Jetting is very subjective

[firffighter]

Thought I would give the CCK needle a try since many on this site have found great results. I have a '05 DE300 that runs fairly crisp with some blubber right off idel, but otherwise pretty spot on with the jetting that was supplied upon purchase (168main, 38 pilot, DDM #3, #7 slide). I am looking for that perfect "linear", smooth, roll on response (I know, sometimes a pipe dream with a 2-stroke). I do still get some pretty good spooge, which is weird since this is fairly lean compared to others who ride the same altitude and temps.

I put in the CCK and went with a 172 main and 40 pilot. I found the bike to be "fighting itself". In other words, it felt like the rich jetting was holding the bike back and it was not able to run crisply or cleanly. Plus, like others have reported, I got about 1/2 as good MPG. A weird side result was no spooge, which is weird since it was much richer than before.

So, I decided to try something different. Instead of stiffling the bike with fat jetting, I am going back to the crisp, clean, somewhat lean jetting I had when I purchased the bike. I changed back to 170 main, 38 pilot, DDM#2 and the bike runs very crisp and clean.

So, in order to obtain that smooth linear delivery I am looking for, I decided to try the G2 throttle and #4 cam. I am hoping this set up will accomplish what I am looking for.

[einsteingarage]

Ok, I finally got around to looking up the needle that I currently using and get great results with. Very responsive will a linear pull.

I ride at sea level to 1500 feet in NH

Here it is

[2whlrcr]

I've got a 2010 300 and don't know if there are any differences in the motor or carb in your 2005. I run the exact same jetting and my bike runs very smooth and linear. Yes, it feels a little rich and doesn't carburate cleanly, until it's thoroughly warm. I can get about 3.0 hours of riding on a stock tank in tight single track conditions.

It's very warm and humid here now, 1000MSL and I'm using these settings.

40 pilot
air screw 3 turns out
CCK dropped all the way
172 main

Plug reads slightly rich and the bike runs smooth linear, with a nice clean surge very late in the powerband. If I were to change anything in these conditions, I would go to a 38 pilot and call it good.

[Bailey28]

The reason for the poor fuel mileage is the straight diameter size on the needle. If you run a smaller straight, D, E, F, in stock Keihin lettering or a K, L diameter in Sudco lettering the needle will pass more fuel than needed at the lower rpms especially at closed throttle.

These 300's pull a lot of manifold vacuum when you close the throttle and having a small needle diameter contributes to the extra fuel being added during these high vacuum conditions, hence the bad mileage.

I have always had luck with the larger needle diameter and a larger pilot jet combo. The purpose of the air screw is to emulsify the fuel air mix at the lower throttle settings including the idle mixture. The air screw cannot control the fuel being pulled around the needle and needle jet. I found it best to minimize this extra source of fuel by going fatter on the needle diameter. I am still at 1 turn out on the pilot screw which is now very responsive to small adjustments. The bike idles perfectly.

My combo at sea level on my '10 300 is : 42 pilot NOZH-1 160 main jet. "H" diameter is leaner by two steps over stock, from 2.705 to 2.725mm. The 42 compensates for this but in a more controlled consistent delivery. My mileage is also great. 160 is a bit lean, but we are at 95+degrees and the NOZx series needle has a very rich 3rd taper from 3/4 throttle onward. In the fall, I will go to a 45 pilot 165 main and raise the needle to clip 2.

Firffighter, you could try a CCN, or a CCP, but with a 42 or 45 up in Oregon, maybe a 165 main.

[firffighter]

einstein,

Curious as to what main and pilot you are running with the Yami needle?

I think Reverup and others are using that needle as well with good results.

The reason I titled this thread "Jetting is very subjective", is because we all have different likes and dislikes when it comes to power delivery. Different ignitions will make a difference as well. This may get overlooked, but a 2K2 will run differently than a 2K3. KTM was notorious for this with tough jetting on their 300's because of different ignitions. Another issue is personal preference when it comes to how you ride your bike. Some always ride a gear or 2 high and never get past 1/4 throttle. Some ride mid throttle and some crazy skilled guys actually ride on the pipe!

I took the time to read through every jetting setting I could find on this site, taking into consideration similar altitude, temps, 300cc motor and even similar year bike. What suprised me was a very wide variety of settings!

So, my conclusion is to get it jetted to my preferences or very close and adjust from there.

I have not had the chance to test out the G2 yet, but am hoping this will help as well.

[forgiven]

I sent my carb off to RB designs before I ever had gas in it. I have not messed around for even 5 minutes, and as an owner of an older GG 300...it is the best 165 I ever spent as far as spending time jetting...not to mention performance enhancement.

[firffighter]

You arent kidding! Ron's work is worth every penny and you wont have to mess with jetting again. I had him do 2 of my KDX's and I had a KTM with his carb already done. Absolutely flawless jetting and just slight adjustments with the AS.

Will probably be my next move.

[einsteingarage]

Originally Posted by firffighter

einstein,

Curious as to what main and pilot you are running with the Yami needle?

I think Reverup and others are using that needle as well with good results.

I can't remember for sure, I want to say 42 /178 2nd clip air at 1 3/4

That is just a guess.

[Troy F collins]

Ive been running the N3EH #2 40/175 in my 2011 EC250 at 5000-7000ft elevation all season long.....its snappy and clean in the tight stuff also good flat out

I'll call it good when your slogged down in mucky tight stuff with continuous small blips of the throttle.....and its still clean/snappy when you need it to loft the front with little effort to get over the big logs......or attacking really steep hills in third(or 4th lol)..really shows off the tractability of that motor

linear and predictable is how I like it......the N1EF set up was all burble then the "surprise" for me(usually side ways at the wrong time lol)

[Eric K]

A key factor to consider in jetting is how hard you ride.

When I ride with my youngest son at a moderate pace, my GG300 runs borderline rich. With the same jetting, riding hard it is too lean.

You need to tune it to your conditions & riding style.

Another factor to consider is that the needle and the nozzle jet wear over time, so the straight diameter of the needle & the clip position need to be compensated over time. Or better yet, send it to RB Designs for a nozzle jet replacement.