Little jetting help

[cthomps07]

Ok heres what I have for specs so far.

08 450er with uni and outerwears air box lid cover and a rossier full exhaust.

162 main
crf bike needle in 4th pos.
48 pilot

500ft elevation there abouts
75 degrees +/- 2

Ok I turned up my idle and turned my fuel screw all the way in and it wouldnt quit. My quad doesnt like to stay running and if you snap the throttle it quits and it starts hard now. I am thinking my pilot is is too big? It runs best when the fuel screw is all the way in and even then its not good. But when I am running say 3/8-1/2 throttle it spits and sputters like its running out of gas. You will be going along and its like you let of the throttle for a second and then it comes back on. Any idea what I need to do. It pulls like hell in the top end and it has good power but doesnt seem too lean I might be able to go to a 165 but not until it gets a touch colder.

[d3ktrix]

Slap in a #55 leak jet to start.

[cthomps07]

Yeah I remembered seeing this in the HRC kit and figured Rossier would put one in their kit. I didnt get one though so I figured they knew something I didnt. I will get one and put it in.

[moogie]

Try maybe, pilot back to std, 175 main, pushing needle down, 55 leak like said previous, screw up accel pump timing screw

spluttering and spits is more like too rich
Poping sound is too lean

Use that principle and work out throttle position
up to 1/4 pilot
1/4 to 3/4 needle
3/4 up main

Or there abouts as there is crossover
AP helps the flat spot from idle to quick acceleration

hope this helps

[pro-rider46]

Originally posted by d3ktrix
Slap in a #55 leak jet to start.

if you ask me, a 55 pilot is WAY to big, and his is an 08. 04/05's usaully have bigger jets, but the 06+ have leaner ones, cthomps07 i would try to take you needle to the 3rd clip. and that should lean it out some more, and maybe play with you main but that doesnt seem to by the problem, then bring you pilot down to a 46 if that doesnt help. i dont know. sputtering is mostly to rich,

[cthomps07]

Leak and pilot arent the same thing so 55 would be right. As for leaning it out I dont think its the problem. When its on the pipe am I am going down the road it runs great might try a 165 main though Im still not sure. Its when I let off that it pops and at about 1/4-1/2 throttle it has the occasional cut out like you just pulled the choke out. i am still thinking the pilot is too big. when it starts to cut out a simple little push on the throttle cures it. I think its still in the pilot stage when it cuts out so maybe 1/4 throttle max. I am going to ride some more this weekend and see how it is I know as of right now when going to stop I need to hold the throttle on or it quits and is a pain to start.

[d3ktrix]

Did u try the A/F screw at 2.5 turns out?
The 48pilot should be fine.

Going by ur last post it sounds like ur pilot circuit is running SUPER lean, or also extremely rich somewhere also might cause that.

How many turns out did u have ur A/F screw during that test?

[d3ktrix]

Also about the CRF needle, is it the same as the HRC needle for ur year bike?
If so try the middle clip, 4th sounds a little rich.

[cthomps07]

Yup its for my year. As for the screw I did a test at 1.75 turns and 2 turns. I did the test where you turn the idle up and then turn the fuel screw in and it should quit when the screw is all the way in.... it idles best when its all the way in so I am guessing its too big. As for the mid range I have no idea on the needle it seems to run quite good. I believe it is the middle clip right now. I will look at it tomorrow.

[moogie]

Sometimes over compensating the adjustment will put you in the right direction
EG, put a bigger main, not just 165, say 175

If problem goes away or diffrent at least you will know you are going in the right direction, then just adjust back

The same principle applies with going smaller
Its also like smaller pilot and screwed in versus bigger and screwed out. From heer you start to get an idea to what happens to your bike to go from one extreme to the other and you can work in between

Just confirm when throttle up giving it to it it runs OK, and only faults when backing off throttle.
If this then too lean on needle, also bigger jet will help as it still means more fuel at a mid point on needle

Pilot jet normally on 06+ models generally dont need bigger #

The main can be changed easy in situ so just change and go for a spin
Get yourself an extended pilot screw adjuster so easy to do on the spot

[cthomps07]

Ok so now I am going to go with the 45 pilot as the stock is a 42 and my 48 seems rich. About the needle which way do I move the clip to richen it up. To the pointed or flat end?

[d3ktrix]

Moving the clip up (to the flat end) on the needle makes it leaner.

Moving the clip down (to the pointed tip) on the needle makes it richer.

Try the pilot before u change the needle, u'll go crazy if u change more then 1 thing at a time. Because u wont know what is affecting what.

[cthomps07]

Yeah thats what I am doing. I changed the pilot and my next thing will be the needle.

[cthomps07]

Ok 45 pilot was much better but its still not right in the mid range. I have one last question before I change the needle. Does the fuel screw affect everything for jetting or just the pilot and what way do I turn it to make it leaner/ richer?

[d3ktrix]

The A/F screw is like a fine adjustment for the pilot jet. They are both on the same path in the carb circuit.

Turning the A/F screw in leans the pilot circuit. Turning it out richens the pilot circuit.
The pilot jet should always be screwed in tight at all times of course.

What is the bike doing now in the mid range that u don't like?

[cthomps07]

Its hesitant still kinda rich I think. I am going to try to lean it down in the mid as well.

[d3ktrix]

Originally posted by cthomps07
Its hesitant still kinda rich I think. I am going to try to lean it down in the mid as well.


Ya try going 1 clip up (Middle) like I said before.

[cthomps07]

Actually its in the middle right now in the 4th pos. I will try the third and see.

[wolfpack13]

First of all the circut that effects the idle is the pilot. Try a 42 and if you have to screw it out more that 2.5-3 turns try a 45. Your HRC needle will most likley be in the 3rd pos. and start with a 162 main. You might end up with a 165 or 168, but 162 will be good to start. You'll def want the #55 leak jet. You might want to get an after market fuel screw also. Remember only change one jet at a time so if it's wrong you know what it wrong.

[cthomps07]

Alright went back to the stock 42 pilot and it runs great in the bottom. I am going to go with the 3rd pos on the needle and see how that works.

[wolfpack13]

Originally posted by cthomps07
Alright went back to the stock 42 pilot and it runs great in the bottom. I am going to go with the 3rd pos on the needle and see how that works.

Sounds like your on the right track. The needle effect the mid section the most so that's what you'll be looking at. For the top end change out the main. The best way to tune a carb is with an A/F meter on a dyno.

[cthomps07]

Finally got it right. 42 piolt 1.75 turns out and needle clip in 3rd pos. I will get the 55 leak jet and put that in and see if it gets better but right now the throttle is crisp and when you snap it it lifts the tires and goes instead of bogging or quitting. 1/2-3/4 throttle pulls like hell into the top end and that is still good too. I think I finally got it:rolleyes:

[d3ktrix]

Good to hear =)

[cthomps07]

Haha my neighbors dont think so I guess they just called me and told me to put my quad away and not ride in my yard. That Rossier has some bark to it:D . I have another question though. What exactly will I see with a 55 leak jet?

[d3ktrix]

Originally posted by cthomps07
What exactly will I see with a 55 leak jet?

Better throttle response.
Depending on ur riding / throttle smashing style u might not notice any difference, or it might save ur life.

When I jetted my friends 07, it felt perfect to me, but when he got on it, it bogged for him a lot when he got on it hard, or jumped it.
Guess he smashes the throttle harder/faster.
But once we put the HRC needle and #55 leak jet it was perfect, no more bogging.