Jetting: 2011 250 (38mm carb ASII)
- Thread starter Jakobi
- Start date
Jakobi
Super Moderator
I rode with 45 N3CJ#3 178. I pretty much disregard main for the most as its the last circuit I dial in. In saying that it went well up top. It went well in the middle too. And sputtered and burbled off idle. Coming out on the AS saw the idle speed lift so I must have ended up around 3.5 turns out and still burbling so tomorrow I will run 42 N3EJ#2 178. I had thought about jumping the full clip postion, but decided I'll take it step by step so I can accurately judge one from the other. Even with the jetting a bit richer than the 300 the 250 had much more zing about it when getting into it.
Jakobi
Super Moderator
Did a few test runs including a short stint with 42 N3EJ#1 178. No hesitation or bogging but the magic spot for me has been N3CJ#3. Half a clip richer and the burble on the needle starts, half a clip leaner and the bike runs like a raped ape once on the second taper, but is a tad weaker on the first. I suspect I will lean the main out a size or two possibly to give the top end some more over rev. The rest is unreal! Fanastic torque right off idle, into the mid and then explodes to life! So stoked.
Jakobi
Super Moderator
After a few longer and challenging rides I've come to discover a few things. The J diameter doesn't give enough grunt off the bottom. Its too lean and lacks balls. The same way N3Ex#2 is too lean and makes the needle weak. Going up from a 42 pilot with the J the bike starts to develop an irritating burble that doesn't clear up as soon as throttle is give - It lasts more towards 1/4 throttle.
I then gave 42 N3EW#2 178 a run. Too rich on the pilot. Expect 40/W to be the magic combo, but too lean on clip 2. Lacks lugging power with the throttle open on the needle.
Went to 38 N3CH#3 178. The pilot is too lean as it has to almost be right in to give best response. Going richer on the pilot might help out but I think I might run into the extra burbles into the throttle. I'll have to test it. Even with the PJ lean the richer needle diameter gives a significant boost to bottom end torque. The bike will easily chugg a few gears higher.
I think I need to get a N3CW to pair up with the 40 pilot. It should give the best of both worlds. Going another half a clip richer uses more fuel and doesnt give any benefits. Starts to feel too rich on the bottom and particularly into the mid/top
I then gave 42 N3EW#2 178 a run. Too rich on the pilot. Expect 40/W to be the magic combo, but too lean on clip 2. Lacks lugging power with the throttle open on the needle.
Went to 38 N3CH#3 178. The pilot is too lean as it has to almost be right in to give best response. Going richer on the pilot might help out but I think I might run into the extra burbles into the throttle. I'll have to test it. Even with the PJ lean the richer needle diameter gives a significant boost to bottom end torque. The bike will easily chugg a few gears higher.
I think I need to get a N3CW to pair up with the 40 pilot. It should give the best of both worlds. Going another half a clip richer uses more fuel and doesnt give any benefits. Starts to feel too rich on the bottom and particularly into the mid/top
Jakobi
Super Moderator
Running a #7 non notched slide. It should be fine for the 250 and others here have had them work well with the W diameter needle. I ordered a N3CW tonight which I expect will give me the in between N3CJ and N3CH which will be just right. The N3CJ is very close to perfect with a 42 pilot. The N3CW with a 40 will just give it a little more grunt off the bottom end.
I also decided to spend a few extra coins to do some testing. Ordered 2 x Kawi needles. N3WW which might go alright in clip #2, and a NALW which I honestly expect to be pig rich. I had considered a NFTW but decided not. There is very little info on the kawi needles around. I might try the Suzi needles again at some point too.
What slide did your brother end up running?
I also decided to spend a few extra coins to do some testing. Ordered 2 x Kawi needles. N3WW which might go alright in clip #2, and a NALW which I honestly expect to be pig rich. I had considered a NFTW but decided not. There is very little info on the kawi needles around. I might try the Suzi needles again at some point too.
What slide did your brother end up running?
andoman
New member
Jakobi,
In thinking over your many 300 jetting posts, I recall a lot of emphasis on needle selection and concentration on the mid-range. That was my emphasis as I jetted my 300. I tend to ride mostly in the mid-range.
With your 250, it seems that you are concentrating on the off-idle jetting and really noticing when the low end is negatively affected.
Is that due to the lighter displacement of the 250?
Does the lack of torque (compared to the 300) force you to get the bottom end jetted just right?
I"m sincerely curious about differences between the 2 displacements as my next bike may be a 250. I'm worried that the "ride it lazy when I'm dog tired" and "get out of jail free with a stab of the throttle in just about any gear" nature of the 300 will be too sorely missed.
Also, have you considered trying a 36mm carb on the 250? The orange bikes use a 36mm in that displacement except for MX. In fact, my orange 300's came with 36's. One has an oval-bore 36-38 which is the best of both worlds. Plenty of bottom and really screams on top.
I would think that mod would be perfect on a 250.
In thinking over your many 300 jetting posts, I recall a lot of emphasis on needle selection and concentration on the mid-range. That was my emphasis as I jetted my 300. I tend to ride mostly in the mid-range.
With your 250, it seems that you are concentrating on the off-idle jetting and really noticing when the low end is negatively affected.
Is that due to the lighter displacement of the 250?
Does the lack of torque (compared to the 300) force you to get the bottom end jetted just right?
I"m sincerely curious about differences between the 2 displacements as my next bike may be a 250. I'm worried that the "ride it lazy when I'm dog tired" and "get out of jail free with a stab of the throttle in just about any gear" nature of the 300 will be too sorely missed.
Also, have you considered trying a 36mm carb on the 250? The orange bikes use a 36mm in that displacement except for MX. In fact, my orange 300's came with 36's. One has an oval-bore 36-38 which is the best of both worlds. Plenty of bottom and really screams on top.
I would think that mod would be perfect on a 250.
Jakobi
Super Moderator
Hey Ando,
This isn't really something new to me. I went through it all with the 300 too running all the needle diameters from F through to J with many combinations of pilots, looking for the perfect balance of off idle response and cleanliness. I settled on the 42P and the J diameter.
Like you, my general focus is also on the needle clip position as this is where I like to ride when the trail allows, however a lot of my riding is mixed including technical 1st/2nd gear climbing and log hopping and its here where this focus is coming from. The 300 preferred a leaner needle diameter, and a clip position leaner on the needle, and at this point 2 sizes leaner on the main as well.
Don't be turned off the idea of the 250. Its so much more fun to ride and just sings as you smash the throttle through the trees. The engine makes pleanty of power in the meat of the band which is quite well spread through the rpm. Its definately softer off the bottom which is expected and which was mostly why I went to the 250. There is still heaps of bottom end torque to be found on the 250 too, its just requiring a bit more fuel to get it just right. In all honesty I found the same with the 300 where a richer needle diameter would give better response off the bottom, but preffered the leaner needle which gave a smoother transition onto the needle. The 300 had more than enough torque to be able to open the throttle and rip the gear high.
Realistically though its not very surprising that the 2 engines have different fuelling requirements. The 250 runs significantly more compression than the 300 and the smaller capacity always had me thinking it would require larger jets and possibly needle clip position. What I have determined is that N3Ex#3 is too rich for my liking, N3Ex#2 is too lean and lacks the torque on the needle to pull a gear high under load. N3Cx#3 is right on the money. Colours the plugs up nicely and rips along on the needle. The 178 main feels pretty close and I am happy to have it a tad rich while dialling everything in. Its just a matter of getting the pilot response strong without excessive burbling. 40/H isn't far off. 42/J is close on the leaner side. I had tried a 45 but it caused a burble that didn't clear up as earlier as I'd like and I ended up more than 2.5 turns out on the AS. The W will be right on!
This isn't really something new to me. I went through it all with the 300 too running all the needle diameters from F through to J with many combinations of pilots, looking for the perfect balance of off idle response and cleanliness. I settled on the 42P and the J diameter.
Like you, my general focus is also on the needle clip position as this is where I like to ride when the trail allows, however a lot of my riding is mixed including technical 1st/2nd gear climbing and log hopping and its here where this focus is coming from. The 300 preferred a leaner needle diameter, and a clip position leaner on the needle, and at this point 2 sizes leaner on the main as well.
Don't be turned off the idea of the 250. Its so much more fun to ride and just sings as you smash the throttle through the trees. The engine makes pleanty of power in the meat of the band which is quite well spread through the rpm. Its definately softer off the bottom which is expected and which was mostly why I went to the 250. There is still heaps of bottom end torque to be found on the 250 too, its just requiring a bit more fuel to get it just right. In all honesty I found the same with the 300 where a richer needle diameter would give better response off the bottom, but preffered the leaner needle which gave a smoother transition onto the needle. The 300 had more than enough torque to be able to open the throttle and rip the gear high.
Realistically though its not very surprising that the 2 engines have different fuelling requirements. The 250 runs significantly more compression than the 300 and the smaller capacity always had me thinking it would require larger jets and possibly needle clip position. What I have determined is that N3Ex#3 is too rich for my liking, N3Ex#2 is too lean and lacks the torque on the needle to pull a gear high under load. N3Cx#3 is right on the money. Colours the plugs up nicely and rips along on the needle. The 178 main feels pretty close and I am happy to have it a tad rich while dialling everything in. Its just a matter of getting the pilot response strong without excessive burbling. 40/H isn't far off. 42/J is close on the leaner side. I had tried a 45 but it caused a burble that didn't clear up as earlier as I'd like and I ended up more than 2.5 turns out on the AS. The W will be right on!
andoman
New member
Thanks for the detailed response.
Like I said, I'll likely jump onto a 250 next. But I have a year or so to enjoy the 300. I'm seriously thinking about following your lead and re-barreling the 300 down to 250. Mostly because the '11 Gasser is smaller than anything out there. At 5'6" (167.6 cm) it really is a Goldilocks bike for me.
Thanks again.
Like I said, I'll likely jump onto a 250 next. But I have a year or so to enjoy the 300. I'm seriously thinking about following your lead and re-barreling the 300 down to 250. Mostly because the '11 Gasser is smaller than anything out there. At 5'6" (167.6 cm) it really is a Goldilocks bike for me.
Thanks again.
Jakobi
Super Moderator
Financially the change over to a 250 is next to nothing. The S3 cylinder and head kit came in at $800 all up. Considering you're usually looking at around $200 for a new top end anyway the extra couple hundred dollars is nothing in the grand scheme of things. Especially when you consider the coin you lose on a trade or new purchase. The whole thing was a bit of an experiment for me. I like to experiment 
and I'm pleased with the change. I'm only 175cm so hardly tall myself and find the bike a good fit. In saying that I try to ride with my feet on the pegs all the time and do miss the ground clearance the yamaha offered. You can't have it all I guess!
and I'm pleased with the change. I'm only 175cm so hardly tall myself and find the bike a good fit. In saying that I try to ride with my feet on the pegs all the time and do miss the ground clearance the yamaha offered. You can't have it all I guess!
Jakobi
Super Moderator
Here is a quick video using the Drift HD on the front fender brace. Lots of chattering from the mount and the vibes through the fender along with wind noise when picking up the pace but you should get a general feel for how the bike is running. You'll probably tell me I'm mad for saying it needs changing. Hah! Running pretty well indeed.
http://www.youtube.com/watch?v=dkosIG7KhIQ
http://www.youtube.com/watch?v=dkosIG7KhIQ
Jakobi
Super Moderator
5kms from home! 
Living the dream mate! About within 10kms any direction from home I'm in pristine trail. Everything from sandy to rocky to hard packed with loose sand on top, thick clay through to rainforest leaf litter. Got it all. Only bad thing is that trying to cut any new trail or riding unmaintained trail includes battling through wait-a-while. Builds a new respect for the original explorers to the area.
You had a chance to get some more seat time on your 300 yet Mark?
Living the dream mate! About within 10kms any direction from home I'm in pristine trail. Everything from sandy to rocky to hard packed with loose sand on top, thick clay through to rainforest leaf litter. Got it all. Only bad thing is that trying to cut any new trail or riding unmaintained trail includes battling through wait-a-while. Builds a new respect for the original explorers to the area. You had a chance to get some more seat time on your 300 yet Mark?
Jakobi
Super Moderator
Definately enjoying the 250 Glenn. Will be perfect once I get some more fuel to the bottom end. I will probably set it up with a 45P and the J until the N3CW arrives.
Looking forward to hearing how the new lens works compared to your last testing. Not sure what the FOV is on the Drift but I'm yet to get any good audio out of it. I think I need to glue some foam over the mic. The gopro audio is so much better and I somewhat prefer the view from the chest as well. I too was surprised how stable the picture is from the fender.
Looking forward to hearing how the new lens works compared to your last testing. Not sure what the FOV is on the Drift but I'm yet to get any good audio out of it. I think I need to glue some foam over the mic. The gopro audio is so much better and I somewhat prefer the view from the chest as well. I too was surprised how stable the picture is from the fender.
