I have not found the replacement pilot jet size yet, but I have this information on our carbs.

99101-116 Main Jet

http://www.jetsrus.com/a_jets_by_carburetor_type/jets_keihin_99101-116_main_round_small_and_38-xxx.htm


http://www.rockymountainatvmc.com/p/43/53/213/930/-/25594/Keihin-99101-116-Series-Main-Jet

http://www.iwt.com.au/mikunicarb.htm

It doesn't look like I will need to change the pilot jet size. I will know more once I install the jets again and see if the clogged pilot was the reason for poor take off. The 1/4 to 3/4 throttle worked great and full throttle will need to be richer. RPM's increased and no speed or power change. I think it is lean and will be buying the 99101-116-70, 72 and 65 jets. My dirt bike uses three jet sizes when running in the temp ranges of 40 degrees to 100. I will be getting the jets to do the same on the quads.


High-Boost. Did you look at your pilot and see if the holes are open yet? I am curious how this is on your machine and what the results were.

 

Found the pilot jet size!!!!

GENUINE MIKUNI PILOT JET N224.103

 

I actually cant get the bowl off of my carb..
instead of screws, it has brass press fittings or something.. I started drilling on them, but decided my new carb will be here in a few days, why bother?

in the mean time I tried pying off the timing cover..
http://www.flickr.com/photos/78121832@N00/7104354667/http://www.flickr.com/photos/78121832@N00/7104354667/ by http://www.flickr.com/people/78121832@N00/, on Flickr
and bam, made the quad useless in the process

as far as I can guess the cam timing is really retarded
http://www.flickr.com/photos/78121832@N00/6958284180/http://www.flickr.com/photos/78121832@N00/6958284180/ by http://www.flickr.com/people/78121832@N00/, on Flickr
I assume the mark on the gear should be centered between the teeth? that is just a guess though

I guess tomorow I will try and order that stupid cover..
would have popped right off if I had unscrewed the bolt first.. sigh

 

I was doing some googling and it looks like I am 180 degress out..
on my motor there is no mark on the other side, but there is one on the outside of the casing that looks to be centered and I am about a tooth retarded..

supposedly that is the best way to be off..
unfortunately since I broke the cover I cant change it and try it for a while

1 $8 part with $12 in shipping.. love that

 

Hello everyone.
.Great to find a current thread. I actually have my drilled/unlocked carb here at work, already ordered a61-80 drill set, and found that my pilot jet is also clogged. Looks like fit right in on this one.

After messing around for a while with the little quad, both my kids and I want more bottom end torque. Today, I will reinstall my carb with the cleaned out pilot jet and post results.

My settings are just the same as yours, between 1.5 and 2 turns out on a/f screw.
The only differance is I installed the performance CDI, a very bright emergency headlight, and a 2000lb atv winch just for fun, and because the winch only cost $49.

I will post tonight.

 

so did you have to drill the pins out to get into the bowl as well?

one thing I noticed when I was messing with my cam is my sparkplug was straight up black.. that may be because my son was just putsing around on it last time it was ridden, but I may be too rich when I thought I was too lean?

did the cdi make any differance?

I advanced my cam 1 tooth on the gear and it is close to correct now, still a little retarded, and I reset my valve lash. Now I am just waiting for that stupid cover.. fedex brought it (and my new carb) yesterday while I was at work, but didnt leave it since I wasn't home.. doh! I should have that tonight and be able to see if the cam timing makes any differance.. I will make sure to report my findings tonight as well

 

Are you drilling out your pilot jet? The hole on the inside is not the same size as what you see in the shaft. Let me know what size you drill and how it runs.
My spark plug was black also. The low end improved when I turned the screw in, which richened the fuel mix. A bit confused and will need more time to mess with mine. Just cleaning out the pilot jet helped so far. I want to raise the needle with a washer as a shim to see what will happen. This will richen it more. I don't know the size of my pilot jet so I have no reference for buying other sizes. My main jets are on order and will have to play with the top end later.

Anyone help with this knowledge. I read somewhere about a backfire in the carb versus in the tail pipe. What causes what? When messing with the carb, I got a pop in the carb and didn't know if that is from lean or rich. Forgot where my setting were and the results got mixed. I recall reading about the carb pop and can't find info again.

 

usually either a lean condition or cam timing being too retarded - just like mine was.. basically the intake valve is still slightly open when the mixture fires

on mine I would occassionally get a loud metalic popping sound, but it wasnt regular, it commonly occured if I didnt let the motor warm up enough before riding.. perhaps that was a carb backfire and I didnt know what was happening

 

High Boost,
yes Iused an easy out kit to remove the pins/screws. Then I sloted them with a dremel to accept a flat head.
The CDI made a strong differance, but is limited by this carb problem we all share, and the exhaust, which I just drilled out. Drilling the exhaust made it sound more throghty , and should make the rejeting work very well.
I will find out in three hours how the cleaned pilot works.
I have not yet messed with the timeing.

Youngnbald ,
I will let you, and everyone know size I use, and how well it works.

Just a note, yesterday, I found out the stock carb is a PZ20. This opened up alot of in while looking into this carb.

 

Do you have instructions on how to check the timing and/or change it? You mention 180 out? That seams like it would not work. How do I check mine and what steps to take?