it has a good idle and good off idle response.

Off idle it is a tad rich and will burble away until it starts coming onto the taper. Having said that its not too bad and adds torque which allows the bike to lug up hills. The one downside to this is it makes the off idle response a bit doughy and isn't as snappy as I'd like.

Transitioning onto the taper it gets a tad buzzy (sounds like an angry swarm of bees are loose inside the expansion chamber) but I don't think its a lean symptom, more the power valve starting to open and the exhaust getting louder. From here on in its all smiles. Crack the throttle from this position in 2,3,4 gears and the front wheel will loft, no clutch required. The power continues to build smoothly but powerfully all the way to the upper end of the revs.

The ride today was 65ks of good terrain, 40k's of it was single track, 50/50 tight/flowy. There were also some techy trails like sections and hill climbs.

Fuel use = 5.6l for 65ks = 8.6l / 100ks.

Edit: I went for a ride at sea level altitudes (300m) and normal temps (10 degC) and the transition onto the taper was pretty snappy and not at all smooth like the NExx needles are known for. This is due to it being rich off the bottom and then leaning out to a nice mixture as it comes on to the taper. Fuel consumption was also up, I used about 4l for 38ks = 10.5l / 100ks.

I changed the jetting back to what it was pre-head mod and dropped a pilot, so 40p, NEDW#2, 172m, as1.5 to. Today I went for a ride to a local area 300m asl, 55% humidity, 13 degC and did 38k's most of which was a nice little test loop about 5k long. Most of the riding was tight 1st, 2nd, 3rd gear single with a small amount of faster twin trail.
Again even though it is spot on on the idle and off idle response as soon as the throttle starts opening its rich right up until it comes onto the taper at which point its perfect. The transition from rich to lean was present again and whilst not as noticeable as the NECJ#2 was its enough to indicate I have a lot of room for improvement in cleaning up the bottom.
Fuel use was 4.3l / 38ks = 11.2l / 100ks.

 

[n_green]

I copied the above info as information of what has gone on since my head was modified.

What happened is I got the head back and the new squish was 1.5mm, I rang the tuner and was told it should have been 1.3mm. The tuner was going away on holidays for a while so until he got back and after consulting with him about it we agreed a suitable option would be to replace the stock .5mm base gasket with a .3mm base gasket which would reduce the squish to 1.3mm. With the .3mm base gasket with new squish came in at 1.2 ish. I don't know what the new CR of the modified head is. The tuner reduced squish, re-cut the squish band angle to match the piston and modified the bowl. I was told he would raise compression a little as he isn't a fan of how low they are stock.

Now, obviously the ports have been lowered .2mm. Stock with a .5mm gasket the piston at BDC was a mm or 2 above the floor of the exhaust port, now it would be 5mm or so above the bottom of the exhaust port.

As far as I can tell this hasn't cost me any top end or mid end, in fact these are probably stronger since the mod.

But the bottom end has gone to hell, its still just as strong as pre head mod, however I can't for the life of me get the jetting dialled in. Pre head mod I was super happy with the jetting and fuel economy. It did have a burble at 1/8 throttle that I couldn't get out but that was about my only complaint.

Since the head mod the jetting has constantly been super rich off the bottom. I've tried a W and J diameters and even when they are perfect at idle and off idle as indicated by the air screw and feel, as soon as the throttle gets twisted it breaks up and burbles all the way through to just before 1/4. From there, as it was pre head mod it is beautiful.

One thing the head mod has done is allow me to drop down a size on the pilot, whereas I had to use a 42 and W dia needle, I can now get away with a 40p, alternately I can use a J dia with the 42 pilot.

There was less of a burble using the J dia 42 pilot but it was still rich, and no matter what combination I've used since the head mod it is consistently using more fuel then pre head-mod.

I'm almost considering buying an NECK and throwing that and a 45 pilot in.

So my question is this, has changing port timing somehow turned my bike into a thirsty hard to jet on the bottom mongrel? Because at this point in time I think it has.

Either way tomorrow I'm swapping the .3mm for a .5mm base gasket, and sending the head back to the tuner to be re-corrected. I'll also speak with him about this issue and see what his take on it is.

 

[Jakobi]

My 2013 model isn't as clean off the bottom as my 2010. It doesn't feel as strong and punchy either. But they are running different jetting setups. I wonder how this latest batch of cylinders looks casting wise?

 

[n_green]

My '14 looked just as clean as the '11 cylinder casting wise. Nice smooth ports. No idea about anything else, I didn't take measurements and it wouldn't have meant much to me if I did anyway.
What's confusing me is I can have it perfect at idle and off idle response but then it breaks up rich instantly.
Leaning it all out by raising the clip then leans out the mixture as it comes into the taper too much and it becomes snappy and loses some power.
Maybe I just need to custom grind my own needle.... Haha

 

[n_green]

Pulled the jug this morning, confirmed that using a .3mm base gasket I have 1.22-1.25mm squish. With no base gasket I have 1.02-1.05mm squish. With a .5mm I'll expect 1.45ish mm squish.
The head shows that on the carb side it is a nice mixture and the bowl was a light caramel/honey colour. At the front of the head/exhaust port side it was black and spoogey.

 

[n_green]

I didn't take any photos of the jug but it looks the same as the one off my '11. It's also stamped 's3' on the bottom. What changes were made to this 'new cylinder'?
If anyone's interested and tells me what to measure I can while it's off.

 

[Jakobi]

I have a 2010 300 jug here I can run some calipers over if you want to compare. Basically you'll be looking at the height of all the ports. Are the boost ports at the same height as the transfers, etc. Google port mapping.

I've noticed my 250 starting to feel a bit soft in the mid. Not soft, but just not as snappy. At around 55hrs now I think she's starting to show initial signs of wanting some rings/piston. They haven't been a soft 55hrs.

 

[n_green]

I'll have a google and if it looks easy enough ill measure it and put the numbers up. Maybe they'll make sense to someone, not me though

I measure my ring gap and after 25 hrs they are exactly the same as they were when brand new clearly I don't thrash it as much as I would like to believe.

 

[n_green]

http://www.macdizzy.com/cyl_primer.htm

Very interesting reading.
Well some may call it interesting.

 

[n_green]

I didn't bother taking measurements, looks like unless you are very accurate there is not point, plus the figures won't mean anything to me, and to be honest the Gasser is responsible for my pedantic jetting and suspension already, I don't want it to be the cause of some newfound passion for porting :roll eyes:

I did however take the jug with me today to my local dealer as the mechanic wanted to compare it to previous years, he had a brand new '13 cylinder there and to the naked eye they look identical.

 

[n_green]

Follow up, got the head back from being re-machined. By my verniers the squish with a .5mm base gasket was 1.42-1.45mm. The tuners verniers gave a reading of 1.35mm. 1mm was shaved off the gasket surface which should have given a squish of 1.25mm. By my verniers the new squish is 1.33mm. Close enough



Threw in the tuners recommended specs based on 14's he has run on the dyno - 40p, NECJ#3, 168m. I erred on the side of caution and left a 170 main in, down from the 172 I had been running previously and had been happy with.



Surprisingly the bike is happy running a 40p and J diameter needle, air screw is set at 1 turn out. Previously it would not have liked this and the air screw would have been at .5 or similar, so the closer squish has helped.



I only rode for 30k's at the test track I've found nearby (thanks to whoever it is cut that in), avg temp 14 deg C, altitude of 350m, humidity between 80-90%.



As per usual whilst the bike had a good idle (which got worse as the day went on thanks to the approaching rain storm and skyrocketing humidity) and then broke up burbly and rich immediately.



Today was a bit different too in that the top end wasn't as good as I remember, at the start of the ride when the humidity was lowest (though probably still at least 80%) it struggled to lift the front wheel under power, as the day went on and the rain came in it seemed to get better but still not as good as it has been. Not sure if I'm rich or lean, more testing will reveal the truth.



And as per usual economy was ordinary - 3.4l used for 30k's = 11l per 100km.



Not good enough


http://youtu.be/1gbScbv_1Ew