Jetting questions...still waiting on my FCR

[TORO1968]

Hey guys,

Since I'm still waiting on my FCR 39mm carb (Is it ever gonna get here?? :confused: ), I figure I might as well install the HMF Ballance full system and my MSD ignition with the stock carb.

Could you guys give me some insight as to what might be a good baseline for jetting my stock carb. My 400ex is currently stock, and I will be installing an HMF Bill Ballance Pro Series full system w/aluminum silencer and an MSD digital ignition that puts out about twice as much voltage as the stock system (30,000 Volts vs. 16,000 Volts :eek2: ) . MSD recommends that I step down to the colder DPR9Z plug, so I have that on hand.

Where should I start? Also, are the jets in the stock 400 carb just standard Keihin jets? Can I get these at my local dealer?

Thanks,
Jordan

[TORO1968]

Anyone?

[skemp]

Yes;, they are just Keihin jets and should be available at your dealer. I would go to a 42 pilot, and 160 main jet. You might also want to go down one clip on the needle. This should compensate for the hotter ignition and pipe. I would probably call MSD to see if they have any advice for jetting, as that ignition will give a much more intense spark.

[TORO1968]

Thanks for the info...

[TORO1968]

Any other suggestions?

[cals400ex]

i am not sure of your elevation or temperature but if you just have the pipe and igniton with the airbox lid on i say a good starting place is a 155 keihin mainjet, 40 or 42 pilot jet, stock clip position or 4th position.

[TORO1968]

Oh yeah, I forgot to mention that I'm gonna run it with the lid off and with a K&N and outerwears in place of the stock filter.

My elevation is roughly 600-700 feet above sea level.

Looks like 155-160 on the main jet, 42 on the pilot jet, and the stock needle one position lower should get me in the ballpark...

Keihin jet sizes go up in 5's, right?

Thanks again guys...

-Jordan

[zephead400ex]

Originally posted by TORO1968
Oh yeah, I forgot to mention that I'm gonna run it with the lid off and with a K&N and outerwears in place of the stock filter.

My elevation is roughly 600-700 feet above sea level.

Looks like 155-160 on the main jet, 42 on the pilot jet, and the stock needle one position lower should get me in the ballpark...

Keihin jet sizes go up in 5's, right?

Thanks again guys...

-Jordan

Your intended jetting specs look like a great place to start. Keihin jet sizes vary on how they increase.

Main jet: stock 148, 150, 152, 155, 158 , 160, etc.
Pilot jet: stock 38, 40, 42, 45, etc

I am not a carb expert, just speaking from a little experience. If I am incorrect, please let me know:D

[cals400ex]

yep, these size increments are right for the keihin main and pilot jets. yeah somewhere between a 160 and 155 keihin should work. you might just want pick up the 160, 158 and 155.

[TORO1968]

Originally posted by cals400ex
yep, these size increments are right for the keihin main and pilot jets. yeah somewhere between a 160 and 155 keihin should work. you might just want pick up the 160, 158 and 155.

That's what I was thinking...

Do very many people swap out the stock needle? Or, do they usually just change the clip position?

-Jordan

[cals400ex]

Originally posted by TORO1968
That's what I was thinking...

Do very many people swap out the stock needle? Or, do they usually just change the clip position?

-Jordan

i have have contacted several places on a new needle. however, they don't show listings for aftermarket needles for a 400ex. the only one i know of is the one that comes in the jet kits. they said other keihins would work but it is going to be trial and error. i ended up just messing with the clip even though i felt like it needed a different needle.

[Knips178]

I ordered my fcr 39mm carb and it's on back order too. I heard there is a huge back order of over 1000! and right now there are only a few trickling in a day, so who knows when I'll get mine.

anyone know if this is a nation wide thing? It looks like it to me.

[Silverfox@C&DRacing]

Good news Toro I shipped your carb today. :D

[Knips178]

hey silverfox, are you guys still backordered on fcr carbs? I'm just wondering if this is a problem for everyone, or just where I get mine from?

[TORO1968]

:D :D :D Sweet! Could you PM me the tracking number if possible?

Guess I'll forget messing w/my stock carb!

Thanks,
Jordan