ready to purchase carb stuff

After reading and asking I am ready to buy the stuff i need for my carb. I want to run the list past everyone here first to make sure I am getting what I need, and not getting what I do not need. Don't have money to waste. If I have made a bad choice, or should be getting a different brand or style, please let me know. I have already purchased the GYTR AIS removal kit. On the list is:

JD jet kit

Merge Racing fuel screw

Merge Racing accerlator pump spring

Boysen AP cover

And I am on the fence between the PMB instert or a slip on such as the FMF Q4? Which will help my bike perform better and jet easier?

Not sure how necessary the ap spring and cover are or even what is involved when installing them?

Save all of the money you are about to spend on the carb, except for the fuel screw. If your bike still has stock jetting, just go and get the stock YZ needle, and main jet from the same model year (assuming it's an '09 or older).

Use that money you save for a FMF Q4

Edited by 2grimjim
Save all of the money you are about to spend on the carb, except for the fuel screw. f your bike still has stock jetting, just go and get the stock YZ needle, and main jet from the same model year (assuming it's an '09 or older).

Use that money you save for a FMF Q4

my bike is 100% stock.
my bike is 100% stock.

What year is it?

'05. And not to go against you, because i really dont know, but your advice seems a little off to me as it is WAY different than everything i have read here.

You do whatever you feel you need to do, but I have never found a reason to buy a jetting kit for anything with an FCR carb. There are hundreds of different OEM needles that can be chosen from to get the FCR dialed in perfectly. Same goes for the variety of OEM AP diaphrams.

Paying close attention to details like the float level can get you noticable improvements fo free. Float level is something that almost everyone overlooks, but if it's off by more than 0.5mm, it will be madening when you start changing jets.

I've had the JD needles since I got my bike in '05, so I can't say if any of a variety of Yamaha needles wouldn't work just as well, but the JD stuff does work very well. Red needle most of the year, blue needle in the winter.

The Merge fuel screw or most of the other aftermarket fuel screws will make tuning the pilot easier, but offer no performance gain. Still worth it, if you ask me because I can adjust it while riding :bonk:

The Merge AP spring is cheap and will outlast the o-ring and work better than safety wire on the linkage. You can further tune the AP with different diaphragms and leak jets, but they do not address the specific issue that the AP spring corrects.

Forget the Boyesen AP cover.

Forget the WR exhaust with or without an insert. You're better off with a stock YZ exhaust (cheap) or aftermarket (expensive). You can add a spark arrestor endcap to the YZ pipe if needed.

thanks for the input bg.

any others have opinions on the matter before i decide?

??? :bonk:

JD jet kit

You can download Sudco's cataog and they have a diagram and description of the FCR needle numbering system on page 16.

http://www.sudco.com/SudcoCatalog36CompletePDF.pdf

If you feel motivated, you can do a little research and for the price of the JD kit, you can have a half dozen needles to try out. It's not the easiest way out, but will learn a lot more about how your carb responds to jetting changes and how to diagnose them them.

Just remember to only make one change at a time.

Merge Racing fuel screw

Well worth the money

Merge Racing accerlator pump spring

Not really necessary if you have the AP properly adjusted. Safety wire or o-rings are just a mickey mouse fix used because people are to lazy to understand what's going on. There's absolutely no reason the stock AP circuit can't be made to work good without expensive and useless parts.

Boysen AP cover

Comment from above applies here too.

And I am on the fence between the PMB instert or a slip on such as the FMF Q4? Which will help my bike perform better and jet easier?

The stock exhaust on the WR is horrible no matter how you modify it. Definately spend the money on the Q4. You will be much happier with it.

You do whatever you feel you need to do, but I have never found a reason to buy a jetting kit for anything with an FCR carb. There are hundreds of different OEM needles that can be chosen from to get the FCR dialed in perfectly. Same goes for the variety of OEM AP diaphrams.

Paying close attention to details like the float level can get you noticable improvements fo free. Float level is something that almost everyone overlooks, but if it's off by more than 0.5mm, it will be madening when you start changing jets.

I agree 100%. Jet kits are just unwarranted and a waste of money IMHO

For my situations, a JD jet kit is worth way more than it costs, and is far superior to purchasing a few needles and trying them until you find the one that works for you. You've got to remember, one of the greatest things about the JD jet kit is the jetting chart supplied with it, and all of the people on here that have run it. I'll explain.

I live in Montana, so my riding will take me from 2,000 ft to 9,000 ft. and temperatures ranging from 0 degrees to 100 degrees. And that's just the riding I did in Montana! So, with the supplied chart or the help from the ThumperTalk faithful, I can get my ride dialed in BEFORE I get to the new riding area!!!

Case in point: The first week in December, I made my first trip to Baja in a lifetime of trying. Didn't want any issues, so I googled the elevation & temperature in Baja, and whipped out the JD jetting chart and installed the recommended jetting. Spent the next week living on a dirtbike with absolutely no bike issues at all!!!

Being able to set your jetting prior to a trip is priceless to me!!! Your results may vary! Maniac

For my situations, a JD jet kit is worth way more than it costs, and is far superior to purchasing a few needles and trying them until you find the one that works for you. You've got to remember, one of the greatest things about the JD jet kit is the jetting chart supplied with it, and all of the people on here that have run it. I'll explain.

I live in Montana, so my riding will take me from 2,000 ft to 9,000 ft. and temperatures ranging from 0 degrees to 100 degrees. And that's just the riding I did in Montana! So, with the supplied chart or the help from the ThumperTalk faithful, I can get my ride dialed in BEFORE I get to the new riding area!!!

Case in point: The first week in December, I made my first trip to Baja in a lifetime of trying. Didn't want any issues, so I googled the elevation & temperature in Baja, and whipped out the JD jetting chart and installed the recommended jetting. Spent the next week living on a dirtbike with absolutely no bike issues at all!!!

Being able to set your jetting prior to a trip is priceless to me!!! Your results may vary! Maniac

There are generic charts for that purpose and work on stock jets. You actually bought the chart for adjustments because the needles are nothing special.

By the way most carbed 4 strokes will run in those conditions with no adjustments or at most a fuel screw adjustment. How do I know that? I run my bike in those same conditions and only have to tweak the fuel screw slightly. And yes I ran the same jetting in Baja.

I've used YZ needles and JD needles and both work.

I use a YZ needle, Merge fuel screw and accel pump and I'm done.

The stock exhaust is garbage.

Gunner, I can see your point. Yes, the engines will run "with no adjustments or at most a fuel screw adjustment", as you stated. But I don't want my bike to just run, I want it to run well. And that's why I run the JD jet kit. That's just me, your results may vary. Maniac

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now