YZ 426 to 444 conversion Jetting suggestions

I just got my cylinder back from Bear Boring with the 444 kit parts. New piston, gaskets and the like.

Once I get this all back together, do any of you out there that have done this conversion have any jetting suggestions right off the bat? I am pretty much at sea level (San jose, California)

I will also be installing a set of the Hot Cams in this set up.

Any suggestions will be apreciated.

Thanks!

Dustykat

:thumbsup:

I have the same set up...Wiseco 13.5:1, 444 CC, and Hot Cams. I am running a 42 pilot, 165 main, and JD red needle on the 2nd clip from the top. I have a PowerNow installed and a Quickshot as well as a YZF pipe with a PMB end cap and insert. Starts first time almost every time, with no bog off the bottom or when I whack the throttle. While my scooter is a WR, I have the Air Cut Valve disabled so things should be really similar. I ride primarily the desert (2500-3500 ft), but have had no issues up as high as Kennedy Meadows and the LPNF.

By the way, with that set up, first gear will be unusable except for digging trenches. I went up one tooth on the countershaft sprocket to calm it down a bit.

You will love the power!

Thanks Birdy. I already have a Powernow installed and did the accelerator pump mod. I bought the bike used so the original owner may have gone up a tooth on the front sprocket already, I'll have to check vs. stock in the manual.

I have the white brothers exhaust (Both long and short cans) so I will test on both. I have been thinking on getting one of the quieter pipes though, this baby barks pretty loud.

:thumbsup:

Thanks Birdy. I already have a Powernow installed and did the accelerator pump mod. I bought the bike used so the original owner may have gone up a tooth on the front sprocket already, I'll have to check vs. stock in the manual.

I have the white brothers exhaust (Both long and short cans) so I will test on both. I have been thinking on getting one of the quieter pipes though, this baby barks pretty loud.

:thumbsup:

I thought you just got the kit? He means it will have more power than it does now and you will need to regear for it. Re: jetting, how was it before? Spot on? The jetting should remain very close to how it was before.

You guys are tearing me up with the 444 kits. I have a cylinder on my bench waiting to be punched and plated. I was going to wait for winter, but I may send it off sooner. :thumbsup:

Just did the same thing to mine with cams, porting but I scraped the FCR and put an Edelbrock on it. It pulls harder through the mid range and top end. But the FCR is still a good carb, just wanted to try something different. Birdy is right on with his set up. You'll love the new power!!!

You guys are tearing me up with the 444 kits. I have a cylinder on my bench waiting to be punched and plated. I was going to wait for winter, but I may send it off sooner. :thumbsup:

I thought you had already done it. I wondered why the comment on not being that fresh on the cam post. I just got my jug and piston from Lukes. Should be assembled by Monday, but then there is a debate about the frame getting powdercoated and since it continues to rain daily, and maybe the Zipty's carb mod:thinking: :ride:

I thought you had already done it.

Not yet. I normally freshen up both our bikes every winter and I was going to wait until then. Winter sucks for riding around here, so its a good time for tear downs.

But, everytime I read Birdy's posts about the extra power it makes me want to do it now. :thumbsup:

Not yet. I normally freshen up both our bikes every winter and I was going to wait until then. Winter sucks for riding around here, so its a good time for tear downs.

But, everytime I read Birdy's posts about the extra power it makes me want to do it now. :thumbsup:

C'mon, dude...if you already have a barrel sitting there to get plated, order up from Lukes, overnight your barrel, and they will send you a barrel that's already done as soon as they receive it! (Or they will charge you a core charge and refund it when they got your barrel). Get it in the mail today, and by Wednesday next week you can have the parts sitting on your doorstep. It's about a 4 hour job to do the swap, and on Saturday, you're roostin' BIG! There's never a bad time for MORE POWER!...and the power this mod makes is sweet.

I'm only kidding, 642...no peer pressure to get it done. Just wanted to let you know that you will really like the power, and the folks at Lukes are very accommodating

no peer pressure to get it done.

I was going to buy some rims for my Tundra and then save up for the 444, but the rims may have to wait...... :thumbsup::ride:

You guys are tearing me up with the 444 kits. I have a cylinder on my bench waiting to be punched and plated. I was going to wait for winter, but I may send it off sooner. :thumbsup:

YOU GUYS ARE KILLING ME WITH THIS BIG BORE STUFF.....HAVE ANY OF YOU GUYS DONE A STROKER KIT....IT MAKE IT A 440 WITH TON OF LOW END TORQ, GOOD MID RANGE AND IMPROVES A BIT ON TOP AS WELL.....YOU REALLY DONT GET MUCH POWER BY PUNCHIN OUT THE CYLINDER MORE.....NOW STROKEN THE CRANK IS AWESOME...IT MOVES THE POWER DOWN LOW..TO MAKE IT A "STUMP PULLIN MONSTER" MINE RIPS...I BEAT A 03 KTM 525 ALLL DAY LONG LOCALLY AND AT DUMONT ON HILL PULLS....AND I CAN STILL USE 1ST GEAR AND I DID HAVE TO REJET, IT ALSO BUMPS COMP BY HALF A POINT, I HAVE 12.5 IN MINE AND I DONT NEED TO, BUT I MIX MY GAS 50/50 PUMP AND C12 JUST TO BE SAFE..... THE COST ITS NOT MUCH MORE AT ALL...AND BESIDES ITLL GIVE YOU A CHANCE TO LOOK INSIDE HER AND CHECK HER OUT....TO SEE IF ANY PARTS ARE WORN...ITLL GIVE YA SOME EXPERIENCE TOO...I BUILT MINE..IT WAS THE FIRST I HAVE EVER DONE A NEWER 4STROKE AND IT WAS EASY BUT DOES NEED TO BE TAKEN SLOWLY AND STEP BY STEP...AND RECHECKED IF ITS YOUR FIRST...I DID MINE IN SIX HRS WITH A BEER BREAK HERE AND THERE.....WITH MY KIT AND THE CAMS....SHES A ROCKET...I HAVE THE POWER NOW...BIG GUN AND "RPM'S" DID THE PORTING....I BUILD STROKER TRUCK MOTORS FOR FUN...I LOVE MY CHEVY'S AND YAMAHAS......SO IF YOUR GUNNA DO IT GO BIG....I EVEN PUT A 426 IN MY GIRL FRIENDS BLASTER CHASSIS...SHE IS SO MUCH HAPPIER NOW....IT STANDS ON IT TAIL FOR A WEEK IF YA GOOSE IT

JUST GIVEN YOU GUYS SOMETHING TO THINK ABOUT PROFORMANCE WISE THATS OUTSIDE THE AVERAGE RIDERS "BOX"

LATER

I was going to buy some rims for my Tundra and then save up for the 444, but the rims may have to wait...... :thumbsup::ride:

Pffft, who needs rims when you can have horsepower?! :bonk:

YOU GUYS ARE KILLING ME WITH THIS BIG BORE STUFF.....HAVE ANY OF YOU GUYS DONE A STROKER KIT....IT MAKE IT A 440 WITH TON OF LOW END TORQ, GOOD MID RANGE AND IMPROVES A BIT ON TOP AS WELL.....YOU REALLY DONT GET MUCH POWER BY PUNCHIN OUT THE CYLINDER MORE.....NOW STROKEN THE CRANK IS AWESOME...IT MOVES THE POWER DOWN LOW..TO MAKE IT A "STUMP PULLIN MONSTER" MINE RIPS...I BEAT A 03 KTM 525 ALLL DAY LONG LOCALLY AND AT DUMONT ON HILL PULLS....AND I CAN STILL USE 1ST GEAR AND I DID HAVE TO REJET, IT ALSO BUMPS COMP BY HALF A POINT, I HAVE 12.5 IN MINE AND I DONT NEED TO, BUT I MIX MY GAS 50/50 PUMP AND C12 JUST TO BE SAFE..... THE COST ITS NOT MUCH MORE AT ALL...AND BESIDES ITLL GIVE YOU A CHANCE TO LOOK INSIDE HER AND CHECK HER OUT....TO SEE IF ANY PARTS ARE WORN...ITLL GIVE YA SOME EXPERIENCE TOO...I BUILT MINE..IT WAS THE FIRST I HAVE EVER DONE A NEWER 4STROKE AND IT WAS EASY BUT DOES NEED TO BE TAKEN SLOWLY AND STEP BY STEP...AND RECHECKED IF ITS YOUR FIRST...I DID MINE IN SIX HRS WITH A BEER BREAK HERE AND THERE.....WITH MY KIT AND THE CAMS....SHES A ROCKET...I HAVE THE POWER NOW...BIG GUN AND "RPM'S" DID THE PORTING....I BUILD STROKER TRUCK MOTORS FOR FUN...I LOVE MY CHEVY'S AND YAMAHAS......SO IF YOUR GUNNA DO IT GO BIG....I EVEN PUT A 426 IN MY GIRL FRIENDS BLASTER CHASSIS...SHE IS SO MUCH HAPPIER NOW....IT STANDS ON IT TAIL FOR A WEEK IF YA GOOSE IT

JUST GIVEN YOU GUYS SOMETHING TO THINK ABOUT PROFORMANCE WISE THATS OUTSIDE THE AVERAGE RIDERS "BOX"

LATER

Why are you yelling at me? :thumbsup:

Pffft, who needs rims when you can have horsepower?! :thumbsup:

Don't you think it needs the rims?

IMAG0031.jpg

No. It looks quite capable of carrying your bike the way it is. :thumbsup:

No. It looks quite capable of carrying your bike the way it is. :thumbsup:

Thats what my wife says.

Thats what my wife says.
Spend your money on your bike and a Caribbean vacation. :thumbsup:

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