carb swap 426 to 400

[caseyinnv]

What carbs can be used on the YZ400, I have a 99 with a worn out carb, seen alot of 426 and 450 carbs on ebay thanks

[642MX]

What's worn out on your carb? You may be able to fix it cheaper than buying another one.

[grayracer513]

Not according to Eddie Sisneros. From my own experience, there gets to be a point at which you just can't do anything with them anymore. Ans Eddie will tell you that a large number of 10 year old FCR's are just plain junk. For the $200 or so it will cost you to get a used 450 carb, the headaches it will save you could be well worth it.

[642MX]

Not according to Eddie Sisneros. From my own experience, there gets to be a point at which you just can't do anything with them anymore. Ans Eddie will tell you that a large number of 10 year old FCR's are just plain junk. For the $200 or so it will cost you to get a used 450 carb, the headaches it will save you could be well worth it.

Hummm... What makes them junk?

[grayracer513]

Hummm... What makes them junk?

Worn carb bodies, mostly. The older carbs are not as sophisticated as the newer ones, anyway.

[642MX]

Worn carb bodies, mostly. The older carbs are not as sophisticated as the newer ones, anyway.

I would think the slide would wear out before the body.... I agree that the newer carbs are nicer with the LJ and all.

[Wfomx463]

u need the whole carb and cables if making the switch. make sure u adj the tps to yz400 spec. did the swap on my 400 way back in the day. 400 carb sucks, its a fcr street flat slide converted to dirt, get a 426 carb. dont kno how the 450 carb would work?

[umu24013]

For the $200 or so it will cost you to get a used 450 carb, the headaches it will save you could be well worth it.

Good advice! Last summer I installed a stock 07 YZ450F carb on my 01 426 and since then, my bike has been working perfectly! It starts first kick cold or warm and 2nd or 3rd kick when flooded. If I'd known this before, I'd have upgraded it a long time ago.

[umu24013]

. dont kno how the 450 carb would work?

The throttle cables that come with the 07-08 carbs are about 1 7/8 inch shorter than those on the 426. Not sure about the 400.

The yz400f rubber joint (engine<->carb) has a smaller inner diameter on the carb side. It's just too small for the newer 450 carb - very very tight fit as a result.

[caseyinnv]

so 426 has a 39mm like the 400, I think the 450 have a 41mm

[caseyinnv]

how do you set the tps on these fcr's isnt it for ignition timing?

[umu24013]

so 426 has a 39mm like the 400, I think the 450 have a 41mm

They all have a 39mm inner diameter. I meant the outer diameter on the carb

[umu24013]

AFAIK the tps sensor is essentialy the same. ..and the sockets/plugs are identical

[grayracer513]

so 426 has a 39mm like the 400, I think the 450 have a 41mm

Nope. The YZ450 is a 39mm, too. The CRF uses a 41.

The TPS on the later carbs is physically different, but electrically identical. The procedure for adjusting them is in the manual. You set them to a particular output voltage at idle.

[umu24013]

Nope. The YZ450 is a 39mm, too. The CRF uses a 41.

The TPS on the later carbs is physically different, but electrically identical. The procedure for adjusting them is in the manual. You set them to a particular output voltage at idle.

grayracer513, should I adjust mine or just leave it as it is. (bone stock 07 450 carb on a 426)

[grayracer513]

If you run it plugged in, it should be adjusted to specs. If it's plugged in and the bike runs alright, maybe it's all good.

[642MX]

Nope. The YZ450 is a 39mm, too. The CRF uses a 41.

I wonder if there is an advantage running a CRF carb?...

[grayracer513]

Ron Hamp commonly bores the carbs on his racing YZ450's. Don't know what size he bores to, but yes, there is a power boost available by upsizing the carb.

[642MX]

Ron Hamp commonly bores the carbs on his racing YZ450's. Don't know what size he bores to, but yes, there is a power boost available by upsizing the carb.

I think I might keep an eye out for one....

[DEEMOTONUTT]

I made the misstake a year ago to rebuild mine (myself). Parts , mostly aftermarket and some dealer and some not available costs over $200 and more than a month down time. If i knew this then i would try a 450 carb. How about those Edelbrook pumper's ???

anyone.....?