trying to get me jetting dialed in...in the bike now (2010 ec300) is jd needle, clip pos 2 from the top, 170 main, 42 pilot. Im currently waiting for a gasket to adjust the preload on the PV assembly because it rattles and i will clean in while im in there because i believe it is sticking after long fast close to wide open sections (zero bottom end, trouble getting on the pipe, i shut the bike off and it usually runs fine so i believe its sticking open). So when the PV isnt being sticky the bike is clean on the bottom, and midrange, but uphill or with a load (like deep sand) it has a hard time clearing out. Downhill light load the bike runs amazing, zero hesitation, very crisp. I think i still may be a little rich but there is zero spooge and if i was rich would the high load sections require a little more fuel and run better? plug is kind of black and has never fouled although i have changed it just to rule that out. Thanks for the help!
jetting help
- Thread starter BryanMcc
- Start date
Jakobi
Super Moderator
The lack of torque or pulling power is a lean condition. If its a 38mm ASII, and its hot, humid and a bit of elevation JD recommends 40 JDRed#4 180. I could see people running around clip#3 and 175 main maybe.
FWW I think there was a typo on JDs sheet (http://www.gasgasrider.org/forum/showpost.php?p=83194&postcount=24 - second attachment) says to start with a 180 but then drops straight down to 168 for altitude. I think it should read, 178, 172,168 respectively.
Move the needle back to clip #3 and drop in a larger main and then see if it'll pull up a hill any better. Do you find the engine racing or running hot as well after a run on the main jet?
ya i guess i forgot that, 5 to 8k feet 70-90 degrees for temp, JD red, and yes i believe it is an AS2, has shallow float bowl and it does not have a plastic screw on top to get to the needle. I also meant to post this in the intake section, whoops! Thanks for the help Jakobi! you are the jetting guru!
Jakobi
Super Moderator
No worries mate. Definitely try going back to 40 pilot red needle clip 3 and a 175 main. With the temps you might have to lean it off a bit more yet, but it will give you something to compare it to. I'd also suggest setting your float level if you haven't already. See sticky at top of the 2T jetting section courtesy of Andoman!
In other news, I personally experienced a sticking powervalve and it stuck wide open and wouldn't come back until I manually readjusted it back, and then it stuck again revving on the stand. I'd still investigate it if you think it might be at fault. My bike lost bottom end and sounded like a bucket of bolts. It wasn't just a bit mushy or flat feeling. It felt like serious internal damage to the extent that I wasn't game to rev it hard enough to put it anywhere near being on the pipe.
As stated previously, lean will be really crisp under low load but lack balls when forced to work. Will feel more like a 125. Really zippy but needs more clutch work to make it sing. It'll sound tinny/raspy and may hesitate before responding to throttle if really lean, or even stall out. Rich will burble, smoke, and won't want to take revs cleanly at all. It'll sound dull, blubbery and wet. Ideally you want some light burbling at low loads, but clean response when opening the throttle.
ok, i will give it a go and see. I know what you mean about noise with the power valve being stuck open, although mine not to the extent you have heard. mine has a lot of noise in the exhaust pipe, lots of rattle. this bike has to be the pickiest bike to jet i have ever owned. My brother has a gas gas ec250 2010 and his bike has never even had the carb open. Runs a little fat but no hesitation at all. for some reason his also has more power than mine. leaves me scratching me head all the time
Jakobi
Super Moderator
I chased my tail around in jetting circles for a long time with my 2010 model. In the end I measured the squish and found it to be 2.6mm which is about twice as large as you'd like. Fixed that and now the bike is much more stable. I'd definitely factor in for your first top end.
Good luck with it.
Good luck with it.
already plan on it, just trying to decide what to do with the port height, right now i have 3 green gaskets on it if i remember right, so im going to continue to do some research on that... Where would you set that for a decent mix of lowend power with some big grunt on top for the sand dunes?
Jakobi
Super Moderator
Keeping the piston top level with the bottom of the exhaust port (for me it was 1.3mm of gasket) made the 300 feel like a big bad 250. Same engine characteristics of softer bottom, hard hitting and would rev to 10,000rpm.
When I did the 250 I set the piston 0.5mm above the port (from memory), but I was also using a race ported cylinder which sacrificed bottom end for top end, so it all worked out about the same in the grand scheme of things.
I'd be having a look at how the piston sits with the current stack and how the engine delivery is now. If you bump the CR up a bit will you gain some bottom end, not to mention the bike will have more power from top to bottom once you close the squish gap.
When I did the 250 I set the piston 0.5mm above the port (from memory), but I was also using a race ported cylinder which sacrificed bottom end for top end, so it all worked out about the same in the grand scheme of things.
I'd be having a look at how the piston sits with the current stack and how the engine delivery is now. If you bump the CR up a bit will you gain some bottom end, not to mention the bike will have more power from top to bottom once you close the squish gap.
