05 yz 85 jetting help!!!

kx450kid13
enu
Videos Bike Checks Product Forum
Need Help. Yz85 jetting issues!!!

MEMBER BLOG
hello all so I recently just picked up a 05 yz 85. Has stock jetting I just changed plug , air filter , and cleaned carb. Stock pilot stock main and needle clip is in middle position. I had it in 2nd position but bike was very boggish if you chopped throttle hard from idle. Bike idles fine. I played with air screw nothing really. Bike barely smoked I moved clip to middle and bike smoked alot but ran a little better low end wot is great no break ups or sputtering at all. Just right off idle. Very baaaaahhhhh then opens right up like a bat out of hell. Once I moved clip to fenter I played with air screw bog went away completely now but the air screw is adjusted all the way in. What is the issue here any help would be greatly appreciated. Im familiar with jetting someone but just need a little guidance if possible. Thanks all.
|
DTHA70
Profile picture for user DTHA70
Posts
336
Joined
9/25/2008
Location
Surprise, AZ US
DTHA70 2/23/2017 1:13pm
2/23/2017 1:13pm
needs a bigger pilot
3D
Profile picture for user 3D
Posts
938
Joined
5/1/2008
Location
Tamaqua, PA US
3D 2/23/2017 1:28pm
2/23/2017 1:28pm
My son's YZ is a 2012 but I think they're the same everything. It does have a pipe and shorty also. They are way rich up top and the pilot is lean. I don't remember the numbers but the main is 3 sizes smaller than stock. Needle is on the second clip from top. The pilot is one size bigger than stock and one turn out on the air screw. Obviously different bike and location could change things but ours is spot on right now. It made huge gains for that bike.
kx450kid13 2/23/2017 1:45pm
2/23/2017 1:45pm
I apologize it has a 138 main and a stock 45 pilot what should I buy as for jet sizes. Bike runs flawlessly up top just right off throttle is boggish but like I said I moved clip to middle from second position and it got better but smoked more . That's with air screw all the way in. What do I need to do as for pilot jet and clip position. I know the air screw all the way in running pretty good isn't correct. Lmk thanks hoping to solve this problem by tonight
kx450kid13 2/23/2017 1:47pm
2/23/2017 1:47pm
Bike has stock fatty and fmf shorty muffler I noticed carb over flow tube had a bit of oil around tube ending and shorty has some splodge coming from where it goes from muffler to Skinny chamber

The Shop

See All »
DTHA70
Profile picture for user DTHA70
Posts
336
Joined
9/25/2008
Location
Surprise, AZ US
DTHA70 2/23/2017 2:08pm
2/23/2017 2:08pm
try 48 or 50 pilot and see if that solves the bottom end issue

main might be a little big.
Tracktor
Profile picture for user Tracktor
Posts
2344
Joined
8/17/2006
Location
The RTF/Amboy, WA US
Tracktor 2/23/2017 2:21pm
2/23/2017 2:21pm Edited Date/Time 2/23/2017 2:33pm
A KX85 slide & needle can help a bunch with bogging issues. It 's what we ran for years on our YZ's and the ran great. I will see if I can find my specs. We had them tuned perfectly to where just adjusting the air screw for atmosphere would solve most issues. They are very sensitive to the air screw..........
138 main
42 Pilot
needle in middle clip (NAPE Needle)
3.5 Slide
Fuel screw 1/4 turn out- Yes, that seems odd but it ran the best with this setup.......

Edit - HGS, DEP or Doma pipes work best on these bikes we found after running pretty much every pipe made......
Falcon
Profile picture for user Falcon
Posts
10123
Joined
11/16/2011
Location
Menifee, CA US
Fantasy
856th
Falcon 2/23/2017 2:37pm
2/23/2017 2:37pm
You need more fuel in the slow circuit - bigger pilot. You may have to open the air screw to compensate. The needle will barely affect the slow circuit, so if it runs well at mid-throttle, I'd leave it where you have it.

Also, check your reeds for damage.
kx450kid13 2/23/2017 3:31pm
2/23/2017 3:31pm
I just picked up a 48 and a 50 pilot I'm going to try both in the morning. Hopefully this fixes the issue. Should I leave clip in middle or go to 2nd position
Tracktor
Profile picture for user Tracktor
Posts
2344
Joined
8/17/2006
Location
The RTF/Amboy, WA US
Tracktor 2/23/2017 3:47pm
2/23/2017 3:47pm
kx450kid13 wrote:
One person says a 42 pilot and others say 48 or 50
Go search the KTMtalk "Other minis" board this topic has been hashed out a bunch over the years. I don't ever remember anyone running over a 45 pilot but it was awhile ago. We were running V-force reeds/HGS or DEP pipes and the jetting I posted. Note: I was running a different slide and needle. I will look to see what I ran with stock slide & needle.............
Ted722
Profile picture for user Ted722
Posts
4487
Joined
9/21/2011
Location
Sacramento, CA US
Ted722 2/24/2017 8:36am
2/24/2017 8:36am Edited Date/Time 2/24/2017 8:38am
kx450kid13 wrote:
I just picked up a 48 and a 50 pilot I'm going to try both in the morning. Hopefully this fixes the issue. Should I leave...
I just picked up a 48 and a 50 pilot I'm going to try both in the morning. Hopefully this fixes the issue. Should I leave clip in middle or go to 2nd position
I would just change one thing at a time. Try the 48. Leave air screw all the way in. Then adjust air screw as needed.

Even if it's running "good", put the clip back at number 2 just to know what that feels like. It might get worse, might get better.

BTW, what are temps like there? 2-strokes run leaner in cold weather. Also, are you using pump? That's fine, but that could be contributing to needing a little fatter jetting too.
xnationalwrench 2/24/2017 8:46am
2/24/2017 8:46am
Do you know how to properly adjust your air screw? Set you idle at about 3000 rpm (about 2/3 throttle) slowly screw the air screw in, you will hear the idle drop, then slowly turn the air screw out, you want to bring the idle to its highest rpm, then bring your idle back down to where you want it. Its not to uncommon to set it in the morning before practice then check it again in the afternoon.
kx450kid13 2/24/2017 9:33am
2/24/2017 9:33am
Yea using pump 93 with yamalube r2 and mixing 32:1. It's golden up top but i was just riding it messing around and it's breaking up if I crack throttle hard from barley moving at all then comes alive not a bog it's like it's breaking up then rips out of no where. It's good unless I crack throttle hard out of the gate. What's my issue i haven't moved clip yet its still in middle position bike smokes low end but no so much up top.
xnationalwrench 2/24/2017 12:25pm
2/24/2017 12:25pm
ADJUST THE AIR MIXTURE SCREW! This can get rid of a bog coming off the bottom end. You do have to realize that bike does not have a power valve and when it hits the pipe things happen quickly.
Joel_Joe
Profile picture for user Joel_Joe
Posts
1
Joined
7/13/2019
Location
CA
Joel_Joe 7/13/2019 2:57pm
7/13/2019 2:57pm
xnationalwrench wrote:
Do you know how to properly adjust your air screw? Set you idle at about 3000 rpm (about 2/3 throttle) slowly screw the air screw in...
Do you know how to properly adjust your air screw? Set you idle at about 3000 rpm (about 2/3 throttle) slowly screw the air screw in, you will hear the idle drop, then slowly turn the air screw out, you want to bring the idle to its highest rpm, then bring your idle back down to where you want it. Its not to uncommon to set it in the morning before practice then check it again in the afternoon.
Could you please clarify this process? Hold throttle at 2/3rds, screw in air screw, then turn it out to highest rpm. I guess my questions is after this how do you “bring idle back to where you want it” when you are holding throttle at 2/3rds?

I have this same problem. Bogs down low, and when you cracks throttle quickly. However It’s fine up higher and power band hits Hard! actually goes smoothly throughout if you twist throttle slowly and consistently. TIA!

Post a reply to: 05 yz 85 jetting help!!!